Strain-Cycle Fatigue of Sheet and Plate Steels III: Tests of Notched Specimens

The effect of steel grade on reversals to crack Initiation in notched specimens 2N_i essentially reflected differences in tensile strength. The higher strength grades (B80RK,RQC100) required a greater value of the notch parameter K_fΔS for a given 2N_i than the lower strength grades (1020,A36,B40PO). Stress ratio R had a significant effect on 2N_i with 2N_i increasing as R decreased from 0 to -1. The various predictive models studied (local strain, nominal stress, empirical) gave similar results in terms of the variability in estimates of 2N_i and the relation between the predicted and observed values.