U.S. patent application number 11/664490 was filed with the patent office on 2008-03-20 for hot-dip galvanized sheet and method for manufacturing same.
This patent application is currently assigned to JFE STEEL CORPORATION. Invention is credited to Hisanori Ando, Yusuke Fushiwaki, Takashi Kawano, Yoshitsugu Suzuki, Masahiko Tada, Yoichi Tobiyama.
Application Number | 20080070060 11/664490 |
Document ID | / |
Family ID | 36142790 |
Filed Date | 2008-03-20 |
United States Patent
Application |
20080070060 |
Kind Code |
A1 |
Suzuki; Yoshitsugu ; et
al. |
March 20, 2008 |
Hot-Dip Galvanized Sheet and Method for Manufacturing Same
Abstract
The hot-dip galvanized steel sheet has: a steel sheet containing
0.1 to 3.0% of Si by mass; a hot-dip galvanizing layer; and a
segregated layer, being placed between the steel sheet and the
hot-dip galvanizing layer, having a thickness in a range from 0.01
to 100 .mu.m; containing an oxide containing Si, and being composed
of at least one component selected from the group consisting of S,
C, Cl, Na, K, B, P, F, and N. The hot-dip galvanized steel sheet
shows beautiful surface appearance without generating non-plating
portion and provides excellent plating adhesion and sliding
property in spite of using a base steel sheet containing a large
quantity of Si. Furthermore, the alloy hot-dip galvanized steel
sheet obtained by allying the hot-dip galvanized plating also has
excellent anti-powdering property.
Inventors: |
Suzuki; Yoshitsugu;
(Okayama, JP) ; Fushiwaki; Yusuke; (Okayama,
JP) ; Tada; Masahiko; (Hiroshima, JP) ;
Tobiyama; Yoichi; (Hiroshima, JP) ; Ando;
Hisanori; (Kagawa, JP) ; Kawano; Takashi;
(Hiroshima, JP) |
Correspondence
Address: |
FRISHAUF, HOLTZ, GOODMAN & CHICK, PC
220 Fifth Avenue
16TH Floor
NEW YORK
NY
10001-7708
US
|
Assignee: |
JFE STEEL CORPORATION
2-3 UCHISAIWAI-CHI 2-CHOME
CHIYODA-KU TOKYO JAPAN
JP
100-0011
|
Family ID: |
36142790 |
Appl. No.: |
11/664490 |
Filed: |
October 7, 2005 |
PCT Filed: |
October 7, 2005 |
PCT NO: |
PCT/JP05/18904 |
371 Date: |
April 2, 2007 |
Current U.S.
Class: |
428/659 ;
427/433 |
Current CPC
Class: |
C23C 2/06 20130101; C23C
2/02 20130101; Y10T 428/12799 20150115 |
Class at
Publication: |
428/659 ;
427/433 |
International
Class: |
C23C 2/02 20060101
C23C002/02; C23C 2/06 20060101 C23C002/06 |
Foreign Application Data
Date |
Code |
Application Number |
Oct 7, 2004 |
JP |
2004-294706 |
Mar 31, 2005 |
JP |
2005-101781 |
Jul 8, 2005 |
JP |
2005-200343 |
Claims
1. A hot-dip galvanized steel sheet comprising: a steel sheet
containing 0.1 to 3.0% Si by mass; a hot-dip galvanizing layer; a
segregated layer, being placed between the steel sheet and the
hot-dip galvanizing layer, having a thickness in a range from 0.01
to 100 .mu.m; containing an oxide containing Si, and being composed
of at least one component selected from the group consisting of S,
C, Cl, Na, K, B, P, F, and N.
2. The hot-dip galvanized steel sheet according to claim 1, wherein
the concentration of the component in the segregated layer is
higher than the concentration of the component in the steel sheet
by 10% or more.
3. The hot-dip galvanized steel sheet according to claim 1, wherein
the quantity of the oxide containing the Si in the segregated layer
is in a range from 0.01 to 1 g/m.sup.2 as oxygen.
4. The hot-dip galvanized steel sheet according to claim 1, further
comprising an Fe layer below the hot-dip galvanizing layer.
5. The hot-dip galvanized steel sheet according to claim 1, wherein
the segregated layer is formed by a dispersed compound of the
component and a component of the steel sheet.
6. The hot-dip galvanized steel sheet according to claim 5, wherein
the component is S, the quantity of MnS in a particle shape having
50 nm or larger particle size as the compound is five or more
particles per 20 .mu.m of length on an arbitrary cross section in
parallel with the interface between the hot-dip galvanizing layer
and the steel sheet.
7. The hot-dip galvanized steel sheet according to claim 1, wherein
the hot-dip galvanizing layer is an alloyed hot-dip galvanizing
layer.
8. A method for manufacturing hot-dip galvanized steel sheet
comprising the steps of: adhering at least one substance selected
from the group consisting of S, C, Cl, Na, K, B, P, F, N, and a
compound thereof onto a surface of a steel sheet containing 0.1 to
3% Si by mass; heating the steel sheet after adhering the substance
thereon to form an oxide film containing 70% by mass or less of
hematite on the surface of the steel sheet; reducing the oxide
film; and hot-dip galvanizing the reduced steel sheet.
9. The method for manufacturing hot-dip galvanized steel sheet
according to claim 8, wherein the step of heating is conducted in
an oxidizing atmosphere for Fe at above 500.degree. C. of the
ultimate temperature of the steel sheet.
10. The method for manufacturing hot-dip galvanized steel sheet
according to claim 8, further comprising the step of alloying after
the step of hot-dip galvanizing.
11. A method for manufacturing hot-dip galvanized steel sheet
comprising the steps of: preparing a steel sheet containing 0.1 to
3% Si by mass as the base material; forming an oxide film
containing 70% by mass or less of hematite on a surface of the base
steel sheet before applying hot-dip galvanizing on the surface of
the steel sheet; applying reducing treatment to the steel sheet;
and applying hot-dip galvanizing thereto.
12. The method for manufacturing hot-dip galvanized steel sheet
according to claim 9, further comprising the step of alloying after
the step of hot-dip galvanizing.
13. The hot-dip galvanized steel sheet according to claim 2,
wherein the hot-dip galvanizing layer is an alloyed hot-dip
galvanizing layer.
14. The hot-dip galvanized steel sheet according to claim 3,
wherein the hot-dip galvanizing layer is an alloyed hot-dip
galvanizing layer.
15. The hot-dip galvanized steel sheet according to claim 4,
wherein the hot-dip galvanizing layer is an alloyed hot-dip
galvanizing layer.
16. The hot-dip galvanized steel sheet according to claim 5,
wherein the hot-dip galvanizing layer is an alloyed hot-dip
galvanizing layer.
17. The hot-dip galvanized steel sheet according to claim 6,
wherein the hot-dip galvanizing layer is an alloyed hot-dip
galvanizing layer.
Description
TECHNICAL FIELD
[0001] The present invention relates to a hot-dip galvanized steel
sheet suitable for the fields of automobile, building materials,
household electric appliances, and the like, and to a method for
manufacturing thereof, specifically relates to a hot-dip galvanized
steel sheet having excellent plating adhesion and sliding property
manufactured from a steel containing a large quantity of Si as the
base material, and further relates to an alloyed hot-dip
galvanizing prepared by alloying the hot-dip galvanized steel
sheet.
BACKGROUND ART
[0002] In recent years, varieties of fields including automobile,
building materials, and household electric appliances adopt
surface-treated steel sheets prepared by providing a base material
of steel sheet with rust-preventive property. As of these, there
are specifically adopted hot-dip galvanized steel sheets which are
manufactured at a low cost and which show excellent rust-preventive
property, and alloyed hot-dip galvanized steel sheet prepared by
alloying them.
[0003] Generally the hot-dip galvanized steel sheets are
manufactured by the following process. That is, a slab is
hot-rolled, and further is cold-rolled and heat-treated to form a
thin steel sheet. The surface of thus prepared thin steel sheet is
subjected to a pretreatment to apply degreasing and/or pickling to
clean the surface thereof, or is supplied to a preheating furnace,
without applying the pretreatment, to remove the oil on the surface
of the thin steel sheet by combustion, and then is subjected to
recrystallization annealing in a non-oxidizing atmosphere or in a
reducing atmosphere, thereby obtaining a substrate steel sheet for
plating. After that, the substrate steel sheet is cooled to a
temperature suitable for the plating in a non-oxidizing atmosphere
or a reducing atmosphere, followed by immersing the substrate steel
sheet in a molten zinc bath containing a trace quantity of Al,
(normally about 0.1 to about 0.2% by mass), without exposing to
air, thereby obtaining the hot-dip galvanized steel sheet. The
alloyed hot-dip galvanized steel sheet is manufactured by
succeeding heat-treatment of the hot-dip galvanized steel sheet in
an alloying furnace.
[0004] To attain both the decrease in thickness (decrease in
weight) and the increase in strength of the steel sheets, the
substrate steel sheets in recent years are designed to increase the
strength. Accordingly, there is increasing the consumption of high
strength hot-dip galvanized steel sheets which also have the
rust-preventive property by applying hot-dip galvanizing to the
substrate steel sheets.
[0005] As a means to increase the strength of the steel sheets, a
solid solution strengthening element such as Si, Mn, and P is added
to the steel. Specifically, since Si provides the steel with high
strength without deteriorating the ductility, the Si-containing
steel sheets are expected as the promised high strength steel
sheets.
[0006] However, the hot-dip galvanized steel sheets and the alloyed
hot-dip galvanized steel sheets prepared from the substrates of
Si-containing high strength steel sheets have problems described
below.
[0007] As described above, the substrate steel sheets for hot-dip
galvanizing are subjected to annealing at temperatures in an
approximate range from 600.degree. C. to 900.degree. C. in a
reducing atmosphere, followed by hot-dip galvanizing. Since,
however, the Si in the steel is an element of being readily
oxidized, the Si is selectively oxidized on the surface of the
steel sheet to form an oxide even in a commonly applied reducing
atmosphere, thereby segregating the Si oxide to the surface of the
substrate steel. That type of Si oxide deteriorates the wettability
with the molten zinc during the plating treatment, thus inducing
the generation of non-plating portions. Consequently, increase in
the Si concentration in the steel aiming to increase the strength
decreases the wettability, which induces the generation of many
non-plating portions. Even when the non-plating portion does not
appear, there is a problem of deteriorating the plating
adhesion.
[0008] Furthermore, if the Si in the steel is selectively oxidized
on the surface of the steel sheet, and if the oxidized Si
segregates to the surface, the Si oxide hinders the alloying
reaction between Zn and Fe, thereby significantly delaying the
alloying in the alloying step after the hot-dip galvanizing. As a
result, the productivity is significantly deteriorated. On the
other hand, if the alloying treatment is given at further high
temperatures to assure the productivity, powdering caused by the
excess-alloying likely occurs. As a result, it is difficult to
attain both the high productivity and the good anti-powdering
property at a time in the related art.
[0009] To those problems, there are proposed several means.
[0010] For example, Japanese Patent No. 2587724 proposes a method
for improving the wettability with molten zinc by heating a steel
sheet in an oxidizing atmosphere to form an iron oxide on the
surface of the steel sheet, in advance, then by conducting
reduction-annealing.
[0011] The proposed technology is to suppress the surface
segregation of Si in the reduction-annealing step by forming the
iron oxide on the surface of the steel sheet. As widely known,
however, the oxidation rate of iron on the surface of steel sheet
significantly decreases with increase in the Si concentration in
the steel. For example, for a steel sheet containing 0.1% by mass
or more of Si, sole oxidizing means disclosed in the patent cannot
fully progress the oxidation of the iron, and it is difficult to
attain a necessary quantity of iron oxide to suppress the surface
segregation of Si.
[0012] As a result, the occurrence of non-plating portion during
the hot-dip galvanization cannot fully be suppressed. In addition,
when that hot-dip galvanizing layer is alloyed, the problem of
significant delay of alloying which is expected to occur in the
alloying step cannot fully be solved.
[0013] If the alloying rate is small, the alloying temperature has
to be increased to keep a specified productivity in a CGL which has
a limited length of the alloying furnace. If, however, the alloying
is conducted at elevated temperatures, the anti-powdering property
is unavoidably deteriorated.
[0014] In addition, if the suppression of surface segregation of Si
in the reduction-annealing step is insufficient, the homogeneity of
alloying reaction of Zn and Fe is significantly deteriorated.
Consequently, the plating surface gives significant irregularities
on the Zn--Fe alloy layer caused by the non-homogeneous alloying
reaction, which then significantly deteriorates the sliding
property in the press-forming step.
[0015] For example, according to JP-A-11-50223, (the term "JP-A"
referred to herein signifies the "Unexamined Japanese Patent
Publication"), sulfur or a sulfur compound is adhered to the steel
sheet in a quantity ranging from 0.1 to 1000 mg/m.sup.2 as S before
the hot-dip plating step, then the preheating step is applied to
the steel sheet in a weak oxidizing atmosphere, followed by
annealing the steel sheet in a non-oxidizing atmosphere containing
hydrogen.
[0016] Furthermore, JP-A-2001-279410 discloses a technology in
which an ammonium salt containing S is adhered in a quantity from
0.1 to 1000 mg/m.sup.2 as S to the surface of a high tensile steel
sheet containing Mn, P, and Si, followed by applying heat
treatment, thus letting the S component diffuse into the ground
metal of the steel sheet, thereby forming a sulfur compound such as
MnS, which is the product of reaction with Mn in the steel. The
method suppresses the surface segregation of Mn and shuts off the
diffusion passage of Si to the surface of the steel sheet owing to
the existence of the sulfur-segregated layer, thereby suppressing
the surface segregation of Si.
[0017] Those technologies aim to improve the wettability with the
molten zinc using a sulfide layer formed on the surface of steel
sheet. However, the inventors of the present invention applied
these technologies to steel sheets containing a large quantity of
Si, and found that the sole effect of the sulfide layer cannot
fully suppress the surface segregation of Si. Consequently, similar
to the above-description, these technologies could not solve the
problems of the performance of plating layer. Furthermore, the
preheating step given in a weak oxidizing atmosphere could not
solve the problems of anti-powdering property and sliding property,
similar to above, when these technologies were applied to steel
sheets containing a large quantity of Si.
[0018] In addition, since these technologies are to adhere sulfur
or a sulfur compound onto the surface of steel sheet before the
heat treatment, the succeeding heat treatment step emits large
quantities of sulfur components as corrosive gases such as sulfur
dioxide and hydrogen sulfide in the heating furnace. As a result,
the corrosion damage of the heating furnace body and the
intrafurnace apparatuses becomes significant, which requires
frequent repair and renewal of deteriorated parts, and further
requires to install a desulfurization apparatus in case of venting
the furnace gas to atmosphere from the point of air pollution
prevention. Therefore, practical application of these technologies
in manufacturing lines needs further improvement.
