Influence of the residual stress on the magnetization process in mild steel

The influence of residual stress on the hysteresis properties of mild steel is studied in detail. Magnetic measurements were done in different directions to investigate the stress-induced anisotropy. The hysteresis loops measured in any fixed direction at different levels of deformation crossed at two points known as the coincident points. One possible explanation of this effect is proposed and it makes an assumption about the stress-induced term in the effective field model. Loops measured in different directions at any fixed level of deformation also crossed at two points. It was found that the hysteresis loop follows a very simple formula when changing the direction of the measurement from the easy axis to the hard one. This explained not only the crossing of these loops at the two points but also the results of measurements on ring-shaped samples where all the directions are possible.