High-strength non-oriented electrical steel sheet

Abstract

The invention provides a non-oriented electrical steel sheet excellent in yield strength for use as an iron core material for high rpm motors that does not sacrifice yield or productivity in motor core punching or steel sheet production, which non-oriented electrical steel sheet is given a chemical composition of, in mass %, C: 0.01 to 0.05%, Si: 2.0 to 4.0%, Mn: 0.05 to 0.5%, Al: 3.0% or less and Nb: 0.01 to 0.05%, and optionally Ni at a preferable content of more than 0.5% and less than 3.0%, the balance being Fe and unavoidable impurities, Mn and C contents expressed in mass % are made to satisfy Mn≦0.6-10×C, recrystallized portion area fraction is made 50% or greater, yield strength in tensile testing is made 650 MPa or greater, and average-grain diameter viewed in steel sheet cross-section is made 40 μm or less, and electrical steel sheet production is conducted using a hot-rolled sheet whose transition temperature in impact testing is 70° C. or less.

Dependencies are inferred from the claim text.