Steel plate with low yield-tensile ratio and high toughness and method of manufacturing the same

摘要

A steel plate with a low yield ratio and high toughness. The steel plate comprises components of, by weight: C (0.05-0.08%), Si (0.15-0.30%), Mn (1.55-1.85%), P (less than or equal to 0.015%), S (less than or equal to 0.005%), Al (0.015-0.04%), Nb (0.015-0.025%), Ti (0.01-0.02%), Cr (0.20-0.40%), Mo (0.18-0.30%), N (less than or equal to 0.006%), O (less than or equal to 0.004%), Ca (0.0015-0.0050%), and Ni (less than or equal to 0.40%), a ratio of Ca to S being greater than or equal to 1.5, and the residual being Fe and inevitable impurities.