Method of producing cold-rolled steel sheet exhibiting improved press-formability

A method of producing a cold-rolled steel sheet having improved press-formability, which comprises preparing a molten steel having the following chemical composition:

• C:
• 0.001-0.015%,
• Mn:
• 0.01-1.20%,
• sol. Al:
• not more than 0.10%
• N:
• not more than 0.0060%, at least one element selected from the group consisting of:
• Ti:
• not more than 0.20%,
• Nb:
• not more than 0.20%, and
• Zr:
• not more than 0.20%, at least one element selected from the group consisting of:
• V:
• 0.01-0.20%, P:
• 0.03-0.10%,
• Cr:
• 0.05-1.00%,
• Rare earth metals:
• 0.03-0.20%,
• B:
• 0.0003-0.0040%, and
• Si:
• 0.10-2.00%, and the balance iron and incidental impurities, with the Ti-equivalent defined by the following Formula (1) and the C-equivalent defined by the following Formula (2) satisfying the relationship defined by Formula (3) below:
• Ti-equivalent=Ti(%)+48/93Nb(%)+48/91Zr(%) (1)
• C-equivalent=C(%)+12/14N(%) (2)
• (C-equivalent)-1/4(Ti-equivalent).ltoreq.0.0010(%) (3),
• rapidly cooling the thus prepared molten steel to continuously produce a thin cast plate, coiling the thus produced plate at a temperature of 500.degree.-800.degree. C., and applying cold rolling and then recrystallization annealing to the cast plate after uncoiling.