Process Optimization and Performance Study of Laser Cladding CrMnFeCoNi High-Entropy Alloy Coating on CL60 Steel Surfaces

本研究旨在通过激光熔覆技术在CL60高碳钢表面制备CrMnFeCoNi高熵合金涂层，优化工艺参数以达到最优涂层质量，为能够提高车轮的表面强度、耐磨性和使用寿命，以及为列车车轮的表面改性提供新的技术思路。本研究采用正交实验，分析研究了激光功率、扫描速度和送粉速率对涂层质量的影响。通过宏观形貌、微观形貌、稀释率、成型系数和显微硬度等指标评估涂层的质量，并利用极差分析确定最佳激光功率和送粉速率，再通过变化扫描速度，寻求最佳参数。实验结果表明，激光功率对涂层稀释率和硬度影响最大，扫描速度对成型系数影响显著。最佳工艺参数为激光功率1400 W、扫描速度4 mm/s、送粉速率20 g/min。在此参数下，涂层的稀释率为15.5%，成型系数为4.35，显微硬度为181.25 HV0.5，且涂层组织致密，无明显缺陷。涂层中晶粒组织沿着熔凝方向生长，由底部到顶部从粗大的树枝晶、柱状晶向细小的致密的胞状晶过渡。本研究可以有效提高CL60钢表面高熵合金涂层的综合性能，确定激光熔覆CrMnFeCoNi高熵合金涂层的最佳工艺参数，为高碳钢基体的激光熔覆技术提供了理论依据和实验支持。This study aims to prepare CrMnFeCoNi high entropy alloy coating on the surface of CL60 high carbon steel through laser cladding technology, optimize process parameters to achieve optimal coating quality, and provide new technical ideas for improving the surface strength, wear resistance, and service life of wheels, as well as for surface modification of train wheels. This study used orthogonal experiments to analyze the effects of laser power, scanning speed, and powder feeding rate on coating quality. This study evaluates the quality of the coating through macroscopic morphology, microscopic morphology, dilution rate, molding coefficient, and microhardness indicators, and determine the optimal laser power and powder feeding rate using range analysis. Then, it seeks the best parameters by changing the scanning speed. The experimental results show that laser power has the greatest impact on the dilution rate and hardness of the coating, while scanning speed has a significant impact on the forming coefficient. The optimal process parameters are laser power of 1400 W, scanning speed of 4 mm/s, and powder feeding rate of 20 g/min. Under these parameters, the dilution rate of the coating is 15.5%, the forming coefficient is 4.35, the microhardness is 181.25 HV0.5, and the coating structure is dense with no obvious defects. The grain structure in the coating grows along the melting direction, transitioning from coarse dendritic and columnar crystals to fine and dense cellular crystals from bottom to top. This study can effectively improve the comprehensive performance of high entropy alloy coatings on the surface of CL60 steel, determine the optimal process parameters for laser cladding CrMnFeCoNi high entropy alloy coatings, and provide theoretical basis and experimental support for laser cladding technology of high carbon steel substrates.