EN 8 Round Bars

EN 8 hot rolled round bar is a medium-carbon engineering steel bar, machined and heat treated into shafts, axles and spindles.

16 to 125 mm Carbon steel Made to order

HOT ROLLED ROUND BARS

EN 8 hot rolled round bar

EN 8 hot rolled round bar is a medium-carbon unalloyed engineering steel rolled to a round section. The same grade is written EN8, and appears as 080M40 in BS 970, as C45 in EN 10083-2 and as 1045 in the AISI system. Carbon between 0.36 and 0.44 percent is what sets it apart from the grades either side of it. Low-carbon bar such as 070M20 cuts and welds more easily, but quenching cannot harden it in the same way. Higher-carbon bar such as 070M55 hardens further and resists wear better, at the cost of toughness. EN 8 sits between the two, and is chosen where a part must be stronger than mild steel yet still easy to machine and heat treat.

The bar is supplied black as rolled, spot ground or fully ground, in diameters of 16 to 125 mm and lengths up to 8 metres, with dimensions and straightness to EN 10060. Normalising after rolling refines the grain and evens out machining behaviour along the length. Quenching in oil or water followed by tempering raises strength, although hardening reaches only so far below the surface, so a large diameter hardens at the skin rather than to the centre. Welding calls for preheat and a temper afterwards, because the carbon content leaves the weld and the metal beside it prone to cracking. Laxcon Steels rolls the bar to order. Parts turned from it include transmission shafts, axles, spindles and machine keys.

Composition limits in weight percent are carbon 0.36 to 0.44, manganese 0.6 to 1.0, sulphur 0.06 maximum, phosphorus 0.06 maximum and silicon 0.05 to 0.35.

SPECIFICATION

EN 8 hot rolled round bar supply conditions

Size range: 16 mm - 125 mm (5/8" - 5")
Length: Up to 8 metres
Tolerances: EN10060
Heat treatment: Soft annealing or normalising; oil or water quenching and tempering
Grade: EN 8 (EN8, 080M40, C45, 1045)
Family: Carbon steel
Supply: Made to order in this grade; every published size of the form

Composition of EN 8

Element	Symbol	Minimum %	Maximum %
Carbon	C	0.36	0.44
Manganese	Mn	0.6	1.0
Sulphur	S		0.06
Phosphorus	P		0.06
Silicon	Si	0.05	0.35

Composition, weight percent, balance iron. From the Laxcon Steels grade reference.

Governing standards

EN 10083-1: Steels for quenching and tempering, part 1: general technical delivery conditions for the bars, rods and sections supplied for heat treatment.
EN 10083-2: Steels for quenching and tempering, part 2: technical delivery conditions for non-alloy steels, the C45 class the EN 8 designation maps to.
BS 970-1: Wrought steels for mechanical and allied engineering purposes, part 1: the British numbering behind the EN and M designations and the R to Z heat treatment conditions.
ASTM A29/A29M: Steel bars, carbon and alloy, hot-wrought: general requirements for delivery, the base every carbon and alloy bar order inherits.
ASTM A576: Steel bars, carbon, hot-wrought, special quality: the composition tables for the SAE carbon grades supplied as bar.
EN 10060: Hot rolled round steel bars for general purposes: dimensions and tolerances on shape and dimensions.
NACE MR0175 / ISO 15156: Materials for use in H2S-containing environments in oil and gas production: the sour-service limits on hardness and condition.
EN 10204: Metallic products, types of inspection documents: the 2.2 test report and the 3.1 and 3.2 inspection certificates a purchase order can call for.

Weight per metre

Diameter (mm)	kg per metre	Metres per tonne
16	1.58	633.5
17	1.78	561.2
18	2.00	500.6
19	2.23	449.3
20	2.47	405.5
21	2.72	367.8
22	2.98	335.1
23.2	3.32	301.3
24	3.55	281.6
25	3.85	259.5
26	4.17	239.9
27	4.49	222.5
28	4.83	206.9
30	5.55	180.2
32	6.31	158.4
34	7.13	140.3
36	7.99	125.1
37	8.44	118.5
38	8.90	112.3
40	9.87	101.4
42	10.88	91.9
45	12.49	80.1
47	13.62	73.4
48	14.21	70.4
50	15.41	64.9
53	17.32	57.7
56	19.34	51.7
57.5	20.39	49.1
60	22.20	45.1
63	24.47	40.9
66	26.86	37.2
67.5	28.09	35.6
70	30.21	33.1
73.5	33.31	30.0
75	34.68	28.8
77.5	37.03	27.0
80	39.46	25.3
83	42.48	23.5
85	44.55	22.4
88	47.75	20.9
90	49.94	20.0
93	53.33	18.8
95	55.65	18.0
98	59.22	16.9
100	61.66	16.2
105	67.98	14.7
106	69.28	14.4
110	74.61	13.4
115	81.54	12.3
120	88.79	11.3
125	96.34	10.4

Density 7.85 g/cm³, diameter squared x 0.006166. Sizes are the published range at the nominal diameters shown.

Ordering EN 8 hot rolled round bar

An enquiry for EN 8 in this form states the grade with the standard it is bought to, BS 970 or EN 10083-2, the condition wanted as rolled, normalised or hardened and tempered, the diameter with its tolerance to EN 10060, the surface as black, spot ground or fully ground, the cut length, the quantity, the EN 10204 certificate type, and any test called for, such as ultrasonic testing or PMI confirmation of the grade.