METHOD FOR FINALLY HEAT-TREATING Ni-BASED ALLOY EXCELLENT IN PWSCC RESISTANCE, AND Ni-BASED ALLOY

摘要

PROBLEM TO BE SOLVED: To provide a method for finally heat-treating a Ni-based alloy, in which the amount of carbon to be contained in a 690 series Ni-based alloy and final heat treatment conditions of the alloy are optimized to produce the 690 series Ni-based alloy having the PWSCC (primary water stress corrosion cracking) resistance improved much more than that of the alloy which underwent TT treatment while eliminating TT treatment.;SOLUTION: Such the final heat treatment is applied to the Ni-based alloy, which contains, by mass, 0.02-0.04% C, ≤0.5% Si, ≤0.5% Mn, ≤0.03% P, ≤0.015% S, 27-31% Cr, 7-11% Fe, ≤0.5% Cu, ≥58% Ni and the balance of impurities, that the Ni-based alloy is heated for 1.5-60 minutes at the temperature which is decided according to the carbon amount and is ≤1,150°C but is not less than the temperature when the Ni-based alloy becomes a complete solid solution and the heated Ni-based alloy is air-cooled at 500-150°C/minute cooling rate.;COPYRIGHT: (C)2011,JPO&INPIT