35C8 vs EN8D Steel: Which Grade to Choose

Q: Is EN8D stronger than 35C8?

Yes. EN8D carries more carbon (about 0.40-0.45% vs about 0.35% in 35C8), giving higher tensile strength (typically 620-700 MPa vs 550-640 MPa) and a higher attainable hardness. The trade-off is slightly lower ductility and a little more care needed when welding.

The short answer

Choose EN8D when the component needs higher strength, surface hardness, or better wear resistance — gears, axles, crane wheels, and parts hardened to a higher hardness. Choose 35C8 when moderate strength is enough and you value easier welding, better ductility, and lower cost — general shafts, studs, levers, and weld-fabricated or formed parts. Both are medium-carbon plain-carbon steels; EN8D simply carries about 0.05–0.10% more carbon, which is what drives almost every difference below.

35C8 vs EN8D — side-by-side comparison

Typical values. Mechanical properties depend on section size and heat-treatment condition.
Property	35C8	EN8D
Type	Medium-carbon unalloyed steel	Medium-carbon unalloyed steel (closely controlled EN8 variant)
Carbon (C)	0.30 – 0.40%	0.40 – 0.45%
Manganese (Mn)	0.60 – 0.90%	0.70 – 0.90%
Silicon (Si)	0.10 – 0.35%	0.10 – 0.35% (typical)
Sulphur (S)	0.045% max	0.045% max
Phosphorus (P)	0.045% max	0.045% max
Tensile Strength	550 – 640 MPa	620 – 700 MPa (≈90,000 psi+)
Yield Strength	320 – 370 MPa	340 – 450 MPa (≈50,000 psi+)
Elongation	18 – 22%	16 – 20%
Hardness (normalised)	170 – 200 HB	180 – 220 HB
Max. hardness (hardened, thin section)	≈ 48 – 55 HRC	≈ 53 – 58 HRC
Hardenability	Low (plain carbon)	Low–moderate (slightly better — more carbon)
Machinability	Good; best in annealed/normalised state	Good; slightly harder on tooling at higher hardness
Weldability	Good with normal precautions	Fair–good; preheat more often needed
Relative cost	Lower	Slightly higher
Equivalent grades	AISI 1035 · C35 · S35C · BS 970 080M36	EN8 · BS 970 080M40 · AISI 1040 · JIS S40C
Typical applications	Shafts, studs, levers, links, general machine parts	Gears, axles, crane wheels, bolts, higher-stress shafts

EN8D chemistry and properties shown are typical mill values; 35C8 sulphur and phosphorus are each held to 0.045% maximum. Confirm exact values against the mill test certificate for your heat.

When to choose each grade

Choose 35C8 when…

Moderate strength is sufficient for the part.
The component will be welded or cold-formed.
Better ductility and toughness matter.
Cost is a deciding factor on a high-volume part.
Typical parts: general shafts, studs, levers, links, brackets, fabricated assemblies.

Choose EN8D when…

You need higher tensile strength and surface hardness.
The part will be hardened and tempered to a higher hardness.
Wear resistance or fatigue performance is important.
Typical parts: gears, axles, crane wheels, bolts, spindles, higher-stress shafts.
Read the full EN8D steel page.

How to decide between 35C8 and EN8D

Fix the strength target. If the design needs tensile strength above ~640 MPa or higher surface hardness, lean towards EN8D. If moderate strength is enough, 35C8 will do the job at lower cost.
Check welding and forming. If the part is welded or cold-formed, 35C8's lower carbon makes it more forgiving. EN8D needs more care (preheat, controlled cooling).
Confirm the heat-treatment goal. If you will harden and temper to a higher hardness, EN8D reaches a higher value. Both are best hardened in smaller sections.
Weigh cost and availability. 35C8 is usually the cheaper of the two for the same form and size.
If neither fits, step up. For much higher strength with hardenability in larger sections, move to an alloy grade such as EN19 or SAE 4140. If machinability dominates, consider free-cutting EN1A; for a little more carbon than 35C8, look at S45C.

35C8 vs EN8D — frequently asked questions

Is EN8D stronger than 35C8?

Yes. EN8D carries more carbon (≈0.40–0.45% vs ≈0.35% in 35C8), giving higher tensile strength (typically 620–700 MPa vs 550–640 MPa) and a higher attainable hardness. The trade-off is slightly lower ductility and a little more care needed when welding.

Can 35C8 replace EN8D?

Sometimes. If the part only needs moderate strength and the design allows it, 35C8 is a lower-cost substitute with easier welding. Where the drawing specifies EN8D for strength, hardness, or wear reasons, do not substitute without checking the load case and getting design approval.

Which is easier to weld, 35C8 or EN8D?

35C8. Its lower carbon content gives a lower carbon equivalent, so it is more tolerant of welding. Both grades benefit from preheating and controlled cooling on thicker sections; EN8D needs these precautions more often.

Which is cheaper?

35C8 is usually slightly cheaper than EN8D for the same product form and size, because it is a lower-carbon, very widely produced grade. For an exact quote on either grade, contact Ambhe Ferro.

Are 35C8 and EN8D interchangeable?

Not automatically. They are close cousins on the medium-carbon scale, but EN8D's higher carbon changes strength, hardness, and weldability. Treat them as distinct grades and select based on the component's strength, hardness, welding, and cost requirements.

What is the carbon difference between 35C8 and EN8D?

35C8 contains about 0.30–0.40% carbon (nominal 0.35%), while EN8D contains about 0.40–0.45%. That difference of roughly 0.05–0.10% carbon is what makes EN8D stronger and harder, and 35C8 more ductile and weldable.

Need 35C8 or EN8D? Let's Talk

Tell us the grade, form, size, and tonnage. Ambhe Ferro responds with pricing, availability, and lead time — and a mill test certificate on every heat.

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35C8 vs EN8D Steel — How to Choose