The Effect of Thermal Ageing on The Transformation Temperatures of Superelastic Nitinol Tubing

A. Kokkinos, V. Kostopoulos, D. Aslanidis

Ni- Ti shape memory alloys (nitinol) have become widely known for both their shape memory effect and their pseudoplasticity (superelasticity).  Their properties are depending upon the thermomechanical processing during the manufacturing phase of the material.  Thermal ageing is the long term exposure of the shape memory alloys at a relatively high temperature (in some cases long term exposure (more than 240 h) at temperature close to austenitic transformation could be considered as a post-processing treatment phase used for the final tuning of the transformation characteristics). 

In the present paper, the effect of thermal ageing on the transformation characteristics is analyzed and discussed.