Stress-relief cracking studies of O.5Cr-Mo-V and 2Cr-Mo steels using HAZ simulation

A laboratory test procedure is described in which the material properties influencing weld heat-affected zone stress-relief cracking are identified. Several 0.5Cr-Mo-V and 2Cr-Mo steels containing known quantities of trace elements are compared using this test procedure and new criteria are developed to assess the experimental data in terms of material susceptibility to cracking. It is shown that trace elements can adversely affect the properties of Cr-Mo- V steels, and this finding is supported by reference to other work. In contrast, 2Cr-Mo steels have a higher general ductility and a faster tempering response than Cr-Mo- V steels and prove to be more tolerant to the presence of impurities. It is concluded that 2Cr-Mo is less susceptible than Cr-Mo- V to weld heat-affected zone stressrelief cracking.