Process of producing steel strip or sheet comprising strain-induced martensite

摘要

There is provided a steel of working-induced martensitic type steel consisting essentially, by mass, of 0.01 to 0.10% carbon, not more than 3.0% silicon, more than 5.0 but not more than 10.0% manganese, 1.0 to 12.0% nickel, 4 to 18% chromium, at least one kind of 0.1 to 4.0% in total in terms of Mo + 1/2 W which at least one kind is selected from the group consisting of molybdenum and tungsten, from 0 inclusive but not more than 5.0% copper, from 0 inclusive but not more than 0.15% nitrogen, not more than 0.10% aluminum, not more than 0.005% oxygen, and the balance substantially iron, "A" value, which is defined by        "A"= Ni + 0.65Cr + 0.98Mo + 0.49W + 1.05Mn + 0.35Si + Cu + 12.6(C + N)     (1)with a proviso that any element which is not added is calculated as zero,being in a range of 13 to 27%, said steel containing in austenite a martensite phase of not less than 30 volume % after cold working.