Properties of Inconel 718 Superalloy Coating on K418 Alloy Surface for Laser Remanufacture

For the high temperature and high rotational speed working conditions of K418 superalloy impeller, the problems of deformation out of tolerance and reduction of mechanical properties after remanufacture for layer become the research focus. Based on the optimized process of waveform modulation pulsed laser, the Inconel 718 alloy layer was remanufactured. The metallographic microscope, SEM, XRD, EDS, microhardness, and dynamic balance testing machine were used to research the microstructure morphology, phase structure, interface composition distribution, basic mechanical properties of Inconel 718 layer. The results show that there is metallurgical bonding between the cladding layer and the substrate. Coarse dendrites exist in the middle layer, and there is a 30~45° angle between the coarse dendrite and the laser scanning direction. From the middle of the forming layer to the top and to the bottom, the coarse dendrite degenerates into equiaxed and cellular crystals, respectively. The microhardness of the forming layer is 4100~4400 MPa, which is slightly higher than that of the substrate. A small amount of Laves phase are precipitated in the grains and intergranular, which reduce the impact on the hard-brittleness of the forming layer, the friction and wear coefficient is slightly lower than that of the matrix, but the requirements of remanufacture is still met. © 2020, Science Press. All right reserved.