基于主成分分析法与逼近理想解法的38MnVS6激光熔覆工艺研究

采用激光熔覆在燃烧室部件表面制备高性能涂层对延长柴油机寿命有重要意义,多工艺参数的优化是获得高性能熔覆层的关键。以激光功率、扫描速度和送粉速率为优化对象，以熔覆层宽度、稀释率和表面硬度为优化目标，对活塞用38MnVS6中碳钢基体表面激光熔覆镍基合金粉末进行了L₉（3³）正交试验。基于主成分分析法计算各目标权重，并采用马氏距离的逼近理想解法对试验数据进行分析，获得了如下最佳工艺参数组合：激光功率850 W、扫描速度3 mm/s、送粉速率3.13 g/min. 经试验验证，与L₉（3³）正交试验最佳方案相比，稀释率下降了1.13%，平均硬度提高了4.56%. 通过极差分析，得到工艺参数对熔覆层综合质量和熔池尺寸的影响由大到小依次为激光功率、送粉速率、扫描速度。

Research on Laser Cladding Processing for 38MnVS6 by PCA-TOPSIS Method

Preparing high performance coating on piston surface by laser cladding is of significance for prolonging the life of diesel engine. In laser cladding process, the selection of appropriate parameters is the key to improve the performance of cladding layer. Whereas the relationship between these factors is non-linear, stochastic and discrete, it is significant to optimize some of them, such as laser power, scanning speed, and powder feed rate. For the laser cladding of nickel-based alloy powder on 38MnVS6 medium carbon steel, L₉(3³) orthogonal array is designed. Taking cladding width, dilution rate and surface hardness as evaluation indicators, the weights of three parameters are obtained by the principal component analysis (PCA). The optimal combination of laser power, scanning speed, and powder feed rate is obtained by the technique for order preference by similarity to ideal solution (TOPSIS) based on Mahalanobis distance. The results show that, when the laser power is 850 W, the scanning speed is 3 mm/s, the powder feed rate is 3.13 g/min, and the coating has the best properties. The dilution rate of cladding layer is decreased by 1.13% and the average hardness of cladding layer is increased by 4.56% compared with those at the scanning speed of 3 mm/s. The range analysis shows that the laser power has the most important effect on the size and overall quality of cladding layer. Key