Multi-objective cyclic plastic modelling of cyclic hardening and softening characteristics of nuclear piping SA333 gr. 6 carbon steel

The cyclic hardening/softening behaviour of C-Mn piping material has been studied in detail. The material exhibits cyclic hardening-hardening-hardening (H-H-H) at higher strain ranges, softening-softening-hardening (S-S-H) at lower strain ranges. Quantitative investigations of isotropic transformations show strain range dependent variation of cyclic yield strength. Higher translations of centre of yield surface have been observed at higher strain ranges. Present work has explored cyclic hardening/softening primarily due to variation of isotropic softening. The material exhibits additional hardening under multistep asymmetric strain cycling. New multi -objective plasticity model has been developed, results in excellent prediction of cycle-cycle behaviour, H-H-H, S-S-H, additional hardening till failure.