Japanese SK-4F free-cutting steel
Chemical composition:
C 0.70 - 0.80,
Si ≤ 0.25,
Mn 0.40 - 0.70,
S 0.16 - 0.24
P 0.04 - 0.09
Japan imports SK-4F (equivalent to 20AP) high-precision grinding rod, shaft parts are widely used, especially for higher surface hardness after heat treatment of thin small shaft parts.
