STAINLESS STEEL MATERIAL WITH HIGH STRENGTH AND SUPERIOR RESISTANCE TO CORROSION, STRESS CORROSION CRACKING AND CRACKING DUE TO SULFIDE AND ITS MANUFACTURE

摘要

PURPOSE:To obtain a stainless steel material with high strength and superior resistance to corrosion, stress corrosion cracking and sulfide corrosion cracking, by austenitizing a steel material having a specified composition and contg. a restricted amount of ferrite and by subjecting it to rapid cooling, temperaturing and rapid cooling. CONSTITUTION:A steel material consisting of 0.05-0.15% C, =1.00% Si, 0.50- 2.00% Mn, =0.025% P, =0.010% S, =0.20% Ni, 0.02-0.10% Nb, =0.20% Cu, 11.0-14.0% Cr, 0.02-0.10% N, =0.10% Al and the balance Fe with inevitable impurities or further contg. Mo and V and having 20% ferrite content is austenitized at 900-1,150 deg.C. It is rapidly cooled from 800 deg.C to 500 deg.C at =10 deg.C/sec average cooling rate, tempered at 600-830 deg.C, and rapidly cooled from 500 deg.C to 300 deg.C at =5 deg.C/sec cooling rate. By this method the titled steel material suitable for use as the material of an oil well, etc. is obtd.