The effect of laser power on the microstructure and wear performance of IN718 superalloy fabricated by laser additive manufacturing

In this study, Inconel 718 (IN718) superalloys were fabricated by laser additive manufacturing (LAM) under different laser power. The microstructure and precipitation phase of IN718 superalloys were examined by optical microscope (OM), X-ray diffraction (XRD), scanning electron microscope (SEM), and energy-dispersive X-ray spectrometer (EDS) methods. The results show that the micropores of the specimens decrease with the increasing laser power. Meanwhile, the morphology of Nb-rich Laves phase changed from skeleton-like to island-like, and the sizes reduced from 10 to below 2 μm. When the laser power of 1200 W is applied, the dense microstructure and the uniformly distributed Laves phase with smallest volume and quantity are observed. The dry sliding test is performed to record the coefficient of friction (CoF) and wear loss of IN718 superalloys, and then the wear surface is detected by a laser scanning confocal microscope (LSCM) and a SEM. The results indicate that the laser power played a crucial role in wear performance of the specimens. At an optimal laser power of 1200 W, a relatively stable friction state and the lowest wear rate of 1.355 × 10−3 mm3 N−1 m−1 are obtained during the wear process. Less debris and slighter plastic deformation are detected and the wear mechanism is abrasive wear and adhesive wear.