Multi-physical field simulation to yield defect-free IN718 alloy fabricated by laser powder bed fusion

In this study, we used a model that combines thermal, mechanical, and fluid dynamics principles to analyze the melting and solidification process in laser powder bed fusion (LPBF). To ensure accurate simulation results, our computational fluid dynamics model takes into account various factors, such as heat transfer, radiation, molten metal flow, phase change, and the interaction between the laser and the material. We found that the combined effects of recoil pressure, Marangoni convection, and surface tension play a crucial role in the evolution of the melted IN 718 alloy. Excessive recoil force can cause powder spatters and keyholes, while inefficient Marangoni effect leads to non-uniform melting. Through our simulation-experimental investigation, we were able to achieve a high-density (99.96 %) IN 718 alloy at a scanning speed of 700 mm/s. This research demonstrates the ability of a multi-physical model to accurately predict the quality of melted materials and contribute to the development of new materials, not limited to nickel-based alloys in LPBF.