[0019] The present invention has been perfected to cope with the
above situations, and an object of the present invention is to
provide a hot-dip galvanized steel sheet that has excellent plating
adhesion and sliding property to sufficiently endure as the steel
sheet for automobile that requests specifically severe plating
characteristics even with a substrate steel sheet containing a
large quantity of Si, and to provide a method for manufacturing the
hot-dip galvanized steel sheet. Another object of the present
invention is to provide an alloyed hot-dip galvanized steel sheet
also having excellent anti-powdering property.
DISCLOSURE OF THE INVENTION
[0020] The present invention provides a hot-dip galvanized steel
sheet having: a steel sheet containing 0.1 to 3.0% of Si by mass; a
hot-dip galvanizing layer; and a segregated layer, being placed
between the steel sheet and the hot-dip galvanizing layer, having a
thickness in a range from 0.01 to 100 .mu.m, containing an oxide
containing Si, and being composed of at least one component
selected from the group consisting of S, C, Cl, Na, K, B, P, F, and
N.
[0021] For the hot-dip galvanized steel sheet, the concentration of
the component in the segregated layer is preferably higher than the
concentration of the component in the steel sheet by 10% or
more.
[0022] For these hot-dip galvanized steel sheets, the quantity of
the oxide containing the Si in the segregated layer is preferably
in a range from 0.01 to 1 g/m as oxygen.
[0023] For any of these hot-dip galvanized steel sheets, an Fe
layer preferably exists below the hot-dip galvanizing layer.
[0024] For any of these hot-dip galvanized steel sheets, the
segregated layer is preferably formed by a dispersed compound of
the component and a component of the steel sheet. In particular, it
is more preferable that the component is S, and that the quantity
of MnS in a particle shape, having 50 nm or larger particle size as
the oxide is five particles or more per 20 .mu.m of length on an
arbitrary cross section in parallel with the interface between the
hot-dip galvanizing layer and the steel sheet.
[0025] For any of these hot-dip galvanized steel sheets, the
hot-dip galvanizing layer is preferably an alloyed hot-dip
galvanizing layer.
[0026] Furthermore, the present invention provides a method for
manufacturing hot-dip galvanized steel sheet having the steps of:
adhering at least one substance selected from the group consisting
of S, C, Cl, Na, K, B, P, F, N, and a compound thereof onto a
surface of a steel sheet containing 0.1 to 3% Si by mass; heating
the steel sheet after adhering the substance thereon to form an
oxide film containing 70% by mass or less of hematite; reducing the
oxide film; and hot-dip galvanizing the reduced steel sheet.
[0027] For the method for manufacturing hot-dip galvanized steel
sheet, the step of heating is preferably conducted in an oxidizing
atmosphere for Fe at above 500.degree. C. of the ultimate
temperature of the steel sheet.
[0028] For any of the above methods for manufacturing hot-dip
galvanized steel sheet, it is preferable to further apply the step
of alloying after the step of hot-dip galvanizing.
[0029] The present invention provides a method for manufacturing
hot-dip galvanized steel sheet having the steps of: preparing a
steel sheet containing 0.1 to 3% Si by mass as the substrate;
forming an oxide film containing 70% by mass or less of hematite on
the surface of the substrate steel sheet before applying hot-dip
galvanizing onto the surface of the steel sheet; applying reducing
treatment to the steel sheet; and applying hot-dip galvanizing.
BRIEF DESCRIPTION OF THE DRAWINGS
[0030] FIG. 1 is a graph illustrating an example of depth profile
of a cross section of an alloyed hot-dip galvanized steel sheet,
drawn by the linear analysis of EPMA.
[0031] FIG. 2 is a graph illustrating an example of depth profile
of a surface layer of an alloyed hot-dip galvanized steel sheet,
drawn by GDS.
BEST MODE FOR CARRYING OUT THE INVENTION
[0032] The present invention is described in detail in the
following.
[0033] To solve the above problems, the inventors of the present
invention carried out detail studies, and found the following. To
prevent the segregation of Si in the steel to the surface thereof,
a segregated layer for a specified element is formed below the
hot-dip galvanizing layer, and an oxide containing Si is formed in
the segregated layer, thereby drastically improving the adhesion of
the hot-dip galvanizing layer even with a steel sheet containing a
large quantity of Si. Furthermore, by the existence of that oxide
containing Si and of that segregated layer for the specified
element, the homogeneous alloying is enhanced, and the formation of
irregular plating layer is suppressed to attain a smooth plating
surface, thereby significantly improving the sliding property.
[0034] For a means to suppress the generation of non-plating
portion and to enhance the plating adhesion and the alloying on the
steel sheet containing 0.1% or more of Si by mass, the inventors of
the present invention conducted detail studies, and derived a
conclusion that, for a steel sheet containing a large quantity of
Si, simple enhancement of oxidation to form a sufficient quantity
of iron oxide cannot fully improve the wettability with molten
zinc, and cannot fully suppress the generation of non-plating
portion.
[0035] To this point, the inventors of the present invention gave
further studies, and found that it is important to form a
sufficient quantity of iron oxide and further to specify the
composition of the iron oxide. That is, for a steel sheet
containing a large quantity of Si, it was found that the above
objects are achieved by controlling the composition of the iron
oxide being formed on the surface of the steel sheet when the sheet
is oxidized, thus the present invention has been perfected.
[0036] That is, the inventors of the present invention provides a
method for manufacturing hot-dip galvanized steel sheet having the
steps of: adhering at least one substance selected from the group
consisting of S, C, Cl, Na, K, B, P, F, N, and a compound thereof
onto a surface of a steel sheet containing 0.1 to 3% Si by mass;
heating the steel-sheet after adhering the substance thereon to
form an oxide film containing 70% by mass or less of hematite;
reducing the oxide film; and hot-dip galvanizing the reduced steel
sheet.
[0037] The description begins with the composition of the base
sheet for plating, (substrate steel sheet), according to the
present invention.
[0038] The present invention specifies the Si content in the
substrate steel sheet to a range from 0.1 to 3.0% by mass because
that level of Si quantity is necessary to increase the strength of
the steel sheet, though a steel containing a large quantity of Si
as the substrate steel sheet raises problems of plating adhesion
and sliding property, and because the existence of Si in the
substrate is necessary to form the above-described oxide containing
Si. If the Si content in the steel is less than 0.1% by mass, the
above-described oxide containing Si cannot fully be formed below
the plating layer, which fails to attain the effect of the present
invention.
[0039] According to the present invention, there is no specific
limitation on the elements other than Si, and known component
systems can be applied. Typical components are the following.
[0040] C, 0.5% by mass or less
[0041] Carbon is an element existing in steel, normally existing in
a range from 0.0001 to 0.5% by mass. The present invention accepts
that range of C content in the substrate steel sheet. Carbon is
useful not only for the strengthening of steel but also for the
structural control such as forming a residual austenite to improve
the balance between strength and ductility. A preferred C content
to realize these effects is 0.05% by mass or more. On the other
hand, the C content of 0.25% by mass or less is preferred to also
give superior weldability.
[0042] Mn: 5% by mass or less
[0043] Manganese is useful for strengthening steel, and the
substrate steel sheet may contain Mn by 5% by mass or less.
Specifically, the Mn content of 0.1% by mass or more, preferably
0.5% by mass or more, performs the effect significantly. Similar to
Si, the Mn is an element to form an oxide film in the annealing
step, and the Mn content of 3.0% by mass or less tends to improve
the plating adhesion on forming the segregated layer for a
specified element and on forming the oxide containing Si below the
plating layer, and furthermore is preferable for assuring
weldability and the balance between strength and ductility.
Accordingly, the Mn content is preferably specified to 3.0% by mass
or less, and more preferably in a range from 0.5 to 3.0% by
mass.
[0044] Al: 5.0% by mass or less
[0045] Aluminum is an element added together with Si as a
supplemental additive. A preferable content of Al is 0.01% by mass
or more. On the other hand, 5.0% by mass or less of Al content
tends to improve the plating adhesion on forming the segregated
layer for a specified element and on forming the oxide containing
Si below the plating layer, and furthermore is preferable for
assuring weldability and the balance between strength and
ductility. Accordingly, the Al content is preferably specified to
5.0% by mass or less, and more preferably in a range from 0.01 to
3.0% by mass.
[0046] Elements in steel other than those given above include Ti,
Nb, V, Cr, S, Mo, Cu, Ni, B, Ca, N, P, and Sb. The confirmed
content ranges of these elements to attain the effect of the
present invention are: up to 1% by mass for Ti, up to 1% by mass
for Nb, up to 1% by mass for V, up to 3% by mass for Cr, up to 0.1%
by mass for S, up to 1% by mass for Mo, up to 3% by mass for Cu, up
to 3% by mass for Ni, up to 0.1% by mass for B, up to 0.1% by mass
for Ca, up to 0.1% by mass for N, up to 1% by mass for P, and up to
0.5% by mass for Sb.
[0047] One or more of the elements selected from the above group
may be added within a range of 5% by mass or less as the sum of
them. Balance is Fe and inevitable impurities.
[0048] According to the present invention, before the annealing
step in the CGL (continuous galvanizing line), at least one
substance selected from the group consisting of S, C, Cl, Na, K, B,
P, F, N, and a compound thereof is adhered to the surface of the
above steel sheet (substrate steel sheet).
[0049] Examples of those substances are:
[0050] a compound containing P, such as phosphoric acid
(H.sub.3PO.sub.4), potassium phosphate (K.sub.3PO.sub.4), ammonium
phosphate ((NH.sub.4).sub.3PO.sub.4), sodium phosphate
(Na.sub.3PO.sub.4), sodium hydrogenphosphate (Na.sub.2HPO.sub.4),
iron phosphate (FePO.sub.4), phosphonic acid (H.sub.3PO.sub.3), and
phosphinic acid (H.sub.3PO.sub.2);
[0051] a compound containing Na, such as sodium hydroxide (NaOH),
sodium sulfate (Na.sub.2SO.sub.4), sodium sulfide (Na.sub.2S),
sodium thiosulfate (Na.sub.2S.sub.2O.sub.3), sodium chloride
(NaCl), sodium carbonate (Na.sub.2CO.sub.3), sodium citrate
(Na.sub.2C.sub.6H.sub.5O.sub.7), sodium cyanate (NaCNO), sodium
acetate (CH.sub.3COONa), sodium hydrogenphosphate
(Na.sub.2HPO.sub.4), sodium phosphate (Na.sub.3PO.sub.4), sodium
fluoride (NaF), sodium hydrogencarbonate (NaHCO.sub.3), sodium
nitrate (NaNO.sub.3), sodium oxalate ((COONa).sub.2), sodium
tetraborate (Na.sub.2B.sub.4O.sub.7), and sodium oxide
(Na.sub.2O);
[0052] a compound containing K, such as potassium hydroxide (KOH),
potassium acetate (CH.sub.3COOK), potassium borate
(K.sub.2B.sub.4O.sub.7), potassium carbonate (K.sub.2CO.sub.3),
potassium chloride (KCl), potassium cyanate (KCNO), potassium
hydrogencitrate (KH.sub.2C.sub.6H.sub.5O.sub.7), potassium fluoride
(KF), potassium molybdate (K.sub.2MoO.sub.4), potassium nitrate
(KNO.sub.3); potassium permanganate (KMnO.sub.4), potassium
phosphate (K.sub.3PO.sub.4), potassium sulfate (K.sub.2SO.sub.4),
potassium thiocyanate (KSCN), and potassium oxalate
((COOK).sub.2);
[0053] a compound containing Cl, such as hydrochloric acid (HCl),
sodium chloride (NaCl), ammonium chloride (NH.sub.4Cl), antimony
chloride (SbCl.sub.3), potassium chloride (KCl), iron chloride
(FeCl.sub.2, FeCl.sub.3), titanium chloride (TiCl.sub.4), copper
chloride (CuCl), barium chloride (BaCl.sub.2), molybdenum chloride
(MoCl.sub.5), and sodium chlorate (NaClO.sub.3);
[0054] a compound containing S, such as sulfuric acid
(H.sub.2SO.sub.4), sodium sulfate (Na.sub.2SO.sub.4), sodium
sulfite (Na.sub.2SO.sub.3), sodium sulfide (Na.sub.2S), ammonium
sulfate ((NH.sub.4).sub.2SO.sub.4), ammonium sulfide
((NH.sub.4).sub.2S), sodium thiosulfate (Na.sub.2S.sub.2O.sub.3),
sodium hydrogensulfate (NaHSO.sub.4), ammonium hydrogensulfate
(NH.sub.4HSQ.sub.4), potassium sulfate (K.sub.2SO.sub.4), iron
sulfate (FeSO.sub.4, Fe.sub.2(SO.sub.4).sub.3), ammonium
ironsulfate (Fe(NH.sub.4).sub.2(SO.sub.4).sub.2,
FeNH.sub.4(SO.sub.4).sub.2), barium sulfate (BaSO.sub.4), antimony
sulfate (Sb.sub.2S.sub.3), ironsulfate (FeS), thiourea
(H.sub.2NCSNH.sub.2), thiourea dioxide ((NH.sub.4).sub.2CSO.sub.2),
a thiophenic acid salt having SCH group, and a thiocyanic acid salt
having SCN group;
[0055] a compound containing F, such as antimony fluoride
(SbF.sub.3), ammonium fluoride (NH.sub.4F), potassium fluoride
(KF), ammonium hydrogenfluoride (NH.sub.4HF.sub.2), hydrofluoric
acid (HF), sodium fluoride (NaF), barium fluoride (BaF), and cobalt
fluoride (CoF.sub.3);
[0056] a compound containing B, such as boric acid
(H.sub.3BO.sub.3), potassium borate (K.sub.2B.sub.4O.sub.7), sodium
tetraborate (Na.sub.2B.sub.4O.sub.7), lead borate
(Pb(BO.sub.2).sub.2), and manganese borate
(MnH.sub.4(BO.sub.3).sub.2); and
[0057] a compound containing C and N, such as oxalic acid, an
oxalic acid salt, citric acid, a citric acid salt, nitric acid, and
a nitric acid salt.
[0058] The method to adhere the above substances to the steel sheet
is not specifically limited, and a method of physical adhesion of
them may be applied, such as a method of immersing the steel sheet
in an aqueous or organic solvent solution or suspension of the
substance, a method of spraying that solution or suspension, and a
method of coating thereof using a roll coater and the like.
Succeeding step of drying the adhered compound does not affect the
effect of the present invention. Alternatively, direct coating of
the compound also provides similar effect to above.
