HOT ROLLED STEEL SHEET FOR EXTRA-LOW CARBON COLD ROLLED STEEL SHEET

摘要

PROBLEM TO BE SOLVED: To obtain a hot rolled steel sheet for the stock of an extra-low carbon cold rolled steel sheet in which surface roughening resistance and workability are made compatible by forming the surface layer part to a specified thickness from the surface of an extra-low carbon hot rolled steel sheet having a specified C content of a recrystallized structure and forming the internal layer part in a specified ratio of the total sheet thickness with a sheet thickness center as the center of a worked structure. ;SOLUTION: A hot rolled steel sheet in which the surface layer part occupying 1/10 of the total sheet thickness from the surface of an extra-low carbon hot rolled steel sheet contg., by weight, ≤0.01% C is formed of a recrystallized structure, and the internal layer part occupying 1/2 of the total sheet thickness with a sheet thickness center as the center is formed of a worked structure is prepd. The componential compsn. of this hot rolled steel sheet is composed of the one contg., by weight, ≤0.01% C, ≤1.0% Si, 0.05 to 2.0% Mn, ≤0.15% P, ≤0.02% S, 0.01 to 0.1% Al and ≤0.005% N, furthermore contg. one or more kinds among 0.002 to 0.1% Ti, 0.002 to 0.1% Nb, 0.002 to 0.1% V and 0.01 to 0.5% Cr, and the balance Fe with inevitable impurities.;COPYRIGHT: (C)1999,JPO