Definition of BS7608 fatigue classes for structural steels with thermally cut edges

Thermal cutting, which includes oxy-fuel, plasma and laser cut technologies, is frequently used in engineering practice to obtain the final shape of structural components. These cutting methods generate cut surfaces and material transformations that determine the final fatigue behaviour. Nevertheless, in practice, design codes such as the BS7608 provide fatigue design curves for oxy-fuel cuts, while other relevant technologies such as plasma and laser cutting are not generally covered, something that limits their use in many engineering applications. This research analyses the effect of the three above mentioned thermal cutting methods on the fatigue behaviour of cut straight edges performed on a wide range of structural steels (S355M, S460M, S690Q and S890Q). The S-N results obtained have been used to derive the corresponding BS7608 design classes, which have been finally validated by comparing them to numerous experimental data found in the literature.