Effect of heat treatment on deformation behavior of superelastic alloy Ti-Ni-Co

Effect of annealing(Ta) and deforming(Td) temperatures and stress-strain cycle on the deformation behavior of Ti-49.8Ni-1.0Co(atomic fraction,%) superelastic(SE) alloy wire and coil spring was investigated by tensile and stress-strain cycling test.The results show that the platform stress on the stress-strain curve of Ti-Ni-Co alloy wire increases and the platform strain increases firstly and then decreases with increasing the annealing temperature.With the increase of annealing and deforming temperatures,the critical shear stress of the coil spring increases.The strain recovery ratio of the coil spring decreases with the increase of stress-strain cycle number.The prior cyclic training can enhance the SE stability of Ti-49.8Ni-1.0Co alloy spring.