U.S. patent application number 15/350126 was filed with the patent office on 2017-05-18 for modification body.
The applicant listed for this patent is Georg Fischer Automobilguss GmbH, Georg Fischer Automotive (Kunshan) Co Ltd., Georg Fischer GmbH. Invention is credited to Werner Menk, Eric Thomas.
Application Number | 20170136537 15/350126 |
Document ID | / |
Family ID | 54979362 |
Filed Date | 2017-05-18 |
United States Patent
Application |
20170136537 |
Kind Code |
A1 |
Thomas; Eric ; et
al. |
May 18, 2017 |
MODIFICATION BODY
Abstract
The invention relates to a modification body for the production
of spheroidal graphite cast iron and to the method for producing a
cast part using the modification body according to the invention,
and to the cast part itself. The modification body serves for the
production of spheroidal graphite cast iron, in particular with a
predominantly ferritic structure, containing a carrier material,
preferably an iron-silicon alloy, wherein the modification body
contains 7-16 weight percent of boron.
Inventors: |
Thomas; Eric; (Mettmann,
DE) ; Menk; Werner; (Schaffhausen, CH) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Georg Fischer GmbH
Georg Fischer Automobilguss GmbH
Georg Fischer Automotive (Kunshan) Co Ltd. |
Mettmann
Singen
Kunshan City Jiangsu |
|
DE
DE
CN |
|
|
Family ID: |
54979362 |
Appl. No.: |
15/350126 |
Filed: |
November 14, 2016 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
B22D 1/007 20130101;
B22D 1/00 20130101; B22D 27/20 20130101; C22C 37/00 20130101; B22C
9/086 20130101; C22C 33/08 20130101; C21C 1/105 20130101; C22C
37/04 20130101; C22C 37/10 20130101; C21C 1/025 20130101 |
International
Class: |
B22D 27/20 20060101
B22D027/20; C22C 37/04 20060101 C22C037/04 |
Foreign Application Data
Date |
Code |
Application Number |
Nov 17, 2015 |
EP |
15 194 848.6 |
Claims
1. A modification body for the production of spheroidal graphite
cast iron with a predominantly ferritic structure, the modification
body comprising: a carrier material; and boron, wherein the boron
content of the modification body is 7-16 percent weight.
2. A method for production of a cast part made of spheroidal
graphite cast iron, the method comprising: inserting, into a
casting system prior to casting, at least one modification body
comprising a carrier material and boron, wherein the boron content
of the modification body is 7-16 percent weight.
3. The method for the production of a cast part made of spheroidal
graphite cast iron according to claim 2, wherein the at least one
modification body is inserted, prior to casting, into the casting
system between a pouring cup and a filter.
4. The method for the production of a cast part made of spheroidal
graphite cast iron according to claim 2, wherein at least one
modification body is added to a melt prior to casting.
5. The method for the production of a cast part made of spheroidal
graphite cast iron according to claim 2, wherein a number of the at
least one modification body is chosen so as to achieve a boron
content in the cast part of 0.002-0.008 percent weight.
6. The method for the production of a cast part made of spheroidal
graphite cast iron according to claim 2, wherein a number of the at
least one modification body is chosen so as to achieve a Brinell
hardness of at most 170 HB.
7. A cast part, the cast part being produced by a method
comprising: inserting, into a casting system prior to casting, at
least one modification body comprising a carrier material and
boron, wherein the boron content of the modification body is 7-16
percent weight, wherein the cast part is made of spheroidal
graphite cast iron and has a boron content of 0.002-0.008 percent
weight.
8. The cast part according to claim 7, wherein the cast part has a
maximum Brinell hardness of 170 HB.
9. The cast part according to claim 7, wherein the cast part has a
predominantly ferritic structure.
10. The modification body according to claim 1, wherein the carrier
material is an iron silicon alloy.
11. The method for the production of a cast part made of spheroidal
graphite cast iron according to claim 5, wherein the cast part made
of spheroidal graphite cast iron has a predominantly ferritic
structure.
12. The method for the production of a cast part made of spheroidal
graphite cast iron according to claim 6, wherein the Brinell
hardness is in the range 140-170 HB.
