Effect of lanthanum content on microstructure and magnetic properties of non-oriented electrical steels

The effect of lanthanum content in the range of 0–0.011 wt.%, on the inclusion size distribution, microstructure, texture and magnetic properties of three non-oriented electrical steels was studied. After final annealing, lanthanum effectively inhibited the precipitation of MnS precipitates in steel, the formations of La2O2S and LaS inclusions not only acted as nuclei of AlN precipitates, but also combined with Al2O3 and formed composite inclusions with larger size. Grain size firstly increased and then decreased with lanthanum content increasing. Steel containing 0.0066 wt.% lanthanum obtained the largest grain size, the strongest {110}<110> texture and the weakest {112}<110> texture among all the tested steels. Magnetic flux density firstly increased and then decreased, core loss firstly dramatically decreased and then slightly decreased with lanthanum content increasing. Among the three tested steels, steel with 0.0066 wt.% lanthanum demonstrated the best comprehensive magnetic properties mainly through the development of favorable texture and appropriate final grain size.