EX55 HITACHI 50Mn Steel Bottom Track Rollers

Roller Shell: Induction hardening on tread surface + tempering.

Surface Hardness: HRC 50–58 (hardened layer depth: 4–7 mm) for wear resistance.

Core Hardness: HRC 28–35 to absorb impact loads.

Shaft: Quenching and tempering for balanced strength.

Surface Hardness: HRC 50–55; Core Hardness: HRC 30–38.