US4406713A
Expired / Lapsed
US
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Method of making high-strength, high-toughness steel with good workability
Assignee: KAISHA KOBE SEIKO SHO KK
•
Filing: 1981-03-20
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Granted: 1983-09-27
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Expires: 2001-03-20
Abstract
Abstract A high-strength, high-toughness steel with good workability is produced by working a steel containing 0.005-0.3% C and 0.3-2.5% Mn and optionally up to 1.5% Si, in the course of hot working thereof, at temperatures within the range of from the Ar 3 point to 930° C. or to 980° C. (for a steel containing Nb, V, Ti and/or Zr) at an area reduction rate of at least 30%, and, in the course of cooling, rapidly cooling the steel in the ferrite phase precipitation temperature range when the ferrite phase has occupied 5-65% or 5-60% (for a steel with Si and/or Nb, V, Ti and/or Zr) of the steel, whereby a two-phase structure comprising ferrite and martensite is produced.
Inventors
- 👤 Toshiaki Yutori
- 👤 Rikuo Ogawa
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 08:58
CPC Classifications
C; C21; C21D; C21D8/00; C21D8/06; C21D2211/00; C21D2211/005; C21D2211/008
Claims Analysis
Total Claims: 18
Claim 1
Independent Claim
89 words
A method for making a high-strength, high-toughness steel with good workability which comprises working a steel containing 0.005-0.3% C and 0.3-2.5% Mn, in the course of hot working thereof, at temperatures within the range of from the Ar 3 point to 930° C. at an area reduction rate of at least 30%, and, in the course of cooling, rapidly cooling the steel in the ferrite phase precipitation temperature range when the ferrite phase has occupied 5-65% of the steel whereby a two-phase structure comprising ferrite and martensite is produced.
Claim 2
Independent Claim
89 words
A method for making a high-strength, high-toughness steel with good workability which comprises working a steel containing 0.005-0.3% C and 0.3-2.5% Mn, in the course of hot working thereof, at temperatures within the range of from the Ar 3 point to 930° C. at an area reduction rate of at least 30%, and, in the course of cooling, rapidly cooling the steel in the ferrite phase precipitation temperature range when the ferrite phase has occupied 5-65% of the steel whereby a two-phase structure comprising ferrite and martensite is produced.
Claim 3
Dependent Claim
31 words
The method of claim 1, wherein the steel further contains up to 1.5% Si and the rapid cooling is carried out when the ferrite phase has occupied 5-60% of the steel.
Claim 4
Dependent Claim
18 words
The method of claim 2, wherein the steel contains 0.005-0.2%, C, 0.3-2.5% Mn and up to 1.5% Si.
Claim 5
Dependent Claim
18 words
The method of claim 2, wherein the steel contains 0.005-0.2% C, 0.3-2.5% Mn and up to 1.0% Si.
Claim 6
Independent Claim
124 words
A method of making a high-strength, high-toughness steel with good workability which comprises working a steel containing 0.005-0.3% C, 0.3-2.5% Mn and at least one element of the group consisting of Nb, V, Ti and Zr in amounts of up to 0.1%, up to 0.15%, up to 0.3% and up to 0.3%, respectively, in the course of hot working thereof following heating to 1,000°-1,300° C., at temperatures within the range of from the Ar 3 point to 980° C. at an area reduction rate of at least 30%, and, in the course of cooling, quenching the steel in the ferrite phase precipitation temperature range when the ferrite phase has occupied 5-65% of the steel, whereby a two-phase structure comprising ferrite and martensite is produced.
Claim 7
Independent Claim
124 words
A method of making a high-strength, high-toughness steel with good workability which comprises working a steel containing 0.005-0.3% C, 0.3-2.5% Mn and at least one element of the group consisting of Nb, V, Ti and Zr in amounts of up to 0.1%, up to 0.15%, up to 0.3% and up to 0.3%, respectively, in the course of hot working thereof following heating to 1,000°-1,300° C., at temperatures within the range of from the Ar 3 point to 980° C. at an area reduction rate of at least 30%, and, in the course of cooling, quenching the steel in the ferrite phase precipitation temperature range when the ferrite phase has occupied 5-65% of the steel, whereby a two-phase structure comprising ferrite and martensite is produced.
Claim 8
Dependent Claim
30 words
The method of claim 5, wherein the steel further contains up to 1.5% Si and the quenching is carried out when the ferrite phase has occupied 5-60% of the steel.
Claim 9
Dependent Claim
49 words
The method of claim 6, wherein the steel contains 0.005-0.2% C, 0.3-2.5% Mn, up to 1.0% Si and at least one element of the group consisting of Nb, V, Ti and Zr in amounts of up to 0.1%, up to 0.15%, up to 0.3% and up to 0.3%, respectively.
Claim 10
Independent Claim
51 words
The method of any one of claims 1-7 wherein said steel, after hot working, is air cooled in the ferrite phase precipitation temperature range until the ferrite phase occupies 5-65% of the steel, then cooled rapidly, whereby the remainder of the steel is converted into a phase comprised predominantly of martensite.
Claim 11
Dependent Claim
20 words
The process of claim 1 wherein said rapid cooling is carried out to a temperature below the M s temperature.
Claim 12
Dependent Claim
21 words
The process of claim 1 wherein said high strength steel has a tensile strength of at least 70 kg/mm 2 .
Claim 13
Dependent Claim
35 words
The process of claim 1 wherein said high strength steel has a tensile strength of at least 70 kg/mm 2 and a value of (tensile strength in kg/mm 2 ×% elongation) of at least 1700.
Claim 14
Dependent Claim
9 words
A steel produced by the process of claim 1.
Claim 15
Dependent Claim
9 words
A steel produced by the process of claim 5.
Claim 16
Dependent Claim
24 words
A steel produced by the process of claim 1 wherein said rapid cooling is carried out to a temperature below the M s temperature.
Claim 17
Dependent Claim
20 words
A steel produced by the process of claim 1 having a tensile strength of at least 70 kg/mm 2 .
Claim 18
Dependent Claim
34 words
A steel produced by the process of claim 1 having a tensile strength of at least 70 kg/mm 2 and a value of (tensile strength in kg/mm 2 ×% elongation) of at least 1700.
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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) | 1986-09-26 | 1987-03-28 | 1987-09-27 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1990-09-26 | 1991-03-28 | 1991-09-27 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1994-09-26 | 1995-03-28 | 1995-09-27 | $7700.00 | Window Closed / Lapsed |