13. The cast part according to claim 8, wherein the Brinell
hardness is in the range 140-170 HB.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] This application claims benefit to European Patent
Application No. EP 15 194 848.6, filed Month Nov. 17, 2015, which
is incorporated by reference herein.
FIELD
[0002] The invention relates to a modification body for the
production of spheroidal graphite cast iron, to a method for
producing a cast part using such a modification body, and to a cast
part produced using such a method.
BACKGROUND
[0003] Cast iron generally contains between 2 and 4 weight percent
of carbon. The carbon is intimately mixed with the iron and the
form that the carbon adopts in the solidified cast iron defines the
features and properties of the cast iron parts. If the carbon
adopts the form of graphite, the cast iron is rather soft and can
be processed mechanically.
[0004] Graphite can occur in various forms. Spheroidal graphite
cast iron has high strength, but it is necessary to take into
account the structure types. Cast iron with spherical graphite
having a purely ferritic structure, and thus contains no cementite,
is soft and easily worked. By contrast, spheroidal graphite cast
iron and a pearlitic structure has good abrasion properties due to
the high strength. In turn, a pearlitic/ferritic structure is
stronger than a purely ferritic structure.
[0005] The production of cast iron involves the use of steel scrap
and also circulating material as starting material. Since such a
starting material generally contains a large amount of Mn and Cu,
the pearlite content in the resulting cast iron or cast part is
higher than desired. In addition, the excessive pearlite content in
the cast part is promoted by accelerated cooling.
[0006] In order to reduce or suppress the excessive formation of
pearlite, the strategy high-purity steel scrap and/or high-grade
pig iron, which contain little Mn and Cu, can be added into the
casting alloy. Market availability of steel scrap and pig iron of
this type is limited, and they are therefore expensive to source.
If the excessive Mn and/or Cu content is identified only after
melting, this can at best be corrected only by diluting the melt
with a melt having low Mn and/or Cu content. However, this is
expensive and in most cases very difficult to achieve, such that
the parts produced have excessive pearlite content and therefore
excessive strength, and cannot be used for the intended purpose and
must be scrapped.
SUMMARY
[0007] In an embodiment, the present invention provides.
BRIEF DESCRIPTION OF THE DRAWING
[0008] The present invention will be described in even greater
detail below based on the exemplary figures. The invention is not
limited to the exemplary embodiments. All features described and/or
illustrated herein can be used alone or combined in different
combinations in embodiments of the invention. The features and
advantages of various embodiments of the present invention will
become apparent by reading the following detailed description with
reference to the attached drawings which illustrate the
following:
[0009] The FIGURE shows a schematic illustration of a casting
system having a modification body according to an embodiment of the
invention.
DETAILED DESCRIPTION
[0010] A modification body and an associated method for the
production of spheroidal graphite cast iron are described herein
that can reduce the pearlite structure in cast iron or a cast part
and thus ensure a lower hardness and a greater elongation at break,
without increasing the production cost of the cast iron or the cast
part.
[0011] A modification body according to an embodiment of the
invention serves for the production of spheroidal graphite cast
iron, in particular with a predominantly ferritic structure,
containing a carrier material, preferably an iron-silicon
alloy.
[0012] A modification body according to an embodiment of the
invention is configured to be inserted into the casting system,
where the cast iron or the melt flows around it. A modification
body according to an embodiment of the invention is configured to
be added to the melt and dissolved thereby prior to casting. This
produces a cast part made of spheroidal graphite cast iron, having
a boron content of 0.002-0.008 weight percent.
[0013] The pearlite-reducing influence of boron is known, but
hitherto considered negative in the production of spheroidal
graphite cast iron since excessive boron content can lead to
microporosity and carbides, which are problematic above 0.01 weight
percent, and, when further increased, also lead to great
degeneration of graphite.
[0014] In order to reduce the pearlite content in the cast iron,
and thus increase the elongation at break and reduce the hardness,
at least one modification body according to an embodiment of the
invention, containing 7 to 16 weight percent of boron, is inserted,
prior to casting, into the casting system for a cast part. During
the mould-filling procedure, the cast iron, or the melt, flows
around the modification body such that the modification body
continuously yields boron which is taken up by the cast iron. To
that end, at least one modification body is inserted, prior to
casting, into the casting system. It is also possible for multiple
modification bodies to be arranged in the casting system. The
number of modification bodies arranged in the casting system can be
chosen depending on the required boron content in the cast
part.
