Parameters Optimization and Friction and Wear Properties for Laser Cladding Ni60AA Coating on 45 Steel Shaft Surface

To improve the service life of 45 steel shaft parts, we aim to study optimum process parameters of laser cladding Ni60AA coating on 45 steel shaft surface. The cladding process test of shaft surface was carried out with multi-pass spiral lap technology, namely, a Ni60AA alloy cladding layer was prepared on a 45 steel substrate. Based on the single variable method, the single factor cladding experiments were carried out on three process parameters, namely laser power, powder feeding rate and shaft speed. The thickness of cladding layer, dilution ratio and micro-hardness were selected as the evaluation indexes of coating quality. Based on the single factor experiment, the orthogonal experiment of three-factor and three-level was completed. The multi-objective comprehensive optimization of the process parameters was finished by the weight matrix method, and the microstructure and micro-hardness of the optimized cladding coating were analyzed. At the same time, friction and wear experiments were carried out at different working temperatures, and the friction coefficient, wear rate and wear scar morphology were analyzed and the feasibility of process optimization is verified. Powder feeding rate has the largest comprehensive influence ability, followed by laser power and shaft speed. The optimal parameters are laser power of 1400 W, powder feeding rate of 16. 3 g/min, and shaft speed of 2. 3 r/min. The thickness and micro-hardness of the cladding coating were increased by 3. 49% and 2. 8% respectively compared with those before optimization. When the test temperature is 35, 80 and 125 degrees C, the average friction coefficient of the cladding coating is 28. 5%, 21. 1% and 11. 8% lower than that of 45 steel and the wear rate of the cladding coating is 87. 6%, 86. 6% and 80. 9% less than that of the substrate. Ni60AA cladding coating with high forming quality and significantly improved hardness and wear resistance can be obtained by optimizing the laser cladding process parameters.