US4414024A
Expired / Lapsed
US
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Martensitic heat-resistant steel
Assignee: Hitachi Ltd
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Filing: 1982-08-26
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Granted: 1983-11-08
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Expires: 2002-08-26
Abstract
Abstract This invention discloses martensitic heat-resistant steel consisting essentially of 0.1 to 0.2 wt. % of C, up to 0.4 wt. % of Si, up to 1 wt. % of Mn, 9 to 12 wt. % of Cr, 0.1 to 0.3 wt. % of V, 0.02 to 0.25 wt. % of Nb, 0.03 to 0.1 wt. % of N, up to 1 wt. % of Ni, molybdenum and tungsten in amounts falling within the range encompassed by lines connecting a point A (0.7 wt. % of Mo and 1.1 wt. % of W), a point B (1.2 wt. % of Mo and 1.1 wt. % of W), a point C (1.6 wt. % of Mo and 0.33 wt. % of W) and a point D (0.7 wt. % of Mo and 0.33 and wt. % of W) as shown in FIG. 1 and the balance of iron. The martensitic heat-resistant steel in accordance with the present invention is suitable for use in steam turbine blades and rotor shafts.
Inventors
- 👤 Masao Siga
- 👤 Seishin Kirihara
- 👤 Mitsuo Kuriyama
- 👤 Takatoshi Yosioka
- 👤 Shintaro Takahashi
- 👤 Takehiko Yoshida
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-02 07:07
CPC Classifications
C; C22; C22C; C22C38/00; C22C38/18; C22C38/22
Claims Analysis
Total Claims: 10
Claim 1
Independent Claim
172 words
A martensitic heat-resistant steel consisting essentially of 0.1 to 0.2 wt.% of carbon, up to 0.4 wt.% of silicon, up to 1 wt.% of manganese, 9 to 12 wt.% of chromium, 0.1 to 0.3 wt.% of vanadium, 0.02 to 0.25 wt.% of niobium, 0.03 to 0.1 wt.% of nitrogen, up to 1 wt.% of nickel, molybdenum and tungsten in amounts falling within the range encompassed by lines connecting a point A (0.7 wt.% of molybdenum and 1.1 wt.% of tungsten), a point B (1.2 wt.% of molybdenum and 1.1 wt.% of tungsten), a point C (1.6 wt.% of molybdenum and 0.33 wt.% of tungsten) and a point D (0.7 wt.% of molybdenum and 0.33 wt.% of tungsten), and the balance of iron; said steel having a fully tempered martensitic structure and a Cr equivalent of up to 10 and showing substantially no δ ferritic structure and when said steel is subjected to tempering after quenching, the creep rupture strength for 10 5 hours at 600° C. is 11 kg/mm 2 or more.
Claim 2
Dependent Claim
172 words
A martensitic heat-resistant steel consisting essentially of 0.1 to 0.2 wt.% of carbon, up to 0.4 wt.% of silicon, up to 1 wt.% of manganese, 9 to 12 wt.% of chromium, 0.1 to 0.3 wt.% of vanadium, 0.02 to 0.25 wt.% of niobium, 0.03 to 0.1 wt.% of nitrogen, up to 1 wt.% of nickel, molybdenum and tungsten in amounts falling within the range encompassed by lines connecting a point A (0.7 wt.% of molybdenum and 1.1 wt.% of tungsten), a point B (1.2 wt.% of molybdenum and 1.1 wt.% of tungsten), a point C (1.6 wt.% of molybdenum and 0.33 wt.% of tungsten) and a point D (0.7 wt.% of molybdenum and 0.33 wt.% of tungsten), and the balance of iron; said steel having a fully tempered martensitic structure and a Cr equivalent of up to 10 and showing substantially no δ ferritic structure and when said steel is subjected to tempering after quenching, the creep rupture strength for 10 5 hours at 600° C. is 11 kg/mm 2 or more.
