Revealing nanoscale material deformation mechanism and surface/subsurface characteristics in vibration-assisted nano-grinding of single-crystal iron

Abstract

Ultrasonic vibration-assisted grinding (UVAG) has attracted extensive attention as it can significantly improve the surface integrity of the machined workpiece. However, the atom-scale material deformation mechanism with the presence of ultrasonic vibration is still unclear, which hider the application of the UVAG to the ultra-precision machining process. To fill this gap, we present a molecular dynamics (MD) model for the vibration-assisted nano-grinding process (VANG) of single-crystal iron. The characteristics of the material deformation process induced by ultrasonic vibration are studied, including material accumulation, temperature, dislocation, subsurface damage (SSD), contact area, and grinding force. The results show that vibration changes the dislocation distribution in the plastic zone, forms the phenomena of expansion and contraction and causes the fluctuation of SSD depth. Due to the different distribution of stress and temperature during VANG, the details of plastic deformation, such as dislocation movement, dislocation nucleation and phase transformation, change with the varying vibration frequency. In addition, the reduction of the projected contact area is the main reason for the reduction of grinding force. However, dislocation pileup in the grinding zone and chips further increase the grinding hardness. This research could enrich the understanding of nano-scale deformation mechanisms in vibration-assisted processing of metallic materials.