Molecular dynamics study on surface formation and phase transformation in nanometric cutting of β-Sn

Atomic motion and surface formation in the nanometric cutting process of β-Sn are investigated using molecular dynamics (MD). A stagnation region is observed that changes the shape of the tool edge involved in nanometric cutting, resulting in a fluctuation in the cutting forces. It is found that single-crystal tin releases the high compressive stress generated under the tool pressure through slip and phase transformation. The tin transformation proceeds from a β-Sn structure to a bct-Sn structure. The effects of the cutting speed, undeformed chip thickness (UCT) and tool edge radius on material removal are also explored. A better surface is obtained through material embrittlement caused by a higher speed. In addition, a smaller UCT and sharper tool edge help reduce subsurface damage.