Final thermomechanical treatment of thin NiTi filaments for textile applications by electric current

Abstract

Functional properties of NiTi filaments can be in a large extent controlled by the heat treatment after final cold drawing. Conventionally, this is being performed by straight annealing in long tubular electrical furnace by SMA providers. An alternative heat treatment method by Joule heating called Final Thermomechanical Treatment by Electric Current /FTMT-EC/ is presented in this work. Results of key experiments performed while developing the method are discussed in this paper. A prototype of a compact device for FTMT-EC treatment of continuous NiTi filaments is presented and differences compared to the conventional heat treatment in a furnace are discussed. Note to the reader: On page 05024-p2 several mistakes have been corrected on October 19, 2009.