Grade Designations.
| BS EN 10083-2:2006 | C55E / 1.0535 |
| BS 970:1991 (withdrawn) | 070M55 |
| AISI/SAE | 1055 |
| DIN | C55 / 1.0535 |
| ISO | C55E |
Availability & Supply Condition.
Bright Rounds: 10–80mm | Black Rounds: 25–300mm
Supply condition: Bright Drawn or Hot Rolled Black. Typically supplied in the normalised condition.
Cut to length from 1 piece — −0/+2mm standard tolerance — 2–3 day turnaround — Cutting service details ›
Chemical Analysis.
Values shown as percentages by weight (% wt). Values are ranges unless stated as maxima.
| Designation | C | Si | Mn | P max | S max |
|---|---|---|---|---|---|
| 070M55 | 0.50–0.60 | 0.10–0.40 | 0.50–0.80 | 0.05 | 0.05 |
| C55E | 0.52–0.60 | 0.17–0.37 | 0.60–0.90 | 0.035 | 0.035 |
For full chemical analysis with heat number, request an EN 10204 3.1 material test certificate when ordering — available on all alloy grades. Certificate types explained ›
Mechanical Properties.
Values shown for standard supply condition. Properties vary by section size and heat treatment condition.
| Condition | Size (mm) | Tensile Rm (N/mm²) | Yield Re (N/mm²) | A% min |
|---|---|---|---|---|
| Normalised | ≤16 / >16–40 / >40–100 | 620–770 / 600–750 / 580–730 | ~370 / ~350 / ~330 | 10 / 10 / 10 |
Hardness values: see our hardness conversion table to convert between HRC, HB, HV and tensile strength.
Typical Applications.
- Springs and spring components
- Wear-resistant agricultural blades and shares
- Chisels and hand tools
- High-wear rollers and guides
- Clutch plates and friction discs
- Punches and dies (light duty)
Key Benefits.
- Higher hardness and wear resistance than EN8
- Good response to heat treatment — wide hardness range achievable
- Suitable for spring applications
- Cost-effective for wear-resistant applications
Remarks & Guidance.
Welding is difficult due to the high carbon content and should be avoided in most applications. If welding is necessary, preheat to 200–300°C and carry out post-weld stress relief. For through-hardening, quench from 820–840°C in oil and temper at 550–660°C. Core hardness 185–235 HB is typical after heat treatment.
Relevant Heat Treatment Processes.
This grade responds to the following heat treatment processes. Click any card for temperatures, cooling methods and expected hardness values.
Annealing softens this grade for machining by heating and slow cooling.
Normalising refines grain structure and relieves stress after forging or machining.
This grade responds to quench hardening — oil or water quench from austenitising temperature.
Temper after hardening to achieve the required tensile range and reduce brittleness.
