Creep behavior and microstructure evolution of GH4169 superalloy joint produced by linear friction welding

To clarify the creep properties of linear friction welding superalloy joint, providing reference for engineering application, reliable GH4169 superalloy joints were achieved by linear friction welding (LFW), the creep properties were tested, creep mechanism and microstructure evolution were analyzed. This study investigated the creep failure mode and microstructure evolution of LFW GH4169 joint at 650 °C/700 MPa and 700 °C/660 MPa. Optical microscopy, Electron backscatter diffraction, Vickers microhardness and transmission electron microscopy were used to characterize microstructure evolution of the as-weld joint and crept features. The experimental results show that LFW joint exhibits excellent creep resistance at 650 °C, and creep life rapidly decreases with increase of creep temperature. The fracture took place within base metal, which is different from conventional creep rule, and main failure mode is grain boundary debonding or sliding. The plastic deformation capacity of large-sized grains in the base metal is low, resulting in a high degree of stress concentration. The high stress local concentration at interface leads to initiation, coalescence and propagation of microcracks, resulting in failure of joint.