Claim 3
Dependent Claim
172 words
A martensitic heat-resistant steel consisting essentially of 0.1 to 0.2 wt.% of carbon, 0.05 to 0.3 wt.% of silicon, 0.4 to 0.8 wt.% of manganese, 10.5 to 11.5 wt.% of chromium, 0.1 to 0.3 wt.% of vanadium, 0.02 to 0.25 wt.% of niobium, 0.04 to 0.08 wt.% of nitrogen, 0.4 to 0.8 wt.% of nickel, molybdenum and tungsten in amounts falling within the range encompassed by lines connecting a point A (0.7 wt.% of molybdenum and 1.1 wt.% of tungsten), a point B (1.2 wt.% of molybdenum and 1.1 wt.% of tungsten), a point C (1.6 wt.% of molybdenum and 0.33 wt.% of tungsten) and a point D (0.7 wt.% of molybdenum and 0.33 wt.% of tungsten) and the balance of iron; said steel having a fully tempered martensitic structure and a Cr equivalent of up to 10 and showing substantially no δ ferritic structure and when said steel is subjected to tempering after quenching, the creep rupture strength for 10 5 hours at 600° C. is 11 kg/mm 2 or more.
Claim 4
Dependent Claim
172 words
A martensitic heat-resistant steel consisting essentially of 0.1 to 0.2 wt.% of carbon, 0.05 to 0.3 wt.% of silicon, 0.4 to 0.8 wt.% of manganese, 10.5 to 11.5 wt.% of chromium, 0.1 to 0.3 wt.% of vanadium, 0.02 to 0.25 wt.% of niobium, 0.04 to 0.08 wt.% of nitrogen, 0.4 to 0.8 wt.% of nickel, molybdenum and tungsten in amounts falling within the range encompassed by lines connecting a point A (0.7 wt.% of molybdenum and 1.1 wt.% of tungsten), a point B (1.2 wt.% of molybdenum and 1.1 wt.% of tungsten), a point C (1.6 wt.% of molybdenum and 0.33 wt.% of tungsten) and a point D (0.7 wt.% of molybdenum and 0.33 wt.% of tungsten) and the balance of iron; said steel having a fully tempered martensitic structure and a Cr equivalent of up to 10 and showing substantially no δ ferritic structure and when said steel is subjected to tempering after quenching, the creep rupture strength for 10 5 hours at 600° C. is 11 kg/mm 2 or more.
Claim 5
Dependent Claim
183 words
A steam turbine blade made of forged steel, said forged steel consisting essentially of 0.1 to 0.2 wt.% of carbon, up to 0.4 wt.% of silicon, up to 1 wt.% of manganese, 9 to 12 wt.% of chromium, 0.1 to 0.3 wt.% of vanadium, 0.07 to 0.25 wt.% of niobium, 0.03 to 0.1 wt.% of nitrogen, up to 1 wt.% of nickel, molybdenum and tungsten in amounts falling within the range encompassed by lines connecting a point A (0.7 wt.% of molybdenum and 1.1 wt.% of tungsten), a point B (1.2 wt.% of molybdenum and 1.1 wt.% of tungsten), a point C (1.6 wt.% of molybdenum and 0.33 wt.% of tungsten) and a point D (0.7 wt.% of molybdenum and 0.33 wt.% of tungsten) and the balance of iron, and said steel having a fully tempered martensitic structure and a Cr equivalent of up to 10 and showing substantially no δ ferritic structure, said steel having been subjected to tempering after quenching in oil, to exhibit a creep rupture strength for 10 5 hours at 600° C. of 15 kg/mm 2 or more.
Claim 6
Dependent Claim
183 words
A steam turbine blade made of forged steel, said forged steel consisting essentially of 0.1 to 0.2 wt.% of carbon, up to 0.4 wt.% of silicon, up to 1 wt.% of manganese, 9 to 12 wt.% of chromium, 0.1 to 0.3 wt.% of vanadium, 0.07 to 0.25 wt.% of niobium, 0.03 to 0.1 wt.% of nitrogen, up to 1 wt.% of nickel, molybdenum and tungsten in amounts falling within the range encompassed by lines connecting a point A (0.7 wt.% of molybdenum and 1.1 wt.% of tungsten), a point B (1.2 wt.% of molybdenum and 1.1 wt.% of tungsten), a point C (1.6 wt.% of molybdenum and 0.33 wt.% of tungsten) and a point D (0.7 wt.% of molybdenum and 0.33 wt.% of tungsten) and the balance of iron, and said steel having a fully tempered martensitic structure and a Cr equivalent of up to 10 and showing substantially no δ ferritic structure, said steel having been subjected to tempering after quenching in oil, to exhibit a creep rupture strength for 10 5 hours at 600° C. of 15 kg/mm 2 or more.
