PRODUCTION OF FERRITIC STAINLESS STEEL HAVING EXCELLENT STRESS CORROSION CRACKING RESISTANCE AND CARBON DIOXIDE CORROSION RESISTANCE

摘要

PURPOSE:To permit production of a titled steel having uniform acicular ferrite structure with one time of heat treatment, by specifying the mutual ratios of Cr, C and N to be added to a ferritic stainless steel having a specific compsn. CONSTITUTION:The steel having the compsn. contg., by weight %, =0.25 C, 0.1-0.5 Si, 0.2-1.0 Mn, 9-16.0 Cr, =0.02 P, =0.02 S, 0.01-0.05 Al, and 0.01-0.25 N, consisting of the balance Fe and satisfying the formula is prepd. Further, =1 kinds among 0.2-2.5 Ni, 0.2-1.5 Mo, 0.02-1.5 V, 0.001-0.2 Ti, and 0.02-1.5 Nb may be incorporated into the above-mentioned compsn. This steel is heated to 910-1,020 deg.C austenite region and is then cooled at a cooling rate below air cooling. The steel which has excellent stress corrosion cracking resistance and CO2 corrosion resistance and is used in an energy field of about =135ksi (94.5kg/mm2) yield strength is produced at a low cost by this method.