Comparison of Microstructure and Defects Formation of Pure Tungsten Fabricated by Selective Laser and Electron Beam Melting

Pure tungsten were fabricated by selective laser melting (SLM) and selective electron beam melting ( SEBM). Microstructure and mechanical properties of pure tungsten were compared under different process parameters. The crack initiation location and formation mechanism were analyzed by SEM and EBSD. The results show that the crack generation of pure tungsten printing process can be effectively reduced by adjusting the process parameters in SLM and SEBM process. The relative density and hardness of pure tungsten samples are proportional to the energy density input by SLM and SEBM. Compared with SLMed specimen, SEBMed pure tungsten has lower temperature gradient, less thermal stress accumulation and fewer cracks. There are many cracks in SLMed samples, which mostly exist in the lap areas. Cracks in SLMed and SEBMed samples are distributed along grain boundaries, most of which are initiated at high-angle grain boundaries.