Abstract A nonoriented electrical sheet steel containing not more than 0.03 percent carbon and from about 0.5 percent to about 4.5 percent silicon and a process for manufacturing said electrical sheet steel. The process includes preparing low carbon sheet steel by conventional methods of melting, pouring and rolling, coating the surfaces of the sheet steel with a layer of siliconcontaining powder, compacting the powder onto the sheet and heat treating the composite thus formed in a protective environment to cause a solid-state diffusion of silicon into the sheet steel. The core losses of electrical sheet steel thus prepared are equivalent to or better than electrical sheet steel of the same silicon content and gage prepared by additions of silicon to the steel while it is in a molten state.
A process for manufacturing electrical sheet steel comprising: a. coating the surfaces of a sheet steel containing not more than 0.01 percent carbon, not more than 1.00 percent manganese, balance iron and incidental impurities, with a powder containing not less than 25 percent silicon and not more than 0.40 percent carbon, balance iron, b. compacting the powder on the sheet steel, c. heating the sheet steel in a protective environment for a time and at a temperature sufficient to cause diffusion of silicon through at least 50 percent of the thickness of the sheet and to thereby produce a sheet steel containing not more than 0.03 percent carbon and from about 0.5 percent to about 4.5 percent silicon, d. cold rolling the product of step (c), and e. annealing the cold rolled product.