Claim 7
Dependent Claim
73 words
The steam turbine blades as defined in claim 3 wherein the amounts of molybdenum and tungsten are within the range encompassed by lines connecting a point E (0.9 wt.% of molybdenum and 0.95 wt.% of tungsten), a point F (1.3 wt.% of molybdenum and 0.95 wt.% of tungsten), said point C (1.6 wt.% of molybdenum and 0.33 wt.% of tungsten) and a point G (1.1 wt.% of molybdenum and 0.33 wt.% of tungsten).
Claim 8
Dependent Claim
181 words
A rotor shaft for steam turbines made of forged steel, said forged steel consisting essentially of 0.1 to 0.2 wt.% of carbon, up to 0.4 wt.% of silicon, up to 1 wt.% of manganese, 9 to 12 wt.% of chromium, 0.1 to 0.3 wt.% of vanadium, 0.02 to 0.12 wt.% of niobium, 0.03 to 0.1 wt.% of nitrogen, up to 1 wt.% of nickel, molybdenum and tungsten in amounts falling within the range encompassed by lines connecting a point A (0.7 wt.% of molybdenum and 1.1 wt.% of tungsten), a point B (1.2 wt.% of molybdenum and 1.1 wt.% of tungsten), a point C (1.6 wt.% of molybdenum and 0.33 wt.% of tungsten) and a point D (0.7 wt.% of molybdenum and 0.33 wt.% of tungsten) and the balance of iron, said steel having a fully tempered martensitic structure and a Cr equivalent of up to 9 and showing substantially no δ ferritic structure, and said steel having been subjected to tempering after quenching to exhibit a creep rupture strength for 10 5 at 600° C. of 11 kg/mm 2 .
Claim 9
Dependent Claim
181 words
A rotor shaft for steam turbines made of forged steel, said forged steel consisting essentially of 0.1 to 0.2 wt.% of carbon, up to 0.4 wt.% of silicon, up to 1 wt.% of manganese, 9 to 12 wt.% of chromium, 0.1 to 0.3 wt.% of vanadium, 0.02 to 0.12 wt.% of niobium, 0.03 to 0.1 wt.% of nitrogen, up to 1 wt.% of nickel, molybdenum and tungsten in amounts falling within the range encompassed by lines connecting a point A (0.7 wt.% of molybdenum and 1.1 wt.% of tungsten), a point B (1.2 wt.% of molybdenum and 1.1 wt.% of tungsten), a point C (1.6 wt.% of molybdenum and 0.33 wt.% of tungsten) and a point D (0.7 wt.% of molybdenum and 0.33 wt.% of tungsten) and the balance of iron, said steel having a fully tempered martensitic structure and a Cr equivalent of up to 9 and showing substantially no δ ferritic structure, and said steel having been subjected to tempering after quenching to exhibit a creep rupture strength for 10 5 at 600° C. of 11 kg/mm 2 .
Claim 10
Dependent Claim
75 words
The rotor shaft for steam turbines as defined in claim 5 wherein the amounts of molybdenum and tungsten are within the range encompassed by lines connecting a point E (0.9 wt.% of molybdenum and 0.95 wt.% of tungsten), a point F (1.3 wt.% of molybdenum and 0.95 wt.% of tungsten), said point C (1.6 wt.% of molybdenum and 0.33 wt.% of tungsten) and a point G (1.1 wt.% of molybdenum and 0.33 wt.% of tungsten).
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) | 1986-11-07 | 1987-05-09 | 1987-11-08 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1990-11-07 | 1991-05-09 | 1991-11-08 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1994-11-07 | 1995-05-09 | 1995-11-08 | $7700.00 | Window Closed / Lapsed |