Effect of initial microstructure on performance and corrosion behavior of GH4169 superalloy joint produced by linear friction welding

The pre-weld heat treatment was carried out to obtain different initial microstructures of the GH4169 superalloy, and then Linear Friction Welding (LFW) was performed. The effect of the pre-weld heat treatment on the microstructure evolution and mechanical properties of the joint was analyzed, and the joint electrochemical corrosion behavior as well as the hot corrosion behavior was studied. The results show that the joint hardness of Base Metal (BM) increases after pre-weld heat treatment, and the strengthening phases γ′ and γ″ further precipitate. However, the precipitation phases dissolve significantly in the Weld Zone (WZ) due to the thermal process of LFW. The corrosion resistance in BM is reduced after the pre-weld heat treatment, while it is similar in WZ with a slight decrease. The surface morphology of the BM and WZ can be generally divided into a loose and porous matrix and a scattered oxide particle layer after hot corrosion. The joint cross section exhibits a Cr-depleted zone with the diffusion of Cr to form an oxide film. The corrosion product mainly consists of Fe₂O₃/Fe₃O₄ as the outer layer and Cr₂O₃ as the inner layer.