100 1000 10000 1000 10000 Cycles to Small Crack Initiation (Ni ) Pseudostress Amplitude (S' a - MPa) No Primary Load, D.O.=8ppm No primary Load, D.O.=2ppm 90MPa Primary Load, D.O.=8ppm 90MPa Primary Load, D.O.=2ppm ASME VIII Fatigue Data Curve Figure 1: Effect of primary load and dissolved oxygen Level (D.O.) on small crack initiation lifetime. 1.E-07 1.E-06 1.E-05 10 100 ∆KI (MPa.m1/2) da/dN (m/cycle) (R=0) (0.25<R<0.3) (0.3<R<0.35) (0.35<R<0.45) ASME, Water, R>0.65 ASME, Water, R<0.25 ASME, Air, R=0.9 ASME, Air, R=0 D.O. = 2ppm D.O. = 8ppm High R-ratio Low R-ratio Figure 2: Crack growth rates as a function of stress intensity factor. Squares correspond to measurements made during testing with D.O.≈8ppm, triangles correspond to D.O.≈2ppm. The large arrows indicate only trends for individual crack growth – no curve fitting is implied.
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