Modeling Plastic Deformation Effects in Steel on Hysteresis Loops With the Same Maximum Flux Density

Abstract

Plastic deformation affects the hysteretic magnetic properties of steels because it changes the dislocation density, which affects domain-wall movement and pinning, and also because it places the specimen under residual strain. An earlier paper proposed a model for computing hysteresis loops on the basis of the effect of grain size d and dislocation density /spl zeta//sub d/. In that paper, hysteresis loops were compared that all had the same maximum flux density B/sub max/. The result was that coercivity H/sub c/ exhibited a linear relationship with inverse grain size (1/d) and /spl zeta//sub d//sup 1/2/. The same was true of hysteresis loss W/sub H/. If one compared hysteresis loops all with the same H/sub max/, these linear dependences were only approximately found. Because the relationships are simpler for loops of constant B/sub max/, core loss experimenters compare loops that all have the same B/sub max/. In this paper, we modify the model to study the effect of plastic tensile deformation on hysteresis loops with the same B/sub max/. We found linear relationships between H/sub c/ and residual plastic strain /spl epsiv//sub r/ and between W/sub H/ and /spl epsiv//sub r/. With increasing residual tensile strain, H/sub c/ increases (whereas with increasing elastic tensile strain, H/sub c/ decreases). Also, with increasing residual tensile strain, the slope of the hysteresis loop decreases (whereas with increasing elastic tensile strain, the slope increases). We also consider the effect of compressive plastic deformation.