Dynamic strain aging behavior of modified 9Cr–1Mo and reduced activation ferritic martensitic steels under low cycle fatigue

Influence of temperature and strain rate on low cycle fatigue (LCF) behavior of modified 9Cr–1Mo ferritic martensitic steel and 1.4W–0.06Ta reduced activation ferritic martensitic (RAFM) steel in normalized and tempered conditions was studied. Total strain controlled LCF tests between 300 and 873 K on modified 9Cr–1Mo steel and RAFM steel and at various strain rates on modified 9Cr–1Mo steel were performed at total strain amplitude of ±0.6%. Both the steels showed continuous cyclic softening at all temperatures. Whereas manifestations of dynamic strain aging (DSA) were observed in both the steels which decreased fatigue life at intermediate temperatures, at higher temperatures, oxidation played a crucial role in decreasing fatigue life.