Influence of heat treatment temperature on grain structures and properties of a Ni-based superalloy fabricated via selective laser melting

Abstract

This paper investigated the grain structures and mechanical properties of GH3625 alloy fabricated by Selective Laser Melting （SLM）technology at different heat treatment temperatures. GH3625 alloy samples were fabricated using SLM and subjected to heat treatment at different temperatures. Microstructural characterization was conducted using Optical Microscopy (OM), Scanning Electron Microscopy (SEM), and Electron Backscatter Diffraction (EBSD). Tensile tests were also performed to evaluate the mechanical properties. It was found that the heat treatment temperature significantly affects the microstructure of SLM-fabricated GH3625 alloy. As the temperature increases from 950°C to 1100°C, the grains gradually become uniform equiaxed morphologies with weakened grain preferred orientation, increased grain size, reduced average misorientation, and increased proportion of high-angle grain boundaries. The transformation of microstructure leads to a decrease in tensile strength and an increase in plasticity of the alloy. Samples treated at 950°C have higher tensile strength,while at 1100°C exhibits higher plasticity. The study shows that by controlling the heat treatment temperature, the grain size, grain boundary characteristics, and dislocation density of SLM GH3625 alloy can be adjusted, thereby affecting the mechanical properties of the alloy, providing important technical support for its application in high-performance fields.