| 摘要 |
PURPOSE:To avert the defect in hole shapes during etching and to obtain stable press formability by punching holes in a cold rolled aluminum killed steel plate by a photoetching treatment then annealing the same at low temp. in an adequately regulated atmosphere. CONSTITUTION:A cold rolled aluminum killed steel plate of <=0.2mm. thickness is punched with holes by a photoetching treatment, whereby the problems of defect in hole shapes are averted. In this case, the cold rolled aluminum killed steel plate consists of <=0.004% C, 0.01-0.08% sol.Al, 0.15-0.40% Mn, <=100ppm N, and the balance Fe and unavoidable impurities. The above-mentioned steel plate after punching with holes is annealed at 600-800 deg.C in an atmosphere consisting of <=15ppm CO+CO2 (based on volume), 0.5-25vol% H2 and the balance substantially N2 and H2O. The annealed steel plate is formed by pressing. |
