The Effects of Laser Forming on NiTi Superelastic 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 superelasticity 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, postprocess 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, when 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 desired deformation while maintaining desired material behavior. Characterization of the residual stress field, plastic deformation, and phase transformation is carried out numerically and is then subsequently validated via experimental results.