China C55 Carbon steel


China C55 Carbon steel is an unalloyed medium carbon engineering steel which has 0.52%-0.6% Carbon as per EN10083 standard.It will obtain high hardness and high strength  after hardening due to the relatively high carbon content,and also can be flame or induction hardened to surface hardness Min 58HRC.C55 steel is generally supplied in an untreated or normalised condition.

Reference standard

EN 10277-2: 2008 Bright steel products. Technical delivery conditions. Steels for general engineering purposes

EN 10083-2: 2006 Steels for quenching and tempering. Technical delivery conditions for non alloy steels

EN 10250-2: 2000 Open steel die forgings for general engineering purposes. Non-alloy quality and special steels


C55 is a medium carbon steel suitable for various type of applications where high strength is needed.It is used for components of small cross section requiring low tensile strength, and heavy forgings in the normalized condition for automotive and general engineering such as axles, clutch members, shafts, pressed and punched parts, piston rods and gear racks.

Chemical composition

C Mn Ni P S Cr Si Mo
0.52-0.6 0.6-0.9 max 0.4 max 0.045 max 0.045 max 0.4 max 0.4 Max 0.1

Equivalent Grades

EU Germany USA Russia Japan China Inter
C55 1.0535 1055 50


S55C 55 C55


Size Tolerance

Surface Finish Size Tolerance Length
Black For Forged condition (0,+5 mm) Multiple Length/Fixed Length
Black For Rolled condition (0,+1mm)
Rough Turned (0,+3mm)

Mechanical properties

Tensile Strength:min 500 N/mm2          Yield Strength:min. 350 N/mm2

Elongation:min.11 %(l)                             Kv-Imapct value:min.55J (l)

Heat Treatment Conditions

  • +A   Soft annealed/Soft annealing
  • +N   Normalized/Normalizing
  • +QT  Quenched and Tempered
  • +U   Untreated
  • +SR  Stress Relieved

Normalizing:825℃-885℃,Cooling in air

Soft Annealing:650℃-700℃,Cooling in furnace

Hardening:870 – 990°C,water or oil quench

Tempering:550°C – 660°C,Cooling in air

Drawn and hot-rolled bars, flat bars C55, 1.0535

Forgings and forged bars in grade C55, 1.0535

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