What metals are best for use in a magnetic circuit?
Solid steel is generally best, in terms of economics, for the yoke, or frame, of static field devices. The mass of material required to efficiently carry flux between the far poles of an assembly make anything else impossible to justify. The reluctance of this part of the magnetic circuit is relatively low, even without annealing, compared to that of the working gap, so the losses associated with driving flux through the material are a small portion of overall losses. Pole pieces are another story as their purpose is to redistribute and redirect flux over the surface of the gap. Low carbon steel (ASME 1006 – 1018) should be used for pole pieces if possible, and it should be hydrogen annealed after machining. The 400 series stainless steels can be used, but they are not as good magnetically as low carbon steel, so parts may have to be larger to compensate, and/or the magnet stack may have to be larger. Hiperco 50, or an equivalent 50/50 iron cobalt material is needed in the rare case wh
