Optimization of process parameters and microstructure of GH3230 alloy by selective laser melting

GH3230 alloy, due to its excellent high-temperature performance, is widely used in the manufacturing of high-temperature critical components such as combustion chambers. Selective laser melting (SLM) technology is often used to prepare such highly alloyed nickel-based superalloys. However, due to significant element segregation and uneven distribution of residual stress, hot cracks are highly likely to occur during the SLM preparation process, which affects the material properties. Based on this, this study systematically explored the effects of laser power, scanning speed and volume energy density (VED) on the densification behavior of GH3230 alloy prepared by SLM, aiming to clarify the process parameter window. The experimental results show that with the increase of laser power and VED, the porosity of the sample significantly decreases and the density significantly improves. The optimal process window corresponds to VED of approximately 64.94 to 102.27 J/mm³, achieving a relative density exceeding 99.5%, while the increase in scanning speed leads to an increase in porosity. Microstructure analysis shows that the GH3230 alloy prepared by SLM is mainly composed of single-phase austenite γ phase, with refined grains and columnar crystal growth. The molten pool structure is continuous and closely bonded. The element distribution is uniform. There is no microscopic segregation of carbon elements, and no carbides precipitate. The hardness test results show that the decrease in porosity is accompanied by a significant increase in microhardness. In conclusion, by optimizing the SLM process parameters, the density and mechanical properties of GH3230 alloy have been significantly enhanced, providing a theoretical basis and technical support for the additive manufacturing of high-performance nickel-based superalloys.