Method of producing a ferromagnetic member by cold rolling

A ferromagnetic member comprising an alloy consisting of 78 to 95% by weight cobalt, 0 to 4% by weight vanadium, remainder iron, is produced by reducing a body of the alloy by cold rolling with at least a 90% reduction. The above method results in a constricted hysteresis loop Fig.1A, but if after rolling, the body is subjected to partial annealing, a four quadrant loop is formed, Fig.3. When the ferromagnetic member to be cold rolled is a strip, it may be formed from a casting or ingot which is hot rolled to a flat strip, surface defects are removed by machining, pickling, or shot blasting, and the strip is annealed in a protective atmosphere of hydrogen forming gas, nitrogen, argon, or helium. Several examples of different alloys treated in different ways are described. A current limiter has a core 1, Fig.7, of a constricted loop composition, fabricated from flat strips of ferromagnetic material, and has turns of wire 2 wrapped around it, and connected to a D.C. source 3, and a load 4. A memory element or twistor comprises a metallic conductor 10 Fig.8, having a helical winding 14 of ferromagnetic material as described.