Influence of Varying Ingot Transformation On Fatigue Endurance of Nitinol Alloys

The correlation between ingot transformation temperatures and mechanical fatigue endurance is important when developing applications using NiTiNOL.  Understanding the relationship between the ingot transformation temperature and fatigue properties will enhance the medical device design process.  Each specimen consists of a slightly different nickel weight percent composition, which causes variance in the ingot austenite start temperature.  These compositions are an influential factor in manipulating the properties of NiTiNOL.  The coldwork reduction, melting source, and thermal treatment in this experiment are constant.  Endurance of the NiTiNOL is determined by rotary beam fatigue testing.  This test setup entails a temperature-controlled RO water bath at body temperature (37⁰C ± 2⁰C). This paper will disclose a fatigue endurance analysis of NiTiNOL wires with various ingot austenite start temperatures.

 

Keywords:  NiTiNOL Wire, NiTiNOL Ingot Austenite Start (A_s) Transformation, Fatigue, Medical Device