The combined effect of frequency and load level on fatigue crack growth in stainless steel 304

The crack growth behavior in stainless steel 304 was investigated at 538 degreesC. Compact tension specimens, 50 mm wide and 12.5 mm thick, were subjected to fatigue loading under R=0.05 load control. The combined effect of frequency (0.05 Hz less than or equal tof less than or equal to 10 Hz) and load level (6 kN less than or equal toP(max)less than or equal to 16 kN) on the crack growth rate was examined. Parameters DeltaK and DeltaJ were shown to correlate crack growth rates reasonably well. Two (f-P-max) domains were suggested, in each of which crack growth can be characterized by a single da/dN-DeltaK equation. For DeltaKm, crack growth rates appear to be independent of f x P-max values, except at the lowest where faster crack growth occurred because of environmental effects. For DeltaK>25 MPa rootm, crack growth rates were found higher for larger values of f x P-max. The mode of crack growth was transgranular for all test conditions. (C) 2001 Published by Elsevier Science Ltd.X1113sciescopu