Steel material having excellent corrosion resistance and excellent magnetic properties and production method therefor

A steel material, consisting of:

• from 0.001 mass % to 0.025 mass % of C;
• from 1.8 mass % to 4.0 mass % of Si;
• from 0.1 mass % to 1.0 mass % of Mn;
• more than 0 mass % and 0.030 mass % or less of P;
• more than 0 mass % and 0.10 mass % or less of S;
• more than 0 mass % and 4.0 mass % or less of Cr;
• more than 0 mass % and 0.010 mass % or less of Al;
• and
• more than 0 mass % and 0.01mass % or less of N;
• and
• optionally, at least one selected from the group consisting of:
• more than 0 mass % and 0.5mass % or less of Cu;
• more than 0 mass % and 0.5mass % or less of Ni;
• and
• more than 0 mass % and 1.0 mass % or less of Pb;
• with the remainder consisting of iron and unavoidable impurities,
• wherein said steel material comprises an oxide coating on its surface, and
• wherein the oxide coating comprises Si, Cr, or a combination thereof, includes a non-crystalline layer, and has a thickness of from 50 nm to 500 nm, and
• wherein the steel material has a coercive force no more than 80 A/m and a magnetic flux density no less than 1.20 T, as determined by JIS C2504 on a ring shaped specimen of the steel material having a size of 18 mm in outer diameter×10 mm in inner diameter×3 mm in thickness.