55# hot rolled and forged round bars are fine carbon structural steel under the standard of GB/T 699-1999 After treating,55# hot rolled and forged round bars, with high surface hardness and strength, but low plasticity and toughness.
JIS G4053 SCM435 steel is an alloy structural steel. It has high static strength, impact toughness and high fatigue limit and its hardenability is higher than 40Cr.