Microstructure and mechanical properties of linear friction welded P/M superalloy FGH96

Linear friction welding (LFW) of powder metallurgy superalloy FGH96 was carried out by using homemade LFW machine (XMH-160). The microstructure was analyzed and tensile property and microhardness of joints were examined.The results show that the joint could be divided into three zones: weld zone, thermomechanically affected zone (TMAZ) and base metal. The weld zone presents typical fine grains, while the coarse and fine grains co-exist in the TMAZ. The tensile strength of joints is comparable to the base metal, but the ductility of joints is worse than that of the base metal. The microhardness presents a high-low-high tendency across the weld line with the lowest value in the middle of TMAZ. The mechanical properties of joints in different zones are associated with the content and distribution of strengthening phases and the lattice distortion in addition the grain size. Therefore, for LFW FGH96 superalloy, the optimization of process parameters and post-weld heat treatment are necessary to improve the joint properties.