Dynamic recovery and recrystallization during high temperature low cycle fatigue and characteristics of fatigue behavior of sintered molybdenum

Nishi, Hiroshi; Enoeda, Mikio; Yokobori, Toshimitsu*

Low cycle fatigue behavior of molybdenum has been investigated at high temperatures in order to examine the influence of test temperatures and strain wave. The molybdenum exhibited cyclic softening below its static recrystallization temperature. The cyclic softening was dynamic recovery and recrystallization caused by dislocation movement during fatigue. The cyclic softening occurred progressively in some parts of the specimen. The plastic deformation was consequently concentrated in the softening region of the specimen. Therefore, the low cycle fatigue lives of the molybdenum at temperatures below 1073 K were shorter than those at 1223 K. As for the effect of strain wave on the low cycle fatigue lives, the fatigue lives of non-symmetrical strain wave forms were lower than those of symmetrical strain wave form due to large strain concentration compared to symmetrical strain wave forms.