[0059] It is possible that, before adhering the above substance,
conventional pretreatment such as electrolytic degreasing and
pickling is applied, at need. Even when the pretreatment is given
after adhering the above substance, the effect of the present
invention is attained if only the substance is adhered to the steel
sheet. Furthermore, a rolling oil containing the above compound may
be used to adhere the compound to the steel sheet in the rolling
step.
[0060] For any of above methods, it is important to adhere the
above substance to the surface of the steel sheet during oxidizing
the steel sheet.
[0061] A preferable range of the coating weight of the above
substance is from 0.01 to 1000 mg/m.sup.2 as the sum of the
substances, converted to the quantity of elements specified in the
present invention, (hereinafter referred to also as the "quantity
of specified element"), because that range is easy for controlling
the hematite content to 70% by mass or less, and because the
segregated layer is easily formed below the plating layer if the
quantity of specified element is 0.01 mg/m.sup.2 or more. The
quantity of specified element is specified to 1000 mg/m.sup.2 or
less rather because of economical advantage than because of the
effect of the present invention.
[0062] An applicable method for quantitatively determining the
substance adhered to the steel sheet is a wet-system analysis. That
is, the quantity of the adhered substance is readily determined by
subtracting the quantity of specified element in the substrate
steel sheet from the total amount of the specified element
(including the substance) in the substrate steel sheet.
[0063] According to the present invention, an oxide film containing
hematite in a quantity of 70% by mass or less is formed on the
surface of the steel sheet by heating the steel sheet, on which
steel sheet at least one substance selected from the group
consisting of above S, C, Cl, Na, K, B, P, F, N, and a compound
thereof is adhered, in advance.
[0064] For example, the oxide film is readily formed by heating the
steel sheet with the adhered above substance. The difference in the
oxidizing means does not affect the effect of the present
invention, and any means can be adopted if only the means oxidizes
the steel sheet.
[0065] The heating means is not specifically limited, and
conventional heating means such as burner heating, induction
heating, radiation heating, and electric heating may be applied.
For example, the burner heating method can use a conventional
heating furnace such as oxidizing furnace and non-oxidizing
furnace.
[0066] For the case of non-oxidizing furnace, the steel sheet is
readily oxidized by selecting the air-fuel ratio of the
direct-firing burner to larger than 1.0, for example.
[0067] The oxidation is preferably conducted in an oxidizing
atmosphere. For the cases of induction heating method, radiation
heating method, and electric heating method, the steel sheet is
readily oxidized by adjusting the atmosphere in the vicinity of the
heating steel sheet to an oxidizing atmosphere. Although common
oxidizing atmosphere is the one containing at least one of
oxidizing gases such as oxygen, steam, and carbon dioxide, the
atmosphere is not necessarily limited if only it oxidizes the steel
sheet.
[0068] The above description gives typical examples, and any means
may be applicable if only it oxidizes the steel sheet, thus the
means is not specifically limited.
[0069] The description given below is the reason why the hematite
content can be controlled to 70% by mass or less by adhering at
least one substance selected from the group consisting of S, C, Cl,
Na, K, B, P, F, N, and a compound thereof to the surface of the
steel sheet.
[0070] For a steel sheet in which the Si content is high, the
conventional oxidation means allows the Si in the steel to
segregate to the interface between the iron oxide and the substrate
steel sheet, thereby forming a layered and dense film of Si oxide.
Since the layered Si oxide hinders the Fe diffusion from the
substrate, the oxidation of iron at surface of the steel sheet is
significantly suppressed so that there is formed an iron oxide
containing a large quantity of hematite (Fe.sub.2O.sub.3) which is
an oxide of a type of excess metallic ion (n-type).
[0071] On the other hand, if the substance is adhered to the
surface of the steel sheet, the formation of Si oxide at the
interface between the iron oxide and the substrate steel sheet is
hindered, thereby allowing easy Fe diffusion from the substrate. As
a result, the iron is easily oxidized at surface of the steel
sheet, thus allowing formation of an iron oxide containing a large
quantity of magnetite (Fe.sub.3O.sub.4) and wuestite (FeO) which
are the metallic ion deficient type (p-type), thereby allowing
decreasing the hematite content.
[0072] According to the present invention, when oxidation is
applied to the steel sheet to which at least one substance selected
from the group consisting of S, C, Cl, Na, K, B, P, F, N, and a
compound thereof is adhered, the heating is preferably conducted in
an oxidizing atmosphere giving an ultimate temperature of above
500.degree. C. The ultimate temperature is determined by observing
the surface of the steel sheet using, for example, a radiation
thermometer or a contact thermometer. If the heating temperature is
above 500.degree. C., the hematite content in the oxide film is
easily controlled to 70% by mass or smaller, and the surface
segregation of Si is suppressed, thereby improving the wettability
with molten zinc. Although the upper limit of the heating
temperature is not specifically limited, there is an economical and
practical upper limit, at or lower than the steel sheet temperature
required to the succeeding reducing treatment, or, for example, in
an approximate range from 750.degree. C. to 800.degree. C.
[0073] Generally, when the steel sheet is oxidized, an oxide film
composed of wuestite (FeO), magnetite (Fe.sub.3O.sub.4), and
hematite (Fe.sub.2O.sub.3) is formed. It is known that a steel
sheet containing Si at or higher than 0.1% by mass results in
increased content of hematite in the oxide film, (refer to, for
example, Nisshin Seiko Technical Review No. 77, p. 1, (1998)). By
adjusting the hematite content in the oxide film to 70% by mass or
less, the wettability with molten zinc in the succeeding step is
improved, and the generation of non-plating portion can be
completely prevented. Furthermore, after plating, if the steel
sheet and the hot-dip galvanizing layer are alloyed with each
other, the alloying between the steel sheet and the zinc plating
also becomes easy. If the hematite content exceeds 70% by mass, the
wettability with molten zinc deteriorates, which fails to
completely prevent the generation of non-plating portion. Since the
quantity of hematite in the oxide film is preferably as small as
possible, the hematite content of 0% by mass is naturally
preferable. Ordinarily, however, a preferable range of hematite
content is approximately from 10 to 70% by mass.
[0074] The mechanism of improvement in the wettability with molten
zinc through the adjustment of hematite content in the oxide film
on the steel sheet surface to 70% by mass or less is not fully
analyzed. It is, however, presumed that the composition of the
oxide film affects the behavior of segregation of Si on the surface
of the steel sheet in the succeeding reducing step, and that the
hematite content of 70% by mass or less results in complete
prevention of surface segregation of Si, thus attaining excellent
plating adhesion.
[0075] The term "oxide film" referred to herein does not limit to
the above-described FeO, Fe.sub.3O.sub.4, and Fe.sub.2O.sub.3. Even
when an oxide containing Si and the like which are the additives
for steel exists, the effect of the present invention is not
affected by the additives.
[0076] The determination of hematite content can be done by an
X-ray diffractometry using a rotary vibration sample table, (Cu
tube, 50 kV of tube voltage, and 250 mA of tube current). That is,
the respective powder standard samples of hematite
(Fe.sub.2O.sub.3), magnetite (Fe.sub.3O.sub.4), and wuestite (FeO)
are prepared, and three kinds of samples each having different
mixing rates (% by mass) are prepared for the X-ray diffractometry.
There are determined the diffraction peak intensity (cps) of (104)
plane for hematite (Fe.sub.2O.sub.3), (400) plane for magnetite
(Fe.sub.3O.sub.4), and (200) plane for wuestite (FeO). From these
determined diffraction peak intensities, the relation between the
mixing rate (% by mass) and the diffraction peak intensity (cps) is
derived to draw a working curve. Based on thus drawn working curve
and from the obtained diffraction peak intensity, the hematite
content (% by mass) can be determined.
[0077] The oxide film obtained by the above method is preferably an
iron oxide of 0.01 to 5 g/m.sup.2 as oxygen quantity. The oxygen
quantity of 0.01 g/m.sup.2 allows easy suppression of surface
segregation of Si owing to the sufficient quantity of oxygen. On
the other hand, the oxygen quantity of 5 g/m.sup.2 or less allows
the succeeding step to be conducted easily, and the alloying step
given after the hot-dip galvanizing proceeds with enhanced
alloying.
[0078] An example of the method for determining the quantity of
oxygen in the oxide film is the following. That is, the
determination is readily done by subtracting the quantity of oxygen
in the substrate steel sheet from the total quantity of oxygen in
the hot-dip galvanized steel sheet according to the present
invention, using the wet-system analysis. If a working curve is
drawn in advance, a simplified determination method such as
fluorescent X-ray and GDS are also applicable.
[0079] According to the method to prepare an oxide film containing
70% by mass or more of hematite by adhering at least one substance
selected from the group consisting of S, C, Cl, Na, K, B, P, F, N,
and a compound thereof to the steel sheet, followed by oxidizing
them, the substance is not emitted into the oxidizing atmosphere,
thereby increasing the quantity of the substance entrapped in the
oxide film or in the substrate steel sheet. Consequently, the
method also provides an effect to suppress the entering of toxic
gases into the heating furnace for oxidation treatment and the
entering thereof from the heating furnace to the vent gas.
[0080] Then, according to the present invention, the oxide film
thus formed on the surface of the steel sheet is reduced. The
reducing method is not specifically limited, and a conventional
method can be applied.
[0081] For example, it is a common practice that the reducing
treatment is given in a reducing atmosphere containing hydrogen in
an annealing furnace of radiation heating type at temperatures from
about 600.degree. C. to about 900.degree. C. The method is,
however, not specifically limited, and any method is applicable if
only the method reduces the oxide layer at the surface of the steel
sheet.
[0082] Furthermore, according to the present invention, the
substrate steel sheet thus reduced is immersed in a plating bath to
apply hot-dip galvanization. The hot-dip galvanization may be a
conventional method. For example, the substrate steel sheet is
cooled to a temperature suitable for the plating treatment,
normally, a temperature near the temperature of the plating bath in
a non-oxidizing or reducing atmosphere. The plating bath is
normally prepared at approximate temperatures from 440.degree. C.
to 520.degree. C. with the Al concentration of approximately from
0.1 to 0.2%.
[0083] Depending on the uses of the products, the plating
conditions such as plating temperature and plating bath composition
may be changed. The changes in the plating conditions, however, do
not affect the effect of the present invention, thus these
conditions are not specifically limited. For example, inclusion of
elements such as Pb, Sb, Fe, Mg, Mn, Ni, Ca, Ti, V, Cr, Co, and Sn,
other than Al, in the plating bath does not affect the effect of
the present invention.
[0084] In addition, the method to adjust the thickness of the
plating layer after plating is not specifically limited. Generally
the gas-wiping method is applied. The thickness of the plating
layer is adjusted by adjusting the gas pressure of gas-wiping, the
distance between the wiping nozzle and the steel sheet, and the
like. Although the thickness of the plating layer is not
specifically limited, it is preferably adjusted to a range from
about 3 to about 15 .mu.m because 3 .mu.m or larger thickness gives
sufficient rust-preventive property, and because 15 .mu.m or
smaller thickness is advantageous in view of workability and
economy.
[0085] Furthermore, according to the present invention, alloying
treatment may be given after the above hot-dip galvanization
treatment.
[0086] As described above, the present invention suppresses the
surface segregation of Si in the annealing step, thus the present
invention solves the problem of related art of significant delay of
alloying even in a steel sheet containing a large quantity of Si.
As a result, an alloyed hot-dip galvanized steel sheet having
excellent anti-powdering property can be manufactured without
deteriorating the productivity.
[0087] The alloying treatment may use any of conventional heating
methods such as gas heating, induction heating, and electric
heating, and the method is not specifically limited.
[0088] Consequently, the inventors of the present invention has
developed a process of: adhering at least one substance selected
from the group consisting of S, C, Cl, Na, K, B, P, F, N, and a
compound thereof onto the surface of a substrate steel sheet
containing 0.1 to 3% Si by mass; forming an oxide film by oxidizing
the steel sheet in, preferably, an annealing furnace of CGL;
applying reduction-annealing to the steel sheet to reduce the oxide
film; and then applying hot-dip plating to the steel sheet.
[0089] According to the present invention, by adhering the
substance to the substrate steel sheet before annealing the
substrate steel sheet, or before oxidation thereof, a larger
quantity of iron oxide film is formed than in the related art in
the oxidation step even on a steel sheet containing a large
quantity of Si. Consequently, generation of surface segregation of
Si is effectively suppressed, which Si segregation on the surface
is occurred on the surface of substrate steel sheet after
succeeding reduction-annealing step in the related art. As a
result, when the substrate steel sheet after reduction-annealing
processed by the method of the present invention is subjected to
hot-dip galvanization, a plating layer giving good surface
appearance free from non-plating portion thereon is attained, and a
hot-dip galvanized steel sheet having both excellent plating
adhesion and sliding property is obtained.
[0090] Furthermore, if the above oxidation suppresses the surface
segregation of Si, the adhered substance can enter the surface
layer of the steel sheet by the heat treatment such as oxidation
treatment. As a result, after the hot-dip galvanization or after
the succeeding alloying treatment, there becomes existence of
segregated layer containing at least one component selected from
the group consisting of S, C, Cl, Na, K, B, P, F, and N below the
plating layer.
[0091] The term "segregated layer" referred to herein signifies a
zone in which the concentration of at least one component
(hereinafter referred to also the "segregated component") selected
from the group consisting of S, C, Cl, Na, K, B, P, F, and N is 10%
or higher than the concentration of the component in the substrate
steel sheet.
[0092] That segregated layer is represented as a zone where the
peak intensity appeared in the vicinity of interface is higher by
10% or more than the component intensity in the substrate steel
sheet, which peak intensity is determined by a depth profile of the
segregated component (element) in the depth direction from the
surface of the plated steel sheet using GDS, or determined by a
depth profile derived from the linear analysis of EPMA on a cross
section of the plated steel sheet, as given in the examples.
[0093] The segregated layer is specified to the zone where the peak
intensity of the segregated component appeared in the vicinity of
interface is higher by 10% or more than the component intensity in
the substrate steel sheet because smaller than 10% of increase in
the intensity cannot fully prevent the surface segregation of Si
during the reduction annealing step.
[0094] The determination of the depth profile of the segregated
layer may be done by the linear analysis of cross section using GDS
or EPMA, which are described above. As described below, however,
the segregated layer is preferably the one in which the compound of
the segregated component and the component in the substrate steel
sheet is dispersed, thus the linear analysis by EPMA needs a
special caution. That is, if the compound with the component in the
substrate steel sheet is dispersed, the linear analysis of cross
section by EPMA may analyze a portion of absence of the component.
Accordingly, the linear analysis by EPMA is conducted by the
following procedure. The measurement is given on arbitrary five
positions on a cross section of the steel sheet to determine the
thickness of a zone where the intensity of the segregated component
is higher by 10% or more than the intensity of the component in the
substrate steel sheet, and then the average thickness of the five
observed values is calculated as the thickness of the segregated
layer.
