Molecular dynamics simulation of cutting mechanism of polycrystalline Fe-Cr-W alloy

Abstract

In order to study the effect of cutting parameters on the machining mechanism of AISI M2 alloy tool steel during ultra-precision machining, the effects of cutting speed and depth of cut on crystal structure change, cutting force, cutting temperature, and transformation of amorphous atoms during turning are analyzed. The polycrystalline molecular dynamics model of alloy tool steel is established with three elements Fe, Cr, and W, and the molecular dynamics model of the tool is established with B and N two elements. Four potential energy functions of Tersoff, EAM, Morse, and L-J are used to characterize the interaction between atoms in the model. The following research results can be obtained by analyzing the microstructure changes of the material during the cutting process: (1) With the progress of cutting, some of the workpiece atoms accumulate on the rake face of the tool to form chips, and another part of the atoms flow to both sides of the tool to form surface peaks. (2) The shear extrusion effect of the tool on the material causes the reconfiguration and transformation of the grains inside the polycrystalline alloy. (3) The cutting temperature and cutting force of the molecular dynamics simulation system show an upward trend with the increase in cutting speed and cutting depth. Moreover, the cutting force fluctuates due to the existence of irregular grains, discrete atoms, and grain boundaries.