U.S. patent application number 12/727136 was filed with the patent office on 2010-07-29 for sports gear apparatus made from cr-mn-n austenitic stainless steel.
This patent application is currently assigned to ADVANCED INTERNATIONAL MULTITECH CO., LTD. Invention is credited to Wei-Ming Liu.
Application Number | 20100189589 12/727136 |
Document ID | / |
Family ID | 42354300 |
Filed Date | 2010-07-29 |
United States Patent
Application |
20100189589 |
Kind Code |
A1 |
Liu; Wei-Ming |
July 29, 2010 |
SPORTS GEAR APPARATUS MADE FROM CR-MN-N AUSTENITIC STAINLESS
STEEL
Abstract
A Cr--Mn--N austenitic stainless steel, in which moderate
manganese (Mn) and nitrogen (N) are essentially substituted for the
costly nickel to produce a novel Cr--Mn--N steel, is provided,
whereby reducing the cost of materials while maintaining the
original physical and mechanical properties. The composition
thereof includes by weight: 0.005% to 0.08% carbon, 0.3% to 0.9%
silicon, 12.1% to 14.8% manganese, 0.001% to 0.04% phosphorus,
0.001% to 0.03% sulfur, 16% to 19% chromium, 0.001% to <0.82%
nickel, 0.2% to 0.45% nitrogen, 0.001% to 0.3% molybdenum, 0.001%
to 0.3% copper, 0.001% to 1.0% niobium by weight; 0.001% to 0.5%
titanium by weight; and trace elements unavoidable in most
manufacturing processes.
Inventors: |
Liu; Wei-Ming; (Jiangxi
Province, CN) |
Correspondence
Address: |
MORRIS MANNING MARTIN LLP
3343 PEACHTREE ROAD, NE, 1600 ATLANTA FINANCIAL CENTER
ATLANTA
GA
30326
US
|
Assignee: |
ADVANCED INTERNATIONAL MULTITECH
CO., LTD
Kaohsiung City
TW
|
Family ID: |
42354300 |
Appl. No.: |
12/727136 |
Filed: |
March 18, 2010 |
Related U.S. Patent Documents
|
|
|
|
|
|
Application
Number |
Filing Date |
Patent Number |
|
|
11905922 |
Oct 5, 2007 |
|
|
|
12727136 |
|
|
|
|
Current U.S.
Class: |
420/57 ; 420/56;
420/59 |
Current CPC
Class: |
C22C 38/48 20130101;
C22C 38/02 20130101; C22C 38/50 20130101; C22C 38/001 20130101;
C22C 38/42 20130101; C22C 38/44 20130101; C22C 38/58 20130101 |
Class at
Publication: |
420/57 ; 420/59;
420/56 |
International
Class: |
C22C 38/58 20060101
C22C038/58; C22C 38/44 20060101 C22C038/44 |
Foreign Application Data
Date |
Code |
Application Number |
Aug 29, 2007 |
TW |
096132137 |
Claims
1. A sports gear apparatus made from Cr--Mn--N austenitic stainless
steel, the Cr--Mn--N austenitic stainless steel comprising: 0.005%
to 0.08% carbon by weight; 0.3% to 0.9% silicon by weight; 12.1% to
14.8% manganese by weight; 0.001% to 0.04% phosphorus by weight;
0.001% to 0.03% sulfur by weight; 16% to 19% chromium by weight;
0.001% to <0.82% nickel by weight; 0.2% to 0.45% nitrogen by
weight; 0.001% to 0.3% molybdenum by weight; 0.001% to 0.3% copper
by weight; 0.001% to 1.0% niobium by weight; 0.001% to 0.5%
titanium by weight; and trace elements unavoidable in most
manufacturing processes.
2. The sports gear apparatus made from Cr--Mn--N austenitic
stainless steel, the Cr--Mn--N austenitic stainless steel
comprising: 0.048% carbon by weight; 0.73 silicon by weight; 12.67%
manganese by weight; 0.023% phosphorus by weight; 0.007% sulfur by
weight; 17.11% chromium by weight; 0.39% nickel by weight; 0.35%
nitrogen by weight; 0.061% molybdenum by weight; 0.12% copper by
weight; 0.34% niobium by weight; 0.21% titanium by weight; and
trace elements unavoidable in most manufacturing processes.