[0095] When the substance according to the present invention is
adhered to the steel sheet, and is subjected to oxidation
treatment, the quantity of the formed iron oxide increases, and the
Si oxide is formed at interface between the iron oxide and the
ground metal and/or within the ground metal. After that, the
succeeding reducing treatment reduces the iron oxide to iron, thus
the Si oxide remains in the ground metal. As a result, after the
succeeding hot-dip galvanizing, a (reduced) iron layer exists below
the plating layer, and the segregated layer containing the oxide
containing Si exists below the (reduced) iron layer.
[0096] The "oxide containing Si" referred to herein essentially
needs the existence of Si and oxygen. Since, however, the oxide
containing Si includes the case of containing an oxide of a steel
component and the case of containing double salt, complex salt, and
the like of the oxide, the oxide containing Si is not limited to
the Si oxide, and the kind is not the limited one. Typical "oxide
containing Si" includes SiO.sub.2, FeSiO.sub.3, Fe.sub.2SiO.sub.4,
MnSiO.sub.3, and a mixture thereof.
[0097] That is, the hot-dip galvanized steel sheet according to the
present invention has: a steel sheet containing 0.1 to 3.0% Si by
mass; a hot-dip galvanizing layer; and a segregated layer between
the steel sheet and the hot-dip galvanizing layer, containing an
oxide containing Si, having a thickness in a range from 0.01 to 100
.mu.m, and containing at least one component selected from the
group consisting of S, C, Cl, Na, K, B, P, F, and N.
[0098] The mechanism that the hot-dip galvanized steel sheet
according to the present invention provides excellent plating
adhesion and sliding property is not fully analyzed. The inventors
of the present invention, however, speculate the mechanism as
follows.
[0099] As in the case of the present invention, when the segregated
layer having the above component is formed on the surface of the
substrate steel sheet, the compatibility between the Fe-Al
intermetallic compound, formed at the interface between the zinc
plating and the steel sheet, and the substrate steel sheet varies
toward advantageous side for the adhesion in the hot-dip
galvanizing step.
[0100] Furthermore, when the segregated layer of the component is
formed on the surface of the substrate steel sheet, the component
is unavoidably eluted into the plating layer in the hot-dip
galvanizing step, and a part of the eluted component comes to exist
in the plating layer in the vicinity of interface with the steel
sheet. The mechanism presumably improves the sliding property
compared with the ordinary hot-dip galvanized steel sheet which
does not contain the segregated layer.
[0101] Furthermore, the mechanism of improving the plating adhesion
and sliding property by the existence of an oxide containing Si in
the segregated layer is speculated as follows.
[0102] When an oxide containing Si exists in the segregated layer,
the shape of interface between the plating layer and the steel
sheet becomes irregular to generate an anchor effect, which anchor
effect improves the adhesion, and the sliding property in the
working step also improves. The anchor effect is the same for both
the hot-dip galvanized steel sheet and the alloyed hot-dip
galvanized steel sheet.
[0103] Accordingly, when the segregated layer of the component is
formed below the plating layer, and when the oxide containing Si is
brought to exist in the segregated layer, the synergy effect of
them drastically improves the adhesion, and also improves the
sliding property.
[0104] The thickness of the segregated layer according to the
present invention is required to be controlled in a range from 0.01
to 100 .mu.m because the thickness of smaller than 0.01 .mu.m
cannot sufficiently attain the effect to improve the adhesion, and
because the thickness of larger than 100 .mu.m deteriorates the
fatigue characteristics. Further preferable range of the thickness
of the segregated layer is from larger than 1 .mu.m to not larger
than 50 .mu.m.
[0105] According to the present invention, the concentration of the
component in the segregated layer is preferably higher by 10% or
more than the concentration of the component in the substrate steel
sheet because that kind of segregated layer makes the surface
segregation of Si sufficiently and easily suppress in the reduction
annealing step.
[0106] That kind of segregated layer is represented as a zone where
the peak intensity appeared in the vicinity of interface is higher
by 10% or more than the intensity of the ground metal, determined
by a depth profile drawn on a cross section of the plated steel
sheet using GDS, or determined by a depth profile derived from the
linear analysis of EPMA, as given in the examples.
[0107] The segregated layer is preferably formed by a dispersed
compound of the segregated component and the component of the
substrate steel sheet. The component in the substrate steel sheet
is expected as, Fe naturally, and as Si, Mn, Ti, Nb, V, Cr, S, Mo,
Cu, Ni, B, Ca, N, P, Sb, and the like. To form the segregated layer
of a desired substance, the formation of a compound with the
component of the substrate steel sheet is expected to more stably
fix the segregated component. According to an analysis, most part
of the compound exists at grain boundaries in the substrate steel
sheet. Therefore, a presumable advantage of the dispersed state of
the compound is that the compound plugs the passage of Si
diffusion, thereby effectively suppressing the surface segregation
of Si in the steel.
[0108] Furthermore, if the compound in the segregated layer is MnS,
the effect of the present invention is more stably attained
because, among the expected compounds, MnS is a very stable
compound in the steel so that MnS is easily formed and easily
controls the manufacturing conditions. To form MnS, when S is
selected as the element to adhere to the steel sheet before the
above-oxidation treatment, the S reacts with Mn in the steel in the
surface layer of the steel sheet, (below the plating layer after
the plating step), during oxidation treatment and reducing
treatment, thereby segregates.
[0109] In that case, a favorable quantity of the formed compound is
five or more of the MnS grains having a grain size of 50 .mu.m or
larger, in an arbitrary cross section, per 20 .mu.m of length in
parallel with the interface between the plating layer and the
substrate steel sheet. The MnS referred to herein means that the
main component is formed by Mn and S, and the inclusion of other
element such as Fe raises no problem.
[0110] Determination and judgment of dispersion and the number of
compound particles can be given by, adding to the SEM observation
or the TEM observation of cross section of the plated steel sheet,
using EDS, electron diffractometry (TED), and the like, at
need.
[0111] The quantity of the oxide containing Si in the segregated
layer is preferably adjusted in a range from 0.01 to 1 g/m.sup.2 as
oxygen. If the quantity of the oxide containing Si is 0.01
g/m.sup.2 or more, the plating adhesion and the sliding property
are significantly improved, and the quantity thereof at 1 g/m.sup.2
or less is economical.
[0112] On determining the oxide, the existence of Si in the oxide
can be confirmed by the EDX analysis of a sample prepared by the
TEM replica method.
[0113] By alloying the above-described hot-dip galvanized steel
sheet according to the present invention, there is obtained an
alloyed hot-dip galvanized steel sheet which can be alloyed at a
low temperature, and which provides not only excellent, plating
adhesion and sliding property but also excellent anti-powdering
property.
[0114] When the conventional hot-dip galvanized steel sheet is
alloyed, a .GAMMA. phase having higher hardness than that of the
substrate steel sheet is formed at the interface between the zinc
plating and the substrate steel sheet, and the deterioration of
plating adhesion is unavoidably occurs caused by the difference in
the hardness between the .GAMMA. phase and the steel sheet. When,
however, the hot-dip galvanized steel sheet according to the
present invention is alloyed, there is existed a segregated layer
of the component below the plating layer so that the mechanical
characteristics in the vicinity of interface between the zinc
plating layer and the substrate steel sheet, specifically the
hardness of the substrate steel sheet, become close to those of the
.GAMMA. phase, thereby effectively decreasing the strain applied to
the interface during the deformation of the substrate steel sheet.
As a result, the plating adhesion presumably improves.
[0115] Since the hot-dip galvanized steel sheet according to the
present invention suppresses the surface segregation of Si in the
annealing step, the alloying is available at relatively low
temperatures. As a result, there is attained a merit of suppressing
the formation of .GAMMA. phase which is not favorable to the
plating adhesion.
[0116] Generally, the sliding property of alloyed hot-dip
galvanized layer appears depending on the variations of alloying
behavior. That is, as described above, the material of
Si-surface-segregated material appeared on the surface of the
substrate steel sheet in the annealing step delays the alloying
rate because the surface-segregated material which is segregated by
the selective oxidation on the surface after annealing suppresses
the alloying reaction between Zn and Fe. As a result, the plating
layer after completing the alloying reaction becomes the one having
significantly irregular surface resulted from the interference of
homogeneous reaction of Zn and Fe. In addition, the alloy crystals
of Zn and Fe become coarse. Owing to the irregular surface of
plating layer and to the coarse crystal grains caused by the
suppression of alloying, the sliding property of the plating layer
deteriorates.
[0117] The hot-dip galvanized steel sheet according to the present
invention, however, contains a segregated layer having the
component below the plating layer, similar to the above case of
adhesion. Thus, compared with the normal cases, the surface
segregation of Si in the annealing step is suppressed, and the
alloying is enhanced. As a result, the reaction between Zn and Fe
proceeds homogeneously, and the plating layer becomes smooth. In
addition, the crystal grains become fine, thereby providing good
sliding property compared with the Si-containing steel manufactured
by the conventional method.
[0118] It was described above that the hot-dip galvanized steel
sheet according to the present invention contains a layer of
(reduced) iron below the plating layer, and further contains the
segregated layer containing an oxide containing Si below the
(reduced) iron layer. When, however, the hot-dip galvanized steel
sheet according to the present invention is subjected to alloying
treatment, naturally the alloying between the zinc plating layer
and the (reduced) iron proceeds. Consequently, the obtained alloyed
hot-dip galvanized steel sheet may fail to identify the iron layer
below the galvanized layer. That type of alloyed hot-dip galvanized
steel sheet, however, is within the range of the present invention
because the steel sheet has the "segregated layer of the component
containing an oxide containing Si" below the plating layer.
EXAMPLES
Example A
[0119] Electrolytic degreasing was conducted on eight types of test
specimens of cold-rolled steel sheets and hot-rolled steel sheets,
given in Table 1, in a solution of 5% NaOH by mass, under the
condition of 5 A/dm.sup.2, 80.degree. C. for 5 seconds. Each of
aqueous solutions containing the respective substances of (a)
phosphoric acid (100 g/l), (b) hydrochloric acid (1 g/l), (c)
sodium fluoride (2g/l), (d) sodium thiosulfate (20 g/l), (e)
Potassium hydroxide (100 g/l), (f), ammonium thiocyanate (50 g/l),
(g) sulfuric acid (50 g/l), (h) ammonium sulfate (30 g/l), (i)
thiourea (20 g/l), (j) sodium sulfate (50 g/l), (k) iron sulfate
(20 g/l), (l) sulfuric acid (10 g/l), (m) ammonium sulfate (5 g/l),
(n) thiourea (1 g/l), and (o) ammonium sulfate (150 g/l), was
applied onto the surface of the respective steel sheets using a
bar-coater at the respective coating weights given in Table 2-1,
Table 3-1, and Table 4-1. After that, the applied aqueous solution
was dried in a drier.
[0120] Thus prepared test specimens were heated in a heating
furnace in an oxidizing atmosphere. Once taken out specimens were
treated by annealing, followed by plating in a hot-dip plating
simulator. The oxidation condition and other conditions are given
in Table 2-1, Table 3-1, and Table 4-1.
[0121] For comparison, annealing and plating were given to the
specimen without applying heating treatment.
[0122] The heating was given in air while varying the ultimate
temperature of the steel sheet. The holding time at the ultimate
temperature was 1 second, and then rapid cooling was applied using
nitrogen gas.
[0123] The annealing was given in an atmosphere of (10% by volume
of hydrogen+nitrogen) of -35.degree. C. of dew point, at
830.degree. C. of the steel sheet temperature and 45 seconds of
holding time.
[0124] The plating was done in a zinc plating bath containing 0.14%
Al by mass (Fe-saturated) at 460.degree. C., with an immersing
sheet temperature of 460.degree. C., and an immersing time of 1
second. The surface appearance after plating was evaluated. After
the plating, the coating weight was adjusted to 45 g/m.sup.2 on one
side using a nitrogen gas wiper.
[0125] For thus prepared hot-dip galvanized steel sheets, the
following-given procedure was applied to determine the thickness of
the segregated component, and the degree of segregation, and to
determine the oxide containing Si below the plating layer, and
further the following-given evaluation criterion was applied to
evaluate the plating appearance and the plating adhesion. The
properties of segregated layer are given in Table 2-2, Table 3-2,
and Table 4-2.
[0126] Furthermore, some of the plated steel sheets were subjected
to alloying treatment, after the plating, in an electric heating
furnace at 40.degree. C./s of temperature-rise rate with 10 seconds
of holding time, thus evaluating the alloying rate based on the
alloying temperature that gives 10.+-.0.5% by mass of the Fe
content in the plating layer. The evaluation criterion is given
later. Using a sample having 10.+-.0.5% by mass of the Fe content
in the plating layer, a 90.degree. bend test was given to evaluate
the anti-powdering property based on the evaluation criterion given
later. Furthermore, the sliding property was evaluated based on the
criterion given later.
[0127] Those evaluation results are shown in Table 2-3, Table 3-3,
and Table 4-3.
[0128] As seen in Tables 2-1 to 4-3, even for the case of using a
substrate steel sheet containing a large quantity of Si, prepared
by adhering a compound containing at least one substance selected
from the group consisting of S, C, Cl, Na, K, B, P, F, N, and a
compound thereof onto the surface of steel sheet, and prepared by
oxidizing the adhered substance to form an oxide film containing
70% by mass or less of hematite, and then by annealing in a
reducing atmosphere, there is obtained excellent anti-powdering
property and sliding property without generating non-plating
portion and without significant delay of alloying. The obtained
hot-dip galvanized steel sheet or alloyed hot-dip galvanized steel
sheet has a segregated layer below the plating layer, and the
segregated layer contains an oxide containing Si. It was confirmed
that the oxide film formed after the oxidation treatment has a
structure of hematite and balance of mainly magnetite and
wuestite.
Example B
[0129] The plated steel sheets were prepared under the same
conditions to those in Example A except that the substance was each
of (o) potassium chloride (50 g/l), (p) ammonium oxalate (100 g/l),
(q) sulfuric acid (50 g/l), (r) sodium hydroxide (30 g/l), and (s)
sodium tetraborate (3 g/l), at the respective coating weights given
in Table 5-1, and the heating condition of (0.1% by volume of
oxygen+nitrogen) atmosphere. Evaluation to them was given on the
same criterion to that of Example A. The properties of the
segregated layer are given in Table 5-2. The evaluation of thus
prepared plated steel sheets is given in Table 5-3.
[0130] As seen in Tables 5-1 to 5-3, for the case of a substrate
steel sheet containing a large quantity of Si, prepared by adhering
the substance onto the surface of steel sheet, and by oxidizing the
adhered substance to form an oxide film containing 70% by mass or
less of hematite, and then by annealing in a reducing atmosphere,
there was obtained excellent anti-powdering property and sliding
property without generating non-plating portion and without
significant delay of alloying. The obtained hot-dip galvanized
steel sheet or alloyed hot-dip galvanized steel sheet has a
segregated layer below the plating layer, and the segregated layer
contains an oxide containing Si. It was confirmed that the oxide
film formed after oxidation treatment has a structure of hematite
and balance of mainly magnetite and wuestite.
