Notched Tensile Fracture of Ti–6Al–4V Laser Welds at Elevated Temperatures

Notched tensile tests of Ti–6Al–4V laser welds that were subjected to post-weld heat treatments (PWHTs) at 482 and 704°C were carried out in air at temperatures from 25 to 450°C. The experimental results were also compared with those of the mill-annealed base metal (MB) specimens tested at similar temperatures. Generally, the notched tensile strength (NTS) of the specimens was sensitive to the test temperature. The NTS of laser welds was lower than that of the MB specimen at room temperature, but the trend reversed at 450°C. The presence of thick grain boundary α layers, which promoted intergranular fracture at elevated temperatures, could account for the lowered NTS of the weld after PWHT at 704°C.