Low and high cycle fatigue interaction in 316L stainless steel

The interaction between initial low cycle fatigue (LCF) and high cycle fatigue (HCF) in 316L stainless steel is reported. Specimens were introduced to varying degrees of LCF and subsequently subjected to HCF until failure. LCF involves bulk plasticity where stress levels are usually above the yield strength of the material. On the other hand, HCF is predominantly elastic, and stress levels are below the yield strength of the material. Fatigue was carried out under strain control where two strain amplitudes in the LCF range with a common HCF strain amplitude were investigated. Results show that fatigue life decreased when specimens were introduced to increasing numbers of initial LCF. A linear life trend is observed for high numbers of LCF introduction, which deviates from linearity when lower numbers of LCF were introduced. It is therefore concluded that initial LCF causes substantial irreversible damage, subsequently reducing fatigue life in the HCF regime.