Example C
[0131] The plated steel sheets were prepared under the same
conditions to those in Example A except that the substance was each
of (t) antimony chloride (20 g/l), (u) ammonium sulfate (30 g/l),
(v) lead chloride (1 g/l), (w) thiourea (20 g/l), and (x) sodium
chloride (25 g/l), at the respective coating weights given in Table
6-1, and the heating condition of direct-firing burner at 1.15 of
air/fuel ratio. Evaluation to them was given on the same criterion
to that of Example A. The properties of the segregated layer are
given in Table 6-2, and the evaluation results for thus prepared
steel sheets are given in Table 6-3.
[0132] As seen in Tables 6-1 to 6-3, for the case of a substrate
steel sheet containing a large quantity of Si, prepared by adhering
the substance onto the surface of steel sheet, and by oxidizing the
adhered substance to form an oxide film containing 70% by mass or
less of hematite, and then by annealing in a reducing atmosphere,
there was obtained excellent anti-powdering property and sliding
property without generating non-plating portion and without
significant delay of alloying. The obtained hot-dip galvanized
steel sheet or alloyed hot-dip galvanized steel sheet has a
segregated layer below the plating layer, and the segregated layer
contains an oxide containing Si. It was confirmed that the oxide
film formed after oxidation treatment has a structure of hematite
and balance of mainly magnetite and wuestite.
[0133] The criteria for evaluating the plating quality are the
following.
<Determination of the Thickness of Segregated Component and of
the Degree of Segregation>
[0134] To the hot-dip galvanized steel sheet and the alloyed
hot-dip galvanized steel sheet, the linear analysis of EPMA and/or
the GDS measurement were given on their cross sections. Based on
the drawn depth profiles (for example, FIG. 1 and FIG. 2), the
thickness of segregated layer was determined as the thickness of a
zone where the peak intensity of the segregated component (element)
appeared in the vicinity of interface is higher by 10% or more than
the intensity of the component in the ground metal portion, at a
ground metal side from the interface between the plating layer and
the substrate steel sheet. In addition, the increase in the peak
intensity A of the component in the segregated layer to the peak
intensity B of the component in the ground metal is determined as
the degree of segregation. That is, [the degree of segregation
(%)={(the intensity A-the intensity B)/(the intensity
B)}.times.100%]. For the case of the degree of segregation smaller
than 10%, the thickness of the zone where the intensity of the
segregated component in the depth profile becomes slightly higher
than the intensity B of the segregated component in the ground
metal is given in the table as the thickness of the segregated
layer. For the linear analysis of EPMA, the measurement was given
at five arbitrary positions on a cross section of the steel sheet,
and the thickness of the zone where the intensity of the segregated
component is higher than the intensity of the ground metal by 10%
or more was determined. The thickness of the segregated layer and
the degree of segregation were derived by determining the average
thickness and the average peak intensity A for the five measured
values. In the GDS measurement, conversion from the sputtering time
into the thickness of segregated layer was calculated on the basis
of 0.04 .mu.m/sec of the iron sputtering rate under the following
GDS condition.
[0135] (EPMA Measurement Condition)
[0136] Acceleration voltage: 20 kV
[0137] Beam current: 0.05 .mu.A
[0138] (GDS Measurement Condition)
[0139] Tube current: 30 mA
[0140] Argon gas flow volume: 400 ml
<Method for Determining the Oxide Containing Si Below the
Plating Layer>
[0141] To the hot-dip galvanized steel sheet and the alloyed
hot-dip galvanized steel sheet, the plating layer was removed by
dissolving in an alkali solution given below. The oxide quantity
was determined from the difference in the oxygen analysis result
between thus prepared steel sheet and a steel sheet which was
mechanically polished to 100 .mu.m of surface irregularity on both
sides thereof. The existence of Si in the oxide was confirmed by
the EDX analysis on a test specimen prepared by TEM replica
method.
[0142] (Alkali Solution)
[0143] NaOH: 8.2%
[0144] Triethanolamine: 2.1%
[0145] H.sub.2O.sub.2: 1.2%<
Plating Appearance>
[0146] Appearance of thus prepared hot-dip galvanized steel sheet
was observed visually and with a (.times.10) magnifier. The
evaluation was given as "No non-plating portion exists" for the
case of absence of non-plating portion, "Slight non-plating portion
exists" for the case that the (.times.10) magnifier-recognized fine
non-plating portion, and "Non-plating portion exists" for the case
that visual observation recognized non-plating portion.
[0147] .largecircle.: No non-plating portion exists.
[0148] .DELTA.: Slight non-plating portion exists.
[0149] X: Non-plating portion exists.
<Plating Adhesion>
[0150] A ball-impact test was given to thus prepared hot-dip
galvanized steel sheet to evaluate the plating separation on
tape-peeling test. The test was conducted by positioning a hot-dip
galvanized steel sheet on a hemispherical protrusion (1/2 inch of
diameter), and by dropping a 2.8 kg weight onto the steel sheet
from 1 m of height. After that, the tape-peeling test was given on
the convex side.
[0151] .largecircle.: No plating separation occurred.
[0152] X: Plating separation occurred.
<Alloying Rate>
[0153] .largecircle.: Alloying temperature: alloying completed at
500.degree. C. or below.
[0154] X: Alloying temperature: alloying completed at above
500.degree. C.
<Anti-Powdering Property>
[0155] A test specimen (25 mm in width and 40 mm in length) was cut
from the alloy hot-dip galvanized steel sheet, and a scotch tape
(24 mm in width, manufactured by NICHIBAN CO., LTD.) was attached
to the test specimen at 20 mm position in the length thereof. After
bending the taping side by 90.degree. inward, the specimen was
again straightened. The scotch tape was peeled, and the quantity of
Zn grains adhered to the scotch tape was counted under fluorescent
X-ray. The Zn count was converted into the count per unit length of
the test specimen (1 m), and the evaluation was given on the basis
of the following criterion.
[0156] .largecircle.: Good (count: 1 to 5000)
[0157] X: Bad (count: more than 5000)
<Sliding Property Test>
[0158] The sliding property test was given under the following
condition using a tool having a shape described below. From the
ratio of the drawing-out force F to the pressing load P, the
friction factor .mu. was derived by the following formula. The
evaluation was given on the basis of the criterion described below.
.mu.=2P/F
[0159] Face pressure of 9.8 MPa, sliding distance of 100 mm,
sliding rate of 10 mm/s, specimen width of 20 mm, mold of flat tool
(shoulder radius of 5 mm, polished to #1200), contact area with
specimen of 10.times.20 mm, oil-applying condition of NOX-RUST
550KH, 1.0 g/m.sup.2.
[0160] .largecircle.: Good (.mu.: less than 0.12)
[0161] X: Bad (.mu.: 0.12 or more)
Example D
[0162] The plated steel sheet was prepared under the same condition
to that of Example A. The evaluation method was almost the same to
that of Example A. For the anti-powdering property, however, the
evaluation criterion was changed to the following-given one for
evaluating finer differences.
[0163] .circleincircle.: Excellent (count: less than 4000)
[0164] .largecircle.: Good (count: 4000 to 5000)
[0165] X: Bad (count: more than 5000)
[0166] For each of the test specimens, confirmation was given on
the determination of segregated substance in the vicinity of
interface with the plating layer and on the distribution thereof
using SEM and TEM. The analytical samples were prepared from the
test specimens by working the cross section using the focused ion
beam (FIB). The SEM observation determined the size and the number
of the generated compound particles of segregated component, and
the TEM-EDS and the electron beam diffraction determined the
compound. Regarding the evaluation of the number of compound
particles, within a visual field of cross sectional observation by
SEM, the number of compound particles having 50 nm or larger size
existing in the vicinity of interface in a zone of 20 .mu.m in
width in parallel with the interface between the plating layer and
the substrate steel sheet was counted at arbitrarily selected five
positions. The average of the values of these five positions was
adopted as the evaluation index.
[0167] The results are given in Table 7 together with adhered
substance, oxidation treatment, and the properties of segregated
layer.
[0168] As shown in Table 7, among the segregated layers formed
adequately in the vicinity of the interface with the plating layer,
further excellent characteristics are attained specifically
bringing the segregated layer to establish a state of sufficiently
dispersing the compound of the segregated component and the
component in the substrate steel sheet. TABLE-US-00001 TABLE 1
(mass %) Steel Steel type sheet C Si Mn P S Al Other A Cold-rolled
0.002 0.15 1.5 0.07 0.004 0.03 -- B steel sheet 0.1 0.25 2.0 0.05
0.002 0.70 -- C 0.5 0.5 2.0 0.01 0.003 0.04 -- D 0.002 0.75 1.5
0.06 0.007 0.04 -- E 0.1 1.0 3.5 0.01 0.003 0.05 -- F 0.003 1.1 0.3
0.05 0.008 0.02 -- G 0.15 1.5 2.5 0.01 0.003 0.03 -- H 0.1 2.9 1.5
0.01 0.003 0.03 -- I Hot-rolled 0.15 0.3 1.5 0.03 0.005 0.05 -- J
steel sheet 0.1 2.0 1.0 0.10 0.005 0.03 -- K Cold-rolled 0.15 0.5
2.0 0.01 0.003 0.04 Ti: 0.02 L steel sheet 0.1 0.25 1.6 0.05 0.002
0.30 Nb: 0.03 M 0.002 0.25 1.5 0.07 0.004 0.03 V: 0.03 N 0.08 0.5
2.0 0.01 0.01 0.02 Cr: 0.1 O 0.15 1.5 2.1 0.01 0.003 0.03 Mo: 0.2 P
0.1 2.8 0.8 0.01 0.003 0.03 Cu: 0.2 Q 0.07 0.3 1.5 0.09 0.005 0.05
Ni: 0.2 R 0.18 1.5 2.5 0.01 0.003 0.3 B: 0.002 S 0.003 1.1 1.5 0.05
0.008 0.02 Ca: 0.02 T 0.003 0.8 1.9 0.01 0.008 0.02 N: 0.01 U 0.1
1.0 4.5 0.01 0.003 0.8 Sb: 0.02 V 0.2 1.9 1.2 0.10 0.005 0.03 Ti:
0.03, Nb: 0.04 W 0.08 0.35 2.2 0.02 0.002 0.70 Nb: 0.03, Mo: 0.25 X
0.1 2.9 2.5 0.06 0.003 0.03 Cu: 0.15
[0169] TABLE-US-00002 TABLE 2-1 Adhered substabce Oxidation
treatment Quantity of Oxygen specific UIltimate quantity in
Hematite Steel Concentrtion element Applied/ temperature oxide film
content No. type Kind (g/l) (mg/m.sup.2) Not applied (.degree. C.)
