Effect of Cold Working on Transformation and Deformation Behavior after Pre-Deforming in Ti–50 at%Ni Shape Memory Alloy

It is reported that the transformation characteristics of Ti–Ni shape memory alloys (SMAs) are influenced by manufacturing conditions, such as composition, heattreatment temperature, cold working, and so on. To understand correctly the effects of these manufacturing conditions on transformation characteristics of Ti–Ni SMAs make it possible to control the transformation temperature and recovery stress. The purpose of this work is to clarify the effect of cold working ratio on transformation and deformation behavior after pre-deforming SMA. The specimens were Ti–50 at%Ni annealed at 673 K for 3.6 ks. The variation of the recoverable strain, recovery stress and transformation temperature with cold working ratio was investigated experimentally. The solution treated material was also used as a reference material. The effect of cold working ratio on the transformation and deformation behavior is discussed in relation to the volume fraction of the residual martensite subjected to slip deformation.