ULTRAHIGH STRENGTH STEEL EXCELLENT IN DELAYED FRACTURE RESISTANCE

摘要

PROBLEM TO BE SOLVED: To provide an ultrahigh strength steel having ≥150kgf/mm² tensile strength and excellent in delayed fracture resistance. ;SOLUTION: This steel has a composition consisting of, by weight, 0.005-0.1% C, 25-35% Ni, 0.01-0.1% Al, further one or ≥2 kinds among 0.01-1% Mn, 0.01-0.05% Ti, 0.01-0.05% Zr, and 0.001-0.006% Ca, and the balance iron with inevitable impurities and also has a dual phase structure consisting of martensite and austenite and having 5-60% volume fraction of austenite.;COPYRIGHT: (C)1997,JPO