(g/m.sup.2) (%) Example 1 A Phosphoric 100 70 Applied 650 0.62 50
Example 2 B acid 0.58 50 Example 3 C 0.59 55 Example 4 D 0.6 60
Example 5 G 0.55 60 Example 6 H 0.57 65 Example 7 B Hydrochloric 1
0.1 Applied 550 0.45 0 Example 8 C acid 0.48 0 Example 9 G 0.52 5
Example 10 H 0.45 5 Example 11 I 0.49 10 Example 12 J 0.5 10
Example 13 A Sodium 2 1 Applied 700 0.75 0 Example 14 B fluoride
0.71 0 Example 15 C 0.68 0 Example 16 E 0.77 0 Example 17 F 0.69 0
Example 18 H 0.69 0 Example 19 A Sodium 20 70 Applied 600 0.55 0
Example 20 B thiosulfate 0.52 0 Example 21 C 0.54 0 Example 22 D
0.5 0 Example 23 G 0.52 5 Example 24 H 0.53 5 Example 25 A
Potassium 100 100 Applied 600 0.51 0 Example 26 B hydroxide 0.49 0
Example 27 C 0.48 5 Example 28 E 0.45 5 Example 29 F 0.45 10
Example 30 H 0.45 20 Comparative Example 1 B None None None Applied
600 0.18 90 Comparative Example 2 C 0.12 90 Comparative Example 3 G
0.07 90 Comparative Example 4 H 0.05 95 Comparative Example 5 I 0.2
90 Comparative Example 6 J 0.08 95 Comparative Example 7 A Sodium 2
1 Not -- -- -- Comparative Example 8 B fluoride applied -- --
Comparative Example 9 C -- -- Comparative Example 10 E -- --
Comparative Example 11 F -- -- Comparative Example 12 H -- --
Comparative Example 13 A Sodium 20 70 Applied 500 0.07 75
Comparative Example 14 B thiosulfate 0.07 80 Comparative Example 15
C 0.07 80 Comparative Example 16 D 0.05 85 Comparative Example 17 G
0.06 85 Comparative Example 18 H 0.05 85 Comparative Example 19 A
Hydrochloric 1 0.1 Applied 400 0.006 80 Comparative Example 20 B
acid 0.007 80 Comparative Example 21 C 0.006 75 Comparative Example
22 D 0.006 80 Comparative Example 23 G 0.005 80 Comparative Example
24 H 0.002 75 Comparative Example 25 A Phosphoric 100 70 Applied
400 0.01 85 Comparative Example 26 B acic 0.02 85 Comparative
Example 27 C 0.02 85 Comparative Example 28 D 0.01 85 Comparative
Example 29 G 0.005 90 Comparative Example 30 H 0.005 90 Comparative
Example 31 A Ammonium 50 70 Applied 500 0.01 80 Comparative Example
32 B thiocyanate 0.02 80 Comparative Example 33 C 0.02 80
Comparative Example 34 D 0.01 80 Comparative Example 35 G 0.005 90
Comparative Example 36 H 0.005 90
[0170] TABLE-US-00003 TABLE 2-2 Properties of segregated layer
Segregated component Thickenss of segregated Degree of Quantity of
oxide below plating component (.mu.m) segregation (%) containing Si
No. layer GDS EPMA GDS EPMA (g/m.sup.2) Example 1 P 7 -- 400 -- 0.1
Example 2 7 -- 400 -- 0.1 Example 3 7 -- 400 -- 0.15 Example 4 7 --
400 -- 0.12 Example 5 7 -- 400 -- 0.5 Example 6 7 -- 400 -- 0.7
Example 7 Cl 1.1 -- 100 -- 0.05 Example 8 1.2 -- 100 -- 0.05
Example 9 1.1 -- 100 -- 0.05 Example 10 1.1 -- 100 -- 0.05 Example
11 1.1 -- 100 -- 0.05 Example 12 1.1 -- 100 -- 0.04 Example 13 F,
Na F: 1.5, Na: 1.4 -- F: 100, Na: 100 -- 0.12 Example 14 F: 1.5,
Na: 1.4 -- F: 100, Na: 100 -- 0.13 Example 15 F: 1.5, Na: 1.4 -- F:
100, Na: 100 -- 0.12 Example 16 F: 1.5, Na: 1.4 -- F: 100, Na: 100
-- 0.12 Example 17 F: 1.5, Na: 1.4 -- F: 100, Na: 100 -- 0.14
Example 18 F: 1.5, Na: 1.4 -- F: 100, Na: 100 -- 0.13 Example 19 S,
Na S: 3.0, Na: 2.0 -- S: 400, Na: 400 -- 0.1 Example 20 S: 3.0, Na:
2.0 -- S: 400, Na: 400 -- 0.15 Example 21 S: 3.0, Na: 2.0 -- S:
400, Na: 400 -- 0.1 Example 22 S: 3.0, Na: 2.0 -- S: 400, Na: 400
-- 0.11 Example 23 S: 3.0, Na: 2.0 -- S: 400, Na: 400 -- 0.12
Example 24 S: 3.0, Na: 2.0 -- S: 400, Na: 400 -- 0.1 Example 25 K
3.0 -- 500 -- 0.12 Example 26 3.0 -- 500 -- 0.13 Example 27 3.0 --
500 -- 0.11 Example 28 3.0 -- 500 -- 0.1 Example 29 3.0 -- 500 --
0.12 Example 30 3.0 -- 500 -- 0.13 Comparative Example 1 None -- --
-- -- 0.001 Comparative Example 2 -- -- -- -- 0.001 Comparative
Example 3 -- -- -- -- 0.001 Comparative Example 4 -- -- -- -- 0.001
Comparative Example 5 -- -- -- -- 0.001 Comparative Example 6 -- --
-- -- 0.001 Comparative Example 7 F, Na (F: 0.004, Na: 0.003) -- F:
5, Na: 5 -- 0.002 Comparative Example 8 (F: 0.004, Na: 0.003) -- F:
5, Na: 5 -- 0.003 Comparative Example 9 (F: 0.004, Na: 0.003) -- F:
5, Na: 5 -- 0.002 Comparative Example 10 (F: 0.004, Na: 0.003) --
F: 5, Na: 5 -- 0.002 Comparative Example 11 (F: 0.004, Na: 0.003)
-- F: 5, Na: 5 -- 0.003 Comparative Example 12 (F: 0.004, Na:
0.003) -- F: 5, Na: 5 -- 0.002 Comparative Example 13 S, Na (S:
0.004, Na: 0.004) -- S: 6, Na: 6 -- 0.004 Comparative Example 14
(S: 0.004, Na: 0.004) -- S: 6, Na: 6 -- 0.005 Comparative Example
15 (S: 0.004, Na: 0.004) -- S: 6, Na: 6 -- 0.004 Comparative
Example 16 (S: 0.004, Na: 0.004) -- S: 6, Na: 6 -- 0.003
Comparative Example 17 (S: 0.004, Na: 0.004) -- S: 6, Na: 6 --
0.003 Comparative Example 18 (S: 0.004, Na: 0.004) -- S: 6, Na: 6
-- 0.003 Comparative Example 19 Cl (0.003) -- 5 -- 0.002
Comparative Example 20 (0.003) -- 5 -- 0.003 Comparative Example 21
(0.003) -- 5 -- 0.004 Comparative Example 22 (0.003) -- 5 -- 0.003
Comparative Example 23 (0.003) -- 5 -- 0.003 Comparative Example 24
(0.003) -- 5 -- 0.004 Comparative Example 25 P (0.004) -- 5 --
0.002 Comparative Example 26 (0.004) -- 5 -- 0.004 Comparative
Example 27 (0.004) -- 5 -- 0.003 Comparative Example 28 (0.004) --
5 -- 0.002 Comparative Example 29 (0.004) -- 5 -- 0.004 Comparative
Example 30 (0.004) -- 5 -- 0.003 Comparative Example 31 S, C, N (S:
0.004, C: 0.003, N: 0.004) -- S: 5, N5 -- 0.004 Comparative Example
32 (S: 0.004, C: 0.003, N: 0.004) -- S: 5, N5 -- 0.005 Comparative
Example 33 (S: 0.004, C: 0.003, N: 0.004) -- S: 5, N5 -- 0.004
Comparative Example 34 (S: 0.004, C: 0.003, N: 0.004) -- S: 5, N5
-- 0.004 Comparative Example 35 (S: 0.004, C: 0.003, N: 0.004) --
S: 5, N5 -- 0.003 Comparative Example 36 (S: 0.004, C: 0.003, N:
0.004) -- S: 5, N5 -- 0.004
[0171] TABLE-US-00004 TABLE 2-3 Plating quality Anti- Plating
Plating Alloying powdering Sliding No. appearance adhesion rate
property property Example 1 .largecircle. .largecircle.
.largecircle. .largecircle. .largecircle. Example 2 .largecircle.
.largecircle. .largecircle. .largecircle. .largecircle. Example 3
.largecircle. .largecircle. .largecircle. .largecircle.
.largecircle. Example 4 .largecircle. .largecircle. .largecircle.
.largecircle. .largecircle. Example 5 .largecircle. .largecircle.
.largecircle. .largecircle. .largecircle. Example 6 .largecircle.
.largecircle. .largecircle. .largecircle. .largecircle. Example 7
.largecircle. .largecircle. .largecircle. .largecircle.
.largecircle. Example 8 .largecircle. .largecircle. .largecircle.
.largecircle. .largecircle. Example 9 .largecircle. .largecircle.
.largecircle. .largecircle. .largecircle. Example 10 .largecircle.
.largecircle. .largecircle. .largecircle. .largecircle. Example 11
.largecircle. .largecircle. .largecircle. .largecircle.
.largecircle. Example 12 .largecircle. .largecircle. .largecircle.
.largecircle. .largecircle. Example 13 .largecircle. .largecircle.
.largecircle. .largecircle. .largecircle. Example 14 .largecircle.
.largecircle. .largecircle. .largecircle. .largecircle. Example 15
.largecircle. .largecircle. .largecircle. .largecircle.
.largecircle. Example 16 .largecircle. .largecircle. .largecircle.
.largecircle. .largecircle. Example 17 .largecircle. .largecircle.
.largecircle. .largecircle. .largecircle. Example 18 .largecircle.
.largecircle. .largecircle. .largecircle. .largecircle. Example 19
.largecircle. .largecircle. .largecircle. .largecircle.
.largecircle. Example 20 .largecircle. .largecircle. .largecircle.
.largecircle. .largecircle. Example 21 .largecircle. .largecircle.
.largecircle. .largecircle. .largecircle. Example 22 .largecircle.
.largecircle. .largecircle. .largecircle. .largecircle. Example 23
.largecircle. .largecircle. .largecircle. .largecircle.
.largecircle. Example 24 .largecircle. .largecircle. .largecircle.
.largecircle. .largecircle. Example 25 .largecircle. .largecircle.
.largecircle. .largecircle. .largecircle. Example 26 .largecircle.
.largecircle. .largecircle. .largecircle. .largecircle. Example 27
.largecircle. .largecircle. .largecircle. .largecircle.
.largecircle. Example 28 .largecircle. .largecircle. .largecircle.
.largecircle. .largecircle. Example 29 .largecircle. .largecircle.
.largecircle. .largecircle. .largecircle. Example 30 .largecircle.
.largecircle. .largecircle. .largecircle. .largecircle. Comparative
.DELTA. X X X X Example 1 Comparative X X X X X Example 2
Comparative X X X X X Example 3 Comparative X X X X X Example 4
Comparative .DELTA. X X X X Example 5 Comparative X X X X X Example
6 Comparative X X X X X Example 7 Comparative X X X X X Example 8
Comparative X X X X X Example 9 Comparative X X X X X Example 10
Comparative X X X X X Example 11 Comparative X X X X X Example 12
Comparative .DELTA. X X X X Example 13 Comparative .DELTA. X X X X
Example 14 Comparative X X X X X Example 15 Comparative X X X X X
Example 16 Comparative X X X X X Example 17 Comparative X X X X X
Example 18 Comparative X X X X X Example 19 Comparative X X X X X
Example 20 Comparative X X X X X Example 21 Comparative X X X X X
Example 22 Comparative X X X X X Example 23 Comparative X X X X X
Example 24 Comparative X X X X X Example 25 Comparative X X X X X
Example 26 Comparative X X X X X Example 27 Comparative X X X X X
Example 28 Comparative X X X X X Example 29 Comparative X X X X X
Example 30 Comparative X X X X X Example 31 Comparative X X X X X
Example 32 Comparative X X X X X Example 33 Comparative X X X X X
Example 34 Comparative X X X X X Example 35 Comparative X X X X X
Example 36
[0172] TABLE-US-00005 TABLE 3-1 Adhered substance Oxidation
treatment Quantity of Quantity of specific Ultimate oxygen in
Hematite Steel Concentration element Applied/ temperature oxide
film content No. type Kind (g/l) (mg/m.sup.2) Not applied (.degree.
C.) (g/m.sup.2) (%) Example 31 A Sulfuric 50 70 Applied 600 0.55 0
Example 32 B acid 0.55 0 Example 33 C 0.53 5 Example 34 D 0.52 5
Example 35 G 0.61 10 Example 36 H 0.51 10 Example 37 B Ammonium 30
100 Applied 650 0.56 0 Example 38 C sulfate 0.61 0 Example 39 G
0.52 5 Example 40 H 0.54 5 Example 41 I 0.53 10 Example 42 J 0.51
10 Example 43 A Thiourea 20 70 Applied 700 0.64 0 Example 44 B 0.64
0 Example 45 C 0.62 5 Example 46 E 0.71 5 Example 47 F 0.62 10
Example 48 H 0.51 10 Example 49 A Sodium 50 70 Applied 600 0.55 0
Example 50 B sulfide 0.51 0 Example 51 C 0.58 5 Example 52 D 0.54 5
Example 53 G 0.56 10 Example 54 H 0.51 10 Example 55 A Iron 20 80
Applied 550 0.41 0 Example 56 B sulfide 0.34 0 Example 57 C 0.35 5
Example 58 E 0.41 5 Example 59 F 0.38 10 Example 60 H 0.36 10
Comparative Example 37 B None None None Applied 600 0.21 90
Comparative Example 38 C 0.25 90 Comparative Example 39 G 0.18 90
Comparative Example 40 H 0.21 90 Comparative Example 41 I 0.24 95
Comparative Example 42 J 0.19 90 Comparative Example 43 A Sulfuric
10 5 Not -- -- -- Comparative Example 44 B acid applied -- --
Comparative Example 45 C -- -- Comparative Example 46 E -- --
Comparative Example 47 F -- -- Comparative Example 48 H -- --
Comparative Example 49 A Ammonium 5 10 Applied 400 0.006 80
Comparative Example 50 B sulfate 0.008 84 Comparative Example 51 C
0.004 86 Comparative Example 52 D 0.006 82 Comparative Example 53 G
0.004 80 Comparative Example 54 H 0.003 86 Comparative Example 55 A
Thio urea 1 0.1 Applied 400 0.004 85 Comparative Example 56 B 0.003
90 Comparative Example 57 C 0.004 89 Comparative Example 58 D 0.006
86 Comparative Example 59 G 0.004 91 Comparative Example 60 H 0.002
90 Comparative Example 61 A None None None Applied 850 3.1 75
Comparative Example 62 B 2.9 72 Comparative Example 63 C 2.6 80
Comparative Example 64 D 2.8 85 Comparative Example 65 E 2.9 72
Comparative Example 66 F 2.8 71 Comparative Example 67 G 2.9 75
Comparative Example 68 H 2.5 86
[0173] TABLE-US-00006 TABLE 3-2 Properties of segregated layer
Segregated component Thickness of segregated Degree of Quantity of
oxide below plating component (.mu.m) segregation (%) containing Si
No. layer GDS EPMA GDS EPMA (g/m.sup.2) Example 31 S 4.5 5 300 300
0.1 Example 32 4.6 5 300 300 0.1 Example 33 5.1 5 300 300 0.9
Example 34 5.1 5 300 300 0.9 Example 35 4.9 5 300 300 0.7 Example
36 5.3 5 300 300 0.7 Example 37 S 10.5 10 500 500 0.12 Example 38
10.4 10 500 500 0.12 Example 39 10.2 10 500 500 0.1 Example 40 10.1
10 500 500 0.1 Example 41 9.8 10 500 500 0.9 Example 42 10.0 10 500
500 0.9 Example 43 S 3.1 3 400 400 0.08 Example 44 3.0 3 400 400
0.08 Example 45 3.0 3 400 400 0.07 Example 46 2.8 3 400 400 0.07
Example 47 3.5 3 400 400 0.06 Example 48 3.2 3 400 400 0.06 Example
49 S 15.1 15 100 100 0.03 Example 50 14.8 15 100 100 0.03 Example
51 15.0 15 100 100 0.03 Example 52 15.8 15 100 100 0.02 Example 53
15.3 15 100 100 0.02 Example 54 15.4 15 100 100 0.02 Example 55 S
20.0 20 600 600 0.2 Example 56 20.1 20 600 600 0.2 Example 57 20.1
20 600 600 0.18 Example 58 20.4 20 600 600 0.17 Example 59 20.4 20
600 600 0.15 Example 60 19.9 20 600 600 0.15 Comparative Example 37
None -- -- -- -- 0.001 Comparative Example 38 -- -- -- -- 0.001
Comparative Example 39 -- -- -- -- 0.001 Comparative Example 40 --
-- -- -- 0.001 Comparative Example 41 -- -- -- -- 0.001 Comparative
Example 42 -- -- -- -- 0.001 Comparative Example 43 S (0.006)
(0.006) 8 8 0.006 Comparative Example 44 (0.005) (0.005) 8 8 0.005
Comparative Example 45 (0.004) (0.004) 8 8 0.004 Comparative
Example 46 (0.004) (0.004) 8 8 0.004 Comparative Example 47 (0.003)
(0.003) 8 8 0.003 Comparative Example 48 (0.003) (0.003) 8 8 0.003
Comparative Example 49 S (0.005) (0.005) 7 7 0.005 Comparative
Example 50 (0.005) (0.005) 7 7 0.005 Comparative Example 51 (0.004)
(0.004) 7 7 0.004 Comparative Example 52 (0.004) (0.004) 7 7 0.004
Comparative Example 53 (0.003) (0.003) 7 7 0.003 Comparative
Example 54 (0.003) (0.003) 7 7 0.003 Comparative Example 55 S
(0.005) (0.005) 5 5 0.005 Comparative Example 56 (0.004) (0.004) 5
5 0.004 Comparative Example 57 (0.004) (0.004) 5 5 0.004
Comparative Example 58 (0.003) (0.003) 5 5 0.003 Comparative
Example 59 (0.003) (0.003) 5 5 0.003 Comparative Example 60 (0.003)
(0.003) 5 5 0.003 Comparative Example 61 None -- -- -- -- 0.03
Comparative Example 62 -- -- -- -- 0.03 Comparative Example 63 --
-- -- -- 0.02 Comparative Example 64 -- -- -- -- 0.02 Comparative
Example 65 -- -- -- -- 0.03 Comparative Example 66 -- -- -- -- 0.02
Comparative Example 67 -- -- -- -- 0.02 Comparative Example 68 --
-- -- -- 0.04
[0174] TABLE-US-00007 TABLE 3-3 Properties of plating layer Anti-
Plating Plating Alloying powdering Sliding No. appearance adhesion
rate property property Example 31 .largecircle. .largecircle.
