steel JIS SNCM240 Steel: Ni-Cr-Mo Alloy Steel for Medium-Section Shafts and Gears
SNCM240 (JIS G4103) is a Ni-Cr-Mo alloy structural steel — Ni addition over SCM440 improves toughness and hardenability for 30–60 mm sections. Full guide: composition, Q&T heat treatment, and when SNCM240 fills the gap between SCM440 and SNCM439.