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激光熔覆铁基涂层工艺交互分析与多目标优化

Interaction analysis and multi-objective optimization of process for iron-based coatings by laser cladding

  • 摘要: 针对多工艺参数交互作用下激光熔覆工艺优化问题,在Q345B钢板上激光熔覆铁基合金涂层. 采用响应曲面法(response surface methodology,RSM)建立激光功率、扫描速度、送粉速率与涂层硬度、稀释率、宽高比之间的关联模型,分析工艺参数及其交互作用对涂层性能的影响. 兼顾涂层性能和工艺经济性,采用第二代快速非支配算法(non-dominated sorting genetic algorithm II,NSGA-II)和优劣距离法(technique for order preference by similarity to an ideal solution,TOPSIS)优化工艺参数. 结果表明,扫描速度与激光功率交互作用对硬度影响显著,与送粉速率的交互作用对稀释率和宽高比的影响显著. 优化的工艺参数为:激光功率900 W、扫描速度447 mm/min、送粉速率0.67 r/min、搭接率40%. 涂层平均硬度612 HV、高度0.66 mm,与基体相比,涂层平均摩擦系数降低约27%,最大磨损深度降低约76%,耐磨性能明显提升. RSM与NSGA-II-TOPSIS组合能发挥RSM快速建模、NSGA-II多目标优化及TOPSIS综合评价的优势,为激光熔覆工艺智能优化提供有益参考.

     

    Abstract: To solve the process optimization problem of laser cladding under the interaction of multiple process parameters, iron-based alloy coatings were prepared on Q345B steel plates by laser cladding. A correlation model between laser power, scanning speed, powder feeding rate and coating hardness, dilution rate, and aspect ratio was established using the response surface methodology (RSM), and the effects of process parameters and their interactions on coating performance were analyzed. Process parameters were optimized using the non-dominated sorting genetic algorithm II (NSGA-II) and the technique for order preference by similarity to an ideal solution (TOPSIS) with consideration of coating performance and process economy. The results show that the interaction between scanning speed and laser power has a significant effect on hardness, and the interaction between scanning speed and powder feeding rate has a significant effect on dilution rate and aspect ratio. The optimized process parameters are as follows: laser power of 900 W, scanning speed of 447 mm/min, powder feeding rate of 0.67 r/min, and overlapping rate of 40%. The average hardness and height of the coating are 612 HV and 0.66 mm, respectively. Compared with the substrate, the average friction coefficient of the coating decreases by about 27%; the maximum wear depth decreases by about 76%, and the wear resistance is significantly improved. The combination of RSM and NSGA-II-TOPSIS can exert the advantages of rapid modeling of RSM, multi-objective optimization of NSGA-II, and comprehensive evaluation of TOPSIS, which provides a useful reference for the intelligent optimization of the laser cladding process.

     

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