.largecircle. .largecircle. .largecircle. Example 32 .largecircle.
.largecircle. .largecircle. .largecircle. .largecircle. Example 33
.largecircle. .largecircle. .largecircle. .largecircle.
.largecircle. Example 34 .largecircle. .largecircle. .largecircle.
.largecircle. .largecircle. Example 35 .largecircle. .largecircle.
.largecircle. .largecircle. .largecircle. Example 36 .largecircle.
.largecircle. .largecircle. .largecircle. .largecircle. Example 37
.largecircle. .largecircle. .largecircle. .largecircle.
.largecircle. Example 38 .largecircle. .largecircle. .largecircle.
.largecircle. .largecircle. Example 39 .largecircle. .largecircle.
.largecircle. .largecircle. .largecircle. Example 40 .largecircle.
.largecircle. .largecircle. .largecircle. .largecircle. Example 41
.largecircle. .largecircle. .largecircle. .largecircle.
.largecircle. Example 42 .largecircle. .largecircle. .largecircle.
.largecircle. .largecircle. Example 43 .largecircle. .largecircle.
.largecircle. .largecircle. .largecircle. Example 44 .largecircle.
.largecircle. .largecircle. .largecircle. .largecircle. Example 45
.largecircle. .largecircle. .largecircle. .largecircle.
.largecircle. Example 46 .largecircle. .largecircle. .largecircle.
.largecircle. .largecircle. Example 47 .largecircle. .largecircle.
.largecircle. .largecircle. .largecircle. Example 48 .largecircle.
.largecircle. .largecircle. .largecircle. .largecircle. Example 49
.largecircle. .largecircle. .largecircle. .largecircle.
.largecircle. Example 50 .largecircle. .largecircle. .largecircle.
.largecircle. .largecircle. Example 51 .largecircle. .largecircle.
.largecircle. .largecircle. .largecircle. Example 52 .largecircle.
.largecircle. .largecircle. .largecircle. .largecircle. Example 53
.largecircle. .largecircle. .largecircle. .largecircle.
.largecircle. Example 54 .largecircle. .largecircle. .largecircle.
.largecircle. .largecircle. Example 55 .largecircle. .largecircle.
.largecircle. .largecircle. .largecircle. Example 56 .largecircle.
.largecircle. .largecircle. .largecircle. .largecircle. Example 57
.largecircle. .largecircle. .largecircle. .largecircle.
.largecircle. Example 58 .largecircle. .largecircle. .largecircle.
.largecircle. .largecircle. Example 59 .largecircle. .largecircle.
.largecircle. .largecircle. .largecircle. Example 60 .largecircle.
.largecircle. .largecircle. .largecircle. .largecircle. Comparative
X X X X X Example 37 Comparative X X X X X Example 38 Comparative X
X X X X Example 39 Comparative X X X X X Example 40 Comparative X X
X X X Example 41 Comparative X X X X X Example 42 Comparative X X X
X X Example 43 Comparative X X X X X Example 44 Comparative X X X X
X Example 45 Comparative X X X X X Example 46 Comparative X X X X X
Example 47 Comparative X X X X X Example 48 Comparative X X X X X
Example 49 Comparative X X X X X Example 50 Comparative X X X X X
Example 51 Comparative X X X X X Example 52 Comparative X X X X X
Example 53 Comparative X X X X X Example 54 Comparative X X X X X
Example 55 Comparative X X X X X Example 56 Comparative X X X X X
Example 57 Comparative X X X X X Example 58 Comparative X X X X X
Example 59 Comparative X X X X X Example 60 Comparative
.largecircle. X .largecircle. .largecircle. X Example 61
Comparative .largecircle. X .largecircle. .largecircle. X Example
62 Comparative .largecircle. X .largecircle. .largecircle. X
Example 63 Comparative .largecircle. X .largecircle. .largecircle.
X Example 64 Comparative .largecircle. X .largecircle.
.largecircle. X Example 65 Comparative .largecircle. X
.largecircle. .largecircle. X Example 66 Comparative .largecircle.
X .largecircle. .largecircle. X Example 67 Comparative
.largecircle. X .largecircle. .largecircle. X Example 68
[0175] TABLE-US-00008 TABLE 4-1 Adhered substance Oxidation
treatment Quantity of Quantity of specified Ultimate oxygen in
Hematite Steel Concentration element Applied/ temperature oxide
film content No. type Kind (g/l) (mg/m.sup.2) Not applied (.degree.
C.) (g/m.sup.2) (%) Example 61 K Ammonium 150 90 Applied 650 0.82
10 Example 62 L sulfate 0.8 10 Example 63 M 0.8 15 Example 64 N 0.8
10 Example 65 O 0.77 15 Example 66 P 0.77 20 Example 67 Q 0.85 25
Example 68 R 0.82 20 Example 69 S 0.82 10 Example 70 T 0.82 15
Example 71 U 0.77 20 Example 72 V 0.79 15 Example 73 W 0.79 20
Example 74 X 0.8 20
[0176] TABLE-US-00009 TABLE 4-2 Properties of segregated layer
Segregated component Thickness of segregated Degree of Quantity of
oxide below plating component (.mu.m) segregation (%) containing Si
No. layer GDS EPMA GDS EPMA (g/m.sup.2) Example 61 S 3 -- 300 --
0.15 Example 62 3 -- 300 -- 0.15 Example 63 3 -- 300 -- 0.16
Example 64 3 -- 300 -- 0.15 Example 65 3 -- 300 -- 0.12 Example 66
3 -- 300 -- 0.1 Example 67 3 -- 300 -- 0.18 Example 68 3 -- 300 --
0.15 Example 69 3 -- 300 -- 0.15 Example 70 3 -- 300 -- 0.15
Example 71 3 -- 300 -- 0.14 Example 72 3 -- 300 -- 0.15 Example 73
3 -- 300 -- 0.15 Example 74 3 -- 300 -- 0.15
[0177] TABLE-US-00010 TABLE 4-3 Plating quality Anti- Plating
Plating Alloying powdering Sliding No. appearance adhesion rate
property property Example 61 .largecircle. .largecircle.
.largecircle. .largecircle. .largecircle. Example 62 .largecircle.
.largecircle. .largecircle. .largecircle. .largecircle. Example 63
.largecircle. .largecircle. .largecircle. .largecircle.
.largecircle. Example 64 .largecircle. .largecircle. .largecircle.
.largecircle. .largecircle. Example 65 .largecircle. .largecircle.
.largecircle. .largecircle. .largecircle. Example 66 .largecircle.
.largecircle. .largecircle. .largecircle. .largecircle. Example 67
.largecircle. .largecircle. .largecircle. .largecircle.
.largecircle. Example 68 .largecircle. .largecircle. .largecircle.
.largecircle. .largecircle. Example 69 .largecircle. .largecircle.
.largecircle. .largecircle. .largecircle. Example 70 .largecircle.
.largecircle. .largecircle. .largecircle. .largecircle. Example 71
.largecircle. .largecircle. .largecircle. .largecircle.
.largecircle. Example 72 .largecircle. .largecircle. .largecircle.
.largecircle. .largecircle. Example 73 .largecircle. .largecircle.
.largecircle. .largecircle. .largecircle. Example 74 .largecircle.
.largecircle. .largecircle. .largecircle. .largecircle.
[0178] TABLE-US-00011 TABLE 5-1 Adhered substance Oxidation
treatment Quantity of Quantity of speficied Ultimate oxygen in
Hematite Steel Concentration element Applied/ temperature oxide
film content No. type Kind (g/l) (mg/m.sup.2) Not applied (.degree.
C.) (g/m.sup.2) (%) Example 75 A Potassium 50 100 Applied 600 0.41
0 Example 76 B chloride 0.43 0 Example 77 C 0.39 0 Example 78 D
0.35 0 Example 79 G 0.42 0 Example 80 H 0.41 0 Example 81 B
Ammonium 100 800 Applied 550 0.39 20 Example 82 C oxalate 0.35 25
Example 83 G 0.32 40 Example 84 H 0.36 60 Example 85 I 0.31 20
Example 86 J 0.32 55 Example 87 A Sulfuric 50 80 Applied 550 0.42 0
Example 88 B acid 0.43 0 Example 89 C 0.44 0 Example 90 E 0.42 0
Example 91 F 0.45 0 Example 92 H 0.41 0 Example 93 A Sodium 30 1
Applied 600 0.51 10 Example 94 B hydroxide 0.52 10 Example 95 C
0.53 15 Example 96 D 0.5 20 Example 97 G 0.49 30 Example 98 H 0.56
45 Example 99 A Sodium 3 0.5 Applied 650 0.59 0 Example 100 B
tetraborate 0.58 0 Example 101 C 0.6 5 Example 102 E 0.57 5 Example
103 F 0.55 10 Example 104 H 0.6 20 Comparative Example 69 B none
None None Applied 650 0.32 75 Comparative Example 70 C 0.29 75
Comparative Example 71 G 0.15 90 Comparative Example 72 H 0.12 95
Comparative Example 73 I 0.35 75 Comparative Example 74 J 0.15 95
Comparative Example 75 A Sulfuric 50 80 Not -- -- -- Comparative
Example 76 B acid applied -- -- Comparative Example 77 C -- --
Comparative Example 78 E -- -- Comparative Example 79 F -- --
Comparative Example 80 H -- -- Comparative Example 81 A Ammonium
100 800 Applied 450 0.04 80 Comparative Example 82 B oxalate 0.04
85 Comparative Example 83 C 0.03 85 Comparative Example 84 D 0.03
90 Comparative Example 85 G 0.02 90 Comparative Example 86 H 0.005
95
[0179] TABLE-US-00012 TABLE 5-2 Properties of segregated layer
Segregated component Thickness of segregated Degree of Quantity of
oxide below plating component (.mu.m) segregtion (%) containing Si
No. layer GDS EPMA GDS EPMA (g/m.sup.2) Example 75 Cl, K Cl: 3, K:
3 -- Cl: 300, K: 300 -- 0.15 Example 76 Cl: 3, K: 3 -- Cl: 300, K:
300 -- 0.14 Example 77 Cl: 3, K: 3 -- Cl: 300, K: 300 -- 0.16
Example 78 Cl: 3, K: 3 -- Cl: 300, K: 300 -- 0.14 Example 79 Cl: 3,
K: 3 -- Cl: 300, K: 300 -- 0.13 Example 80 Cl: 3, K: 3 -- Cl: 300,
K: 300 -- 0.13 Example 81 C, N C: 30, N: 30 -- C: 500, N: 500 --
0.06 Example 82 C: 30, N: 30 -- C: 300, N: 300 -- 0.06 Example 83
C: 30, N: 30 -- C: 300, N: 300 -- 0.05 Example 84 C: 30, N: 30 --
C: 300, N: 300 -- 0.07 Example 85 C: 30, N: 30 -- C: 300, N: 300 --
0.06 Example 86 C: 30, N: 30 -- C: 300, N: 300 -- 0.06 Example 87 S
3 -- 300 -- 0.04 Example 88 3 -- 300 -- 0.05 Example 89 3 -- 300 --
0.06 Example 90 3 -- 300 -- 0.04 Example 91 3 -- 300 -- 0.04
Example 92 3 -- 300 -- 0.05 Example 93 Na 2 -- 100 -- 0.17 Example
94 2 -- 100 -- 0.15 Example 95 2 -- 100 -- 0.16 Example 96 2 -- 100
-- 0.14 Example 97 2 -- 100 -- 0.13 Example 98 2 -- 100 -- 0.15
Example 99 Na, B Na: 2, B: 2 -- Na: 100, B: 100 -- 0.14 Example 100
Na: 2, B: 2 -- Na: 100, B: 100 -- 0.15 Example 101 Na: 2, B: 2 --
Na: 100, B: 100 -- 0.14 Example 102 Na: 2, B: 2 -- Na: 100, B: 100
-- 0.16 Example 103 Na: 2, B: 2 -- Na: 100, B: 100 -- 0.16 Example
104 Na: 2, B: 2 -- Na: 100, B: 100 -- 0.13 Comparative Example 69
None -- -- -- -- 0.001 Comparative Example 70 -- -- -- -- 0.001
Comparative Example 71 -- -- -- -- 0.001 Comparative Example 72 --
-- -- -- 0.001 Comparative Example 73 -- -- -- -- 0.001 Comparative
Example 74 -- -- -- -- 0.001 Comparative Example 75 S (0.001) -- 6
-- 0.002 Comparative Example 76 (0.001) -- 6 -- 0.003 Comparative
Example 77 (0.001) -- 6 -- 0.002 Comparative Example 78 (0.001) --
6 -- 0.002 Comparative Example 79 (0.001) -- 6 -- 0.002 Comparative
Example 80 (0.001) -- 6 -- 0.002 Comparative Example 81 C, N
(0.004) -- C: 6, N: 6 -- 0.002 Comparative Example 82 (0.004) -- C:
6, N: 6 -- 0.002 Comparative Example 83 (0.004) -- C: 6, N: 6 --
0.003 Comparative Example 84 (0.004) -- C: 6, N: 6 -- 0.002
Comparative Example 85 (0.004) -- C: 6, N: 6 -- 0.003 Comparative
Example 86 (0.004) -- C: 6, N: 6 -- 0.002
[0180] TABLE-US-00013 TABLE 5-3 Plating quality Anti- Plating
Plating Alloying powdering Sliding No. appearance adhesion rate
property property Example 75 .largecircle. .largecircle.
.largecircle. .largecircle. .largecircle. Example 76 .largecircle.
.largecircle. .largecircle. .largecircle. .largecircle. Example 77
.largecircle. .largecircle. .largecircle. .largecircle.
.largecircle. Example 78 .largecircle. .largecircle. .largecircle.
.largecircle. .largecircle. Example 79 .largecircle. .largecircle.
.largecircle. .largecircle. .largecircle. Example 80 .largecircle.
