Deformation Behavior of TiNi Shape Memory Alloys

Cyclic Characteristics under Constant Temperature and Constant Stress

Abstract

Cyclic loading-unloading experiments at constant temperature and cyclic heating-cooling experiments under constant stress were carried out on TiNi shape memory alloys, and the cyclic characteristics of deformation behavior were discussed. The results are summarized as follows.
(1) The transformation lines on the stress-temperature plane moves toward the lower stress region and the higher temperature region under cyclic deformation.
(2) The transformation stress and the transformation temperature vary significantly in the early thermomechanical cycles, but take almost the constant values after a cetain number of cycles.
(3) There is a similarity of cyclic behavior between the stress-strain curve at constant temperature and the temperature-strain curve under constant stress.