Table of Contents
Smart Materials Research
Volume 2011, Article ID 160927, 6 pages
http://dx.doi.org/10.1155/2011/160927
Research Article

Effect of Annealing on Strain-Temperature Response under Constant Tensile Stress in Cold-Worked NiTi Thin Wire

Department of Metallurgy and Materials Engineering, K.U. Leuven, Kasteelpark Arenberg 44, Bus 2450, 3001 Heverlee, Belgium

Received 17 November 2010; Accepted 6 January 2011

Academic Editor: Yanjun Zheng

Copyright © 2011 Xiaojun Yan and Jan Van Humbeeck. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

The present paper aims to understand the influence of annealing on the strain-temperature response of a cold-worked NiTi wire under constant tensile stress. It was found that transformation behavior, stress-strain relationship, and strain-temperature response of the cold-worked NiTi wire are strongly affected by the annealing temperature. Large martensitic strains can be reached even though the applied stress is below the plateau stress of the martensite phase. At all stress levels transformation strain increases with increasing annealing temperature in the range of 350–450C and decreases with increasing annealing temperature in the range of 450–650C. The martensitic strain at lower stress levels exhibits the same tendency. At higher stress levels the martensitic strain increases with increasing annealing temperature.