Fracture Properties of Quenched and Tempered Steel Weldment Specimens

摘要

Three test procedures were used to evaluate weldability features in seven Q and T steels. Two tests, the drop-weight bulge (DWB) test and the delta specimen test, used relatively large plate specimens containing full-thickness, multiple-pass welded joints. The loading system imposed in testing allowed fracture in them to follow a path of natural least resistance without bias from the loading direction. The third test, the drop-weight test (DWT), was used to determine the nil-ductility transition (NDT) temperature of the HAZ in the seven Q and T steels. The results from the three test methods indicated varying degrees of sensitivity of the HAZ to welding in the seven steels. The DWB and delta specimen results were quite similar and in general agreement. The DWT demonstrated that it was possible to measure an NDT for the HAZ (except in one steel, the high alloy or rich analysis steel, which did not fail in the HAZ). The NDT temperatures in the HAZ of the six steels were significantly higher than the NDT temperatures for the parent plate, suggesting that such measurements may possibly be useful for positioning of the fracture analysis diagram (FAD) to allow for fracturing which might occur in paths lower in toughness than the base plate. The work suggests that drop weight tear test (DWTT) energy measurements in the weld HAZ of high-strength steels should be attempted. (Author)