Effect of Hot Isostatic Pressing on Microstructure and Properties of GH4169 Superalloy Manufactured by SLM

Abstract

During the additive manufacturing of the GH4169 superalloy, various defects including cracks and holes can occur in the alloy. In this study, the effects of distinct HIP temperatures and pressure on the microstructure and mechanical properties of GH4169 were studied utilizing the metallographic microscope(OM), scanning electron microscope(SEM), X-Ray diffraction(XRD), density, microhardness, and tensile experiment. SEM and XRD results indicate that HIP can alter the texture of the matrix phase and dramatically modify the microstructure of the test alloy manufactured by SLM. Following HIP, density increases due to the pore closure of GH4169, and the hardness decreases due to the decomposition of Laves phase. Tensile testing revealed that increasing HIP temperature and pressure led to a slight reduction in the tensile strength and yield strength of the test alloy, while elongation exhibited an opposite trend. Furthermore, the increase in elongation is attributed to the improvement of the microstructure uniformity of the test alloy by HIP. And the evidence suggested that 1165°C, 155MPa is an optimal HIP parameter. Besides, the resulting alloy has a high tensile strength (1046MPa), yield strength (654MPa), and elongation (42%). The Laves phase and carbide are evenly distributed. This optimal HIP parameter will facilitate subsequent heat treatment for obtaining higher mechanical properties of the alloy.