Integrated Thermal and Metallurgical Simulation Framework for Selective Laser Melting Multi-Component and Multi-Phase Alloys

To fully understand the impact of cyclic heating on the solid-state phase transformation behavior (SPTB) of multi-component multi-phase alloys (MCPA) during selective laser melting (SLM) and to provide possibilities for the precise customization of the material microstructure, a thermal-metallurgical coupling framework (TMCF) was developed. This framework integrates (1) an equivalent micro-zone heat source model and (2) a Johnson-Mehl-Avrami (JMA) phase transformation kinetic model. Using IN738 superalloy as an example, TMCF was effectively employed to predict the distribution and evolution of the gamma ' phase during SLM. The results showed that the post-printing distribution of the gamma ' phase is non-uniform, resulting from the interaction between the precipitation and dissolution behaviors occurring at varying temperatures across distinct spatial locations. Furthermore, the dependence of the gamma ' phase on the SLM mode was quantitatively estimated. Specifically, the maximum volume fraction of the gamma ' phase increased by a factor of 17.377, 60.780, and 5.214 when the laser power, scanning speed, and hatch spacing were modified by +50%, -25%, and -16.7%, respectively, within the process window. This finding can provide reference for the fabrication of additional MCPA. In this work, the thermal model within the TMCF was verified by the experimental data reported in the literature.