Claims
- 1. A method of making wrought high tension steel having superior strength, toughness, and weldability which comprises the steps of:
- preparing a steel consisting essentially by weight of; 0.005-0.12% C, not more than 0.6% Si, 0.6-1.4% Mn, not more than 0.005% S, 0.005-0.08% Al, 0.01-0.08% Nb, 0.0005-0.002% B, 0.004-0.03% Ti, not more than 0.006% N, at least one element by weight selected from the group consisting of; 0.01-0.08% V, 0.1-1.0% Ni, 0.1-1.0% Cu, 0.1-1.0% Cr, 0.05-0.3% Mo, 0.0005-0.005% Ca, and 0.001-0.03% in total of rare earth metal or metals, and the remainder being Fe and incidental impurities and the Ti and N contained in the steel satisfy the relationship expressed by a formula
- -0.01%.ltoreq.Ti-3.4N.ltoreq.0.02%;
- heating the steel at a temperature within a range of 1,000.degree.-1,200.degree. C.;
- rolling the steel with a rolling reduction of not less than 60% at a temperature range of not more than 900.degree. C. and the temperature for terminating the rolling is kept within a range of 640.degree.-850.degree. C.;
- cooling the steel, after it has been rolled down, to a pre-determined temperature lower than 550.degree. C. with a cooling rate within a range of 10.degree.-40.degree. C./sec.
- 2. The method of claim 1 wherein the amount of Si is not more than 0.2%.
- 3. The method of claim 1 wherein the amount of S is not more than 0.001%.
- 4. The method of claim 1 wherein the steel further includes P in an amount of less than 0.030%.
- 5. The method of claim 4 wherein the amount of P is not more than 0.010%.
- 6. The method of claim 1 wherein the amount of Si is not more than 0.2%; and the amount of S is not more than 0.001%.
- 7. The method of claim 6 wherein the steel further includes P in an amount of less than 0.030%.
- 8. The method of claim 7 wherein the amount of P is not more than 0.010%.
- 9. The method of claim 1 wherein the steel is cooled after it has been rolled down to a predetermined temperature lower than 550.degree. C. to about 350.degree. C.
- 10. The method of claim 9 wherein the steel is air-cooled below about 350.degree. C.
Priority Claims (1)
Number |
Date |
Country |
Kind |
56-174950 |
Oct 1981 |
JPX |
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CROSS REFERENCE TO RELATED CASES
The present application is a continuation-in-part of our copending U.S. patent application Ser. No. 424,780, filed Sept. 27, 1982 and entitled "A Method of Making Wrought High Tension Steel Having Superior Low Temperature Toughness", abandoned.
US Referenced Citations (1)
Number |
Name |
Date |
Kind |
4219371 |
Nakasugi et al. |
Aug 1980 |
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Continuation in Parts (1)
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Number |
Date |
Country |
Parent |
424780 |
Sep 1982 |
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