PURPOSE: To produce the title high-strength and high-toughness steel sheet having excellent resistance to stress corrosion cracking by specifying the wt.% of C, Si, Mn, Ni, Mo, Cr, and Al in the steel, heating the steel, applying specified rolling and then specified hardening, and tempering the steel.
CONSTITUTION: The steel contg., by weight, 0.02W0.10% C, ≤0.50% Si, 0.4W1.5% Mn, 1.0W8.0% Ni, 0.1W1.5% Mo, ≤1.5% Cr, and 0.001W0.08% SolAl is heated at 1000W1250°C. In the hot rolling, 20W60% draft and 30W70% draft are respectively applied at the temps. where austenite is recrystallized and not recrystallized. Rolling is finished at ≥650°C, then the steel is water-cooled from the temp. higher than the Ar3 point, and cooling is stopped at 150°C. The steel is reheated at Ac3W(Ac3+100°C), hardened, and then tempered at the temp. lower than the Ac1 point. One or more kinds among ≤1.5% Cu, ≤0.12% V, ≤0.04% Nb, ≤0.015% Ti, and ≤0.0050% Ca are added, as required. to the steel. By this method, a high-strength and high-toughness steel sheet having excellent resistance to stress corrosion cracking can be produced.
OKAMURA YOSHIHIRO
MURAOKA HIROHIDE
| JPS6132372A | 1986-02-15 | |||
| JPS6112820A | 1986-01-21 | |||
| JPS58217629A | 1983-12-17 | |||
| JPS61127813A | 1986-06-16 | |||
| JPS63241114A | 1988-10-06 |