Both are medium-carbon steels of similar strength, so the real choice is machinability versus toughness. EN8M is free-cutting and built for high-volume turning; 35C8 is a cleaner steel that forges, welds and takes shock better. Here is how to decide.
Choose EN8M when the part is produced in volume on automatics or CNC and machinability, finish and tool life lead, accepting lower toughness and no welding. Choose 35C8 when the part is forged or welded, or needs better ductility and impact toughness, with only moderate machining volume. In short: EN8M for the machine shop, 35C8 for forging and general engineering.
| Property | EN8M | 35C8 |
|---|---|---|
| Type | Free-cutting medium-carbon | Plain medium-carbon |
| Carbon (C) | 0.35 – 0.45% | 0.30 – 0.40% |
| Manganese (Mn) | 1.00 – 1.30% | 0.60 – 0.90% |
| Silicon (Si) | 0.25% max | 0.10 – 0.35% |
| Sulphur (S) | 0.12 – 0.20% (added) | 0.045% max |
| Phosphorus (P) | 0.06% max | 0.045% max |
| Tensile (normalised) | 550 – 700 MPa | 550 – 640 MPa |
| Yield (normalised) | 330 – 450 MPa | 320 – 370 MPa |
| Elongation | 14 – 18% | 18 – 22% |
| Hardness | 152 – 217 HB | 150 – 200 HB |
| Hardenable? | Yes, in small sections; induction / flame | Yes, in small sections, with better toughness |
| Machinability | Very good (free-cutting) | Moderate (standard medium carbon) |
| Toughness / ductility | Lower (sulphide inclusions) | Higher (cleaner steel) |
| Weldability | Poor (added sulphur) | Fair with preheat and control |
| Forging suitability | Limited | Good |
| Relative cost | Comparable, slightly higher | Comparable |
| Equivalents | 212M36, AISI 1140/1146, 36SMn14 | 080M36, AISI 1035, C35, S35C |
| Typical applications | High-volume turned parts needing strength | Shafts, studs, levers, links, forgings |
EN8M trades toughness for machinability through its added sulphur; 35C8 keeps sulphur low for cleaner, tougher steel. Values confirmed on the mill test certificate.
EN8M and 35C8 carry almost the same carbon, so their strength after the same heat treatment is similar. The real difference is what each does with sulphur. EN8M adds 0.12 to 0.20% sulphur and runs higher manganese so it free-machines: the manganese-sulphide inclusions break chips and lubricate the cut, giving faster cutting speeds, longer tool life and a cleaner finish. 35C8 keeps sulphur low, around 0.045% maximum, which makes it a cleaner steel with fewer inclusions but a slower, stickier cut at standard medium-carbon rates.
For a shop turning large volumes on automatics, EN8M's machining advantage compounds across thousands of parts and can outweigh everything else. For a part that is forged, welded or fatigue-loaded, the inclusions that help EN8M cut are exactly what you do not want, and 35C8's cleanliness becomes the deciding factor.
Because 35C8 is a cleaner steel, it has higher transverse ductility and impact toughness than EN8M at the same hardness. The MnS inclusions in EN8M lie along the rolling direction and lower toughness across the grain, which matters for parts that see bending, shock or fatigue rather than a steady pull. If the component is a lever, a link, a forged shaft or anything that takes impact or reversing load, 35C8 is the safer pick. EN8M is intended for machined parts under moderate, steady load where the priority is throughput and finish.
35C8 forges well: its low sulphur and balanced chemistry give good hot ductility and sound forged grain flow, which is why it is a standard pick for forged shafts, levers and links. EN8M can be forged but its sulphur reduces hot ductility and transverse properties, so it is rarely the first choice for forgings. Welding follows the same logic. 35C8 welds with preheat, low-hydrogen consumables and post-weld stress relief, as any medium-carbon steel does. EN8M is not recommended for welding because the added sulphur promotes cracking and porosity. If the assembly must be welded or hot-worked, 35C8 or a lower-carbon grade is the right choice, not the free-cutting EN8M.
Both grades carry enough carbon, roughly 0.30 to 0.45%, to respond to through-hardening in smaller sections and to induction or flame surface hardening. Both are normally hardened from 850 to 880°C, quenched in oil for sections, and tempered at 550 to 660°C to the required strength. The difference is in the result: 35C8 gives tougher hardened parts because it is cleaner, while EN8M's hardened toughness is limited by its sulphide inclusions. Choose the heat-treatment route on the duty of the part, and confirm the achieved properties on the mill test certificate.
On a per-tonne basis the two grades are broadly comparable, with EN8M sometimes carrying a small premium for its higher manganese and free-cutting control. The economics turn on machining, not material: EN8M's faster cutting and longer tool life pay back over a long production run, while 35C8 is the more economical answer when machining volume is modest and the part needs the toughness, forging or welding that a free-cutting steel cannot give. Decide on how the part is made and loaded before the per-tonne price.
Ambhe Ferro supplies both grades as rounds, bright bars, hexagons and RCS, in hot-rolled, annealed, normalised and bright condition. Standard length is 5 to 6 metres, with custom cut lengths on request or multiples thereof, against a minimum of 5 MT per size. Every heat ships with a mill test certificate, and third-party inspection is available on request. For pricing, availability and lead time, send your grade, form, size and tonnage through the quotation form.
Supply condition is part of the choice. Bright EN8M and 35C8 are cold drawn or turned and polished to close diameter tolerances, commonly h9 to h11 by size, with a clean bright surface; hot-rolled black bar suits parts that will be fully machined or forged and costs less. EN8M's free-cutting sulphur gives a brighter finish at higher cutting speed, which is part of why it is preferred for automatic turning, while 35C8 takes a good finish at standard medium-carbon cutting rates. Both grades are supplied straightened, and tighter straightness, specific tolerance bands or a particular delivery condition (annealed for machining, normalised for a uniform structure, or quenched and tempered to a strength band) can be fixed at the order stage. State the diameter tolerance, surface condition and heat-treatment condition you need so the bar is quoted correctly rather than assumed.
EN8M (212M36) is a free-cutting medium-carbon steel at 0.35 to 0.45% carbon with 0.12 to 0.20% sulphur and higher manganese, normalised tensile about 550 to 700 MPa, chosen for high-volume machined parts that need moderate strength. 35C8 is a plain medium-carbon steel at roughly 0.30 to 0.40% carbon with sulphur held to about 0.045% maximum, normalised tensile about 550 to 640 MPa, chosen for forged, welded or impact-loaded parts that need cleaner, tougher steel. Same strength class, opposite priorities: EN8M for the machine shop, 35C8 for forging and general engineering. Confirm the exact analysis and mechanical properties on the mill test certificate for each consignment.
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.
