Prediction of Creep-fatigue Lives of Cr-Mo Steels with Diercks Equation.

Development of generic creep–fatigue life prediction models

“…This section summarizes, Table 1, life prediction methods [1][2][3][4][5][6][7][8][9][10][11][12][13][14] that were developed since 1970. These methods are all empirical, based on phenomenological framework.…”

“…These equations were originally derived to predict the low cycle fatigue response curves of SS 304 and recommended in design by American Society of Mechanical Engineers. Other similar extrapolation equations were developed for SS 304, 316 and 321 [12,13]. Such developments were centered within the laboratories and organizations that managed testing efforts (such as ASME programs, NASA, DoE laboratories and private companies) and controlled testing and therefore the data.…”

“…Therefore, this paper presents this framework of creep-fatigue life prediction and shows a methodology to develop such multivariate best fit equations that may be valuable in the design of engineering components. Multivariate equations were derived by a number of workers [11][12][13][14] to predict the fatigue behavior of stainless steels. These equations were originally derived to predict the low cycle fatigue response curves of SS 304 and recommended in design by American Society of Mechanical Engineers.…”

“…The difference between these two frameworks is in terms of remaining life, after formation of a detectable crack, which is much greater in the case of In this regime, the life prediction is based on the assumption that a crack-like discontinuity is present in a component and modeling its growth till it becomes critical. Numerous empirical life prediction models [1][2][3][4][5][6][7][8][9][10][11][12][13] exist in the literature showing fatigue resistance a function of test and/or material parameters. While test parameters such as dwell time and temperature show interactions of creep and fatigue, complex interactions with environmental processes are very difficult to incorporate in a life prediction model.…”

Applicability of Modified Diercks Equation with NRIM Data

“…With the introduction of the temperature correction factor from reference 111, creepfatigue response of low alloy steels did not change considerably (from 10-15 cycles) when assessed with modified equation (2). Kitagawa et al Ill found that the isostress creep rupture properties of low alloy steels ranged from 50 to 100°C lower than the creep rupture properties of SS 304.…”