Microstructure control to enhance low temperature and cryogenic wear behavior of Inconel 718 produced by laser powder bed fusion

Abstract

In this study, the wear behavior of Inconel 718 samples produced using the Laser Powder Bed Fusion (LPBF) technique at varying laser energy densities was investigated under room temperature, subzero, and cryogenic conditions. Wear tests were conducted using a ball-on-flat configuration with a forward-backward linear motion. The tests were performed under dry sliding conditions against a 6 mm diameter WC-Co abrasive ball, applying a 10 N load, a sliding speed of 20 mm/s, and a test duration of 10 min at temperatures of 23 degrees C, -40 degrees C, and 150 degrees C. The findings of the study revealed that increasing laser energy density led to higher nanohardness (H) values, while the elastic modulus (E) decreased inversely. The wear rates were found to correlate with the H/E and H3/E2 ratios. Evaluation of the effect of ambient temperature on wear behavior exhibited that wear volume loss was highest at -40 degrees C, while plastic deformation and abrasive wear mechanisms were predominant at room temperature. While wear debris spread and exfoliation type wear were observed at -40 degrees C, the lowest volume losses occurred under cryogenic conditions despite obtaining smoother wear surfaces. COF values were similar at RT and - 40 degrees C, but decreased significantly at cryogenic temperature. Oxide formation was observed at RT while no oxide formation was detected at subzero and cryogenic temperatures.