Effect of Heat Treatment on Grain Boundary and Tensile Behavior of Selective Laser Melting GH3536 Alloy

Abstract:

The GH3536 alloy was prepared by selective laser melting, and was subjected to solution treatment and hot isostatic pressing, respectively. The effects of different heat treatment methods on the microstructure, grain boundary morphology and room temperature tensile behavior of GH3536 alloy were studied. The results show that the microstructure of the SLM sample consists of ultra-fine columnar sub-grains and pool boundary, with defects such as pores and microcracks. The relative density of the alloy increases after solution treatment and hot isostatic pressing, respectively, and the microstructures of the two alloys consist of alternating equiaxed grains of different sizes. However, the HIP sample precipitated the M₂₃C₆ phase along the grain boundary, forming a serrated grain boundary. The tensile properties of the SLM samples show obvious anisotropy. The solution treatment can eliminate the anisotropy of the tensile properties of the sample, but the ultimate tensile strength and yield strength are reduced, and the elongation is significantly increased. The HIP sample is similar to the solid solution sample, but its ultimate tensile strength, yield strength and elongation are further improved. Tensile fracture mechanisms of all three alloys are microporous aggregate-type ductile fracture.

Key words:GH3536 alloy; Selective laser melting; Microstructure; Grain Boundary; Mechanical Properties