Technical Datasheet
EN8
EN8 Bright Bar
Medium Carbon Steel
Kalika Enterprises
Bright Bar Manufacturer
Plot No. 12/1, Gut No. 182, Jogeshwari, MIDC Waluj, Chhatrapati Sambhajinagar, Maharashtra 431136, India
+91 94229 27509 · kalikaent9@gmail.com
The standard medium carbon shafting steel — hardens through the section. EN8 is the default medium carbon engineering steel across Indian industry, and for good reason. At 0.36–0.44% carbon it has enough carbon to respond properly to hardening and tempering, letting a designer choose the final strength of the part rather than accept whatever the mill supplied.
Also known as: 080M40 · AISI 1040 · C40 · EN8A
Key advantage
Set the strength you need by heat treatment
EN8 responds reliably to oil hardening and tempering. The same bar can be supplied as-drawn for a lightly loaded pin or hardened and tempered to over 850 MPa for a drive shaft — one stocked grade covering a wide range of duty.
Chemical composition
BS 970 Part 1 : 080M40, certified against our mill supplier’s EN8A specification
| Element | Min % | Max % |
|---|---|---|
| C Carbon | 0.330 | 0.440 |
| Si Silicon | 0.050 | 0.400 |
| Mn Manganese | 0.600 | 1.000 |
| P Phosphorus | — | 0.060 |
| S Sulphur | — | 0.060 |
Mechanical properties
Cold Drawn
| Property | Value |
|---|---|
| Tensile Strength | 600 – 750 MPa |
| Yield Strength | 450 – 520 MPa |
| Elongation (A5) | 10 – 16% |
| Hardness | 179 – 229 HB |
| Impact (Izod) | 28 J typical |
Available sizes and tolerances
| Shape | Size range |
|---|---|
| Round | 6 – 65 mm |
| Hex (AF) | 7 – 46 mm |
| Tolerance | h9 / h10 / h11 |
| Standard lengths | 3, 4, 5, 6 metre or cut to size |
ISO 286 tolerance values (µm)
| Size (mm) | h9 | h10 | h11 |
|---|---|---|---|
| over 6 to 10 | −36 | −58 | −90 |
| over 10 to 18 | −43 | −70 | −110 |
| over 18 to 30 | −52 | −84 | −130 |
| over 30 to 50 | −62 | −100 | −160 |
| over 50 to 80 | −74 | −120 | −190 |
Typical applications
- Drive shafts and axles
- Spindles and machine shafts
- Couplings and connecting rods
- Studs, bolts and tie rods
- Gears in light duty service (through hardened)
International equivalents
| BS (UK) | 080M40 / EN8 |
| AISI / SAE (USA) | 1040 |
| DIN (Germany) | C40 / 1.0511 |
| JIS (Japan) | S40C |
| IS (India) | C40 / 40C8 |
Heat treatment guidelines
| Operation | Parameters |
|---|---|
| Normalising | 830 – 860 °C, cool in still air |
| Annealing | 830 – 850 °C, furnace cool to below 500 °C |
| Hardening | 820 – 860 °C, quench in oil |
| Tempering | 550 – 660 °C, air cool. Higher tempering temperature gives lower strength and higher toughness. |
Machinability index
60 Moderate
Relative to AISI 1212 = 100
Weldability
Fair
Supply condition
Cold Drawn