US4530720A
Expired / Lapsed
US
⏱️ 0.0 years remaining
High temperature oxidation resistant austenitic steel
Assignee: Nippon Stainless Steel Co Ltd
•
Filing: 1983-11-21
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Granted: 1985-07-23
•
Expires: 2003-11-21
Abstract
Abstract The present invention relates to the austenitic steel having improved resistance to oxidation at the high temperature, comprising not more than 0.10% C, 0.1-5.0% Si, not more than 3% Mn, 7-45% Ni, 15-30% Cr and sulfur content being restricted to not more than 0.003%. According to the present invention, by limiting the sulfur content in the austenitic steel to not more than 0.003%, preferably to not more than 0.0015%, the heat-resisting steel material which can show improved resistance to oxidation under severe conditions including repeated heating to high temperatures and cooling to room temperature is provided.
Inventors
- 👤 Taishi Moroishi
- 👤 Hisao Fujikawa
- 👤 Junichiro Murayama
- 👤 Yuji Shoji
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-09 02:37
CPC Classifications
C; C22; C22C; C22C38/00; C22C38/18; C22C38/40; C22C38/58; F; F28; F28F; F28F19/00; F28F19/02; F28F19/06; F28F21/00; F28F21/08; F28F21/081; F28F21/082; F28F21/083
Claims Analysis
Total Claims: 30
Claim 1
Independent Claim
78 words
An austenitic steel, said austenitic steel having improved resistance to oxidation at temperatures above 700° C. and consisting essentially of the following alloying elements: C: not greater than 0.10% Si: more than 1%, but not greater than 5.0% Mn: not greater than 3.0% Ni: 7-15% Cr: 15-20%, the amounts of said alloying elements being adjusted to result in an austenitic microstructure, and a balance of iron and impurities of which sulfur is restricted to not greater than 0.003%.
Claim 2
Dependent Claim
78 words
An austenitic steel, said austenitic steel having improved resistance to oxidation at temperatures above 700° C. and consisting essentially of the following alloying elements: C: not greater than 0.10% Si: more than 1%, but not greater than 5.0% Mn: not greater than 3.0% Ni: 7-15% Cr: 15-20%, the amounts of said alloying elements being adjusted to result in an austenitic microstructure, and a balance of iron and impurities of which sulfur is restricted to not greater than 0.003%.
Claim 3
Dependent Claim
78 words
An austenitic steel, said austenitic steel having improved resistance to oxidation at temperatures above 700° C. and consisting essentially of the following alloying elements: C: not greater than 0.10% Si: more than 1%, but not greater than 5.0% Mn: not greater than 3.0% Ni: 10-15% Cr: 15-25%, the amounts of said alloying elements being adjusted to result in an austenitic microstructure, and a balance of iron and impurities of which sulfur is restricted to not greater than 0.003%.
Claim 4
Dependent Claim
78 words
An austenitic steel, said austenitic steel having improved resistance to oxidation at temperatures above 700° C. and consisting essentially of the following alloying elements: C: not greater than 0.10% Si: more than 1%, but not greater than 5.0% Mn: not greater than 3.0% Ni: 10-15% Cr: 15-25%, the amounts of said alloying elements being adjusted to result in an austenitic microstructure, and a balance of iron and impurities of which sulfur is restricted to not greater than 0.003%.
Claim 5
Dependent Claim
78 words
An austenitic steel, said austenitic steel having improved resistance to oxidation at temperatures above 700° C. and consisting essentially of the following alloying elements: C: not greater than 0.10% Si: more than 1%, but not greater than 5.0% Mn: not greater than 3.0% Ni: 15-25% Cr: 20-30%, the amounts of said alloying elements being adjusted to result in an austenitic microstructure, and a balance of iron and impurities of which sulfur is restricted to not greater than 0.003%.
Claim 6
Dependent Claim
78 words
An austenitic steel, said austenitic steel having improved resistance to oxidation at temperatures above 700° C. and consisting essentially of the following alloying elements: C: not greater than 0.10% Si: more than 1%, but not greater than 5.0% Mn: not greater than 3.0% Ni: 15-25% Cr: 20-30%, the amounts of said alloying elements being adjusted to result in an austenitic microstructure, and a balance of iron and impurities of which sulfur is restricted to not greater than 0.003%.
Claim 7
Dependent Claim
71 words
An austenitic steel, said austenitic steel having improved resistance to oxidation at temperatures above 700° C. and consisting essentially of the following alloying elements: C: not greater than 0.10% Si: 0.1-1.0% Mn: not greater than 3.0% Ni: 30-35% Cr: 20-25%, the amounts of said alloying elements being adjusted to result in an austenitic microstructure, and a balance of iron and impurities of which sulfur is restricted to not greater than 0.003%.
Claim 8
Dependent Claim
71 words
An austenitic steel, said austenitic steel having improved resistance to oxidation at temperatures above 700° C. and consisting essentially of the following alloying elements: C: not greater than 0.10% Si: 0.1-1.0% Mn: not greater than 3.0% Ni: 30-35% Cr: 20-25%, the amounts of said alloying elements being adjusted to result in an austenitic microstructure, and a balance of iron and impurities of which sulfur is restricted to not greater than 0.003%.
Claim 9
Dependent Claim
21 words
An austenitic steel as defined in any one of claims 1 and 2-4, which further comprises not greater than 0.1% Al.
