Effect of plastic working on martensitic phase transformation characteristics of TiNi alloys

Effect of plastic working on martensitic phase transformation characteristics of TiNi wires was investigated. Ti-50.5 at.% Ni wire with a final diameter of 4.2 mm was produced by swaging and groove rolling processes. The wire exhibited multiple-stage martensitic phase transformation behavior after swaging and groove rolling processes followed by heat-treatment at 700 °C for 30 min. The multiple-stage martensitic phase transformation behavior was found to vary with different heat-treatment conditions as well as with the number of groove rolling processes. These results are discussed and possible mechanisms for multiple-stage martensitic phase transformation are proposed.