Fatigue crack growth test and characteristics analysis for ultra-thick crack-arrest steel

The fatigue crack growth rate of materials is an essential aspect of the fatigue life prediction. Within the container ship industry, crack-arrest thick steel plates are extensively utilized to mitigate the fracture risks caused by the increasing vessel dimensions. However, it remains deficient in comprehensive investigations into its fatigue crack growth characteristics. This study conducted a sequence of experiments on 85 mm crack-arrest steel (EH47BCACOD) plates. The experiments include tension tests, through-thickness crack growth tests, and surface crack growth tests, while various thickness-based sampling locations, directions, and stress intensity factor ratios are designated. The results illustrate that the crack-arrest steel exhibits better crack growth resistance than conventional marine steels. Regarding non-homogeneity in the thickness direction, variations are observed among ultra-thick plates situated at different thickness locations. The crack growth rate near the surface of plate is lower than that at interior of plate, resembling the behavior exhibited by the tensile test. Furthermore, evident anisotropy is identified in the resistance of fatigue crack growth.