Thermal Behavior and Molten Pool Morphology during Laser 3D Printing Process of Alloy Steel Powder

Abstract

In this paper, a finite element analysis (FEA) model is proposed to systematically study the thermal behavior of metal material in Selective Laser Melting (SLM) 3D printing process. It is found that the material undergoes a fast and complex thermal cycle process. Laser beam can re-heat the adjacent formed scanning track and layer, and also produce a certain preheating effect on the unformed powder bed of the adjacent scanning track when laser beam scans a track, which is conductive to improve metallurgical bonding performance of SLM-fabricated parts. With the increase of scanning tracks or scanning layers, the peak temperature and molten pool lifetime increase owing to the thermal accumulation effect, but the increasing trend gradually slows down. The peak temperature and lifetime of each scanning track center in the second layer are larger than those of the corresponding scanning tracks in the first layer, respectively. Furthermore, SLM experiments are carried out to study complicated molten pool morphology in SLM process. The results obtained in this study have certain guiding significance for understanding thermal mechanisms of SLM process.