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US4477280A
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US
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Heat resisting steel
Assignee: Hitachi Ltd
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Filing: 1982-12-22
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Granted: 1984-10-16
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Expires: 2002-12-22
Abstract
Abstract A heat resisting steel suitable for use as material of steam turbine parts. The steel has a substantially whole tempered martensite structure and consisting essentially of, by weight, 8 to 13% of Cr, 0.5 to 2% of Mo, 0.02 to 0.5% of V, 0.02 to 0.15% of Nb, 0.025 to 0.1% of N, 0.05 to 0.25% of C, not greater than 0.6% of Si, not greater than 1.5% of Mn, not greater than 1.5% of Ni, 0.0005 to 0.02% of Al, 0.1 to 0.5% of W and the balance substantially Fe, the ratio W/Al between W content and Al content ranging between 10 and 110.
Inventors
- 👤 Masao Shiga
- 👤 Seishin Kirihara
- 👤 Mitsuo Kuriyama
- 👤 Takatoshi Yoshioka
- 👤 Ryoichi Sasaki
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-02 09:01
CPC Classifications
C; C22; C22C; C22C38/00; C22C38/18; C22C38/22
Claims Analysis
Total Claims: 20
Claim 1
Independent Claim
143 words
A heat resisting steel having substantially whole tempered martensite structure and exhibiting, when tempered after quenching at 100° C./h, a 10 5 -hour creep rupture strength at 600° C. of at least 10 Kg/mm 2 , said steel consisting essentially of, by weight, 8 to 13% of Cr, 0.5 to 2% of Mo, 0.02 to 0.5% of V, 0.02 to 0.15% of Nb, 0.025 to 0.1% of N, 0.05 to 0.25% of C, not greater than 0.6% of Si, not greater tban 1.5% of Mn, no greater than 1.5% of Ni, 0.0005 to 0.02% of Al, 0.1 to 0.5% of W and the balance substantially Fe, the ratio W/Al between W content and Al content ranging between 20 and 80, and the Al and N contents being such that a value given by Al (wt. %)/N (wt. %) is not greater than 0.5.
Claim 2
Dependent Claim
143 words
A heat resisting steel having substantially whole tempered martensite structure and exhibiting, when tempered after quenching at 100° C./h, a 10 5 -hour creep rupture strength at 600° C. of at least 10 Kg/mm 2 , said steel consisting essentially of, by weight, 8 to 13% of Cr, 0.5 to 2% of Mo, 0.02 to 0.5% of V, 0.02 to 0.15% of Nb, 0.025 to 0.1% of N, 0.05 to 0.25% of C, not greater than 0.6% of Si, not greater tban 1.5% of Mn, no greater than 1.5% of Ni, 0.0005 to 0.02% of Al, 0.1 to 0.5% of W and the balance substantially Fe, the ratio W/Al between W content and Al content ranging between 20 and 80, and the Al and N contents being such that a value given by Al (wt. %)/N (wt. %) is not greater than 0.5.
Claim 3
Dependent Claim
25 words
A heat resisting steel according to claim 1, wherein the composition is prepared such that a value given by Mo(wt%)+3W(wt%) ranges between 1.4 and 2.6.
Claim 4
Dependent Claim
25 words
A heat resisting steel according to either one of claims 1 and 2, wherein the Cr equivalent of said steel is not greater than 12.
Claim 5
Dependent Claim
30 words
A heat resisting steel according to any one of claims 1 to 3, wherein the composition is prepared such that a value given by (3Mo(wt%)+W(wt%))/C(wt%) is not greater than 34.
Claim 6
Dependent Claim
25 words
A heat resisting steel according to any one of claims 1 to 4, wherein the Cr equivalent of said steel is not greater than 12.
