US4917738A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Steam turbine rotor for high temperature
Assignee: Kobe Steel Ltd
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Filing: 1988-05-31
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Granted: 1990-04-17
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Expires: 2008-05-31
Abstract
Abstract The present invention is directed to a steam turbine rotor which comprises an iron base alloy containing 0.05 to 0.2 wt % of carbon, 0.1 wt % or less of silicon, 0.05 to 1.5 wt % of manganese, more than 8.0 wt % to less than 13 wt % of chromium, less than 1.5 wt % of nickel, 0.1 to 0.3 wt % of vanadium, 0.01 to 0.1 wt % of niobium, 0.01 to 0.1 wt % of nitrogen, 0.02 wt % or less of aluminum, less than 0.50 wt % of molybdenum and 0.9 to 3.0 wt % of tungsten; contents of molybdenum Mo and tungsten W satisfying the following formulae 0.75≦1/2W+Mo and 3≦W/Mo; a δ-ferrite phase and a large grain boundry carbide being scarcely contained basically in the metallic structure; a matrix of martensite being formed therein.
Inventors
- 👤 Yusaku Takano
- 👤 Akio Hizume
- 👤 Yorimasa Takeda
- 👤 Toshio Fujita
- 👤 Shushi Kinoshita
- 👤 Kikuo Morita
- 👤 Masahiro Ikuta
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-03 13:02
CPC Classifications
C; C22; C22C; C22C38/00; C22C38/18; C22C38/22; C22C38/24; C22C38/26
Claims Analysis
Total Claims: 5
Claim 1
Independent Claim
131 words
A steam turbine rotor which comprises an iron base alloy containing 0.05 to 0.2 wt % of carbon, 0.1 wt % or less of silicon, 0.05 to 1.5 wt % of manganese, more than 8.0 wt % to less than 13 wt % of chromium, less than 1.5 wt % of nickel, 0.1 to 0.21 wt % of vanadium, 0.01 to 0.1 wt % of niobium, 0.01 to 0.1 wt % of nitrogen, 0.02 wt % or less of aluminum, 0.10-0.38 wt % of molybdenum and 0.9 to 3.0 wt % of tungsten; contents of molybdenum Mo and tungsten W satisfying the following formulae 0.75≦1/2W+Mo and 3≦W/Mo a δ-ferrite phase and a large grain boundary carbide being scarcely contained basically in the metallic structure; a matrix of martensite being formed therein.
Claim 2
Dependent Claim
131 words
A steam turbine rotor which comprises an iron base alloy containing 0.05 to 0.2 wt % of carbon, 0.1 wt % or less of silicon, 0.05 to 1.5 wt % of manganese, more than 8.0 wt % to less than 13 wt % of chromium, less than 1.5 wt % of nickel, 0.1 to 0.21 wt % of vanadium, 0.01 to 0.1 wt % of niobium, 0.01 to 0.1 wt % of nitrogen, 0.02 wt % or less of aluminum, 0.10-0.38 wt % of molybdenum and 0.9 to 3.0 wt % of tungsten; contents of molybdenum Mo and tungsten W satisfying the following formulae 0.75≦1/2W+Mo and 3≦W/Mo a δ-ferrite phase and a large grain boundary carbide being scarcely contained basically in the metallic structure; a matrix of martensite being formed therein.
Claim 3
Dependent Claim
46 words
A steam turbine rotor according to claim 1 wherein said iron base alloy further contains at least one of 0.05 wt % or less of tantalum, 0.05 wt % or less of titanium, 0.01 wt % or less of boron and 0.1 wt % of zirconium.
Claim 4
Dependent Claim
36 words
A steam turbine rotor according to claim 2 wherein when tantalum and titanium are added simultaneously in manufacturing said iron base alloy, contents of niobium Nb, tantalum Ta and titanium Ti satisfy the following formula Nb+1/2Ti<0.2.
Claim 5
Dependent Claim
20 words
The turbine rotor of claim 1 wherein the nickel content is in the range of 0.6 to 1.0 wt %.
References Cited (Backward Citations)
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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) | 1993-04-16 | 1993-10-16 | 1994-04-17 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1997-04-16 | 1997-10-16 | 1998-04-17 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2001-04-16 | 2001-10-16 | 2002-04-17 | $7700.00 | Window Closed / Lapsed |