COMPRESSIVE TRAINING OF THE SHAPE-MEMORY ALLOY WASHER

This paper evaluates the performance and engineering aspects of 44Ti-4 7Ni-9Nb alloy in a pretensioning washer application. Previously the be havior of this alloy has mainly been studied for tensile predeformatio n with wires and strips up to 1 mm thickness. The present work investi gated the effect of compression deformation and different homogenizati on temperatures on ring-shaped washers with larger dimensions. The bes t results with the compression-trained washer were achieved after homo genization at 1073 K where the compression training deformation was -1 0.4 %, 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, seem ed to be a fairly efficient training method far the studied applicatio n, even though the parallel course of the radial surfaces was poor.