Abstract
So-called “super-elastic materials” like TiNi alloys having large elastic deformability have widely been used for the frame of glasses, the antenna of mobile phones and so on. On the other hand, the unique Ti alloys which have low elastic modulus, high strength and large elastic deformability are developed by Toyota Central R&D., Inc.. These new developed alloys named “GUMMETAL” are put into practical application for the frame of glasses. The alloy belongs to β(bcc)type Ti alloy and the Young's modulus in room temperature is as small as about 40GPa with the 2.5% of elastic deformability to be classified as a super-elasticity. Furthermore, they have nonlinear and nonhysteresis properties without following Hook's law. The authers found them very attractive for applying to new springs having unique characteristics. So, a workshop is established to study the optimum heat treatment condition for spring application observing the accompanying metal structure. Then three kind of spring (compression-, tension- and torsion-type springs) were examined for spring characteristics and discussed their merits in comparison with conventional steel springs.