[0015] A cast part according to an embodiment of the invention,
made of spheroidal graphite cast iron, has a boron content of
0.002-0.008 percent weight, which suppresses or reduces pearlite
formation and achieves the desired properties in terms of hardness
and elongation at break.
[0016] As described herein, at least one modification is configured
to be arranged between the pouring cup and the filter prior to
casting and the cast iron, or the melt, is flowed around the
modification body during casting. It is also possible for at least
one modification body to be configured to be added directly to the
cast iron or to the melt prior to casting.
[0017] A number and an arrangement of modification bodies can be
chosen depending on the boron content required in the cast part, or
to achieve a desired hardness and elongation at break.
[0018] A cast part with spheroidal graphite according to an
embodiment of the invention, produced using a method according to
an embodiment of the invention, preferably has a predominantly
ferritic structure.
[0019] A method according to an embodiment of the invention and the
use of the modification body according to an embodiment of the
invention results in the production of a cast part made of
spheroidal graphite cast iron, which preferably does not exceed a
Brinell hardness of 170 HB. A Brinell hardness of 140-170 HB has
been found to be advantageous.
[0020] The structure of a cast part made of spheroidal graphite
cast iron according to an embodiment of the invention is preferably
predominantly ferritic.
[0021] In an example case, a melt of spheroidal graphite cast iron
has, due to the use of impure steel scrap as the starting material,
a Mn content of 0.35 wt %, which is too high for the desired
application since, according to the analysis specifications in this
case the maximum permissible Mn content is 0.25 wt %. As a
consequence of the excessive Mn content in the present melt or cast
iron, the cast parts had a Brinell hardness of 190 HB instead of
the maximum 170 HB which is permissible according to the
specifications. The actual Brinell hardness of 190 HB and a
corresponding pearlite content of 30% by area, instead of a maximum
prescribed pearlite content of 25% by area, resulted in the cast
parts having to be scrapped.
[0022] For that reason, for a casting weight of 50 kg, a 50-gram
modification body containing 10% boron was inserted into each
casting mould into the casting system, preferably between the
pouring cup and the filter or upstream of the filter. As a result,
boron is continuously given off to the melt during the casting
procedure, such that the cast parts have a boron content of 0.006
wt %, resulting in a pearlite content of 19% by area and a Brinell
hardness of 167 HB, and the cast parts were accordingly fit for use
and corresponded to the stipulated specifications.
[0023] The FIGURE shows a schematic view of a casting system 1,
wherein the modification body 6 according to the invention is
arranged upstream of the filter 3, indicating a possible
arrangement of the modification body 6. The melt of spheroidal
graphite cast iron is introduced into the casting system 1 via the
pouring cup 2. The melt flows around the modification body 6,
drawing therefrom the desired quantity of boron. Then, the melt
flows through the filter 3 in order for undesirable impurities to
be filtered out. The melt in the subsequent feeder 4 serves to
continuously re-supply the melt in the cast part 5 during
cooling.
[0024] While the invention has been illustrated and described in
detail in the drawings and foregoing description, such illustration
and description are to be considered illustrative or exemplary and
not restrictive. It will be understood that changes and
modifications may be made by those of ordinary skill within the
scope of the following claims. In particular, the present invention
covers further embodiments with any combination of features from
different embodiments described above and below.
[0025] The terms used in the claims should be construed to have the
broadest reasonable interpretation consistent with the foregoing
description. For example, the use of the article "a" or "the" in
introducing an element should not be interpreted as being exclusive
of a plurality of elements. Likewise, the recitation of "or" should
be interpreted as being inclusive, such that the recitation of "A
or B" is not exclusive of "A and B," unless it is clear from the
context or the foregoing description that only one of A and B is
intended. Further, the recitation of "at least one of A, B and C"
should be interpreted as one or more of a group of elements
consisting of A, B and C, and should not be interpreted as
requiring at least one of each of the listed elements A, B and C,
regardless of whether A, B and C are related as categories or
otherwise. Moreover, the recitation of "A, B and/or C" or "at least
one of A, B or C" should be interpreted as including any singular
entity from the listed elements, e.g., A, any subset from the
listed elements, e.g., A and B, or the entire list of elements A, B
and C.
* * * * *