Claim 7
Dependent Claim
140 words
A heat resisting steel having substantially whole tempered martensite structure and exhibiting, when tempered after quenching at 100° C./h, a 10 5 -hour creep rupture strength at 600° C. of at least 10 Kg/mm 2 , said steel consisting essentially of, by weight, 10 to 11.5% of Cr, 1 to 1.5% of Mo, 0.01 to 0.3% of V, 0.07 to 0.12% of Nb, 0.04 to 0.07% of N, 0.1 to 0.2% of C, 0.02 to 0.25% of Si, 0.3 to 1.0% of Mn, 0.3 to 1.0% of Ni, 0.001 to 0.01% of Al, 0.2 to 0.45% of W and the balance substantially Fe, the ratio W/Al between W content and Al content ranging between 30 and 60 and the Al and N contents being such that a value given by Al (wt. %)/N (wt. %) is not greater than 0.5.
Claim 8
Dependent Claim
140 words
A heat resisting steel having substantially whole tempered martensite structure and exhibiting, when tempered after quenching at 100° C./h, a 10 5 -hour creep rupture strength at 600° C. of at least 10 Kg/mm 2 , said steel consisting essentially of, by weight, 10 to 11.5% of Cr, 1 to 1.5% of Mo, 0.01 to 0.3% of V, 0.07 to 0.12% of Nb, 0.04 to 0.07% of N, 0.1 to 0.2% of C, 0.02 to 0.25% of Si, 0.3 to 1.0% of Mn, 0.3 to 1.0% of Ni, 0.001 to 0.01% of Al, 0.2 to 0.45% of W and the balance substantially Fe, the ratio W/Al between W content and Al content ranging between 30 and 60 and the Al and N contents being such that a value given by Al (wt. %)/N (wt. %) is not greater than 0.5.
Claim 9
Dependent Claim
152 words
A heat resisting steel for use as the material for steam turbine blades, having substantially whole tempered martensite structure and exhibiting, when tempered after quenching at 100° C./h, a 10 5 -hour creep rupture strength at 600° C. of at least 10 Kg/mm 2 , said steel consisting essentially of, by weight, 8 to 13% of Cr, 0.5 to 2% of Mo, 0.02 to 0.5% of V, 0.03 to 0.15% of Nb, 0.025 to 0.1% of N, 0.05 to 0.2% of C, not greater than 0.6% of Si, not greater than 1.5% of Mn, not greater than 1.5% of Ni, 0.0005 to 0.015% of Al, 0.1 to 0.5% of W and the balance substantially Fe, the ratio W/Al between W content and Al content ranging between 20 and 80, and the Al and N contents being such that a value given by Al (wt. %)/N (wt. %) is not greater than 0.5.
Claim 10
Dependent Claim
152 words
A heat resisting steel for use as the material for steam turbine blades, having substantially whole tempered martensite structure and exhibiting, when tempered after quenching at 100° C./h, a 10 5 -hour creep rupture strength at 600° C. of at least 10 Kg/mm 2 , said steel consisting essentially of, by weight, 8 to 13% of Cr, 0.5 to 2% of Mo, 0.02 to 0.5% of V, 0.03 to 0.15% of Nb, 0.025 to 0.1% of N, 0.05 to 0.2% of C, not greater than 0.6% of Si, not greater than 1.5% of Mn, not greater than 1.5% of Ni, 0.0005 to 0.015% of Al, 0.1 to 0.5% of W and the balance substantially Fe, the ratio W/Al between W content and Al content ranging between 20 and 80, and the Al and N contents being such that a value given by Al (wt. %)/N (wt. %) is not greater than 0.5.
Claim 11
Dependent Claim
25 words
A heat resisting steel according to claim 7, wherein the composition is prepared such that a value given by Mo(wt%)+3W(wt%) ranges between 1.4 and 2.6.
Claim 12
Dependent Claim
25 words
A heat resisting steel according to either one of claims 6 and 7, wherein the Cr equivalent of said steel ranges between 6 and 12.
Claim 13
Dependent Claim
25 words
A heat resisting steel according to claim 1, wherein the composition is prepared such that a value given by (3Mo(wt%)+W(wt%))/C(wt%) is not greater than 34.
