Optimisation of processing and properties of medical grade Nitinol wire

AbstractThe purpose of this paper is to review the current processing and resultant properties of standard Nitinol wire for guide-wire applications. Optimised Ti-50.8at%Ni wire was manufactured according to industry standards by precise control of the composition, cold work and continuous strain-age annealing. Mechanical properties of this wire are reported from -100°C to 200°C to demonstrate the effects of test temperature. Within the ‘superelastic window’ the plateau stresses are linearly related to test temperature. Additional ageing treatments can be used as a tool to fine-tune transformation temperatures and mechanical properties. A review of the fatigue properties of thermomechanically-treated Nitinol wire shows that they are affected by test temperature, stress and strain.Key Words: Nitinolshape-memorysuperelasticitymechanical propertiesageingfatigue