Effect of welding parameters on high-temperature tensile and fatigue properties of FGH96 inertia friction welded joints

This study aims to evaluate the high-temperature tensile and fatigue properties of FGH96 inertia friction welded (IFW) joints obtained using different welding parameters. The joint presented a significant microstructure change across the faying interface, characterized by the very small uniform equiaxed grains of the weld nugget zone (WNZ), obvious grain deformation, and growth of the thermo-mechanically affected zone (TMAZ). The elevated temperature tensile and high-cycle fatigue tests were performed at 700 °C. The results exhibit that the effect of rotational speed on tensile properties is less than that of friction pressure. The change tendency of tensile properties with welding parameters is in agreement with that of the width of WNZ. The tensile failure occurred in the WNZ, which is related to the complete-ordered Ni3Al γ′-phase dissolution. The fatigue limit decreases slightly along with the rotational speed. As the friction pressure increases, the fatigue limit increases firstly, and then decreases. The fatigue failure of the joint is located at the border between WNZ and TMAZ. This is related to the microhardness difference (dH) between TMAZ and WNZ, which reflects the stress concentration factor (Kt). In the end, the fracture mechanism was observed and analyzed.