| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a steel sheet for a rotor core which, when used as a rotor core of an IPM motor, can attain both high strength and high magnetic flux density without reducing a reluctance torque of the IPM motor. <P>SOLUTION: A hot-rolled steel sheet having a component composition including 0.06 to 0.90 mass% C; ≤1.5 mass% Si; ≤0.2 mass% Mn; ≤0.05 mass% P; ≤0.02 mass% S; and 0.005 to 3.5 mass% acid soluble Al under the condition satisfying Si+Al≤5.0 mass%, and balance Fe with inevitable impurities is cold rolled, the resulting cold-rolled steel sheet is heated to ≥750°C in a continuous annealing line or a continuous hardening line, cooled to ≤450°C at a cooling rate of ≥10°C/sec, and thereafter held at a temperature range of 200 to 500°C for ≥120 sec to obtain a steel sheet showing a yield strength of ≥780 N/mm<SP POS="POST">2</SP>and a magnetic field intensity being a magnetic flux density B<SB POS="POST">4000</SB>of ≥1.6T at 4,000 A/m. <P>COPYRIGHT: (C)2012,JPO&INPIT |
