STRESS-RELIEVING process is used to relieve stresses that remain locked in a structure as a consequence of a manufacturing sequence. This definition separates stress-relief heat treating from postweld heat treating in that the goal of postweld heat treating is to provide, in addition to the relief of residual stresses, some preferred metallurgical structure or properties. For example, most ferritic weldments are given postweld heat treatment to improve the fracture toughness of the heat-affected zones . Moreover, austenitic and nonferrous alloys are frequently postweld heat treated to improve resistance to environmental damage.