Description
Iron-based shape memory alloys (Fe-SMA) have been used successfully in the previous years as prestressing reinforcement in the form of rebars, rods and flat strips, for various types of structural elements and loading scenarios. This paper introduces a new application of this material in the form of thin wire. An experimental characterisation study is presented herein for Fe-SMA wire that was drawn to a diameter of 0.5 mm, regarding its tensile stress-strain response and recovery stress development upon heating, for different activation temperatures and prestraining levels. Furthermore, an investigation is presented regarding the effects of heat treatment conditions on the mechanical response and prestressing performance of the wire, with the aid of crystallographic analyses by means of electron backscatter diffraction and high energy X-ray diffraction. For the optimum heat treatment conditions and activation temperature range considered in this study, the measured tensile strength and recovery stress of the Fe-SMA wire was 1200 MPa and up to 430 MPa, respectively. The results indicate a strong potential of Fe-SMA as a candidate prestressing material where small diameter wire cross-sections are desired instead of solid tendons (for example, multi-strand twisted wire ropes), or as novel short fibre reinforcement for concrete with prestressing capabilities.
