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 10084) vs C20 / C22E (case hardening use) (EN) (EN 10084)
| Element | C20 (EN 10084) | C20 / C22E (case hardening use) (EN) | Overlap |
|---|---|---|---|
| C | — | 0.17–0.23% | — |
| Si | — | 0–0.4% | — |
Mechanical properties
Compatibility verdict
C20 and C20 / C22E (case hardening use): 100% composition match
Related materials
C45
1.0503Medium carbon unalloyed quality steel. Good machinability and moderate strength after heat treatment. Widely used for shafts, spindles, pins, studs, and general machine parts.
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).
S235JR
1.0038General-purpose structural steel with minimum yield strength of 235 MPa. The most common structural steel grade in Europe for general construction, frames, and non-critical structural applications.
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