3. The sports gear apparatus made from Cr--Mn--N austenitic
stainless steel, the Cr--Mn--N austenitic stainless steel
comprising: 0.055% carbon by weight; 0.82 silicon by weight; 13.01%
manganese by weight; 0.019% phosphorus by weight; 0.005% sulfur by
weight; 17.59% chromium by weight; 0.42% nickel by weight; 0.31%
nitrogen by weight; 0.043% molybdenum by weight; 0.11% copper by
weight; 0.28% niobium by weight; 0.25% titanium by weight; and
trace elements unavoidable in most manufacturing processes.
4. The sports gear apparatus made from Cr--Mn--N austenitic
stainless steel, the Cr--Mn--N austenitic stainless steel
comprising: 0.061% carbon by weight; 0.75 silicon by weight; 13.78%
manganese by weight; 0.025% phosphorus by weight; 0.005% sulfur by
weight; 16.64% chromium by weight; 0.45% nickel by weight; 0.28%
nitrogen by weight; 0.039% molybdenum by weight; 0.13% copper by
weight; 0.25% niobium by weight; 0.32% titanium by weight; and
trace elements unavoidable in most manufacturing processes.
5. The sports gear apparatus made from Cr--Mn--N austenitic
stainless steel, the Cr--Mn--N austenitic stainless steel
comprising: 0.072% carbon by weight; 0.79 silicon by weight; 14.55%
manganese by weight; 0.018% phosphorus by weight; 0.004% sulfur by
weight; 17.02% chromium by weight; 0.48% nickel by weight; 0.42%
nitrogen by weight; 0.028% molybdenum by weight; 0.1% copper by
weight; 0.51% niobium by weight; 0.45% titanium by weight; and
trace elements unavoidable in most manufacturing processes.
6. The sports gear apparatus made from Cr--Mn--N austenitic
stainless steel, the Cr--Mn--N austenitic stainless steel
comprising: 0.065% carbon by weight; 0.86 silicon by weight; 13.81%
manganese by weight; 0.015% phosphorus by weight; 0.009% sulfur by
weight; 18.51% chromium by weight; 0.29% nickel by weight; 0.36%
nitrogen by weight; 0.045% molybdenum by weight; 0.11% copper by
weight; 0.43% niobium by weight; 0.41% titanium by weight; and
trace elements unavoidable in most manufacturing processes.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS AND PATENTS
[0001] This application is a Continuation-In-Part of U.S. patent
application Ser. No. 11/905,922, filed Oct. 5, 2007, which itself
claims priority of Taiwan Patent Application No. 096132137, Filed
Aug. 29, 2007, the disclosures of which are incorporated herein by
reference in its entireties.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] The present invention relates to an austenitic stainless
steel, in particular to a sports gear apparatus made from Cr--Mn--N
austenitic stainless steel.
[0004] 2. Related Art
[0005] The ordinary stainless steel has the properties of the
pleasing white luster on the surface and the stainless tendency.
There is a variety of stainless steel that is popular among the
consumers and widely used in, for example, stainless steel
kitchenware, water tank, mechanical components, sports gear,
aerospace materials, medical instruments, and 3C industry etc., in
which the most widely and frequently used is the 304 stainless
steel. The standard composition thereof includes 18% chromium plus
8% nickel, i.e., the commonly called 18-8 stainless steel. The
characteristics of such stainless steel include good mechanical
properties, magnetism free, stable metallographic grain structure
unable to be changed by heat treatment, good durability, good
processability, and superior corrosion resistance due to the higher
content of nickel. However, the 304 stainless steel is at a stiff
price because of the worldwide shortage of nickel caused by war.
Accordingly, it is an important issue to reduce the nickel content
in the aforementioned Cr--Ni stainless steel and to use other
elements in the composition thereof to maintain or even enhance the
inherent mechanical properties and corrosion resistance, whereby
saving the resource of nickel and reducing the cost of
materials.
