Numerical transient thermal analysis of 316 L stainless steel/C18400 copper alloy powder layers deployed with multi-track and bi-directional laser based powder bed fusion

The most significant challenge in printing one object comprised of two dissimilar powder materials is to form a strong bond at the interface associated with high quality of surface finish using Laser based Powder Bed Fusion (L-PBF). Therefore, it is mostly important to study the most important parameters controlling the L-PBF process including the laser power, laser beam radius and laser scanning speed. In this paper, non-linear thermal transient finite element models have been developed in ANSYS codes by deploying subroutines coded in ANSYS parametric design language (APDL). This simulates a moving micro-laser beam with a Gaussian distribution over four metallic powder layers built on one powder bed, two layers made of 316 L stainless steel followed by two layers made of C18400 copper alloys. The micro-laser beam scans multi-layer, bi-directional multi-track and multi-materials to enhance the in-depth understanding of this L-PBF process to find significant parameters. It is found that the absorptivity of the powder material plays a key role in the total heat intensity. This in turn requires resetting the L-PBF parameters with depositing a layer of another material. The findings highlight that changing the laser power is much more efficient than other parameters to fuse the interface between the 316 L stainless steel layer and the C18400 copper layer.