C20
1.0402Low-carbon unalloyed steel for case hardening (carburizing). 0.17-0.23% C gives a tough core with a hard, wear-resistant surface after carburizing + quenching. The simplest and cheapest case-hardening steel. Used for pins, bushings, cam followers, light-duty gears, and general machine parts where a hard surface with tough core is needed. ≈ AISI 1020.
International equivalents
| Flag | Standard | Country | Grade | Number | Match |
|---|---|---|---|---|---|
| 🇺🇸 | AISI | USA | AISI 1020 | — | REF |
| 🇪🇺 | EN | Europe | C20 / C22E (case hardening use) | 1.0402 | 100% |
Sources: ASTM A29, EN 10084
Chemical composition comparison (wt%)
Side-by-side: C20 (EN) (EN 10084) vs C20 / C22E (case hardening use) (EN) (EN 10084)
| Element | C20 (EN) | C20 / C22E (case hardening use) (EN) | Overlap |
|---|---|---|---|
| C | 0.17–0.23% | 0.17–0.23% | OK |
| Si | 0–0.4% | 0–0.4% | OK |
| Mn | 0.3–0.6% | 0.3–0.6% | OK |
| P | 0–0.035% | 0–0.035% | OK |
| S | 0–0.035% | 0–0.035% | OK |
Mechanical properties
Normalized
| Property | Value | Unit |
|---|---|---|
| Tensile Strength | 390–540 | MPa |
| Yield Strength | ≥ 210 | MPa |
| Elongation | ≥ 22 | % |
| Elastic Modulus | ≥ 210 | GPa |
| Density | ≥ 7.85 | g/cm3 |
Case Hardened
| Property | Value | Unit |
|---|---|---|
| Hardness HRC | 58–62 | HRC |
Compatibility verdict
C20 and C20 / C22E (case hardening use): 100% 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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