Patent ID: 7267729

Claim:
A soft magnetic low-carbon steel having a chemical composition having a C content of 0.05% by mass or below, a Si content of 0.1% by mass or below, a Mn content in the range of 0.10 to 0.50% by mass, a P content of 0.030% by mass or below, a S content in the range of 0.010 to 0.15% by mass, an Al content of 0.01% by mass or below, a N content of 0.005% by mass or below, and an O content of 0.02% by mass or below; and wherein Mn/S mass ratio is 3.0 or above, ferrite grain size is 100 μm or above, ferrite grains contain precipitated MnS grains of grain sizes of 0.2 μm or above in a density in the density range of 0.02 to 0.5 grains/μm 2 , and the precipitated MnS grains have a mean grain size in the range of 0.05 to 4 μm.