Influence of Parent Metal Microstructure and Post-Weld Heat Treatment on Microstructure and Mechanical Properties of Linear Friction Welded Ti-6Al-4V Joint

Linear friction welding (LFW) of Ti-6Al-4V (Ti-64) titanium alloy with a different microstructure from the previous study was conducted. The joint microstructure, tensile strength and fracture characteristics were studied. Results show that the microstructure of parent metal has a strong influence on the microstructure and properties of LFW Ti-64 joints. Under the specific conditions in this study, unexpected spheric a grains were formed near the bondline, which leads to the steep drop of the joint tensile strength. Although the tensile strength could be improved through post-weld heat treatment, the failure of specimens still took place across the bondline with the cleavage fracture due to the formation of basket-weave structure at the weld center zone and the remaining of spheric a grains.