Effects of Heat Treatment On Microstructure and High-Temperature Tensile Performance Of Ni-Based Gh3230 Superalloy Processed by Selective Laser Melting

Abstract

Selective Laser Melting (SLM) is extensively used to manufacture nickel-based superalloys, as for aerospace engine components and other hot-end materials.  However, due to the high thermal gradient and cooling rate, GH3230 alloy processed by SLM often suffers from high residual stress and anisotropic properties. This study systematically investigates the effects of solution heat treatment on the microstructure and high-temperature tensile properties of GH3230 material prepared by SLM. The results indicate that an appropriate heat treatment temperature can effectively relieve residual stress and reduce the anisotropy of the material's mechanical properties. When heat treated at 1220°C, 1250°C, and 1280°C, the grain morphology of the samples evolves from columnar grains to equiaxed grains. At 1250°C, the samples exhibit the best overall mechanical properties. The transverse yield strength is 213 MPa, the tensile strength is 274 MPa, and the elongation is 49.5%. The longitudinal yield strength is 203 MPa, the tensile strength is 259 MPa, and the elongation is 70.5%. At 1280°C, excessive growth of recrystallized grains leads to stress redistribution, making the grains more prone to deformation, which in turn inhibits the occurrence of recrystallization. This provides a solid theoretical foundation for optimizing the heat treatment process and improving the mechanical properties of nickel-based superalloys.

Keywords: Selective Laser Melting (SLM), Additive manufacturing, Nickel-based superalloy, GH3230, Heat treatment