Recovery stress in cold-drawn superelastic NiTi SMA wire and its mechanical properties under recovery stress

초록

This study examined the recovery stress induced in cold-drawn superelastic NiTi SMA wires and their monotonic and cyclic behavior under recovery stress. Moreover, the results were compared with those of cold-drawn martensitic SMA wires, which have been widely used in previous studies. For this purpose, martensitic SMA wires with a diameter of 0.85 mm were prepared and cold-drawn to a diameter of 0.815 mm resulting in an area reduction ratio of 8.06%. For the superelastic SMA wires, 0.835 mm wires were initially manufactured and then cold-drawn to a diameter of 0.821 mm, giving an area reduction ratio of 3.32%. This study conducted monotonic and cyclic tensile tests on both non-cold-drawn and cold-drawn martensitic and superelastic SMA wires, then recovery and cyclic tensile tests under residual recovery stress. From the results, three parameters of available strain range, secant slope of stress-strain curves, and equivalent viscous damping ratio of hysteresis were compared. The cold-drawn superelastic SMA wire showed a good available strain range, similar to the superelastic SMA wire, and its values exceeded that of the cold drawn martensitic SMA wire. The cold-drawn superelastic SMA wire induced a relatively high recovery stress at room temperature, which was 1.5 times that of the cold-drawn martensitic SMA wire. Based on these results, the cold-drawn superelastic SMA wire could be considered an alternative to the cold-drawn martensitic SMA wire. © 2026 Elsevier Ltd.

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