EN8 carbon steel round bar is the medium carbon engineering steel specified on British Standard (BS 970, grade 070M40) drawings across the UK, Middle East, Africa and Asia. With 0.36–0.44 % carbon and 0.60–1.00 % manganese, EN8 delivers good strength after heat treatment, acceptable machinability and low cost — the reasons it remains one of the highest-volume shaft and fastener steels in international trade. Huaxia-Steel supplies EN8 round bar from 8 mm to 400 mm diameter in hot rolled, cold drawn, turned and polished, and quenched-and-tempered conditions with EN 10204 3.1 certificates.
Product Overview
EN8 (070M40) is an unalloyed medium carbon steel supplied by analysis rather than hardenability guarantee. In the as-supplied condition it offers 150–200 HB hardness; normalized or quenched and tempered, it reaches tensile strengths of 500–850 MPa depending on section size. The grade is the go-to choice for general engineering shafts, studs, axles, crankshafts, hydraulic rams and a wide range of machined components. For customers working to European drawings, EN8’s near equivalents are C45 (1.0503), S45C (JIS) and 1045 (AISI/SAE) — cross-referencing is routine but should always be verified against the governing specification.
Specifications and Dimensions
| Item | Specification |
|---|---|
| Grade | EN8 / 070M40 (BS 970) |
| Diameter | 8 – 400 mm |
| Tolerance, hot rolled | h13 – h15 per EN 10060 (typ. ±0.4–0.8 %) |
| Tolerance, cold drawn | h9 / h10 (e.g. 25 mm +0/−0.052) |
| Tolerance, peeled/turned | h11 (e.g. 100 mm +0/−0.22) |
| Length | 3–6 m random; 5.8 m for containers; cut-to-length ±1 mm |
| Straightness | ≤ 2 mm/m hot rolled; ≤ 1 mm/m bright; ≤ 0.5 mm/m precision |
| Surface | Black (as-rolled), peeled, polished, or ground bar |
Chemical Composition
| Element | Content % |
|---|---|
| Carbon (C) | 0.36 – 0.44 |
| Silicon (Si) | 0.10 – 0.40 |
| Manganese (Mn) | 0.60 – 1.00 |
| Phosphorus (P) max | 0.050 (typ. ≤ 0.030) |
| Sulfur (S) max | 0.050 (typ. ≤ 0.035) |
Mechanical Properties by Condition
| Condition | Tensile Rm | Yield ReH | Elongation | Hardness |
|---|---|---|---|---|
| As supplied (S) | 500 – 650 MPa | ≥ 280 MPa | ≥ 16 % | 150 – 200 HB |
| Normalized (830–870 °C) | 550 – 700 MPa | ≥ 300 MPa | ≥ 18 % | 170 – 200 HB |
| Quenched + tempered | 700 – 850 MPa | ≥ 450 MPa | ≥ 14 % | 200 – 250 HB |
| Cold drawn (R) | 600 – 750 MPa | ≥ 400 MPa | ≥ 10 % | 180 – 220 HB |
| Induction hardened case | — | — | — | 52 – 58 HRC surface |
Values for quenched and tempered bars decrease with section size — a 100 mm bar cannot achieve the same core properties as a 25 mm bar because EN8 hardenability is not guaranteed. Specify required properties at bar diameter when ordering heat treated material.
Equivalent Grades
| UK BS 970 | EU EN 10083-2 | China GB/T 699 | Japan JIS G4051 | USA AISI/SAE | W-Nr |
|---|---|---|---|---|---|
| EN8 / 070M40 | C45 | 45# | S45C | 1045 | 1.0503 |
Applicable Standards
- BS 970 Part 1: specification for carbon steel bars (070M40 designation).
- EN 10204: certification — 3.1 mill certificate standard, 3.2 third-party on request.
- EN 10021 / EN 10163-type visual rules: general delivery and surface requirements by agreement.
- ASTM A29/A29M: general bar requirements when cross-ordered as 1045.
- EN 10083-1 C45: when the European grade is specified instead — same production route, tighter P/S.
Typical Applications
- General engineering shafts, spindles and drive components.
- Studs, bolts and anchor assemblies above grade 8.8 strength requirements.
- Axles, crankshafts and connecting rods for medium-duty machinery.
- Hydraulic rams, piston rods (with induction hardening + chrome plating).
- Gears, sprockets and couplings for moderate duty.
