C45R
1.1201Unalloyed special steel with controlled sulfur (R grade, S 0.020–0.040%) and 0.45% carbon for improved machinability. Same base composition as C45E but with intentional sulfur for better chip formation. The most popular R-grade carbon steel for high-volume automated machining. Used for axles, bolts, connecting rods, spindles, crankshafts, and general machine parts.
International equivalents
| Flag | Standard | Country | Grade | Number | Match |
|---|---|---|---|---|---|
| 🇩🇪 | DIN | Germany | Cm45 | — | REF |
| 🇺🇸 | AISI | USA | AISI 1045 | G10450 | 95% |
Sources: DIN 17200, ASTM A29
Chemical composition comparison (wt%)
Side-by-side: C45R (EN) (EN 10083-2:2006) vs AISI 1045 (AISI)
| Element | C45R (EN) | AISI 1045 (AISI) | Overlap |
|---|---|---|---|
| C | 0.42–0.5% | — | — |
| Si | ≤ 0.4% | — | — |
| Mn | 0.5–0.8% | — | — |
| P | ≤ 0.025% | — | — |
| S | 0.02–0.04% | — | — |
Mechanical properties
Normalized
| Property | Value | Unit |
|---|---|---|
| Tensile Strength | 580–730 | MPa |
| Yield Strength | ≥ 305 | MPa |
| Elongation | ≥ 16 | % |
| Hardness HB | 172–215 | HB |
| Density | ≥ 7.85 | g/cm3 |
| Elastic Modulus | ≥ 210 | GPa |
Heat treatment
| Process | Temperature | Medium | Holding Time | Notes |
|---|---|---|---|---|
| normalizing | 840–870 °C | air | — | — |
| quenching | 820–860 °C | oil | — | Water possible for small sections |
| tempering | 550–660 °C | air | — | — |
| annealing | 650–700 °C | furnace | — | Soft annealing max 207 HB |
Compatibility verdict
C45R and AISI 1045: 95% composition match
Close equivalents but NOT identical.
Related materials
S960QL
1.8933Ultra-high-strength quenched and tempered fine-grained structural steel with minimum yield strength 960 MPa. QL designation indicates impact testing at -40°C. Used for mobile cranes, heavy lift equipment, offshore wind turbine towers, mining machinery, and weight-critical structural applications. Weldable with appropriate precautions (preheating, low hydrogen). Dramatically reduces component weight compared to conventional structural steels.
P355NH
1.0565Weldable fine-grained non-alloy steel for pressure vessels with minimum yield strength 355 MPa. NH designation indicates normalized condition with specified elevated temperature properties and impact testing at -20°C. Very widely used pressure vessel grade for boilers, storage tanks, heat exchangers, and pipes transporting hot liquids and pressurized gases. Good weldability and resistance to brittle cracking.
C45E
1.1191Unalloyed special steel with controlled chemistry (E grade) and 0.42–0.50% carbon. Tighter P and S limits than standard C45 for improved consistency. The most widely used medium-carbon steel for quenching and tempering. Good balance of strength (620–850 MPa QT) and toughness. Through-hardening up to ø60mm. Surface hardening by induction to HRC 58. Used for shafts, gears, bolts, connecting rods, crankshafts, and general machine parts.
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