Statistical behaviour of fatigue crack growth for HY-80 steel plate and its weldments under cathodic protection in seawater and in air

Abstract

This paper deals with fatigue crack growth data for various weldments of HY-80 steel plate in seawater and a statistical method for using this data in life predictions and deviations from mean life estimates. Typical results of crack growth behaviour with crack length and examples of the effect of averaging increment on variability of crack growth data are given. The standard deviation for incremental crack growth rates are determined. Use of the data in the calculation of confidence limits in life cycle determination are discussed. The A and N data, from which crack growth data were obtained, were generated on HY-80 base plate and HY-80 weld containing compact tension specimens. They were fatigue-tested either in air at 23°C or in seawater at 23°C. Specimens tested in seawater were also galvanically protected with zinc electrodes. Fatigue loading was at constant ΔK and R = 0.1 or 0.5. Frequency of loading was 0.3 Hz.