Two Indian medium-carbon steels that differ mainly by carbon: 45C8 at about 0.45% and 35C8 at about 0.35%. That gap decides strength, hardness, weldability and which part each suits best.
45C8 carries about 0.45% carbon; 35C8 carries about 0.35%. That extra carbon gives 45C8 higher strength, hardness and wear resistance and a better response to hardening. 35C8 is more ductile and tougher, easier to weld and cold-form. Pick 45C8 for shafts, axles and parts that are hardened or carry real load; pick 35C8 for general light-to-medium-duty parts, weldments and forgings where toughness and weldability matter more than peak strength.
| Property | 45C8 | 35C8 |
|---|---|---|
| Type | Medium-carbon (~0.45% C) | Medium-carbon (~0.35% C) |
| Carbon (C) | 0.40–0.50% | 0.30–0.40% |
| Manganese (Mn) | 0.60–0.90% | 0.60–0.90% |
| Silicon (Si) | 0.10–0.35% | 0.10–0.35% |
| Sulphur (S) | 0.050% max | 0.045% max |
| Phosphorus (P) | 0.050% max | 0.045% max |
| Tensile (normalised) | 620–720 MPa | 550–640 MPa |
| Yield (normalised) | 340–460 MPa | 320–370 MPa |
| Elongation | 15–20% | 18–22% |
| Hardness (normalised) | 180–230 HB | 150–200 HB |
| Hardenability | Better — more carbon to harden | Lower — softer after hardening |
| Ductility & toughness | Good | Higher — more forgiving |
| Weldability | Fair — preheat on thicker sections | Better — easier to weld |
| Relative cost | Comparable | Comparable |
| Equivalents | 1045, C45 (1.0503), S45C, 080M46 | 1035, C35 (1.0501), S35C, 080M36 |
| Typical applications | Shafts, axles, spindles, gears, forgings | Studs, levers, links, light shafts, weldments |
Both grades are supplied with a heat-wise mill test certificate stating the actual chemistry and properties for the heat you receive.
Both grades machine well, but the lower carbon of 35C8 leaves it softer in the as-rolled and normalised state, so it cuts and forms with less tool wear and bends more readily without cracking. That suits parts that are cold-formed, bent or coined during fabrication. 45C8, at higher carbon, gives a better surface finish after hardening and holds a wear face longer, which is why it is preferred for shafts and gears. For both grades, bright cold-drawn or polished bar gives tighter tolerances and a cleaner finish than hot-rolled black bar.
Where chip control and high turning speeds matter more than strength — high-volume CNC parts, fasteners — a free-cutting grade such as EN1A out-machines both plain-carbon grades. Choose 35C8 or 45C8 when the part needs the strength and hardenability that a free-cutting steel cannot give.
The carbon gap drives the difference. 45C8 has enough carbon to harden to a useful surface hardness and is the choice when a wear face or higher strength is needed; it normalises at 850–880 °C and through-hardens by quenching from the same range, tempered at 550–660 °C. 35C8 hardens to a lower peak hardness and is more often used as-rolled or normalised, where its toughness and ductility are the point.
Both have limited hardenability because neither is alloyed, so the hardened layer is shallow and full through-hardening only works in small to medium sections. For a wear surface on a larger part, induction or flame hardening suits 45C8 better than 35C8 because of the higher carbon. For a hard, uniform core in a big section, move to an alloy grade such as EN19. Always temper immediately after quenching, and normalise after forging to refine grain.
Ambhe Ferro rolls and finishes both grades as rounds (23.5–80 mm diameter), bright bars (21–63.5 mm), hexagons (23.5–52.5 mm across flats) and RCS (55, 63 and 75 mm). Standard length is 5–6 m, with custom cut lengths to order. Supply conditions cover hot rolled, annealed, normalised and bright (cold drawn or polished).
The minimum order quantity is 5 MT per size, and non-standard sizes are often available make-to-order against tonnage. Whichever grade the drawing calls for, every dispatch carries a heat-wise mill test certificate confirming the chemistry and mechanical properties of that heat, with third-party inspection on request.
Both grades are widely available in India and priced similarly; the form, size, finish and tonnage move the price more than the grade. 35C8 and 45C8 are not interchangeable on strength, though — substituting 35C8 where 45C8 is specified can leave a part under-strength or wearing early, while using 45C8 where 35C8 is called for can make welding or forming harder. State the exact grade on the purchase order and confirm it against the mill test certificate before machining.
Ambhe Ferro is an engineering-steel manufacturer with two factories in MIDC Murbad, near Kalyan — about 80 km from Mumbai Port and JNPT. We roll and finish 45C8 and 35C8 steel at our units and dispatch quickly across the Mumbai–Pune–Nashik corridor and pan-India. Regular dispatches go to buyers in Mumbai, Navi Mumbai, Thane, Vasai–Virar, Pune, Pimpri-Chinchwad, Chakan, Nashik, Ahmednagar, Aurangabad, Kolhapur, Nagpur, Rajkot, Ahmedabad and Bengaluru; exports are arranged on request. Order as hot-rolled rounds, bright bars, hexagons or RCS against your size and tonnage, with a heat-wise mill test certificate on every dispatch.
MOQ is 5 MT per size. Send the grade, form, size and tonnage and we will respond with pricing, availability and lead time.
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.
