Effect of martensite reorientation and reorientation-induced plasticity on multiaxial transformation ratchetting of super-elastic NiTi shape memory alloy: New consideration in constitutive model

• A crystal plasticity based micromechanical constitutive model is constructed.
• Reorientation-induced plasticity is newly included in the proposed model.
• Multiaxial transformation ratchetting of super-elastic NiTi alloy is predicted well.
• Cyclic deformation of shape memory NiTi alloy is also predicted well.

Experimental results show that the martensite reorientation and reorientation-induced plasticity play critical roles on the non-proportional multiaxial transformation ratchetting of super-elastic NiTi shape memory alloy (SMA) (Song et al., 2014b). In this paper, the multiaxial transformation ratchetting of the NiTi shape memory alloy is described by developing a new constitutive model in the framework of crystal plasticity. Besides the well-known inelastic mechanisms of NiTi shape memory alloys, such as the martensite transformation, martensite reorientation, transformation-induced plasticity and accumulated residual martensite, a new inelastic deformation mechanism, i.e., reorientation-induced plasticity is included in the proposed model to address its effect on multiaxial transformation ratchetting. The constitutive model is constructed in the single crystal scale and extended to a polycrystalline version by adopting an explicit scale-transition rule. By comparing the predicted results with the corresponding experimental ones, it is verified that the proposed model describes the non-proportional multiaxial transformation ratchetting of super-elastic NiTi shape memory alloy more reasonably by considering the martensite reorientation and reorientation-induced plasticity simultaneously.