基于均匀设计的铁基合金粉末激光熔覆工艺参数优化

Optimization of laser cladding process parameters of iron-based alloy powder based on uniform design

为了在Q235钢基材上制备出性能优良的铁基合金熔覆涂层,开展基于均匀设计的铁基合金粉末激光熔覆工艺参数优化方法研究。根据熔覆机工艺能力和实践经验选取待优化工艺参数范围,运用均匀化设计方法产生混合水平实验表。采用"光内送粉"在Q235钢基材上制备铁基合金(Fe45)熔覆层,利用超景深显微镜和维式显微硬度计分析了熔覆层的表面形貌、稀释率及硬度。基于实验数据逐步回归分析扫描速度、离焦量、激光功率、送粉速度对熔覆层稀释率和显微硬度的影响。结果表明:不同工艺参数对熔覆层的稀释率及显微硬度具有显著影响;回归分析的三次多元多项式适合于表征工艺参数对熔覆层稀释率和显微硬度的影响规律,回归方程的交互项表明扫描速度、离焦量、激光功率、送粉速度的交互作用影响着稀释率和显微硬度;对稀释率和显微硬度进行数学回归,分析发现该铁基合金粉末的激光熔覆最佳工艺参数为:扫描速度7 mm/s、离焦量2 mm、送粉速度22 g/min、激光功率2.7 kW。验证实验表明,以最优参数制备的熔覆层硬度均匀度高、与基材形成了连续的白亮凝合线,无裂纹及气孔,熔覆层整体质量较好。

In order to prepare an iron-based alloy cladding coating with excellent performance on Q235 steel substrate, a study on the optimization method of laser cladding process parameters of the iron-based alloy powder based on uniform design was carried out. The range of process parameters to be optimized was selected according to the process ability of the cladding machine and practical experience, the mixing level experimental table was obtained by using homogenization design method. The iron-based alloy(Fe45) cladding layer was prepared on the Q235 steel substrate by using "light internal powder feeding", and the surface morphology, dilution rate and hardness of the cladding layer were analyzed by using ultra-depth field microscope and Vickers microhardness meter. Based on the experimental data, the effects of scanning speed, defocus distance, laser power and powder feeding speed on the dilution rate and microhardness of the cladding layer were analyzed by stepwise regression. The results show that different process parameters have significant influence on the dilution rate and microhardness of the cladding layer, and the third-order multivariate polynomial of regression analysis is suitable to characterize the influence of process parameters on the dilution rate and microhardness of the cladding layer. The interaction item of regression equation shows that the interaction of scanning speed, defocus distance, laser power and powder feeding speed affects the dilution rate and microhardness of the cladding layer. The mathematical regression of dilution rate and microhardness shows that the optimum process parameters of laser cladding of the iron-based alloy powder are as follows: the scanning rate is 7 mm/s, the defocus distance is 2 mm, the powder feeding speed is 22 g/min, and the laser power is 2.7 kW. The results of verification experiments show that the cladding layer prepared by the optimal parameters has high hardness uniformity, a continuous white bright bonding line coupling with the substrate, and no cracks and pores, and the overall quality of the cladding layer is good.