MANUFACTURE OF TEMPERED 60KGF/MM2 CLASS HIGH TENSION STEEL PLATE SUPERIOR IN SULFIDE AND AMMONIA STRESS CORROSION CRACKING RESISTANCE

摘要

PURPOSE:To manufacture the titled steel plate, by providing a prescribed weld cracking sensibility compsn. i.e. PCM value to steel plate, and decarburizing it at a prescribed temp. CONSTITUTION:Compsn. of steel slab is composed, of, by wt%, 0.06-0.14 C, 0.5 Si, 0.3-1.8 Mn, 0.025 P, 0.02 S, 0.01-0.1 V, 0.01-0.1 Al, 0.005 N, and the balance Fe with inevitable impurity. Further, exhibiting PCM value as a formula, PCM=0.24. The steel slab is rolled to a prescribed thickness, then the plate is heated to 1,100-1,300 deg.C before quenching treatment heating, to form decarburized layer having =0.5mm thickness and contg. =0.05% C at steel plate surface part. Next, the plate is subjected to quenching and tempering treatments.