Effect of Cold Rolling and Hot Rolling on Recrystallization Texture and Superelastic Properties of Ti-30Zr-10Nb-2Sn Shape Memory Alloy

Abstract

A comparative study on the microstructure, texture evolution, and superelasticity of cold-rolled and hot-rolled Ti-30Zr-10Nb-2Sn (at.%) alloys was performed using electron back-scattered diffraction (EBSD), X-ray diffraction (XRD), and tensile test. The cold-rolled sheet was solution-treated at 1173 K after a 98.0% cold rolling at room temperature. Hot rolling was carried out at 1273 K. Both cold-rolled and hot-rolled sheets were solution-treated at 1173 K for 1.8 ks. Both solution-treated alloy specimens consisted of a single beta-phase at room temperature. A very high (200)(beta) peak was observed for the cold-rolled specimen, and a high (110)(beta) peak was observed for the hot-rolled specimen after the solution treatment at 1173 K for 1.8 ks. The {001}(beta) < 110 > (beta) recrystallization texture was obtained in the 1173 K solution-treated alloy specimen owing to grain growth after recrystallization. The {001}(beta) < 110 >(beta) recrystallization texture was not observed in the hot-rolled specimen; instead, a (221)(beta) [(1) over bar(1) over bar4](beta) recrystallization texture was observed. The 1173 K solution-treated alloy specimen exhibited superelasticity with complete recovery resulting from the {001}(beta) < 110 >(beta) recrystallization texture. Superelasticity was also observed for the hot- rolled specimen, but was not complete, probably because of the low critical stress for slip.