Claim 14
Dependent Claim
94 words
A heat resisting steel according to claim 7, having substantially whole tempered martensite structure and consisting essentially of, by weight, 9 to 12% of Cr, 1 to 1.5% of Mo, 0.1 to 0.3% of V, 0.05 to 0.15% of Nb, 0.025 to 0.1% of N, 0.1 to 0.16% of C, 0.02 to 0.25% of Si, 0.3 to 1.0% of Mn, 0.3 to 1.0% of Ni, 0.001 to 0.01% of Al, 0.2 to 0.45% of W and the balance substantially Fe, the ratio W/Al between W content and Al content ranging between 20 and 80.
Claim 15
Dependent Claim
153 words
A heat resisting steel for use as the material for steam turbine rotor shafts, having substantially whole tempered martensite structure and exhibiting, when tempered after quenching at 100° C./h, a 10 5 -hour creep rupture strength at 600° C. of at least 10 Kg/mm 2 , said steel consisting essentially of, by weight, 8 to 13% of Cr, 0.5 to 2% of Mo, 0.02 to 0.5% of V, 0.02 to 0.12% of Nb, 0.025 to 0.1% of N, 0.1 to 0.25% of C, not greater than 0.6% of Si, not greater than 1.5% of Mn, not greater than 1.5% of Ni, 0.0005 to 0.01% of Al, 0.1 to 0.5% of W and the balance substantially Fe, the ratio W/Al between W content and Al content ranging between 20 and 80, and the Al and N contents being such that a value given by Al (wt. %)/N (wt. %) is not greater than 0.5.
Claim 16
Dependent Claim
153 words
A heat resisting steel for use as the material for steam turbine rotor shafts, having substantially whole tempered martensite structure and exhibiting, when tempered after quenching at 100° C./h, a 10 5 -hour creep rupture strength at 600° C. of at least 10 Kg/mm 2 , said steel consisting essentially of, by weight, 8 to 13% of Cr, 0.5 to 2% of Mo, 0.02 to 0.5% of V, 0.02 to 0.12% of Nb, 0.025 to 0.1% of N, 0.1 to 0.25% of C, not greater than 0.6% of Si, not greater than 1.5% of Mn, not greater than 1.5% of Ni, 0.0005 to 0.01% of Al, 0.1 to 0.5% of W and the balance substantially Fe, the ratio W/Al between W content and Al content ranging between 20 and 80, and the Al and N contents being such that a value given by Al (wt. %)/N (wt. %) is not greater than 0.5.
Claim 17
Dependent Claim
25 words
A heat resisting steel according to claim 12, wherein the composition is prepared such that a value given by Mo(wt%)+3W(wt%) ranges between 1.4 and 2.6.
Claim 18
Dependent Claim
25 words
A heat resisting steel according to either one of claims 12 and 13, wherein the Cr equivalent of said steel ranges between 6 and 10.
Claim 19
Dependent Claim
25 words
A heat resisting steel according to claim 12, wherein the composition is prepared such that a value given by (3Mo(wt%)+W(wt%))/C(wt%) is not greater than 32.
Claim 20
Dependent Claim
94 words
A heat resisting steel according to claim 10, having substantally whole tempered martensite structure and consisting essentially of, by weight, 9 to 12% of Cr, 1 to 1.5% of Mo, 0.1 to 0.3% of V, 0.03 to 0.10% of Nb, 0.025 to 0.1% of N, 0.14 to 0.22% of C, 0.02 to 0.25% of Si, 0.3 to 1.0% of Mn, 0.3 to 1.0% of Ni, 0.001 to 0.01% of Al, 0.2 to 0.45% of W and the balance substantially Fe, the ratio W/Al between W content and Al content ranging between 20 and 80.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1987-10-16 | 1988-04-16 | 1988-10-16 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1991-10-16 | 1992-04-16 | 1992-10-16 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1995-10-16 | 1996-04-16 | 1996-10-16 | $7700.00 | Window Closed / Lapsed |