RO126044A8 - Process for rehabilitation of welded heat-resistant alloy steel components by heat treatment - Google Patents

Abstract

The invention relates to a method for the rehabilitation of weldable heat-resistant alloy steels of the types Cr-Ni, Cr-Mo-V, V-Ni-Mo-Cr and the like, wherefrom there are manufactured various structural elements of energetic equipments working or having worked at temperatures of at least 450°C and high pressures of up to 140 bar. According to the invention, the method consists in taking samples from the worn-out energetic equipment components, both from the basic material and the welded area and subjecting said samples to the following operations: a. annealing thermal treatment whose austenitization temperature ranges between 910...1070°C while maintaining it for 60...120 minutes and cooling in still air or oil down to a temperature of 20°C, followed by a secondary thermal treatment at a temperature ranging between 600...780°C while maintaining it, depending on the steel thickness, for 1 hour for a thickness of 25.4 mm and cooling in still air down to 20°C, b. examining the samples from structural microscopic and macroscopic point of view for pointing out the material defects, phases, constituents and granulation, c. subjecting the samples to mechanical hardness, tensile and impact bending tests, d. correlating the determined structural characteristics with the obtained mechanical characteristic values so as to obtain an optimal variant of specific thermal treatment which will be the basis of the rehabilitation of the analyzed weldable heat-resistant alloy steels.