Abstract
Manual metal-arc welding procedures have been used to produce different amounts of heat-affected zone (HAZ) grain refinement in a series of butt welds in a Cr–Mo–V forging which had been removed from service because of its susceptibility to HAZ stress-relief cracking. The forging was high in vanadium but contained normal commercial levels of impurities and was considered typical of many other Cr–Mo–V casts which had exhibited this mode of failure. Cross-weld specimens have been machined from the welds and rupture tested at the stress-relieving temperature of 690°C. The overall specimen deformations and the position of failure have been determined for the various welding procedures and testing conditions, and rupture strengths have been compared with data obtained previously on individual weldment structures tested in isolation. Interrupted tests have also been carried out on cross-weld specimens to determine the mean strain required! to initiate cavitation in the different HAZ structures. These strains have been compared with that likely to occur in a pipe butt weld during stress relief The results are discussed in terms of the influence of HAZ structure on stress-relief cracking and the repair of high-vanadium crack-prone Cr–Mo–V steels in power station plant.
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