| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a method for producing a nonoriented magnetic steel which is excellent in surface property and condition and has both of excellent mechanical characteristic and magnetic characteristic required for a motor rotor rotating at high speed and contributes to lightening of the rotor. <P>SOLUTION: The method for producing the nonoriented magnetic steel for a rotor includes: a rough hot-rolling process of heating a steel ingot or a steel billet to 1,100-1,300°C, then applying rough hot-rolling having a cumulative rolling-reduction ratio of ≥80% to the heated steel ingot or steel billet to obtain a rough bar, wherein the steel ingot or steel billet comprises by mass% ≤0.06% C, ≤3.5% Si, 0.05%-3.0% Mn, >2.5%-6.0% Al, ≤0.30% P, ≤0.04% S, ≤0.02% N, >0.02% Nb, at least one kind of element selected from a group consisting of Nb, Ti, Zr and V in the range satisfying 0<Nb/93+Zr/91+Ti/48+V/51-(C/12+N/14)<5×10<SP>-3</SP>and the balance Fe with impurities; and a finish hot-rolling process of applying finish hot-rolling to the rough bar, and the method is characterized in that the method includes a hot-rolling process of heating the rough bar to 950°C or more before subjected to the above finish hot-rolling process. <P>COPYRIGHT: (C)2009,JPO&INPIT |
