The overload effect on the crack-tip cyclic plastic deformation response in SA333 Gr 6 C-Mn steel.

Highlights • Ratcheting strain behavior tends to decrease after the application of overload which explains the retardation effect in FCG. • The compressive zone of crack-tip residual stress field increases with the decrease in R ratio. • The compressive zone of crack-tip residual stress field increases with the increase of overload. • The compressive part of crack-tip residual stress field increases with the increase of overload ratio and SIF range value. Abstract The present study deals with the investigation of cyclic plastic deformation behavior near crack-tip with/without overload. The effect of overload is studied on single edge notch tension SENT specimen in an elasto-plastic finite element FE analysis. Three different stress ratios, two different overload ratios and a selected stress intensity factor SIF range Δ K value are used. Chaboche model is used for characterizing SA333 Gr 6 C-Mn steel material behavior. Crack-tip cyclic stress/strain hysteresis loops, crack-tip residual stress field and crack-tip ratcheting strain accumulation are simulated with/without overload. Moreover, the effect of overload ratio, stress ratio, background Δ K -level and crack size on controlling the compressive residual stress field, generated near crack-tip after overloading, are discussed. The results show that the progressive accumulation of plastic strain in the crack-tip cyclic plastic zone tends to decrease after overloading. It is also noticed that the maximum magnitude and the size of compressive residual stress zone following a single overload increase with the increase in the overload crack size and the decrease in the background R r a t i o. The finding results provide insight into the understanding of cracked metallic parts' fatigue response under variable amplitude loading. [ABSTRACT FROM AUTHOR]