GS0208-217 Comparative Study on Small Fatigue Crack propagation between two TWIP steels : Importance of Mn-C Interaction on Fatigue Limit

Abstract

The high cycle fatigue properties of Fe-30Mn-3Si-3Al and Fe-22Mn-0.5C twinning-induced plasticity (TWIP) steels were evaluated by rotary bending fatigue testing and a replica technique. More specifically, small fatigue crack propagation and non-propagating fatigue crack phenomenon were comparatively studied in terms of occurrence of dynamic strain aging. In fact, dynamic strain aging occurs in the Fe-22Mn-0.5C TWIP steel because of the presence of Interstitial-substitutional (I-S) atom interactions. Probably due to the occurrence of dynamic strain aging, only the Fe-22Mn-0.5C TWIP steel showed non-propagating fatigue crack phenomenon at the fatigue limit. In contrast, a small fatigue crack of the Fe-30Mn-3Si-3Al TWIP steel continuously propagated even at the fatigue limit which was defined that the specimen does not fracture until 10^7 cycles.