Characterization of Transformation Temperatures with the Bend and Free Recovery Technique: Parameters and Effects

The Bend and Free Recovery (BFR) technique, as described in the ASTM F 2082 standard, is widely used in the medical device industry to determine the transformation temperature(s) of incoming material, partially processed devices, and finished devices. As described in the standard, factors such as the amount of prestrain and the prestraining temperature can potentially affect the result. In practice, these factors can be influenced by complicated device geometries and the availability of adequate cooling systems. This study will investigate the influence of several testing parameters on the resulting transformation temperature measurements. The effects of varying factors such as prestraining temperature, magnitude of prestrain, alloy transformation temperature, heat treatment, and repeated testing of a single part will be investigated.