A Local Approach to Creep-Fatigue -Oxidation Interactions in Inco 718 Alloy
Understanding and modeling hold time effects on fatigue crack growth rate (FCGR)above 500 ℃ in Inco 718DA is a great challenge.Fatigue tests with a trapezoidal wave shape signalincluding hold times from 90 s to 3600 s were carried out on Inco 718DA with a small grain size(5-15 μm) over a wide range of temperatures (500 ℃-650 ℃).FCGRs were measured usingpotential drop technique.SEM observations were carried out to correlate the measured FCGRs withthe trans- or inter-granular aspect of the fatigue fracture surfaces.Two regimes must bedistinguished.The first regime associated with relatively short hold times can be represented by apower law,where da/dN is proportional to tα,α ~ 0.25.This first regime corresponds to thesituation where the fatigue crack does not propagate during the hold time but its propagation takesplace during the cyclic part of the loading over a damaged zone ahead of the crack tip.The secondregime associated with longer hold times corresponds to the case where crack propagation duringhold time (creep crack growth) is predominant.This regime is purely time dependent.Simplemodels are introduced to describe both regimes.
Inco 718 High temperature fatigue hold time effect fatigue crack growth
André Pineau Raul De Moura Pinho Stéphane Pierret Pinho Caroline Mary
Mines ParisTech,Centre des Matériaux,UMR CNRS 7633,BP 97,91003 Evry Cedex,France Snecma-SAFRAN,Villaroche,77550 Moissy-Cramayel,France
国际会议
北京
英文
1-11
2013-06-16（万方平台首次上网日期，不代表论文的发表时间）