EN8 (080M40) Forgings
EN8 is the default medium carbon steel of Indian engineering: 0.36–0.44% carbon, unalloyed, forgiving to forge, responsive to normalising and capable of induction hardening on wear surfaces. It handles the vast majority of general-duty forged parts at the lowest cost per kilogram.
- Carbon
- 0.36 – 0.44%
- Manganese
- 0.60 – 1.00%
- Tensile (normalised)
- 620 – 700 MPa
- Hardness
- 200 – 255 BHN
- Forging Temperature
- 1100 – 1200 °C
- Equivalent
- AISI 1040, C40, 080M40
EN8 (080M40) Forgings at a glance
Quotable facts from Avadh Techno Forge, Gundasara, Gondal, Rajkot.
- Carbon: 0.36 – 0.44%
- Manganese: 0.60 – 1.00%
- Tensile (normalised): 620 – 700 MPa
- Hardness: 200 – 255 BHN
- Forging Temperature: 1100 – 1200 °C
- Equivalent: AISI 1040, C40, 080M40
Chemistry and Character
Carbon 0.36–0.44%, manganese 0.60–1.00%, with no deliberate alloying. That simplicity is the point: predictable forging behaviour, wide temperature window, easy machinability and no supply problems anywhere in India.
Heat Treatment Response
Normalising gives 200–255 BHN and a uniform ferrite-pearlite structure. Through hardening is limited by low hardenability on thick sections, so EN8 is usually induction hardened locally where wear resistance is needed rather than hardened throughout.
- Normalised: 200–255 BHN
- Induction hardened: up to 55 HRC surface
- Limited through-hardening depth
- Excellent machinability
Where EN8 Is the Right Call
Shafts, spindles, levers, brackets, studs, sprockets, pins, hydraulic rods and general machinery parts up to moderate load. Above roughly 700 MPa tensile requirement, or on sections above 60 mm needing uniform hardness, move to EN19.
EN8 Chemical Composition and Mechanical Properties
EN8 is an unalloyed medium carbon steel, known as 080M40 in BS 970 and broadly comparable with C45, AISI 1040–1045 and S45C. It contains no deliberate alloying elements, which keeps it inexpensive, widely available and easy to forge — but also limits how deeply it can be hardened. The values below are representative; confirm limits against the standard named on your drawing.
| Property | Typical value |
|---|---|
| Carbon | 0.36 – 0.44% |
| Manganese | 0.60 – 1.00% |
| Silicon | 0.10 – 0.40% |
| Sulphur / phosphorus | 0.050% maximum each |
| Tensile strength, normalised | 620 – 700 MPa |
| Hardness, normalised | ≈ 200 – 255 HB |
| Induction hardened surface | Up to ≈ 55 HRC |
| Forging temperature | 1,100 – 1,250 °C |
Machining, Welding and Surface Hardening EN8
EN8's practical appeal is how well it behaves in the workshop. In the normalised condition it machines freely with predictable tool wear and good surface finish, which is why it dominates general engineering forgings. It can be welded with preheat and controlled cooling, although its carbon content makes it less weld-friendly than low carbon steel. Where a surface must resist wear, induction hardening raises a journal, cam or spline to around 55 HRC while leaving the body tough and machinable — often a better answer than upgrading the whole part to an alloy grade.
- Normalised at roughly 200–255 HB for consistent machining
- Weldable with preheat; not a naturally weld-friendly grade
- Induction hardens locally to about 55 HRC
- Limited hardenability — a soft core remains in thick sections
Where EN8 Is the Right Choice — and Where It Is Not
EN8 suits parts where loads are moderate and sections are not heavy: brackets, levers, light and medium shafts, pins, studs, hubs, sprockets and general machinery components. It stops being the right answer when the section grows past roughly 60 mm and uniform properties are needed through the core, or when fatigue governs the design. At that point EN19 is the safer choice — the reasoning is set out in EN8 versus EN19. If only a surface wears, stay with EN8 and induction harden it.
People also ask
Can EN8 be through hardened?
Only in thin sections. Its low hardenability leaves a soft core in anything above roughly 60 mm, which is why induction hardening is used for local wear resistance instead.
What is EN8 equivalent to internationally?
AISI 1040, DIN C40 and BS 080M40 — all medium carbon unalloyed steels of substantially the same composition.
Topics covered on this page
- EN8 forging manufacturer India
- 080M40 forged components
- EN8 steel forging Rajkot
- medium carbon steel forging supplier
Based on work carried out at our own forging plant at Gundasara, Gondal, Rajkot — operating since 2008.
Questions Answered
What is EN8 equivalent to?
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AISI 1040, DIN C40 and BS 080M40 are the common equivalents, all medium carbon unalloyed steels.
Can EN8 be hardened?
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Locally, yes — induction hardening reaches around 55 HRC on the surface. Through-hardening thick sections is limited by its low hardenability.
Is EN8 good for forging?
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Very. It has a wide forging temperature window and forgiving flow behaviour, making it the most economical general-purpose forging grade.
When should I upgrade from EN8?
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When tensile requirement exceeds about 700 MPa, when sections above 60 mm need uniform properties, or when fatigue loading is severe.