Optimization Of Inconel718 Alloy Electron Beam Cladding Process Parameters Based On Taguchi Method

Inconel718 alloy has good oxidation resistance and corrosion resistance at high temperature,and can still maintain a certain creep rupture strength and yield strength at high temperature.However,long-term exposure to high temperature and heavy load makes the surface hardness and wear resistance appear to be insufficient,the electron beam cladding technology can improve its surface performance.In the actual electron beam cladding process,the quality of the cladding layer is required to achieve the optimal.The surface quality of the cladding layer is related to the cladding process parameters,and the optimal cladding layer quality can be obtained by studying the optimization process of the process parameters.In this paper,the Ni Cr BSi coating was cladding on the surface of Inconel718 alloy,and the process of optimizing the cladding process parameters by Taguchi method was studied.The quality of the cladding layer was characterized by the dilution rate of the cladding layer,and the structure and performance of the cladding result were corresponding detection and analysis.First,by analyzing the specific energy formula of electron beam cladding,it is determined that the experimental factors in the Taguchi method to optimize the cladding process parameters are electron beam current,focus current and scanning speed.The parameter values,which make the cladding material reach the melting temperature above the melting temperature and the temperature field is uniformly distributed,were found out by the finite element simulation,and the range of process parameters is preliminarily determined.The parameters level is selected as the electron beam current 17 m A,20 m A,23 m A,and the focusing current is 680 m A,690 m A,700 m A,scanning speed is 6mm/s,8mm/s,10mm/s.The dilution rate of the cladding layer was calculated by the size of the cladding layer section.The distribution of isotherm corresponding to the melting point of the material on the test block model was obtained through finite element simulation,so as the simulation value of the cladding layer section size was determined.Compared with the measured values of cladding layer section size,it can be concluded that it is feasible to determine the section size of cladding layer by simulation.In the experimental analysis,it is concluded that the order of the influence of process parameters on the signal-to-noise ratio of the cladding layer dilution rate through the range and variance analysis is as follows: focusing current is greater than scanning speed is greater than electron beam current;Adjusting parameter values,the optimal parameter combination is finally obtained as electron beam current 20 m A,focusing current 680 m A,and scanning speed 10mm/s.The prediction analysis was carried out based on the optimal parameter combination,and the electron beam cladding verification experiment was carried out.The results show that the experimental results and the predicted results are within the appropriate error range,which indicates that the Taguchi method is suitable for optimizing the process parameters of electron beam cladding.Finally,an optical microscope and scanning electron microscope were used to analyze the structure and composition of the cladding layer under the optimal parameters.The results indicate that the cladding layer and the substrate are well combined under the optimal parameter combination,and the defects such as pores and cracks in cladding layer are obviously less than those in the matrix.The composition and content of elements in the cladding layer and matrix have little change,indicating that the dilution rate of the cladding layer is small under the optimal parameter combination.The microhardness and wear resistance of cladding layer under orthogonal parameters and optimal parameters were measured by microhardness tester and material surface properties comprehensive tester.The results show that the hardness value of the cladding layer under the combination of optimal parameters is better and the wear rate is minimum.At the same time,the hardness and wear resistance of the substrate material was measured.The surface hardness and wear resistance of the Ni Cr BSi coating by electron beam cladding of Inconel718 alloy were improved greatly under the appropriate parameters.