Laser Powder Bed Fusion of IN718: Impact of Hatch Distance and Post-Print Heat Treatment on Microstructural Evolution Associated with Mechanical, Tribological and Electrochemical Properties
摘要
In the present work, IN718 parts are fabricated through the laser powder bed fusion (L-PBF) process. The effect of hatch distance (50 µm and 90 µm) on part tensile properties and microhardness is studied. The L-PBFed IN718 is subjected to a post-print heat treatment schedule, designed to include a homogenization treatment (1186 °C/40 min + air cool) followed by a double-stage aging treatment. The first-stage aging is performed at 720 °C/8 h followed by furnace cool (@ 55 °C/h) up to 650 °C. The final-stage aging is performed at 650 °C/8 h followed by natural air cooling. The impact of post-heat treatment on the as-printed microstructure and microhardness is discussed. The room temperature dry sliding wear tests (under ball-on-disk configuration) are conducted to study the tribological behavior while potentiodynamic polarization tests exhibit electrochemical corrosion response of the L-PBFed IN718, at both the as-printed and post-heat-treated conditions. A comparative analysis is carried out with respect to the microstructure and material properties of the conventional wrought counterpart. As compared to AB50, an improved tensile strength (~7.72 %) is achieved by the specimen AB90. The specimen AB90 exhibits ~ 27.8 % and ~ 12.1 % increased microhardness value when compared with the conventional wrought and AB50 counterparts, respectively. The maximum microhardness value is achieved at the post-heat-treated state, which is ~ 66.9 % higher than that of AB50. A lower value (~31.2 % reduced) of the friction wear rate is obtained for the post-heat-treated IN718 in comparison with its counterpart AB90.