| 摘要 |
PURPOSE:To obtain a ultrahigh tensile maraging steel plate superior in surface quality by hot-rolling the ultralow C maraging steel having a specified compsn. under a specified temp. and cumulative reduction ratios, next cold rolling, then applying recrystallization annealing and solution treatment thereto. CONSTITUTION:The steel contg. by weight, <=0.02% C, <=0.1% Si, <=0.2% Mn, <=0.01% P, <=0.01% S, <=0.01% N, >=2 kinds among 15-25% Ni, <=10.0% Co, <=7.0% Mo, <=0.2% Al, <=1.5% Ti and the balance Fe with inevitable impurities is melted. The steel is hot-rolled by the cumulative reduction ratios regulated to <=60% and 20% at <=1,000 deg.C and 950 deg.C respectively, furthermore, under >=900 deg.C condition. Next, the material is wound at 300-600 deg.C, cold-rolled then recrystallization annealing and solution treatment are applied thereto. Furthermore, if necessary, said plate is cooled to <=200 deg.C, and age hardening treatment at 400- 600 deg.C for <=10min is applied. |
