| 摘要 |
PROBLEM TO BE SOLVED: To manufacture a steel sheet sheet for deep drawing, having high r-value and reduced in the plane anisotropy of mechanical properties, such as r-value, elongation, and yield strength, by providing a hot rolled plate which has a specific composition and a structure having an average ferrite grain size of specific size or below and also has an aging index AI within a specific range. SOLUTION: This base plate for cold rolling for hot rolled plate has a composition consisting of, by weight, 0.001-0.0040% C, <=1.5% Si, <=1.0% Mn, <=0.2% P, >0.05-0.30% Ti, 0.0003-0.0030% B, <=0.10% Al, and the balance Fe with inevitable impurities and a structure having <25μm average ferrite grain size and also has 5-30 MPa aging index AI. It is preferable that one or >=2 kinds among the following groups A to C are incorporated into the above composition: group A consisting of <=0.1 wt.% Nb; group B consisting of <=1.0 wt.%, in total, of one or >=2 kinds among >=0.01 wt.% each of Ni, Cr, and Mo; group C consisting of <=0.1 wt.%, in total, of either or both of >=0.0005 wt.% Ca and >=0.0005 wt.% REM.
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