Effect of Aging and Cold Working on the High-Temperature Low-Cycle Fatigue Behavior of Alloy 800H: Part II Continuous Cyclic Loading

摘要

The individual and combined effects of cold working (5 and 10 pct) and aging (4000 and 8000 h in the temperature range 538 to 760 exp 0 C) on the high-temperature low-cycle fatigue behavior of alloy 800H have been investigated. The specimens were tested at the aging temperatures. Both the saturation stress range and the fatigue life were found to be history dependent. A history-independent hardening mechanism, dynamic strain aging, was found to operate over the temperature range approx. 450 to 650 exp 0 C and to be maximized at approx. 550 exp 0 C. It is speculated that carbon is responsible for this dynamic strain aging. Finally, at temperatures above 538 exp 0 C the Coffin-Manson plots indicate the possible existence of a history-independent softening mechanism. (ERA citation 05:005973)