Effect of rare earth elements on magnetic properties of non-oriented electrical steels

The effect of rare earth elements (REMs) on the magnetic properties of non-oriented electrical steels was studied using industrial trials. The variation of the magnetic properties was discussed in terms of the effect of inclusions, precipitates, grain size, and textures in the steel with and without REMs. Inclusions of MgO center dot Al2O3-CaS and (Mg, Mn, Ca)S in REMs-free steel were modified into composite ones of MgO center dot Al2O3-LaAlO3, La2O2S-MgO and (La, Ca)S in the steel with 0.0006% lanthanum, and to (La, Ce)(2)O2S-CaS-MgO, (Ce, La)S in the steel with 0.0007% lanthanum and 0.0015% cerium. The number density of fine MnS was remarkably decreased by the addition of REMs, leading to an increase in the average grain size. The steel containing 0.0006 wt% lanthanum possessed the best combination of core loss and magnetic induction due to the decrease of micro-sized inclusions and fine MnS, the increase of grain size, and the optimization of recrystallization textures. For the steel with excess REMs addition, the large number density of rare earth sulfides with the size of approximately 1 mu m tended to deteriorate the grain size and textures.

Automated summary

The effect of rare earth elements (REMs) on the magnetic properties of non-oriented electrical steels was investigated. The addition of REMs resulted in the modification of inclusions and fine MnS, leading to changes in grain size and textures. The steel with 0.0006 wt% lanthanum exhibited the best combination of core loss and magnetic induction due to the optimization of these factors. However, excessive addition of REMs deteriorated the grain size and textures.