Pure Tungsten Fabricated by Laser Powder Bed Fusion with Subsequent Hot Isostatic Pressing: Microstructural Evolution, Mechanical Properties, and Thermal Conductivity

In this study, pure tungsten parts were fabricated by laser powder bed fusion (LPBF). The effects of volumetric energy density (VED) during LPBF process and hot isostatic pressing (HIP) treatments on the densification behavior, microstructural evolution, mechanical properties and thermal conductivity of printed parts were systematically investigated. The maximum relative densities of 95.91 and 98.97% for the as-built and HIP treated samples were achieved, respectively. The microstructural characterization showed that the as-built samples had columnar grains with a strong texture along the building direction. The preferred orientation disappeared and the deformed microstructure transferred into substructured and recrystallized grains after HIPing at 1600 degrees C. The mechanical testing results indicated that the highest microhardness of 450 HV and the maximum ultimate compressive strength of similar to 1.22 GPa were achieved in the specimen fabricated at the VED of 312.50 J/mm3, respectively, under the conditions of as-built and HIPped at 1600 degrees C. The corresponding thermal conductivity was improved to 158 W/m.K after HIPping, which implies a promising candidate for the application in the nuclear fusion reactor.

Automated summary

This study investigated the fabrication of pure tungsten parts by laser powder bed fusion (LPBF) and its effect on the densification behavior, microstructural evolution, mechanical properties, and thermal conductivity. The results showed that the highest relative densities of 95.91% and 98.97% were achieved for the as-built and HIP treated samples, respectively. The mechanical testing results indicated that the highest microhardness of 450 HV and the maximum ultimate compressive strength of approximately 1.22 GPa were achieved in the specimen fabricated at a volumetric energy density (VED) of 312.50 J/mm3, under the conditions of as-built and HIPped at 1600 degrees C. The corresponding thermal conductivity was improved to 158 W/m.K after HIPping, suggesting its potential application in nuclear fusion reactors.