SUMMARY OF THE INVENTION
[0006] In view of the foregoing, an object of the present invention
is to provide a novel steel of single austenitic structure with
less nickel, and the corrosion resistance, strength, elongation of
which in the marine atmosphere and the acid atmosphere are at the
same level as or even better than those of the 304 stainless
steel.
[0007] To solve the aforementioned problem, the present invention
disposes a technique using moderate manganese (Mn) and nitrogen (N)
in substitution for the costly nickel to produce a novel Cr--Mn--N
steel, whereby providing a Cr--Mn--N austenitic stainless steel
comprising: 0.005% to 0.08% carbon by weight; 0.3% to 0.9% silicon
by weight; 12.1% to 14.8% manganese by weight; 0.001% to 0.04%
phosphorus by weight; 0.001% to 0.03% sulfur by weight; 16% to 19%
chromium by weight; 0.001% to <0.82% nickel by weight; 0.2% to
0.45% nitrogen by weight; 0.001% to 0.3% molybdenum by weight;
0.001% to 0.3% copper by weight; 0.001% to 1.0% niobium by weight;
0.001% to 0.5% titanium by weight; and trace elements unavoidable
in most manufacturing processes.
[0008] The effects obtained by practice of the present invention
lie in: the present invention employs the formation mechanism of
austenitic (or .gamma.) steel, substituting moderate manganese and
nitrogen for the costly nickel to produce a novel Cr--Mn--N steel
of single austenitic structure, while maintaining the corrosion
resistance, strength, elongation thereof in the marine atmosphere
and the acid atmosphere at the same level as or even better than
those of the 304 stainless steel, so as to achieve the purpose of
reducing the cost of materials. The present invention adopts the
method of substituting manganese and nitrogen for nickel to produce
the pure magnetism-free austenitic stainless steel, the mechanical
property UTS of which is approximately 200 MPa higher than that of
the 304 stainless steel, the Y.S of which is approximately one time
higher than that of the 304 stainless steel, the elongation reaches
50%, and the corrosion resistance is equal. And the most important
is that the unit price thereof is less than half of the 304
stainless steel. The characteristics of this novel steel include
excellent fluidity, superior casting properties, and good
resistance to high temperature oxidation.
BRIEF DESCRIPTION OF THE DRAWINGS
[0009] The present invention will become more fully understood from
the detailed description given herein below for illustration only,
and which thus is not limitative of the present invention, and
wherein:
[0010] FIG. 1 is a Schaeffler diagram showing the Ni--Cr equivalent
of the Cr--Mn--N austenitic stainless steel according to one
embodiment of the present invention; and
[0011] FIGS. 2A and 2B are metallographs showing different parts of
the Cr--Mn--N austenitic stainless steel according to one
embodiment of the present invention.
DETAILED DESCRIPTION OF THE INVENTION
[0012] The contents of the present invention are described in
details through specific embodiments with reference to the figures.
The reference numerals mentioned in the specification correspond to
equivalent reference numerals in the figures.
[0013] The present invention essentially includes a Cr--Mn--N
stainless steel of austenitic metallographic structure, which is
melted by electric arc furnace or vacuum induction furnace. The
composition of the Cr--Mn--N austenitic stainless steel includes by
weight: 0.005% to 0.08% carbon; 0.3% to 0.9% silicon; 12.1% to
14.8% manganese; 0.001% to 0.04% phosphorus; 0.001% to 0.03%
sulfur; 16% to 19% chromium; 0.001% to <0.82% nickel; 0.2% to
0.45% nitrogen; 0.001% to 0.3% molybdenum; 0.001% to 0.3% copper;
0.001% to 1.0% niobium by weight; 0.001% to 0.5% titanium by
weight; and trace elements unavoidable in most manufacturing
processes.
[0014] The equations of the composition of the above elements
are:
[0015] Ni equivalent=% Ni+30.times.% C+0.5.times.% Mn+30% N
[0016] Cr equivalent=% Cr+% Mo+1.5.times.% Si+0.5.times.% Cb
[0017] Referring to the phase diagram shown in FIG. 1, where the
ordinate is Ni equivalent and the abscissa is Cr equivalent, if the
point falls in the austenitic area according to computation, then
the requirements in table 1 are satisfied.
