Effect of temperature and sample shape on fatigue behavior of non-oriented electrical steel for new energy vehicles

Taking B20AV1200 non-oriented electrical steel as the research object, based on a large number of fatigue test data, the influence of sample shape and temperature on the fatigue stress-life curve and fatigue limit strength of the steel at 25-200 ℃ was analyzed. The results show that under the same loading conditions, the fatigue limit strength measured by dumbbell-shaped specimen was 40-55 MPa higher than that of funnel-shaped specimen. With the increase of temperature, the fatigue strength of the electrical steel showed an upward trend, but the increase gradually decreased. This was because under the combined action of temperature and stress, the excess carbon and nitrogen atoms in the electrical steel would precipitate in the form of fine dispersed particles, and the ratcheting deformation in the fatigue process also increased. The combined effect of the two increased the yield strength of the material, which in turn inhibited the initiation of fatigue cracks.