C80
1.0609Highest-carbon standard unalloyed spring steel. 0.75-0.85% C gives maximum hardness (60+ HRC) among unalloyed grades but with increased brittleness. Limited hardenability — effective quench diameter ≤10mm. Used for high-hardness springs, saw blades, scrapers, and precision strip where maximum elastic limit is needed. ≈ AISI 1080.
International equivalents
| Flag | Standard | Country | Grade | Number | Match |
|---|---|---|---|---|---|
| 🇺🇸 | AISI | USA | AISI 1080 | — | REF |
| 🇪🇺 | EN | Europe | C80 / C80S | 1.0609 | 100% |
Sources: ASTM A29, EN 10132-4
Chemical composition comparison (wt%)
Side-by-side: C80 (EN) (EN 10132-4) vs C80 / C80S (EN) (EN 10132-4)
| Element | C80 (EN) | C80 / C80S (EN) | Overlap |
|---|---|---|---|
| C | 0.75–0.85% | 0.75–0.85% | OK |
| Si | 0.15–0.4% | 0.15–0.4% | OK |
| Mn | 0.6–0.9% | 0.6–0.9% | OK |
| P | 0–0.025% | 0–0.025% | OK |
| S | 0–0.025% | 0–0.025% | OK |
Mechanical properties
QT
| Property | Value | Unit |
|---|---|---|
| Tensile Strength | 900–1200 | MPa |
| Yield Strength | 550–750 | MPa |
| Elongation | 6–10 | % |
| Elastic Modulus | ≥ 210 | GPa |
| Density | ≥ 7.85 | g/cm3 |
Annealed
| Property | Value | Unit |
|---|---|---|
| Tensile Strength | ≤ 680 | MPa |
| Hardness HB | ≤ 255 | HB |
Heat treatment
| Process | Temperature | Medium | Holding Time | Notes |
|---|---|---|---|---|
| hardening | 780–810 °C | oil or water | — | Effective quench ≤10mm. 60+ HRC as-quenched |
| tempering | 350–500 °C | air | — | Spring temper 380-420°C, saw blade temper 280-320°C |
Compatibility verdict
C80 and C80 / C80S: 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
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