MATERIAL DATASHEET – C45
Medium Carbon Steel
1. General Information
Material Grade: C45
Condition(s): Untreated / Normalised / Annealed / Quench and tempered
Surface Finish: As rolled / As forged / Bright turned
Associated Standards: BS EN 10083, BS EN 10277, BS EN 10250
Description: C45 is a medium carbon steel offering moderate tensile strengths. It is capable of through hardening by quenching and tempering on limited sections, but can also be flame or induction hardened to HRC 55. Supplied untreated or normalized, available in several variations (C45, C45E, C45R) with slight composition differences. Machinability is similar to mild steel, but weldability is reduced.
2. Typical Applications
- Axles
- Spindles
- Studs
- Shafts
- Knives
- Automotive & engineering components
3. Typical Variations
- C45: Basic grade
- C45E: Limited P & S levels
- C45R: Limited P and minimum S level for machinability
4. Typical Conditions
- +U: As rolled
- +A: Soft annealed
- +N: Normalised
- +QT: Quench & tempered
- +SH: Turned
- +H: Hardenability test (C45E/R)
- +HH: Enhanced hardenability test (C45E/R)
5. Chemical Composition (% by weight)
| C | Si | Mn | S* | P* | Cr | Ni | Mo | Cr+Mo+Ni |
|---|---|---|---|---|---|---|---|---|
| 0.42 – 0.50 | ≤ 0.40 | 0.50 – 0.80 | ≤ 0.045 | ≤ 0.045 | ≤ 0.40 | ≤ 0.40 | ≤ 0.10 | ≤ 0.63 |
*Differs with grade variation
6. Typical Mechanical Properties
| Condition | Sample Dia | Yield Strength (Re) | UTS (Rm) | Elong. (A) | R of A (Z) | Hardness (HB) | Impact KV (J) |
|---|---|---|---|---|---|---|---|
| C45 +A | – | Min 207 | – | – | – | – | – |
| C45 +N | >100 ≤ 250mm | Min 275 | 560 | 16% | – | – | – |
| C45 +N | >250 ≤ 500mm | Min 240 | 540 | 16% | 15% | 207 | – |
| C45 +QT | >40 ≤ 100mm | Min 370 | 630 | 17% | 45% | Max 780 | – |
| C45 +SH | >63 ≤ 100mm | Min 580 | 820 | – | – | 172–242 | – |