Claim 10
Dependent Claim
35 words
An austenitic steel as defined in any one of claims 1 and 2-4, which further comprises one or more of Ca, Mg, Y and rare earths, the total amount thereof being not greater than 0.10%.
Claim 11
Dependent Claim
33 words
An austenitic steel as defined in any one of claims 1 and 2-4, which further comprises one or more of Ti, Nb, Zr, and Ta, the total amount thereof being 4XC% to 1.5%.
Claim 12
Dependent Claim
27 words
An austenitic steel as defined in any one of claims 1 and 2-4, which further comprises not greater than 1.5% Cu and/or not greater than 3% Mo.
Claim 13
Dependent Claim
22 words
An austenitic steel as defined in claim 1 or 2, in which Si is 3-5%, Ni is 10-15% and Cr is 15-20%.
Claim 14
Dependent Claim
30 words
An austenitic steel having improved resistance to oxidation at high temperature as defined in any one of claims 1 and 2-4, wherein sulfur is restricted to not greater than 0.0015%.
Claim 15
Dependent Claim
28 words
An austenitic steel as defined in claim 6, which further comprises one or more of Ti, Nb, Zr and Ta the total amount thereof being 4XC% to 1.5%.
Claim 16
Dependent Claim
22 words
An austenitic steel as defined in claim 6, which further comprises not greater than 1.5% Cu and/or not greater than 3% Mo.
Claim 17
Dependent Claim
22 words
An austenitic steel as defined in claim 7, which further comprises not greater than 1.5% Cu and/or not greater than 3% Mo.
Claim 18
Dependent Claim
20 words
An austenitic steel as defined in claim 6, in which Si is 3-5%, Ni is 10-15% and Cr is 15-20%.
Claim 19
Dependent Claim
20 words
An austenitic steel as defined in claim 7, in which Si is 3-5%, Ni is 10-15% and Cr is 15-20%.
Claim 20
Dependent Claim
20 words
An austenitic steel as defined in claim 8, in which Si is 3-5%, Ni is 10-15% and Cr is 15-20%.
Claim 21
Dependent Claim
73 words
An austenitic steel, said austenitic steel having improved resistance to oxidation at temperatures above 700° C. and consisting essentially of the following alloying elements: C: not greater than 0.10% Si: 0.1-1.0% Mn: not greater than 3% Ni: 7-25% Cr: 15-30% the amount of said alloying elements being adjusted to result in an austenitic single phase microstructure; and a balance of iron and impurities of which sulfur is restricted to not greater than 0.003%.
Claim 22
Dependent Claim
73 words
An austenitic steel, said austenitic steel having improved resistance to oxidation at temperatures above 700° C. and consisting essentially of the following alloying elements: C: not greater than 0.10% Si: 0.1-1.0% Mn: not greater than 3% Ni: 7-25% Cr: 15-30% the amount of said alloying elements being adjusted to result in an austenitic single phase microstructure; and a balance of iron and impurities of which sulfur is restricted to not greater than 0.003%.
Claim 23
Dependent Claim
28 words
An austenitic steel as defined in claim 17, which further comprises one or more of Ti, Nb, Zr and Ta the total amount thereof being 4XC% to 1.5%.
Claim 24
Dependent Claim
22 words
An austenitic steel as defined in claim 17, which further comprises not greater than 1.5% Cu and/or not greater than 3% Mo.
Claim 25
Dependent Claim
22 words
An austenitic steel as defined in claim 17, which further comprises not greater than 1.5% Cu and/or not greater than 3% Mo.
Claim 26
Dependent Claim
25 words
An austenitic steel having improved resistance to oxidation at high temperatures as defined in claim 17 wherein sulfur is restricted to not greater than 0.0015%.
Claim 27
Dependent Claim
40 words
An austenitic steel as defined in claim 17, which further comprises less than 0.10% of Al as a deoxidizing agent, and one or more of Ca, Mg, Y and rare earths, the total amount thereof being not greater than 0.10%.
Claim 28
Dependent Claim
105 words
An austenitic steel, said austenitic steel having improved resistance to oxidation at temperatures above 700° C. and consisting essentially of the following alloying elements: C: not greater than 0.10% Si: more than 1%, but not greater than 5.0% Mn: not greater than 3% Ni: 7-25% Cr: 15-30% Al: less than 0.10% as a deoxidizing agent, one or more of Ca, Mg, Y and rare earths, the total amount thereof being not greater than 0.10%, the amount of said alloying elements being adjusted to result in an austenitic microstructure; and a balance of iron and impurities of which sulfur is restricted to not greater than 0.003%.
Claim 29
Dependent Claim
105 words
An austenitic steel, said austenitic steel having improved resistance to oxidation at temperatures above 700° C. and consisting essentially of the following alloying elements: C: not greater than 0.10% Si: more than 1%, but not greater than 5.0% Mn: not greater than 3% Ni: 7-25% Cr: 15-30% Al: less than 0.10% as a deoxidizing agent, one or more of Ca, Mg, Y and rare earths, the total amount thereof being not greater than 0.10%, the amount of said alloying elements being adjusted to result in an austenitic microstructure; and a balance of iron and impurities of which sulfur is restricted to not greater than 0.003%.
Claim 30
Dependent Claim
17 words
An austenitic steel as defined in claim 23 in which Si is present in amount of 3-5%.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1988-07-22 | 1989-01-21 | 1989-07-23 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1992-07-22 | 1993-01-21 | 1993-07-23 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1996-07-22 | 1997-01-21 | 1997-07-23 | $7700.00 | Window Closed / Lapsed |