Effect of Cutting Method on Fatigue Crack Initiation and Fatigue Life of Structural Steel S355M

This paper analyses the effect of the cutting method on both the fatigue crack initiation and the fatigue life of steel S355M. The research covers three cutting methods (plasma, laser and oxy-fuel) and two specimen geometries: plain specimens with rectangular section and cut edges, and specimens with machined edges and a cut hole in the middle section. All the specimens were conducted to failure in a resonance machine by applying fatigue cycles, the stress ratio (R) being 0.1, and the corresponding S-N curves were obtained for each combination of cutting method and specimen geometry. The crack initiation time was estimated by analyzing the evolution of the resonance frequency on each specimen. The results show a significant influence of the cutting method on both the crack initiation and the fatigue life of this particular steel.