High cycle fatigue behavior and magnetic domain structure of non-oriented and grain-oriented electrical steels at Rσ = 0.1 and Rσ = −1

The high cycle fatigue behavior of a non-oriented electrical steel (NOES) and a grain-oriented electrical steel (GOES) was investigated under two loading conditions with respect to the rolling direction and the transverse direction. The deformation behavior under non-symmetric cyclic loading, i.e. R_σ = 0.1 is characterized by strongly pronounced ratcheting. While ratcheting starts within the first cycle after overcoming the cyclic Lüders band propagation for NOES, the onset of ratcheting for GOES is delayed and starts after an incubation period. For symmetric cyclic loading, i.e. R_σ = -1, an anti-buckling device was applied to the specimen. The cyclic deformation behavior was characterized by mostly elastic behavior in a saturated state with cyclic microplasticity leading to material failure. The investigation of the magnetic domain structure after cyclic loading revealed for NOES a refined domain structure of the specimens after non-symmetric cyclic loading due to higher amounts of plastic deformation. After symmetric cyclic loading, the magnetic domain structure was less altered due to the lower amount of plastic deformation from mostly elastic behavior during cyclic loading. The magnetic domain structures of GOES aligned with the loading direction after non-symmetric cyclic loading, whereas after symmetric cyclic loading there was no clear tendency.