Effect of Contact Temperature Rise During Sliding on the Wear Resistance of TiNi Shape Memory Alloys

The high wear resistance of TiNi shape memory alloys has generally been attributed to its pseudoelastic nature. In the present work the hardening effect due to its phase transformation from martensite to austenite due to frictional heating during sliding has been considered. Based on existing constitutive models that represent the experimental results of TiNi shape memory alloys a theoretical model of the dependence of wear-resistance on the contact temperature rise has been developed. The analysis was further extended to include the operating and surface roughness parameters. The model essentially indicates that for these alloys wear decreases with the rise in contact temperature over a wide range of load, speed and surface roughness combination during sliding. This means that the wear resistance of these alloys results from the very cause that is normally responsible for the increased wear and seizure of common engineering materials. Preliminary wear tests were carried out with TiNi alloys at varying ambient temperature and varying load-speed combinations and the results agree well with the theoretical predictions.