MANUFACTURE OF AUSTENITIC STAINLESS STEEL USED IN ATMOSPHERE OF HIGHHTEMPERATURE AND HIGHHPRESSURE WATER

摘要

PURPOSE:To increase strength and to improve the resistance to grain boundary stress corrosion cracking, by subjecting an austenitic stainless steel contg. Nb to heat treatment and to hot rolling at a specific temp. CONSTITUTION:An austenitic stainless steel having the following composition is manufactured: 0.2 % C, 1 % Si, 2 % Mn, 17-20 % Cr, 7-11 % Ni, 0.015 % P, 0.005 % S, 0.025-0.10 % N, =0.45 % C+N, 0.20-0.32 % Nb, or in addn., one or two members selected from the group consisting of 0.02-0.06 % REM, 0.002-0.02 % Ca, further contg. = 0.10 % each of Mo, Co which are present in a specific ratio. The steel material is heated to 1,160-1,280 deg.C, hot rolled at a finishing temp. of 750-950 deg.C, and heat-treated at a precipitation heat- treatment temp. of 980-1,050 deg.C. Hereby, strength and grain boundary cracking type stress corrosion cracking resistance are remarkably improves so that steel material suited for use in manufacturing recycling pipe liners for boiling light-water reactors is obtained.