Influence of temperature on the cutting performance of single-crystal beryllium: a molecular dynamics simulation investigation

In this paper, molecular dynamics (MD) simulations were carried out to investigate the cutting performance of beryllium at various temperatures (25 °C, 200 °C, 300 °C, 400 °C). The cutting forces, friction coefficient, stress in the cutting zone, and surface quality as the key indicators are used to characterize the cutting behaviors of beryllium. An important observation is that the tangential force and normal force decrease by 32% and 36%, respectively when the temperature increases from 25 to 200 °C. During the cutting process, it is found that the friction coefficient is minimum at 25 °C and becomes maximum at 200 °C. The friction coefficient starts to decrease from 25 to 300 °C. It is also observed that compressive stress is the main stress state in the shear deformation zone. The maximum stress is up to 9 GPa, and the tensile stress with the maximum value of 5 GPa is mainly distributed in the friction area of the back surface of the workpiece. Furthermore, with an increase in temperature, the compressive stress in the shear deformation zone gradually decreases, and the tensile stress increases. Finally, the distribution of subsurface defects and the crystal structure of the material at different temperatures are analyzed. It is found that the number and the type of defects in the sub-surface layer of the workpiece fluctuate with an increasing temperature. The number of defects becomes the lowest at 300 °C, and there are burrs on the machined surface that are formed at the beginning of cutting.