Research On Cutting Mechanism Of High Speed Cutting GH4169 Based On Polycrystalline Model

Nickel base superalloy GH4169 has good properties of high temperature resistance and corrosion resistance.It has been gradually applied to aerospace,electric power,ship,automobile,metallurgy,glass manufacturing,atomic energy and other industrial fields.But because GH4169 is a polycrystalline material with complex crystal structure,the complexity of crystal structure will affect the cutting process,make the cutting process discontinuous,produce large cutting force and strong fluctuation,and then produce complex cutting deformation,high cutting temperature,and the surface quality is not easy to guarantee.The improvement of machining performance of GH4169 has a great influence on modern industry,so the research on the mechanism of GH4169 cutting process is of great value and significance.At present,the academic research on the cutting mechanism of GH4169 mainly uses experimental and finite element simulation methods.With the advancement of computer technology,the finite element simulation method has been continuously improved.The finite element simulation method consumes less manpower and material resources than the experimental method,and can also obtain data that is difficult to measure during the experimental process,and the results can be visualized.At present,the combination of the finite element analysis method and the experimental method has become an important means to study the deformation process of GH4169.The traditional finite element simulation method has made great progress in the research of GH4169 cutting process,but the metal cutting simulation model and analysis are based on macro aspects,and the model cannot be reflected in the dislocation slip between grains and other Microscopic aspect.Therefore,in this paper,a polycrystalline model of GH4169 fused with macro and micro features is established,and the deformation mechanism of GH4169 based on the polycrystalline model is studied and analyzed.In order to verify the accuracy of the polycrystalline model,the experimental and simulation results under different cutting conditions are compared.Observe the chip formation process of simulation and experiment,deeply analyze the formation mechanism of serrated chip,analyze the factors that affect the residual stress of machining surface and the factors that affect the burr shape.The results show that the grains in the shear band first appear work hardening phenomenon,and with the increase of temperature,the materialsoftens again,which leads to the formation of the shear band.At the same time,the dislocation produces stress concentration at the boundary of the free surface of the workpiece cutting layer,which leads to the formation of the crack at the boundary.The crack and the shear band converge,accelerating the sliding of the serrated segment,and finally forming the serrated chip.The higher the cutting speed is,the less likely to form the retained burr.The deeper the cutting depth is,the higher the burr height is.The higher the cutting speed is,the residual of the machined surface is The higher the maximum value of residual tensile stress and residual compressive stress;the greater the decreasing rate of residual tensile stress in the workpiece with high cutting speed with the increase of workpiece depth;the greater the cutting depth is,the higher the maximum value of residual tensile stress and residual compressive stress on the machined surface is,and the change of cutting depth has little effect on the residual tensile stress.The research results provide theoretical basis and reference for further optimization of cutting process.