Effects of heat treatment on microstructure and mechanical properties of GH4169 nickel-base superalloy prepared by welding rapid forming

GH4169 nickel-based superalloy sample was prepared by TIG welding rapid forming. The microstructure and mechanical properties of the sample prepared were investigated. Microstructure analysis reveals that coarse columnar crystals are continuously grown from the substrate. The transition between the layers is not obvious, and absence of macro metallurgical defects can be observed. There exists only a few dispersed pores in the sample. Recrystallization occurs during heat treatment, and size distribution of the recrystallized grains are varied at different regions, where grain size at the bottom of the sample exhibits the smallest and uniform, while the dendrite size closer to the top of the sample becomes coarse. The hardness of the sample along the deposition direction shows a decreasing trend from the bottom to the top before and after heat treatment. Tensile tests indicate that the mechanical properties of heat treated samples at different regions are improved. The maximum tensile strength can reach up to 1 250 MPa, which is closer to the forged part standard, however, partial differences in ultimate tensile strength still exist.