| 摘要 |
A method of improving the magnetic characteristics of ferromagnetic material comprises processing the material to produce sheet at least 10 mils. thick and having a surface smoothness reading on the profilometer of no more than 5 micro-inches. The material is selected from the following: Magnetic ingot iron, low-alloy steel, non-oriented silicon-iron, cube-on-edge silicon-iron, nickel-iron magnetic alloys and aluminium-iron oriented alloys. Examples are, in per cent by weight: .oriented silicon-iron.Si.2-4 ..C.0.15-0.303 ..Mn.0.50-0.15 ..S.0.03 max ..Al.0.01 max .non-oriented silicon-iron.. ..Si.0.5-5.0 ..C.0.03-0.1 ..Mn.0.3 max ..S.0.03 max ..Al.0.5 max .low alloy steel.C.0.05-0.1 ..Mn.0.15-1.0 ..Si.0.1 max ..S.0.03 max ..P.0.15 max .magnetic ingot iron.C.0.15 ..Mn.0.03 ..Si.0.003 ..S.0.025 ..P.0.005 .nickel-iron.Ni.20-80 e.g. 47-49 ..C.0.3 max ..Mn.0.3-1.0 ..Si.0.7 max ..S.0.02 max ..P.0.02 max ..Al.0.05 max The magnetic characteristics improved are permeability and core loss at high induction from about the knee of the magnetization curve up to saturation. Excitation requirements for establishing surface flux are decreased and permeability at high frequencies is improved. The sheet stock may be hot rolled, pickled and cold rolled with a reduction of less than 10% to impart a smooth surface. If the stock is reduced by cold rolling, smooth rolls are used only for the final pass or passes, reductions of less than 5% being sufficient to produce a smooth surface. The stock may be hot rolled and then cold-rolled in one or more stages with or without intermediate annealing. A final heat treatment will normally be given. For non-oriented stock smooth rolls may be used after the magnetic properties have been developed. For cube-on-edge stock the smoothing should be performed before the ultimate heat treatment for perfecting the orientation. In an example a steel is hot-rolled, coiled as rolled at a temperature not above 1150 DEG F, pickled, de-carburized at 1250-1600 DEG F to reduce the carbon content to no more than 0.005% and cold-rolled with a reduction of 40-80%. A smooth surface was then produced by machining. In a further example cube-on-edge stock was hot-rolled, cold-rolled, annealed, cold-rolled between smooth rolls and heat treated. |
