Multi-objective Optimization For Hardness And Wear Resistance Of Laser Cladding Layer On Die

In the small batch production stage of automobile,molds made of cold working mold steel cannot give full play to its efficiency.This not only increases the production cost,but also causes serious waste of mold steel materials,which violates the concept of green manufacturing.By using laser cladding technology to strengthen the working surface,low-cost materials can replace cold work die steel.This has become a hot academic research topic,in the field of mold.However,how to meet the multi performance requirements of cold working mold has become an urgent problem to be solved.Therefore,aiming at this engineering problem,I carried out the research of process parameter optimization for multi performance index.By analyzing the performance requirements of the cold working mold,the optimization task of laser cladding process parameters for hardness and wear resistance as the objectives was clarified.I carried out the optimization research using theoretical analysis,multi-objective optimization and experimental research to improve the hardness and wear resistance of cladding layer.The main research contents are as follows:(1)The multi-objective optimization strategy was determined,and the optimization basic data were obtained based on the design experiment.The working condition,failure mode and laser cladding principle of cold working mold were analyzed.Based on this,the optimization objectives,variables and constraints of laser cladding process parameters were determined to form the optimization strategy.According to the various factors and levels of laser cladding process parameters,I used the experimental design method to design experiments and prepared cladding samples.The experimental data of hardness and wear scar depth of samples prepared by different combination of process parameters were obtained through sample detection.It provides the data basis for the construction of the mathematical model about process parameter optimization.(2)The objective functions of hardness and wear resistance were constructed.The least square method was used to fit the experimental data of hardness and wear scar depth of cladding layer,and the objective function model for hardness and wear resistance was established.The reliability of the model was verified by variance analysis.The influence of process parameters and their interaction on the hardness and wear resistance of the cladding layer was analyzed.According to the objective function of hardness and wear resistance,the multi-objective optimization mathematical model of laser cladding process parameters was established.The construction of the model provides a theoretical basis for the optimization of process parameters.(3)According to the multi-objective optimization mathematical model of hardness and wear resistance,the laser cladding process parameters were optimized based on response surface method,and the optimization interval was obtained.I compared the principle of multiobjective optimization method,and combined with the actual situation of laser cladding engineering.In the end,the response surface method was used to optimize the laser cladding process parameters of iron-based alloy with hardness and wear resistance as objectives.The optimal range is: laser power 1600-2000 W,powder feeding rate 24-33g/min,scanning rate 9.5-12.5mm/s.It provides data support for the engineering application of laser cladding Fe based alloy on 45 steel.(4)The multi-objective optimization results of laser cladding process parameters were tested and verified.The samples were prepared by selecting the combination of process parameters in the optimal range,and the optimization results were verified by experiments.The results show that the hardness and wear resistance of the cladding layer samples prepared in the optimal process parameters range reach the optimization goal.The above research provides a optimization method for process parameters aiming at the performance of cladding layer,and provides process data support about the engineering application of laser cladding Fe based alloy on 45 steel.