Constitutive relationship of IN690 superalloy by using uniaxial compression tests

The hot deformation behavior of IN690 superalloy was characterized in a temperature range of 1273–1473 K and a strain rate range of 0.01–10 s−1 using uniaxial compression tests on process annealed material. The constitutive relations between flow stress and effective strain, effective strain rate as well as deformation temperature were studied. It can be concluded that the flow stress significantly reduces with the deformation temperature of IN690 superalloy increasing. Whereas, there is a significant increase of flow stress when the strain rate increases from 0.1 s−1 to 10 s−1. Based on the hyperbolic-sine Arrhenius-type equation, a constitutive equation considering compensation of strain was developed. The activation energy and the material constants (Q, n and ln A) decrease as the deformation strain increases. The strain dependent term is successfully incorporated in the constitutive equation through a quartic equation. A good agreement between the experimental data and the predicted results has been achieved, indicating that the proposed constitutive equation and the methods of determing the material constants are suitable to model the high temperature deformation behavior of IN690 superalloy.