Effects of Composition and Working Conditions on Transformation in NiTi Shape Memory Springs

In the last years, multi-functional materials have become a class of materials which attracted more and more the attention. Among them, shape memory alloys (SMAs) with transformation temperatures between 0-30°C are interesting for the combined functions as sensor-actuator, responding directly to variation of environmental temperature.

These properties can be useful for applications in the field of temperature control (air-conditioning, water heating, etc).

To be successful is of key importance the customization of the SMAs component according to specific requirements, both for the geometry (wire, compression or extension springs) and the transition temperatures, which depend on several parameters such as alloy composition, thermo-mechanical treatments and applied load.

In this paper, the effects of chemical composition and loading conditions upon the shape memory properties will be examined on compression springs with the same design and after the same shape setting treatment.