Claims
- 1. A method of manufacturing a cold rolled steel sheet having a good deep drawability, which comprises beginning a cooling within 2 seconds after the completion of finisher rolling of a hot rolled sheet of steel having a composition of not more than 0.0035% of C, not more than 1.0% of Si, not more than 1.0% of Mn, 0.005-0.10% of Al, not more than 0.15% of P, not more than 0.0035% of N, not more than 0.015% of S, (48/14N(%)+48/32S(%)).about.(3.multidot.48/12C(%)+48/32S(%)) of Ti and (0.2.multidot.93/12C(%)).about.(93/12C(%)) of Nb;
- cooling the final rolled steel sheet at an average cooling rate of not less than 10.degree. C./sec until it arrives at a coiling step;
- coiling the cooled steel sheet at a temperature of not more than 710.degree. C.;
- subjecting the coiled steel sheet to a cold rolling at a reduction of not less than 50%; and
- subjecting the cold rolled steel sheet to a continuous annealing in a heatcycle inclusive of heating from 400.degree. C. to 600.degree. C. at a heating rate of not less than 5.degree. C./sec and soaking at a temperature range of 700.degree. C.-Ac.sub.3 point for not less than one second.
- 2. A method for manufacturing a cold rolled steel sheet having a good deep drawability, which comprises beginning a cooling within 2 seconds after the completion of finisher rolling of a hot rolled sheet of steel having a composition of not more than 0.0035% of C, not more than 1.0% of Si, not more than 1.0% of Mn, 0.005-0.10% of Al, not more than 0.15% of P, not more than 0.0035% of N, not more than 0.015% of S, 4.multidot.(C(%)+N(%)).about.(3.multidot.48/12C(%)+48/14N(%)+48/32S(%)) of Ti and (0.2.multidot.93/12C(%)).about.(93/12C(%)) of Nb;
- cooling the final rolled steel sheet at an average cooling rate of not less than 10.degree. C./sec until it arrives at a coiling step;
- coiling the cooled steel sheet at a temperature of not more than 710.degree. C.,
- subjecting the coiled steel sheet to a cold rolling at a reduction of not less than 50%; and
- subjecting the cold rolled steel sheet to a continuous annealing in a heatcycle inclusive of heating from 400.degree. C. to 600.degree. C. at a heating rate of not less than 5.degree. C./sec and soaking at a temperature range of 700.degree. C.-Ac.sub.3 point for not less than one second.
Priority Claims (1)
Number |
Date |
Country |
Kind |
60-116661 |
May 1985 |
JPX |
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Parent Case Info
This application is a continuation of application Ser. No. 866,220, filed May 22, 1986 now abandoned.
US Referenced Citations (1)
Number |
Name |
Date |
Kind |
4504326 |
Tokunaga |
Mar 1985 |
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Continuations (1)
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Number |
Date |
Country |
Parent |
866220 |
May 1986 |
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