Study On GH4169 Tool-chip Interface Diffusion Mechanism Of Carbide Tool Cutting Based On Molecular Dynamics Simulation

In view of the characteristics of high cutting temperature and severe tool wear in the process of nickel-based superalloy GH4169 cutting,in this paper the material behavior of the tool-chip interface of cemented carbide tools(WC-Co)in the process of cutting GH4169 is studied with the help of molecular dynamics theory,and the mechanism of diffusion and bonding is revealed from the microscopic point of view.Firstly,the basic molecular dynamics theories such as the ensemble,radial distribution function and potential function are introduced in detail.On this basis,the lattice model of molecular dynamics of nickel-based superalloy GH4169 is modified,and the modified model is verified by mechanics.The elastic modulus and Poisson's ratio accord with the real situation.The cutting model of GH4169 for WC-Co cutting is established and Morse potential function between tool and workpiece is derived.Secondly,the modified model is used for simulation analysis,and the data of atomic displacement,velocity and thermodynamics are visualized.By observing the instantaneous displacement image of the workpiece atom and the potential energy distribution of the tool-chip interface,the diffusion phenomenon between the tool and the workpiece is analyzed.Furthermore,by solving the diffusion coefficient,the atomic diffusion velocity is Fe>Ni>Cr under the same conditions.By calculating the vacancy formation energy and diffusion activation energy,the diffusion barrier size is obtained,and the diffusion activation energy Cr<Fe<Ni is obtained,that is,Cr reaches the diffusion condition first.However,because the total energy of the system is higher than those of the three,the diffusion conditions of the three systems can be reached simultaneously without affecting the diffusion results.According to the fact that the activation energy of grain boundary diffusion at tool and workpiece is less than that of lattice diffusion,it is concluded that grain boundary diffusion is the main mode of diffusion.Finally,the bonding molecular dynamics model of carbide tool cutting GH4169 is established,and the micro-bonding mechanism of carbide tool cutting is deeply studied based on the diffusion mechanism analysis.It is found that the right end of the workpiece deviates to the right when the tool has not contacted the workpiece in the cutting process.This is a "jump" phenomenon,which is the phenomenon of mutual attraction between the tool and the workpiece.The force at this point urges the tool to bond with the workpiece.The micro-mechanism of tool-chip bonding is analyzed by solving the surface free energy,bonding force and bonding energy,and the bonding energy and bonding effect,bonding force fluctuation,etc.By counting the number of bonding atoms on the interface between tool and workpiece and calculating the process of tool surface area change,the degree of bonding difficulty between the Rake face and flank face of tool is analyzed.