TABLE-US-00001 TABLE 1 Composition % C % Si % Mn % P % S % Cr % Ni
% N % Mo % Cu Mass 0.002 to 0.08 0.3 to 0.9 12.1 to 14.8 <0.04
<0.03 16 to 19 0.5 to 1.8 0.2 to 0.45 <0.3 <0.3 Percentage
Maximum 0.002 0.3 12.1 16 0.5 0.1 0 Minimum 0.08 0.9 14.8 19 1.3
0.45 0.3
[0018] Minimum Ni
equivalent=0.5+30.times.0.002+0.5.times.12.1+30.times.0.2=12.61
[0019] Maximum Ni
equivalent=1.8+30.times.0.08+0.5.times.14.8+30.times.0.45=25.1
[0020] Minimum Cr
equivalent=16+0+1.5.times.0.3+0.5.times.0=16.45
[0021] Maximum Cr
equivalent=19+0.3+1.5.times.0.9+0.5.times.0=20.65
[0022] The shadowed area in FIG. 1 shows the major austenitic
composition.
[0023] Composition analysis of the test samples is shown in table
2.
TABLE-US-00002 TABLE 2 Composition % % C % Si % Mn % P % S % Cr %
Ni % N Mass 0.0079 0.65 12.27 17.06 1.68 0.42 Percentage
[0024] Maximum Ni
equivalent=1.68+30.times.0.0079+0.5.times.12.27+30.times.0.42=20.652
[0025] Minimum Cr
equivalent=17.06+0+1.5.times.0.65+0.5.times.0=18.035
[0026] Further referring to the phase diagram shown in FIG. 1, the
point falls in the austenitic area, which satisfies the
requirements.
[0027] The present invention essentially employs manganese and
nitrogen in partial or complete substitution for nickel. The
characteristics of manganese and nitrogen are analyzed below.
[0028] The influence of manganese on grain structure includes:
[0029] a. The content of manganese should be 2% or less when used
as deoxidizer.
[0030] b. The content of manganese may be up to 20% when used as an
alloy element.
[0031] c. The substitution of manganese for nickel increases
solubility of nitrogen, achieving the effects of saving nickel and
enhancing strength.
[0032] The influence of manganese on mechanical properties
includes:
[0033] a. When the content of manganese is 2% or less, hardness is
not affected but tensile strength and yield strength decrease.
[0034] b. The high-temperature thermoplasticity of high Ni--Cr
.gamma. S.S is improved.
[0035] The influence of manganese on corrosion resistance
includes:
[0036] MnS inclusion causes decreases in corrosion resistance and
interstitial corrodibility.
[0037] The influence of nitrogen on grain structure includes:
[0038] a. Nitrogen dramatically forms and broadens the .gamma.
phase area, thereby enhancing the .gamma. stability.
[0039] b. Carbide precipitation is suppressed and the precipitation
of .sigma. phase is delayed, which benefits the anti-sensitization
of intergranular corrosion and toughness of the steel. The
influence of nitrogen on mechanical properties includes:
[0040] a. By means of solid solution strengthening (which forms
interstitial solid solution), strength of the steel significantly
increases while plasticity and toughness decrease.
[0041] b. Excess of nitrogen (>0.84% ) results in
plastic-brittle transition.
[0042] According to the Schaeffler diagram of the Ni--Cr equivalent
in FIG. 1, manganese and nitrogen may partially or completely
substitute for nickel in .gamma. stainless steel, whereby enhancing
strength and maintaining elongation as that of the 304 stainless
steel without changing the structure of the steel.
[0043] Harmful elements such as phosphorus and sulfur tend to be
generated by the melted iron in the furnace during smelting, where
the content of phosphorus should be controlled under 0.04% or less,
and the content of sulfur should be controlled under 0.04% or
less.
