Surface-hardened chain link

A surface-hardened chain comprising a plurality of connected chain links each made from a killed steel having a chemical composition consisting essentially of C:

• 0.17-0.35 wt %, Si:
• 0.10-0.25 wt %, Mn:
• 0.40-0.80 wt %, P:
• not more than 0.020 wt %, S:
• not more than 0.020 wt %;
• Ni:
• 0.40-1.5 wt %, Mo:
• 0.15-0.60 wt %, B:
• 0.0005-0.006 wt % and the balance of Fe, said chain link comprising a surface-hardened layer of a high carbon tempered martensite structure and a core layer of a low carbon tempered martensite structure.