Composite magnetic element, useful for motor rotors and magnetic balances, consists of a chromium-aluminum steel with a nonmagnetic portion and a ferromagnetic portion having a specified low carbide content and coarse grain size

摘要

A composite magnetic element, consisting of a chromium-aluminum steel with a nonmagnetic portion and a ferromagnetic portion having a specified low carbide content and coarse grain size, is new. A composite magnetic element consists of a chromium steel containing 0.1-5.0% Al and has a ferromagnetic portion with a maximum magnetic permeability of = 400 and a nonmagnetic portion with a magnetic permeability of }2, the ferromagnetic portion containing }50 carbides of = 0.1 microns particle size per 100 microns 2 area and the ratio of the number of carbides of = 1.0 microns particle size to the number of carbides of = 0.1 microns particle size being = 15%. Independent claims are also included for the following: (i) a similar composite magnetic element, in which the ferromagnetic portion has a coercive field strength of }1000 A/m and a JIS grain size of } 14; (ii) a process for producing the ferromagnetic portion of the above composite magnetic element; and (iii) a process for producing the nonmagnetic portion of the above composite magnetic element. Preferred Features: The steel has the composition (by wt.) 0.30-0.80% C, 12.0-25.0% Cr, 0.1-5.0% Al, 0.1-4.0% Ni, 0.01-0.10% N, }2.0% total Si and/or Mn, balance Fe and impurities.