.largecircle. .largecircle. .largecircle. .largecircle. Example 81
.largecircle. .largecircle. .largecircle. .largecircle.
.largecircle. Example 82 .largecircle. .largecircle. .largecircle.
.largecircle. .largecircle. Example 83 .largecircle. .largecircle.
.largecircle. .largecircle. .largecircle. Example 84 .largecircle.
.largecircle. .largecircle. .largecircle. .largecircle. Example 85
.largecircle. .largecircle. .largecircle. .largecircle.
.largecircle. Example 86 .largecircle. .largecircle. .largecircle.
.largecircle. .largecircle. Example 87 .largecircle. .largecircle.
.largecircle. .largecircle. .largecircle. Example 88 .largecircle.
.largecircle. .largecircle. .largecircle. .largecircle. Example 89
.largecircle. .largecircle. .largecircle. .largecircle.
.largecircle. Example 90 .largecircle. .largecircle. .largecircle.
.largecircle. .largecircle. Example 91 .largecircle. .largecircle.
.largecircle. .largecircle. .largecircle. Example 92 .largecircle.
.largecircle. .largecircle. .largecircle. .largecircle. Example 93
.largecircle. .largecircle. .largecircle. .largecircle.
.largecircle. Example 94 .largecircle. .largecircle. .largecircle.
.largecircle. .largecircle. Example 95 .largecircle. .largecircle.
.largecircle. .largecircle. .largecircle. Example 96 .largecircle.
.largecircle. .largecircle. .largecircle. .largecircle. Example 97
.largecircle. .largecircle. .largecircle. .largecircle.
.largecircle. Example 98 .largecircle. .largecircle. .largecircle.
.largecircle. .largecircle. Example 99 .largecircle. .largecircle.
.largecircle. .largecircle. .largecircle. Example 100 .largecircle.
.largecircle. .largecircle. .largecircle. .largecircle. Example 101
.largecircle. .largecircle. .largecircle. .largecircle.
.largecircle. Example 102 .largecircle. .largecircle. .largecircle.
.largecircle. .largecircle. Example 103 .largecircle. .largecircle.
.largecircle. .largecircle. .largecircle. Example 104 .largecircle.
.largecircle. .largecircle. .largecircle. .largecircle. Comparative
.DELTA. X X X X Example 69 Comparative .DELTA. X X X X Example 70
Comparative X X X X X Example 71 Comparative X X X X X Example 72
Comparative X X X X X Example 73 Comparative X X X X X Example 74
Comparative X X X X X Example 75 Comparative X X X X X Example 76
Comparative X X X X X Example 77 Comparative X X X X X Example 78
Comparative X X X X X Example 79 Comparative X X X X X Example 80
Comparative X X X X X Example 81 Comparative X X X X X Example 82
Comparative X X X X X Example 83 Comparative X X X X X Example 84
Comparative X X X X X Example 85 Comparative X X X X X Example
86
[0181] TABLE-US-00014 TABLE 6-1 Adhered substance Oxidation
treatment Quantity of Quantity of specified Ultimate oxygen in
Hematite Steel Concentration element Applied/ temperarture oxide
film content NO. type Kind (g/l) (mg/m.sup.2) Not applied (.degree.
C.) (g/m.sup.2) (%) Example 105 A Antimony 20 10 Applied 550 0.35 0
Example 106 B chloride 0.39 0 Example 107 C 0.4 0 Example 108 D
0.36 0 Example 109 G 0.37 10 Example 110 H 0.39 10 Example 111 B
Ammonium 30 50 Applied 600 0.54 0 Example 112 C sulfate 0.52 0
Example 113 G 0.49 0 Example 114 H 0.53 0 Example 115 I 0.51 0
Example 116 J 0.5 0 Example 117 A Lead 1 1 Applied 650 0.59 45
Example 118 B chloride 0.6 45 Example 119 C 0.62 50 Example 120 E
0.59 60 Example 121 F 0.58 65 Example 122 H 0.59 65 Example 123 A
Thiourea 20 70 Applied 600 0.56 0 Example 124 B 0.58 0 Example 125
C 0.55 0 Example 126 D 0.54 0 Example 127 G 0.58 0 Example 128 H
0.56 0 Example 129 A Sodium 25 5 Applied 600 0.49 0 Example 130 B
chloride 0.52 0 Example 131 C 0.51 5 Example 132 E 0.49 5 Example
133 F 0.48 10 Example 134 H 0.51 20 Comparative Example 87 B None
None None Applied 550 0.12 90 Comparative Example 88 C 0.03 90
Comparative Example 89 G 0.01 95 Comparative Example 90 H 0.005 95
Comparative Example 91 I 0.09 90 Comparative Example 92 J 0.01 95
Comparative Example 93 A Sodium 25 5 Not -- -- -- Comparative
Example 94 B chloride applied -- -- Comparative Example 95 C -- --
Comparative Example 96 E -- -- Comparative Example 97 F -- --
Comparative Example 98 H -- -- Comparative Example 99 A Thiourea 20
70 Applied 450 0.05 75 Comparative Example 100 B 0.06 75
Comparative Example 101 C 0.05 80 Comparative Example 102 D 0.03 85
Comparative Example 103 G 0.02 95 Comparative Example 104 H 0.008
95
[0182] TABLE-US-00015 TABLE 6-2 Properties of segregated layer
Segregated element Thickness of segregated Degree of Quantity of
oxide below plating component (.mu.m) segregation (%) containing Si
NO. layer GDS EPMA GDS EPMA (g/m.sup.2) Example 105 Cl 2 -- 300 --
0.08 Example 106 2 -- 300 -- 0.05 Example 107 2 -- 300 -- 0.08
Example 108 2 -- 300 -- 0.07 Example 109 2 -- 300 -- 0.06 Example
110 2 -- 300 -- 0.05 Example 111 S 3 -- 400 -- 0.15 Example 112 3
-- 400 -- 0.14 Example 113 3 -- 400 -- 0.13 Example 114 3 -- 400 --
0.14 Example 115 3 -- 400 -- 0.14 Example 116 3 -- 400 -- 0.15
Example 117 Cl 2 -- 300 -- 0.13 Example 118 2 -- 300 -- 0.12
Example 119 3 -- 300 -- 0.14 Example 120 2 -- 300 -- 0.12 Example
121 2 -- 300 -- 0.12 Example 122 2 -- 300 -- 0.13 Example 123 S 5
-- 600 -- 0.14 Example 124 5 -- 600 -- 0.15 Example 125 5 -- 600 --
0.14 Example 126 5 -- 600 -- 0.14 Example 127 5 -- 600 -- 0.16
Example 128 5 -- 600 -- 0.14 Example 129 Na, Cl Na: 2, Cl: 2 -- Na:
300, Cl: 300 -- 0.14 Example 130 Na: 2, Cl: 2 -- Na: 300, Cl: 300
-- 0.14 Example 131 Na: 2, Cl: 2 -- Na: 300, Cl: 300 -- 0.14
Example 132 Na: 2, Cl: 2 -- Na: 300, Cl: 300 -- 0.15 Example 133
Na: 2, Cl: 2 -- Na: 300, Cl: 300 -- 0.15 Example 134 Na: 2, Cl: 2
-- Na: 300, Cl: 300 -- 0.14 Comparative Example 87 -- -- -- -- --
0.002 Comparative Example 88 -- -- -- -- 0.002 Comparative Example
89 -- -- -- -- 0.003 Comparative Example 90 -- -- -- -- 0.002
Comparative Example 91 -- -- -- -- 0.002 Comparative Example 92 --
-- -- -- 0.002 Comparative Example 93 Na, Cl (Cl: 0.004, Na: 0.003)
-- Cl: 5, Na: 5 -- 0.002 Comparative Example 94 (Cl: 0.004, Na:
0.003) -- Cl: 5, Na: 5 -- 0.001 Comparative Example 95 (Cl: 0.004,
Na: 0.003) -- Cl: 5, Na: 5 -- 0.001 Comparative Example 96 (Cl:
0.004, Na: 0.003) -- Cl: 5, Na: 5 -- 0.002 Comparative Example 97
(Cl: 0.004, Na: 0.003) -- Cl: 5, Na: 5 -- 0.002 Comparative Example
98 (Cl: 0.004, Na: 0.003) -- Cl: 5, Na: 5 -- 0.003 Comparative
Example 99 S 0.004 -- 5 -- 0.002 Comparative Example 100 0.004 -- 5
-- 0.003 Comparative Example 101 0.004 -- 5 -- 0.003 Comparative
Example 102 0.004 -- 5 -- 0.002 Comparative Example 103 0.004 -- 5
-- 0.002 Comparative Example 104 0.004 -- 5 -- 0.003
[0183] TABLE-US-00016 TABLE 6-3 Plating quality Anti- Plating
Plating Alloying powdering Sliding NO. appearance adhesion rate
property property Example 105 .largecircle. .largecircle.
.largecircle. .largecircle. .largecircle. Example 106 .largecircle.
.largecircle. .largecircle. .largecircle. .largecircle. Example 107
.largecircle. .largecircle. .largecircle. .largecircle.
.largecircle. Example 108 .largecircle. .largecircle. .largecircle.
.largecircle. .largecircle. Example 109 .largecircle. .largecircle.
.largecircle. .largecircle. .largecircle. Example 110 .largecircle.
.largecircle. .largecircle. .largecircle. .largecircle. Example 111
.largecircle. .largecircle. .largecircle. .largecircle.
.largecircle. Example 112 .largecircle. .largecircle. .largecircle.
.largecircle. .largecircle. Example 113 .largecircle. .largecircle.
.largecircle. .largecircle. .largecircle. Example 114 .largecircle.
.largecircle. .largecircle. .largecircle. .largecircle. Example 115
.largecircle. .largecircle. .largecircle. .largecircle.
.largecircle. Example 116 .largecircle. .largecircle. .largecircle.
.largecircle. .largecircle. Example 117 .largecircle. .largecircle.
.largecircle. .largecircle. .largecircle. Example 118 .largecircle.
.largecircle. .largecircle. .largecircle. .largecircle. Example 119
.largecircle. .largecircle. .largecircle. .largecircle.
.largecircle. Example 120 .largecircle. .largecircle. .largecircle.
.largecircle. .largecircle. Example 121 .largecircle. .largecircle.
.largecircle. .largecircle. .largecircle. Example 122 .largecircle.
.largecircle. .largecircle. .largecircle. .largecircle. Example 123
.largecircle. .largecircle. .largecircle. .largecircle.
.largecircle. Example 124 .largecircle. .largecircle. .largecircle.
.largecircle. .largecircle. Example 125 .largecircle. .largecircle.
.largecircle. .largecircle. .largecircle. Example 126 .largecircle.
.largecircle. .largecircle. .largecircle. .largecircle. Example 127
.largecircle. .largecircle. .largecircle. .largecircle.
.largecircle. Example 128 .largecircle. .largecircle. .largecircle.
.largecircle. .largecircle. Example 129 .largecircle. .largecircle.
.largecircle. .largecircle. .largecircle. Example 130 .largecircle.
.largecircle. .largecircle. .largecircle. .largecircle. Example 131
.largecircle. .largecircle. .largecircle. .largecircle.
.largecircle. Example 132 .largecircle. .largecircle. .largecircle.
.largecircle. .largecircle. Example 133 .largecircle. .largecircle.
.largecircle. .largecircle. .largecircle. Example 134 .largecircle.
.largecircle. .largecircle. .largecircle. .largecircle. Comparative
X X X X X Example 87 Comparative X X X X X Example 88 Comparative X
X X X X Example 89 Comparative X X X X X Example 90 Comparative X X
X X X Example 91 Comparative X X X X X Example 92 Comparative X X X
X X Example 93 Comparative X X X X X Example 94 Comparative X X X X
X Example 95 Comparative X X X X X Example 96 Comparative X X X X X
Example 97 Comparative X X X X X Example 98 Comparative X X X X X
Example 99 Comparative X X X X x Example 100 Comparative X X X X X
Example 101 Comparative X X X X X Example 102 Comparative X X X X X
Example 103 Comparative X X X X X Example 104
[0184] TABLE-US-00017 TABLE 7 Adhered substance Properties of
segregated layer Quantity of Oxidation treatment Segregated
Thickness of specified Ultimate component segregated Steel
Concentration element Applied/ temperature below plating component
(.mu.m) No. type Kind (g/l) (mg/m.sup.2) Not applied (.degree. C.)
layer GDS EPMA Example 135 G Sulfuric 50 70 Applied 600 S 5 5
Example 136 E acid 80 550 S 5 5 Example 137 G 30 600 S 3 3 Example
138 E 30 550 S 3 3 Example 139 G Ammonium 30 100 Applied 650 S 10
10 Example 140 E sulfate 80 550 S 6 6 Example 141 G 30 600 S 3 3
Example 142 E 30 550 S 3 3 Example 143 G Thiourea 20 70 Applied 700
S 2 2 Example 144 E 70 700 S 3 3 Example 145 G 20 700 S 1 1 Example
146 E 20 700 S 1 1 Properties of segregated layer Plating quality
Quantity of oxide Quantity Anti- contining Si (Number/ Plating
Plating powdering Sliding No. (g/m.sup.2) Product 20 .mu.m)
appearance adhesion property property Example 135 0.7 Granular 8.8
.largecircle. .largecircle. .circleincircle. .largecircle. Example
136 0.8 MnS 10.6 .largecircle. .largecircle. .circleincircle.
.largecircle. Example 137 0.5 2.4 .largecircle. .largecircle.
.largecircle. .largecircle. Example 138 0.4 3 .largecircle.
.largecircle. .largecircle. .largecircle. Example 139 0.1 Granular
6.2 .largecircle. .largecircle. .circleincircle. .largecircle.
Example 140 0.1 MnS 8 .largecircle. .largecircle. .circleincircle.
.largecircle. Example 141 0.06 2.2 .largecircle. .largecircle.
.largecircle. .largecircle. Example 142 0.04 2.8 .largecircle.
.largecircle. .largecircle. .largecircle. Example 143 0.09 Granular
6.6 .largecircle. .largecircle. .circleincircle. .largecircle.
Example 144 0.07 MnS 8.4 .largecircle. .largecircle.
.circleincircle. .largecircle. Example 145 0.03 0.2 .largecircle.
.largecircle. .largecircle. .largecircle. Example 146 0.02 1.2
.largecircle. .largecircle. .largecircle. .largecircle.
INDUSTRIAL APPLICABILITY
[0185] The present invention provides a hot-dip galvanized steel
sheet showing excellent plating adhesion and sliding property even
with a substrate steel sheet containing a large quantity of Si.
Furthermore, an alloyed hot-dip galvanized steel sheet obtained by
alloying the hot-dip galvanized steel sheet shows also excellent
anti-powdering property. Both the galvanized steel sheets are
manufactured at high productivity.
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