Hardness and notch toughness of semi austenitic PH 15-7 Mo(Cu) weldments - a study on the effects of pre and post weld thermal treatments

Semi-austenitic precipitation hardened PH 15-7 Mo (Cu) stainless steel was solutionized, destabilized, and aged and TIG welded autogenously. The welds were subjected to different thermal treatments, viz., (1) directly aged, (2) destabilized and aged, (3) solutionized and destabilized and aged. Hardness survey across the weld and charpy V-notch tests were conducted on the welds. Overall, it was found that the hardness of solution treated base metal was relatively low and values varied from point to point because of the duplex structure of austenite and martensite. The toughness of the same was found to be high. As-weld metal showed similar trend.