Researchers from Fort Wayne Metals, Fort Wayne, Ind., presented The Effects of Heat Treatment on the Properties of Shape Memory Nitinol Wires at SMST 2015. In this study, the effects of heat treatment at various temperatures between 673K and 848K, and dwell times ranging from 60 s to 3.6 ks, were investigated for three Ni-Ti alloys after cold-drawing with 45% nominal cold work to a diameter of 0.38 mm. The active austenite-finish transformation temperatures were measured utilizing a linear variable-displacement transducer bend and free-recovery method.
A surge in market interest for shape-memory Nitinol in aerospace and industrial products has occurred due to impressive work output characteristics and functional stability at moderate to high temperatures. Each application requires a unique set of transformational and mechanical properties dependent on thermo-mechanical processing.
The majority of published data focus on understanding and improving the processing of superelastic, medical-grade alloys. Mechanical characterization was determined by uniaxial tensile testing per ASTM F2516 at temperatures above active Af temperatures over a single cycle and up to 10 cycles to examine cyclic functional stability.
This study aims to summarize the impact of heat treatment on active Af temperatures and begin to correlate processing variables with mechanical properties.
Authors:
Mrs. Luciana Prass Rolsen , Fort Wayne Metals Research Products Corp., Fort Wayne, IN
Mr. David Plumley , Fort Wayne Metals, Fort Wayne, IN
Mr. Wayne Buchan , Fort Wayne Metals Research Products Corp., Fort Wayne, IN
Dr. Jeremy E. Schaffer , Fort Wayne Metals Research Products Corporation, Fort Wayne, IN
www.fwmetals.com
