ひずみ制御と応力制御でのTiNi形状記憶合金の変形挙動

抄録

The deformation properties of TiNi shape memory alloy subjected to strain control and stress control were investigated experimentally. The results obtained are summarized as follows. (1) In the case of full loop, the stress-strain curves under stress-controlled condition are similar to those under strain-controlled condition with high strain rate. The overshoot and undershoot do not appear at the start points of the stress-induced martensitic transformation in these curves. (2) In the case of subloop under stress-controlled condition, temperature decreases and therefore strain increases owing to the martensitic transformation at the early stage in the unloading process. At the early stage in the reloading process, temperature increases and therefore strain decreases owing to the reverse transformation. (3) In the case of subloop under stress-controlled condition, the starting stresses of the martensitic transformation and the reverse transformation in the loading and unloading processes coincide with the transformation stresses under strain-controlled condition with low strain rate, respectively. (4) The deformation behaviors for subloop under stress-controlled condition are prescribed by the condition of progress of the martensitic transformation based on the transformation kinetics.