C55
1.0535Medium-high carbon unalloyed steel. Higher strength than C45 with reduced weldability. Used for rail wheels, agricultural equipment, springs, hand tools, and wear-resistant parts. Often used for induction-hardened components.
International equivalents
| Flag | Standard | Country | Grade | Number | Match |
|---|---|---|---|---|---|
| 🇺🇸 | AISI | USA | AISI 1055 | G10550 | REF |
| 🇪🇺 | EN | Europe | C55 | 1.0535 | 100% |
| 🇯🇵 | JIS | Japan | S55C | — | 97% |
| 🇨🇳 | GB | China | 55 | — | 95% |
Sources: ASTM A29, EN 10083-2:2006, JIS G4051, GB/T 699
Chemical composition comparison (wt%)
Side-by-side: C55 (EN) (EN 10083-2:2006) vs S55C (JIS)
| Element | C55 (EN) | S55C (JIS) | Overlap |
|---|---|---|---|
| C | 0.52–0.6% | — | — |
| Si | 0–0.4% | — | — |
| Mn | 0.6–0.9% | — | — |
| P | 0–0.03% | — | — |
| S | 0–0.035% | — | — |
Mechanical properties
QT
| Property | Value | Unit |
|---|---|---|
| Tensile Strength | 800–950 | MPa |
| Yield Strength | ≥ 420 | MPa |
| Elongation | ≥ 13 | % |
| Elastic Modulus | ≥ 210 | GPa |
| Density | ≥ 7.85 | g/cm3 |
Normalized
| Property | Value | Unit |
|---|---|---|
| Tensile Strength | 620–760 | MPa |
| Yield Strength | ≥ 340 | MPa |
Heat treatment
| Process | Temperature | Medium | Holding Time | Notes |
|---|---|---|---|---|
| normalizing | 820–860 °C | air | min 2 min per mm | — |
| quenching | 800–840 °C | water | min 30 min | Oil for larger sections |
| tempering | 550–660 °C | air | min 60 min | — |
| annealing | 680–710 °C | furnace | Several hours | Max 241 HB |
Compatibility verdict
C55 and S55C: 97% composition match
Close equivalents but NOT identical.
Related materials
S355JR
1.0045High-strength low-alloy structural steel with minimum yield strength of 355 MPa. Standard grade for bridges, buildings, cranes, and general structural applications. Impact tested at +20°C (JR).
S690QL
1.8928High-strength quenched and tempered fine-grain structural steel with minimum yield strength of 690 MPa. Used for heavily loaded structures like mobile cranes, mining equipment, bridges, and pressure vessels.
S275JR
1.0044Medium-strength structural steel with minimum yield strength of 275 MPa. Bridges the gap between S235JR and S355JR. Used for general structural applications, lattice towers, masts, and light crane components. Impact tested at +20°C (JR).
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