PRODUCTION OF HOT ROLLED STEEL SHEET EXCELLENT IN SULFIDE STRESS CORROSION CRACKING RESISTANCE IN PLASTIC DEFORMATION ENVIRONMENT

摘要

PURPOSE: To produce a hot rolled steel sheet excellent in sulfide stress corrosion cracking resistance in a plastic deformation environment by subjecting a steel contg. specified ratios of C, Si, Mn, Nb, P, S, Ca and Al to heating, rolling and cooling under specified conditions. ;CONSTITUTION: A steel having a compsn. contg., by weight, ≤0.05% C, ≤0.5% Si, 0.8 to 1.6% Mn, 0.005 to 0.07% Nb, ≤0.005% P, ≤0.001% S, 0.0020 to 0.0040% Ca and ≤0.1% Al, and the balance Fe with inevitable impurities is prepd. This steel is heated to a temp. T calculated from the formula I or above. From the same heating temp. to 950°C, it is rolled at ≥60% in total draft, and, with a temp. lower than the Ar₃ temp. by 20°C calculated from the formula II as a finishing temp. in the unrecrystallization region from 950°C to the finishing temp., it is rolled at ≥80% in total draft. Next, in the temp. range from the finishing temp. to ≤550°C, it is cooled at ≥5°C/s rate.;COPYRIGHT: (C)1995,JPO