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Wednesday, August 25, 2004
POST 1.22

An Investigation of the Effect of Drawing Temperature on Nitinol Processing

G. F. Archer, SMA/Johnson Matthey, San Jose, CA

Nitinol products exhibit properties not common with the majority of other alloys. These properties permit the use of nitinol in many medical applications. These properties though, contribute to the level of difficulty in processing the raw ingots into final form. As we learned in the last ASM conference, performance of nitinol wire differs when subjected to various environmental temperatures especially in the areas of superelasticity and permanent set. Just as change in temperature affects superelasticity of products made of nitinol, processing of nitinol is affected by the temperature at which it is processed. I would like to evaluate this effect and through collection of data produced from processing nitinol at various temperatures, point a direction for more accurate and higher quality processing techniques for this alloy. I plan to do this by collecting drawing force data as nitinol tubes are drawn thru dies at various environmental temperatures. I also want to compare outside diameter springback characteristics during these draws. The goal of this investigation is to identify the optimum process temperature for nitinol tube or wire drawing. I plan also to evaluate processing temperature effect on surface quality, inside diameter surface integrity, and outside diameter surface quality.