COLD ROLLED STEEL SHEET EXCELLENT IN PRESS WORKABILITY AND CHEMICAL CONVERTIBILITY AND ALLOYED GALVANIZED STEEL SHEET EXCELLENT IN PRESS WORKABILITY AND POWDERING RESISTANCE

摘要

PROBLEM TO BE SOLVED: To produce a cold rolled steel sheet and an alloyed galvanized steel sheet producible without requiring special production control and having excellent chemical convertibility and powdering resistance as well as excellent press formability. ;SOLUTION: This cold rolled steel sheet has a compsn. contg., by mass, ≤0.003% C, ≤0.3% Si, 0.05 to 0.5% Mn, ≤0.02% P, ≤0.02S S, 0.01 to 0.1% Al, Ti: 3.43N+1.5S≤Ti≤0.040%, 0.007 to 0.015% Nb, 0.03 to 0.12% Cr, ≤0.005% N, and the balance Fe with inevitable impurities. Furthermore, as for the alloyed galvanized steel sheet, in the above components, the content of P may be prescribed to ≥0.008% and the upper limit of the Ti content to 0.035%. Both steel sheets have characteristics in the prescribed containing ranges of Nb and Cr in particular.;COPYRIGHT: (C)1998,JPO