MEAN VS. LIFE-LIMITING FATIGUE BEHAVIOR OF A NICKEL-BASED SUPERALLOY

摘要

The mean and the life-limiting behavior under fatigue of thenickel-based superalloy, IN100, separated (or converged) as afunction of stress level and dwell loading. This behavior wasrelated to the control of the life-limiting behavior by the smallcrackgrowth regime, producing its much slower response to stresslevel and dwell-time, relative to the mean-lifetime behavior. Thelifetime probability density is therefore, modeled as asuperposition of the crack growth lifetime density and a meanlifetimedensity. The crack growth density is calculated with thehelp of small-crack growth data and the distribution in the crackinitiation size. The mean-lifetime density is estimated from arelatively small number of total lifetime fatigue tests. In IN100,we apply this approach to predict the effects of stress level anddwell time on the lifetime distribution and the B0.1 (1 in 1000probability of failure) lifetime limit.