Influence of shear cutting parameters on the edge properties and the fatigue behavior of non-oriented electrical steel sheets

Abstract

The fatigue behavior of a fully processed, non-oriented electrical steel sheet is investigated for different shear cutting parameters. Therefore, three cutting clearances (15 μm, 35 μm and 50 μm) in combination with two different punching tool wear states (sharp and worn) are compared regarding their mechanical properties. For this purpose, surface measurements, nanoindentation tests and stress-controlled fatigue tests with a positive load ratio are performed for all six parameter sets. During shear cutting the material gets locally strain-hardened and a deformed surface with micro-notches is created. Compared to a polished reference condition, the fatigue strength of the shear-cut sheets is severely deteriorated. However, the intensity of deterioration varies depending on the shear cutting parameters. For small cutting clearances, the highest fatigue life is observed for a sharp cutting tool. In contrast, for medium and high cutting clearances, samples that are cut with a worn tool achieve higher fatigue lives. Surface characteristics in the fracture zone, which act as a failure-critical crack location, are considered as the main influencing factor.