Method of producing austenitic iron/carbon/manganese steel sheets having a high strength and excellent toughness and being suitable for cold forming, and sheets thus produced

摘要

A hot-rolled sheet of iron-carbon-manganese austenitic steel has the following composition (by wt %): 0.5 = C = 0.7; 17 = Mn = 24; Si = 3; Al = 0.050; S = 0.030; P = 0.080; N = 0.1; optionally one or more elements such as Cr = 1, Mo = 0.40, Ni = 1, Cu = 5, Ti = 0.50, Nb = 0.50 and V = 0.50; and iron and inevitable production impurities the remainder. The recrystallized fraction of the steel is greater than 75%, the surface fraction of precipitated carbides is less than 1.5%, and the medium grain size of the steel is less than 18 microns. Independent claims are given for: (a) fabrication of the hot-rolled steel sheet; (b) a cold-rolled steel sheet having the same composition as the hot-rolled sheet; and (c) fabrication of the cold-rolled sheet.