- Die holders, clamps and general tooling plates.
Quality Assurance
Every bar is traceable to its heat. Standard testing: chemical analysis, tensile test, hardness survey, and macro-etch for surface defects on bright bar. Optional: ultrasonic testing to EN 10228-3 / ASTM A388 for larger diameters, magnetic particle inspection for surface cracks on heat treated bars, Jominy data by request, and third-party inspection by SGS, TÜV or BV before shipment. EN 10204 3.1 certificates show actual heat analysis and mechanical results.
Packing and Shipping
Bars are bundled with steel strapping on timber, tagged with grade/size/heat, and shipped in 5.8 m lengths for container loads or up to 6 m/12 m for breakbulk. Bright bar is individually sleeved or VCI-wrapped on request; machined finish bars receive end caps. Each shipment includes packing list with bundle weights, load plan and certificate package.
Weight Per Metre Reference
| Diameter mm | Weight kg/m | Diameter mm | Weight kg/m |
|---|---|---|---|
| 12 | 0.89 | 60 | 22.2 |
| 16 | 1.58 | 80 | 39.5 |
| 20 | 2.47 | 100 | 61.7 |
| 25 | 3.85 | 120 | 88.8 |
| 30 | 5.55 | 150 | 138.7 |
| 40 | 9.86 | 200 | 246.6 |
| 50 | 15.4 | 250 | 385.3 |
Weights assume plain round section at 7.85 g/cm³ and exclude tolerance allowance. A 5.8 m bundle of 40 mm bar in a 2.9 t export bundle contains roughly 13 bars; calculate container payloads on scaled bundle weights, not theoretical values.
Surface Finish Options Explained
The right surface condition depends on what happens to the bar after delivery. Hot rolled black bar (scale surface) suits parts that are machined all over — it is the cheapest per kilo. Peeled or turned bar (h11) removes scale and surface defects for parts machined only on certain faces, saving machining stock of 1–2 mm per side versus black bar. Cold drawn bright bar (h9/h10) provides finished OD dimensions for parts used as-delivered — shafts running in bearings, guide rods, key stock — and its work-hardened surface improves fatigue life by 10–20 %. Ground bar (h7, Ra ≤ 0.8 µm) is reserved for precision spindles and hydraulic rods where the bar is used without further grinding. Choosing one grade coarser than needed typically saves 10–25 % on material cost.
How to Order
For a factory-direct quotation, provide: diameter and tolerance class, length (random, 5.8 m container length, or cut to size), surface condition (hot rolled / peeled / cold drawn / ground), delivery condition (as-rolled, normalized, Q+T with hardness or tensile targets), quantity in tonnes or pieces, certificate requirement (3.1 standard, 3.2 optional), and destination port. For cut-to-length orders, state the length tolerance and end finish (saw cut, chamfered, or faced and centered for machining).
Frequently Asked Questions
What is the difference between EN8 and EN8M bar?
EN8M (212M44) adds 0.20–0.30 % sulfur for free-machining behavior — about 20–30 % faster turning with better chip breaking. Choose EN8M for high-volume turned parts; keep standard EN8 for welded, threaded-critical or fatigue-loaded components.
Can EN8 bar be supplied quenched and tempered to a hardness band?
Yes. We supply Q+T EN8 to hardness bands (e.g. 200–250 HB) or tensile targets with the results reported at your bar diameter. Confirm the section size with us at RFQ stage — achievable properties fall as diameter rises above about 60 mm.
Do you supply EN8 in cut blanks?
Yes — bars are cut to length on band saws to ±1 mm with deburred ends, or faced and centered for lathes. Cut blanks save machining preparation time and reduce freight waste; state blank length tolerance and end treatment when ordering.
Documentation Package With Every Shipment
Standard shipment documentation includes: EN 10204 3.1 mill certificates per heat (actual chemistry and mechanical results at the ordered condition), bundle-level packing list with weights, heat-to-bundle traceability sheet, dimensional report for bright and ground bar, and the loading photo set for claim protection. Optional additions: UT reports for large diameter bars, MT reports on heat treated stock, and third-party inspection certificates from SGS, TÜV or BV witness testing.
Request a Quote
Send us your diameter list, lengths, condition (hot rolled / cold drawn / Q+T) and quantity — Huaxia-Steel responds with a factory-direct quotation and MTC samples within 24 hours. Matching EN8M free-cutting bar, hex bar and flat bar available from the same stock.
