Ratcheting prediction of stainless steel 304 and 316L samples undergoing asymmetric loading cycles at elevated temperatures incorporating dynamic strain aging phenomenon

Abstract

The present study intends to assess the plastic strain accumulation in austenitic stainless steel 304 and 316 L samples undergoing uniaxial loading cycles at elevated temperatures incorporating the dynamic strain aging (DSA) phenomenon. The DSA function was adapted into the dynamic recovery term of the Ahmadzadeh-Varvani (A-V) kinematic hardening rule to address the accumulated plastic strain (ratcheting strain) of steel samples at elevated temperature ranges where materials show a negative strain rate sensitivity. The range of temperature at which stainless steel samples manifested DSA event was evidenced between 573 K and 900 K. At this temperature range, the interaction of solute atoms with dislocations resulted in an elevation in materials strength. The evolution of yield strength at various temperatures was calibrated with a multi-variable function developed earlier by the Voyiadjis-Song-Rusinek (VSR) model. The higher strength due to the interaction of solute atoms and dislocations, suppressed the ratcheting magnitude and rate of steel samples at the DSA domain. Applied loads beyond the elastic limit resulted in the yield surface translation, in the deviatoric stress space, governed by the A-V hardening rule. The DSA phenomenon promoted the yield surface and the backstress evolution for stainless steel samples at the operating temperature of 673 K. The predicted ratcheting curves within the DSA domain were largely associated with the operating temperature, accumulated plastic strain, and asymmetric loading cycles.