Ratcheting of 304 Stainless Steel Alloys subjected to Stress-Controlled and mixed Stress- and Strain-Controlled Conditions evaluated by Kinematic Hardening Rules

The present study predicts ratcheting response of SS304 tubular stainless steel samples using kinematic hardening rules of Ohno-Wang (O-W), Chen-Jiao-Kim (C-J-K) and a newly modified hardening rule under various stress-controlled, and combined stress- and strain-controlled histories. The O-W hardening rule was developed based on the critical state of dynamic recovery of backstress. The C-J-K hardening rule further developed the O-W rule to include the effect of non-proportionality in ratcheting assessment of materials. The modified rule involved terms < d (epsilon) over bar.(a) over bar/vertical bar(a) over bar vertical bar >, and <(n) over bar.(a) over bar/vertical bar(a) over bar vertical bar >(1/2) in the dynamic recovery of the Ahmadzadeh-Varvani (A-V) model to respectively track different directions under multiaxial loading, account for non-proportionality and prevent plastic shakedown of ratcheting data over multiaxial stress cycles. The O-W model persistently overestimated ratcheting strain over the multiaxial loading paths. The C-J-K model further lowered this overprediction and improved the predicted ratcheting curves. The predicted ratcheting curves based on the modified model closely agreed with experimental data under various loading paths.