METHOD FOR MANUFACTURING STEEL SHEET FOR ROTOR CORE FOR IPM MOTOR

摘要

The present invention manufactures a steel sheet for a rotor core for an IPM motor, wherein the steel sheet has a magnetic flux density B8000 of 1.65 T or more as measured when magnetic field strength is 8000 A/m, and a residual magnetic flux density Br of 0.5 T or more as measured at that time, and optionally, a coercivity Hc of 100 A/m or more as measured after magnetization reaches 8000 A/m. By using the steel sheet manufactured according to the present invention for a rotor core of an IPM motor, it is possible to increase further an output torque in a high-speed rotational range and raise further the maximum rotational speed.

主权项

1. A method for manufacturing a steel sheet for a rotor core for an IPM motor, which has a magnetic flux density B8000 of 1.65 T or more as measured when magnetic field strength is 8000 A/m and a residual magnetic flux density Br of 0.5 T or more as measured at that time, wherein a hot-rolled steel sheet having a composition consisting of C: more than 0.0005% by mass to 0.90% by mass, Si: 0% by mass to 3.0% by mass, Mn: 0% by mass to 2.5% by mass, P: 0.05% by mass or less, S: 0.02% by mass or less, acid-soluble Al: 0.005% by mass to 3.0% by mass, and Si+Al: 5.0% by mass or less, with a balance of Fe and inevitable impurities, is cold rolled, heated to 800° C. or more in a continuous annealing line or continuous quenching line, then cooled down to 450° C. or less at a cooling speed of 10° C./sec or more and held at a temperature of 200° C. to 450° C. for 20 seconds or more.