Compressive training of the shape memory alloy washer

This paper evaluates the performance and engineering aspects of 44Ti-47Ni-9Nb alloy in a pretensioning washer application. Previously the behavior of this alloy has mainly been studied for tensile predeformation with wires and strips up to 1 mm thickness. The present work investigated the effect of compression deformation and different homogenization temperatures on ring-shaped washers with larger dimensions. The best results with the compression-trained washer were achieved after homogenization at 1073 K where the compression training deformation was -10.4%, the lowest applied. The deformation training was carried out at 213 K near the martensitic reaction start temperature of the material. The expansion method, applied to the commercial reference ring, seemed to be a fairly efficient training method for the studied application, even though the parallel course of the radial surfaces was poor.