Deformation Behavior and Properties of Titanium Nickelide Rods after Hot Screw Rolling
摘要
Plastometric studies are conducted and hot deformation diagrams are obtained for large-diameter hot-rolled rods made of titanium nickelide of equiatomic and non-equiatomic nickel compositions in the temperature range from 600 to 1100°C at a deformation rate of 2 s–1. The studies are carried out for samples cut from the central and edge rod zones. Based on the analysis of the deformation diagrams, it is found that a decrease in the deformation temperature to 600°C leads to a threefold increase in the deformation resistance at the steady-state stage compared to deformation at 850 and 1100°C for both equiatomic and non-equiatomic in nickel TiNi alloy. Deformation in the temperature range of 850–1100°C is characterized by rapid attainment of the steady-state stage at e < 0.1 and the maximum deformation resistance stress not exceeding 160 MPa for the near-equiatomic alloy and 260 MPa for the non-equiatomic alloy. The deformation resistance values of the samples from the central and edge zones for the two alloys under consideration are almost identical. No obvious anisotropy of the structural-phase state and the complex of properties of the original 40 mm diameter TiNi SMA rods after screw rolling is noted. Based on the data obtained, it is established that there is no need to perform control treatment after screw rolling, and a temperature of 850 ± 50°C is recommended for moderate deformation of TiNi SMA of equiatomic and non-equiatomic in nickel compositions at a deformation rate of 2 s–1.