[0044] The compositions of the embodiments of the present invention
and the contrast material are shown in table 3 below. According to
Embodiment 1-5 in table 3, the compositions of the Cr--Mn--N
austenitic stainless steel are all within the range of 0.005% to
0.08% carbon by weight; 0.3% to 0.9% silicon by weight; 12.1% to
14.8% manganese by weight; 0.001% to 0.04% phosphorus by weight;
0.001% to 0.03% sulfur by weight; 16% to 19% chromium by weight;
0.001% to <0.82% nickel by weight; 0.2% to 0.45% nitrogen by
weight; 0.001% to 0.3% molybdenum by weight; 0.001% to 0.3% copper
by weight; 0.001% to 1.0% niobium by weight; 0.001% to 0.5%
titanium by weight; and trace elements unavoidable in most
manufacturing processes.
TABLE-US-00003 TABLE 3 Composition Content % Element C Si Mn P S Cr
Ni N Mo Cu Nb Ti Embodiment 1 0.048 0.73 12.67 0.023 0.007 17.11
0.39 0.35 0.061 0.12 0.34 0.21 Embodiment 2 0.055 0.82 13.01 0.019
0.005 17.59 0.42 0.31 0.043 0.11 0.28 0.25 Embodiment 3 0.061 0.75
13.78 0.025 0.005 16.64 0.45 0.28 0.039 0.13 0.25 0.32 Embodiment 4
0.072 0.79 14.55 0.018 0.004 17.02 0.48 0.42 0.028 0.1 0.51 0.45
Embodiment 5 0.065 0.86 13.81 0.015 0.009 18.51 0.29 0.36 0.045
0.11 0.43 0.41
[0045] The mechanical properties in the aforementioned embodiments
in table 3 are shown in table 4 below. Here, for observation the
mechanical properties, the tests are heat treatment firstly, and
followed by solution heat treatment. The condition for the heat
treatment is in the temperature of 1038 for 1 hour, and the
condition for the solution heat treatment is in a fast cooling
environment.
TABLE-US-00004 TABLE 4 Mechanical Property Density .sigma..sub.b
.sigma..sub.s .delta. Hardness P Salt Spray Test Specimens Mpa Mpa
% HRB HB kg/cm.sup.3 36 H 48 H 304 Stainless 520 206 40-50
.ltoreq.90 .ltoreq.187 7.85 No rust No rust Steel (Contrast
Material) Embodiment 1 775 460 55 86 175 7.77 No rust No rust
Embodiment 2 760 465 63 87 180 7.76 No rust No rust Embodiment 3
775 471 56 86 175 7.77 No rust No rust Embodiment 4 780 486 58 86
175 7.75 No rust No rust Embodiment 5 785 479 57 86 175 7.75 No
rust No rust
[0046] According to table 4, it shows all of the Embodiment 1-5
represent the single austenitic structure, while maintaining the
corrosion resistance, strength, elongation thereof in the marine
atmosphere and the acid atmosphere at the same level as or even
better than those of the 304 stainless steel, so as to achieve the
purpose of reducing the cost of materials. Specifically, when
adding the element niobium (0.001% to 1.0% by weight) and titanium
(0.001% to 0.5% by weight) into the composition of Cr--Mn--N
austenitic stainless steel, this can increase 5% or more
scalability, due to the increase of condensation nuclei and
enabling the organization of metal grain refinement. Therefore,
when the above compositions are used, these compositions can
provide ways for adjusting the angle of the product, such as sports
gear apparatus.
[0047] In addition, when adding the element niobium (0.001% to 1.0%
niobium by weight) and titanium (0.001% to 0.5% by weight) into the
composition of Cr--Mn--N austenitic stainless steel, it can also
increase the effect of de-oxidation. Therefore, when the above
compositions are used, it can reduce the failure rate by 50%, so
that these compositions are suitable used for mass production.
[0048] Referring to the metallographs of different parts shown in
FIGS. 2A and 2B, it is observed that the structure thereof is
.gamma. before heat treatment. Therefore, the steel is a completely
.gamma. stainless steel.
[0049] To sum up, the present invention is not restricted to the
particular details described herein. Indeed, those skilled in the
art having the benefit of this disclosure will appreciate that many
other variations from the foregoing description and drawings may be
made within the scope of the present invention. Accordingly, it is
the following claims including any amendments thereto that define
the scope of the invention.
* * * * *