Effects of hot isostatic pressing and heat treatment process on microstructure and tensile properties of selective laser melting manufactured GH4169 alloy

GH4169 alloys were manufactured by selective laser melting (SLM). The microstructure evolution and tensile properties of GH4169 alloys during hot isostatic pressing(HIP) and heat treatment(HT) process were analyzed by OM,SEM,EBSD and TEM. The results show that the grains of the as-deposited samples in the building direction are columnar, exhibit very fine cellular-dendritic structure with fine Laves phases precipitating in the interdendritic region. Most of porosities and Laves phases disappear after HIP, and the microstructure parallel to the building direction is transformed into equiaxed grains. Short rod-like δ phases are precipitated along grain boundaries after annealing at 980 ℃ for 1 h. The tensile properties at room temperature and 650 ℃ of specimens after HIP and HT are higher than those of the standard requirements for the forgings, and the temperature has a little influence on the fracture mode