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US4316753A
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Method for producing low alloy hot rolled steel strip or sheet having high tensile strength, low yield ratio and excellent total elongation
Assignee: Nippon Steel Corp
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Filing: 1979-03-21
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Granted: 1982-02-23
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Expires: 1999-03-21
Abstract
Abstract A method for producing a low alloy hot rolled steel strip or sheet comprising hot rolling a steel slab at a finishing temperature not higher than the Ar3 transformation temperature plus 60 DEG C. and cooling and coiling the hot rolled strip at a temperature not higher than 500 DEG C. The steel slab contains not more than 0.20% carbon, 0.50 to 2.50% manganese and 0.05 to 1.0% chromium and optionally contains not more than 1.0% silicon, the balance being iron and unavoidable impurities. The resultant strip or sheet has a high tensile strength of not less than 40 kg/mm2, a low yeild ratio of not more than 70% and an excellent total elongation of not less than 25%.
Inventors
- 👤 Kunishige Kaneko
- 👤 Mamoru Tashiro
- 👤 Nagayasu Takemoto
- 👤 Itaru Imabayashi
- 👤 Takashi Furukawa
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-08 21:10
CPC Classifications
C; C21; C21D; C21D8/00; C21D8/02; C21D8/0221; C21D8/0226; C21D2211/00; C21D2211/001; C21D2211/002; C21D2211/008
Claims Analysis
Total Claims: 12
Claim 1
Independent Claim
124 words
A method for producing a low alloy hot rolled steel strip or sheet comprising: hot rolling a steel slab consisting essentially of not more than 0.20% carbon, 0.50 to 2.50% manganese and 0.05 to 1.0% chromium with the balance being iron and unavoidable impurities at a finishing temperature not higher than the Ar 3 transformation temperature plus 60° C., cooling the hot rolled steel strip or sheet, and coiling the hot rolled steel strip or sheet at a temperature not higher than 500° C., wherein said sheet or strip in the as hot rolled condition has high tensile strength of not less than 40 kg/mm 2 , low yield ratio of less than about 60%, and excellent total elongation of not less than 25%.
Claim 2
Independent Claim
124 words
A method for producing a low alloy hot rolled steel strip or sheet comprising: hot rolling a steel slab consisting essentially of not more than 0.20% carbon, 0.50 to 2.50% manganese and 0.05 to 1.0% chromium with the balance being iron and unavoidable impurities at a finishing temperature not higher than the Ar 3 transformation temperature plus 60° C., cooling the hot rolled steel strip or sheet, and coiling the hot rolled steel strip or sheet at a temperature not higher than 500° C., wherein said sheet or strip in the as hot rolled condition has high tensile strength of not less than 40 kg/mm 2 , low yield ratio of less than about 60%, and excellent total elongation of not less than 25%.
Claim 3
Dependent Claim
26 words
The method of claim 1 wherein the hot rolling is performed at a finishing temperature within the range within which the ferrite and austenite phases coexist.
Claim 4
Dependent Claim
23 words
The method of claim 1 or 2 wherein the hot rolling is carried out at a reduction rate of less than about 40%.
Claim 5
Independent Claim
15 words
The method of claims 1 or 2 wherein up to 1% of silicon is present.
Claim 6
Independent Claim
16 words
The method of claims 1 or 2 wherein the steel contains no more than 0.015% sulfur.
Claim 7
Independent Claim
26 words
The method of claims 1 or 2 wherein the steel contains Zr in an amount such that the ratio Zr/S is between about 2 to 10.
Claim 8
Independent Claim
31 words
The method of claims 1 or 2 wherein the steel contains a rare earth metal in an amount such that the ratio rare earth metal/S is between about 1.3 to 5.0.
Claim 9
Independent Claim
30 words
The method of claims 1 or 2 wherein the steel contains La or Ce in an amount such that the ratio La/S or Ce/S is between about 0.5 to 3.0.
Claim 10
Independent Claim
26 words
The method of claims 1 or 2 wherein the steel contains Ca in an amount such that the ratio Ca/S is between about 0.5 to 3.0.
Claim 11
Independent Claim
42 words
The method of claims 1 or 2 wherein the steel strip or sheet has a tensile strength of not less than 40 kg/mm 2 , a yield ratio of not more than 60%, and a total elongation of not less than 25%.
Claim 12
Independent Claim
29 words
The method of claims 1 or 2 wherein the coiling temperature is less than about 430° C. and the yield ratio of the steel is less than about 60%.
References Cited (Backward Citations)
US4062700A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1985-02-22 | 1985-08-24 | 1986-02-23 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1989-02-22 | 1989-08-24 | 1990-02-23 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1993-02-22 | 1993-08-24 | 1994-02-23 | $7700.00 | Window Closed / Lapsed |