Modeling of the Stress Path-Dependent Strain Ratcheting Behaviour of 304L Stainless Steel Through Crystal Plasticity Frameworks

This study investigates the strain ratcheting behavior of 304L stainless steel under complex stress-controlled cyclic loading conditions employing crystal plasticity models in the DAMASK framework. Strain ratcheting, a phenomenon characterized by the accumulation of plastic strain during cyclic loading, is particularly important in industries such as aerospace and nuclear energy, where components are subjected to non-proportional multiaxial loading. A polycrystalline representative volume element with 200 randomly oriented grains was generated to predict the material response under various stress paths, including Uniaxial, Shear, Cross, Square, and Circle loading conditions. Two crystal plasticity models were used: a phenomenological power-law (PP) model and a combined isotropic-kinematic hardening (IK) model. Simulations were conducted to identify parameters under monotonic and cyclic strain-controlled loading conditions. Model parameters are identified by using experimental results from literature and conducting strain-controlled uniaxial monotonic and cyclic loading simulations for PP and IK models, respectively. In addition, FEM and spectral solvers are compared for monotonic and cyclic loading conditions, and very similar macroscopic responses are obtained. The uniaxial strain ratcheting simulations under stress-controlled cyclic loading were compared against experimental data, with the IK model producing closer results due to its back-stress and memory terms. The analysis also revealed that the mechanical response, both at the macroscopic and local levels, is highly sensitive to the applied stress path, with significant differences in strain accumulation observed across different loading conditions. Torsional and axial strain evolutions were analyzed in detail, showing that the PP and IK models each performed better under certain stress paths. This study emphasizes the critical role of stress path effects in strain ratcheting and the variation in torsional and axial ratcheting predictions of two models for different stress paths.

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