Microstructure and Mechanical Properties of Selective Laser Melting 316L/R-316L Butt Joint Welded by Laser Welding

Utilization of welding technology connecting small precise parts formed by Selective Laser Melting (SLM) and unsophisticated traditional formed parts into significant structural components provides a new way to manufacture large-scale complex 3D-printing parts. It is expected to improve the yield efficiency, save cost, and has a broad development prospect. Existing research results show that SLM forming parts differ quite from traditional casting and forging parts in structure and performance. Whether SLMed parts and rolled ones can be connected by welding and the influence mechanism of the anisotropy on weld performance are unclear. The results show that the joints exhibit good laser weldability without apparent defects. The microstructures of the SLMed base plates and laser-welded joints consist of the cellular dendrite in the austenite matrix within the columnar grains. The tensile strength of the joints is similar to that of rolled ones but lower than that of SLMed base metal; the elongation is about 1.3 times that of the SLMed base metal and 66% of the rolled ones. The corrosion properties of SLM base metal and weld area are superior to rolled plates. The anisotropy of SLM has a noticeable influence on the microstructure and tensile properties of the weld but plays a minor role in determining the element distribution, microhardness, and corrosion resistance. This work provides the theoretical and technical foundation for the innovative manufacture of large-scale, high-quality, and complex-formed metallic parts.