| 摘要 |
PROBLEM TO BE SOLVED: To obtain a thin, wide steel sheet substitutable for a cold rolled steel sheet by specifying respective contents of C, Si, Mn, P, S, Al, and N in a steel composition, forming a part of N into a state of solid solution, and also controlling hot rolling conditions. SOLUTION: A steel, having a chemical composition consisting of, by weight, <=0.10% C, <=0.10% Si, <=0.8% Mn, <=0.04% P, <=0.02% S, <=0.150% Al, 0.0050-0.0200% N, and the balance Fe with inevitable impurities, is used, and further, N in a state of solid solution is allowed to exist by >=0.0030%. A slab of steel with this composition is heated to >=1000 deg.C and hot rolled to <=1.4 mm sheet thickness under the condition of >=800 deg.C finish rolling delivery side temperature. Cooling is started within 2 sec after the completion of finish rolling, and the resultant steel sheet is coiled at >=400 deg.C. By this method, the hot rolled steel sheet having >=340 MPa tensile strength TS can be obtained. As to the inevitable impurities in the steel composition, it is preferable to control the total content of Cu, Ni, Cr, and Mo and also the total content of Nb, Ti, V, and B to <=0.2% and to <=0.01%, respectively.
|
