Fatigue analysis of thermal cut edges with defined post-processing treatment in normal- and high-strength steel

Kurzfassung

Within ships or maritime structures, plate edges are an important detail for the strength and fatigue assessment. Large openings such as hatches on container vessels or windows on cruise ships lead to a stress concentration, which has to be considered for strength calculation. These openings within steel plates are generally manufactured by thermal cutting processes. The recommendations regarding fatigue design by the IIW and classification societies for the structural behavior of these details are limited to general design categories using the nominal stress approach. In addition, no strict differences in cutting technologies and edge treatments such as grinding are taken into account. This paper describes the fatigue behavior of thermal cut edges made of structural steel plates with different thicknesses from 5 to 25 mm including steel grades from S235 up to S690. All specimens were manufactured in an acceptable and comparable quality range according to ISO 9013, quality level 2, and have been treated with a defined chamfer to compare the influences of cutting processes and yield levels. Previous studies already indicated a beneficial effect regarding fatigue strength of thermal cut edges using higher strength steels, but the results were not clearly in line to describe the behavior sufficiently. The aim of this investigation is to present the potential of a defined edge treatment for thermal cut edges on the fatigue performance. Therefore, fatigue tests with constant amplitudes were carried out and the specimens are characterized by identifying important properties such as roughness and hardness