Dimension prediction, property analysis, and application of laser cladding Ni60 coating on 316L steel

Laser cladding of high-quality alloys on metal substrates has been considered as an excellent method to repair or strengthen the surfaces of mechanical parts. In order to prepare Ni60 alloy coatings with required geometric dimensions on 316L stainless steel, dimension prediction methods based on orthogonal experiments and mathematical statistics are proposed. First, the dimension prediction models of the single-track coating are established, which describe the nonlinear relationships between the width and height of the coating and process parameters. Then, based on the single-track dimension prediction models, the prediction models of width and height of the multitrack coating are derived considering the effects of track number and overlap rate. In addition, the microstructure and the phase of the Ni60 coating are observed and analyzed. The results indicate that a good metallurgical bonding between the Ni60 alloy and the 316L substrate is formed, and there exist complex hard phases distributed in the Ni60 coating. The mechanical properties of the two materials including the microhardness, the friction and wear, and the corrosion are tested. The results show that the Ni60 coating has superior performance than the 316L steel. Furthermore, using the particle swarm optimization method, the optimized process parameters for cladding Ni60 alloy coatings with a height of 2.5 mm and a width of 72 mm are obtained as follows: laser power is 1914 W, scanning speed is 3.00 mm/s, powder feeding rate is 0.17 g/s, track number is 32, and overlap rate is 47%. At last, the surface strengthening of a nonmagnetic cardan shaft is realized successfully.