In order to develop a constitutive relation which is able to describe the phase transition and the plasticity behavior of NiTi alloy,based on the irreversible thermodynamics,two internal variables were assumed to characterize the phase transformation evolution and the plastic evolution respectively,then a master equation was derived.Rewritten in one dimension incremental form,the constitutive model was program implemented with Fortran code,in which the parameters were determined in combining with the uniaxial experiment and the nonlinear fitting.The model validation was carried out by comparing the predicted results with five uniaxial tesile tests under different strain rates,and the results showed that the proposed phenomenological constitutive model can not only describe very well the phenomenon of parent phase transformation and martensite plastic yield, but also the strain rate effect.
