Effect of hot isostatic pressing on microstructure and high temperature properties of GH4169 alloy formed by selective laser melting

Abstract

GH4169 alloy usually serves in high temperature environment，and the high temperature performance of GH4169 alloy made by additive material is often lower than that of the standard of forgings，which affects its service safety，thus it is necessary to improve its safety by means of heat treatment. In this work，GH4169 alloy was prepared by selective laser melting（SLM），and the effects of hot isostatic heat treatment process on the microstructure，high temperature tensile properties and high temperature stress rupture properties of the SLM formed GH4169 alloy were investigated by using characterization methods such as optical microscopy（OM），scanning electron microscopy（SEM）and X-ray energy dispersive spectrometry（EDS），etc. The results show that，compared with the conventional heat treatment processes，the grains of GH4169 alloy after hot isostatic treatment are equiaxed，the pores and Laves phases are basically disappeared，the short rod-like δ phase is more continuous at the grain boundaries，a large number of granular γ'' phases are precipitated inside the grains，and the grains are significantly refined. After hot isostatic pressing treatment，the ultimate tensile strengths of GH4169 alloy at 650 ℃ are 1053 MPa and 1051 MPa，the elongations after breaking are 8.6% and 8.5%，the high temperature stress rupture properties are 1620 min and 2065 min，and the high temperature endurance time is improved by 90 times and 30 times respectively in scanning and building direction. The high temperature ultimate tensile strength and high temperature stress rupture properties are higher than wrought standard，while the elongation after breaking has not exceeded the wrought standard.

Keywords

• selective laser melting
• gh4169 alloy
• hot isostatic pressing
• microstructure evolution
• high temperature mechanical properties