Influence of volumetric energy density on the tribological behaviors of pure nickel fabricated by laser powder bed fusion

Abstract

Laser powder bed fusion (L-PBF) enables the fast fabrication of pure nickel parts with complex structures. Tribological behaviors of the printed pure nickel are crucial to its application, and highly dependent on the volumetric energy density (VED), due to the variation of wear mechanisms. In this study, to investigate the wear mechanisms and evaluate the tribological behaviors of L-PBF pure nickel, samples fabricated with different VEDs were tested by a ball-on-disc tribometer under different representative loads. Unlike tribofilms formed on casting samples during sliding, L-PBF samples suffer abrasive wear, and their wear resistance decreases initially and increases afterwards with increasing VED. It suggests that the preferred VED provide good densification behaviors, high microhardness, and sufficient thin columnar subgrains, which decrease the abrasive wear. As a result, the wear resistance of the preferred L-PBF pure nickel can outperform cast counterparts under a load close to the yield strength of pure nickel.

Keywords

• laser powder bed fusion
• pure nickel
• tribological behaviors
• wear mechanisms
• volumetric energy density