Modified Superelasticity for machinability improvement of shape memory alloys

Abstract

Shape memory alloy (SMA) exhibit outstanding superelasticity, yet their elastic recovery during machining severely limits efficiency and dimensional accuracy. To overcome this challenge, we propose a laser-ablation-assisted machining approach and validate it using Ni–Ti SMA as a representative material. The study shows that laser modification induces dense surface microstructures, reduces microhardness, and alters elemental composition within the heat-affected zone, thereby lowering both normal and tangential scratching force by over 60% under optimized parameters. More importantly, the method effectively suppresses elastic recovery, achieving a minimum recovery rate of 25%. Molecular dynamics (MD) simulations further reveal that the suppression of martensitic transformation in the laser-modified layer contributes to the reduced elastic recovery. Belt grinding tests further confirm that the proposed technique suppresses the elastic recovery when machining SMAs. These findings provide new insights into controlling deformation mechanisms in SMA and offer a viable route toward their high-quality machining.