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Visco‐Plastic Constitutive Model for Cyclic Responses Simulation and Lifetime Prediction of Hot‐Work Tool Steel H13 at Elevated Temperature

AISI H13 hot‐work tool steel is extensively used as tool material for the aluminum extrusion process and its working temperature is about 500 °C. It is essential to model cyclic responses and conduct lifetime prediction of H13 reasonably for optimization of the tools. In this study, uniaxial tests are conducted to investigate mechanical properties of H13. It can be observed that the material shows significant rate‐dependence and obvious cyclic softening effects. In addition, the evolution of ratcheting obviously has three stages: gradually decreasing stage, approximately constant stage, and rapidly increasing stage. Considering above‐mentioned characteristics, a modified visco‐plastic constitutive model is proposed to describe the cyclic plasticity responses in the whole lifetime by a combination of modified A‐F kinematic hardening rule and a new proposed isotropic hardening rule. Furthermore, its lifetime is predicted by involving a failure criterion with the critical size of yield surface. Accelerated ratcheting phenomena and peak stress reduction in failure phase are simulated reasonably. In addition, the simulation results of cyclic responses give a good estimation of plastic deformation under cyclic loading conditions. All in all, the comparisons of simulation and experimental results indicate that the proposed constitutive model predicts mechanical properties, as well as lifetime reasonably.