Steel, Structural--Fatigue

This research investigated the plate thickness and weld profile effects upon fatigue of structural steel in sea water. Specific attention was focused on the initiation and propagation behavior of fatigue cracks formed at the toe of different profiled welds and varied plate thicknesses. It was shown that the initiation life was reduced as the thickness increased. The improved weld profile increased the crack initiation life. Analysis of the fatigue data indicated that the Initiation Life to Failure Life Ratio Ni/Nf appeared to be greater for the improved weld profile than for the AWS Basic weld profile. The improved weld profile prolonged the propagation life Np. The thickness factor influenced the propagation life Np for the improved weld profile, but the trend was uncertain for the basic weld profile.

The object of this work was to investigate the fatigue
performance of 25.4mm thick, butt welded ABS DH-32 steel
plate under spectrum loading, which simulated the
environmental conditions of the North Sea. Specimens were
tested in sea water under different levels of cathodic
protection. The results, including the previous freely
corroding data, are discussed with regard to the effect of
cyclic - frequency, loading history, weld profile and
cathodic protection. This study indicated that load
interaction effects are negligible in the present
experiments. However, frequency, weld geometry and
cathodic protection significantly effect fatigue life.