Abstract
In the previou study, it was shown that transformation superplasticity was more effective to reduce the deformation stress than transformation expansion under some conditions and the transformation temperature was concerned in the deformation stress in the midst of cooling.
In the present report, the elongation of specimen was invesigated during transformation at a constant stress in order to clarify the basic behaviour of transfomation superplasticity.
The results are shown as follows ;
1) During transformation a specimen was plastically distored by a small stress of the order of 1 MPa.
2) The displacement by superplasticity transformation is in proportion to the applied stress during transformation. The inclination, however, varied with materials.
3) If the strength restoration module is taken as R and the deformation strength (σ) is writen as σ=εR, R was about 9.0-16.6 GPa that was 1/10-1/20 times as much as Young's module.
4) In the tensile test of the specimen during martensite transformation at room temperature, the specimen was plastically distored by less than quarter of the fracture stress and the strain by applying a small stress of the order of thermal contraction gave rise to martensite. Then the surface relief by martensite was observed.
