The effects of laser forming on superelastic NiTi shape memory alloys

Abstract

This work focuses on application of the laser forming process to NiTi shape memory alloys. While all NiTi shape memory alloys exhibit both superlasticity and the shape memory effect, this study is restricted to a temperature range over which only the superelastic effect will be active. Specifically, this work addresses laser forming induced macroscopic bending deformations, post process residual stress distributions and changes in microstructure. Like traditional ferrous alloys, the laser forming process may be used as a means for imparting desired permanent deformations in superelastic NiTi alloys. However, this process, as applied to a shape memory alloy also has great potential as a means for shape setting “memorized” geometric configurations while preserving optimal shape memory behavior. Laser forming may be used as a monolithic process which imparts both desired deformation as well as controllable material behavior. Characterization of the residual stress field, plastic deformation and phase transformation are carried out numerically and are then subsequently validated via experimental results.This work focuses on application of the laser forming process to NiTi shape memory alloys. While all NiTi shape memory alloys exhibit both superlasticity and the shape memory effect, this study is restricted to a temperature range over which only the superelastic effect will be active. Specifically, this work addresses laser forming induced macroscopic bending deformations, post process residual stress distributions and changes in microstructure. Like traditional ferrous alloys, the laser forming process may be used as a means for imparting desired permanent deformations in superelastic NiTi alloys. However, this process, as applied to a shape memory alloy also has great potential as a means for shape setting “memorized” geometric configurations while preserving optimal shape memory behavior. Laser forming may be used as a monolithic process which imparts both desired deformation as well as controllable material behavior. Characterization of the residual stress field, plastic deformation and phase transfo...