Analysis of microstructures and properties of GH4151 super alloy inertia fricrion welded joints

In this article, the inertial friction welding technology was applied to weld GH4151 alloy, and the microstructure, fracture morphology, and mechanical properties of the joints were observed under OM, SEM, DSC, microhardness tester, and electronic tensile testing machine. The results showed that during the welding process, the inner and outer flying edges had a rough shape and multiple microcracks. The burn-off length was up to 3 mm. Dynamic recrystallization occurred at the interface of the weld. Primary γ´ phase, secondary γ´ phase and carbide (MC) were precipitated in the grain and at the grain boundary. Under the action of residual stress and binding force, several microcracks occurred in the MC and expanded. By changing the forging pressure, the size, morphology, and quantity of MC were optimized, which have solved the problem of microcracking in the MC phase. Mechanical performance testing showed that the microhardness curve after heat treatment had demonstrated an M-shape, with the highest hardness in the TMAZ, which were positively correlated with the quantity and morphology of γ´and MC phase, reaching 546 HV1.0 as the highest . The tensile performance results showed that room and high temperature (750°C) tensile strength up to 97% of base material. From the perspective of crack propagation, room temperature fracture morphology shows along-crystal fracture. The high-temperature fracture morphology shows brittle fracture.