Is C45 the same as EN8?

They are close and often used interchangeably in India, but C45 has a little more carbon (about 0.45% against 0.40%). Name the grade on the drawing if it matters.

What is the hardness of C45?

About 170–220 HB normalised; induction hardening can give a surface of about 55–58 HRC.

An older German name for the low-sulphur, cleaner version of C45, now C45E (1.1191).

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C45 steel

Also called: 1.0503, 45C8, AISI 1045, S45C, CK45, C45 material, 080M46

C45 is a medium-carbon unalloyed steel with about 0.45% carbon (DIN 1.0503, close to AISI 1045). It is a general engineering steel for shafts, gears and machine parts, and in India it is often used in place of EN8.

Quick facts

Type: Medium-carbon (unalloyed) steel
Carbon: About 0.42–0.50%
Typical hardness: About 170–220 HB normalised
Tensile strength: About 600–700 MPa normalised (depends on size)
Surface hardening: Induction or flame hardening to about 55–58 HRC
Weldability: Fair: needs preheating

Equivalent grades

Standard	Closest grade
DIN / EN 10083	C45 (1.0503); low-sulphur C45E / Ck45 (1.1191)
IS 1570 (India)	45C8
AISI / SAE	1045
JIS	S45C
BS 970	080M46 (close to EN8)

Typical chemical composition

Element	%
Carbon (C)	0.42–0.50
Silicon (Si)	0.40 max
Manganese (Mn)	0.50–0.80
Phosphorus (P)	0.045 max
Sulphur (S)	0.045 max

Heat treatment

Normalising: about 840–880 °C, cool in air
Hardening: about 820–860 °C, quench in water or oil, then temper (about 550–660 °C for a tough condition)
Induction or flame hardening gives a wear surface of about 55–58 HRC
Like EN8, it hardens fully only in small sections

Typical uses

Shafts, axles and spindles
Gears and sprockets for moderate loads
Bolts, studs and pins
Hydraulic rods (often chrome plated)
General machine parts

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Questions

Is C45 the same as EN8?: They are close and often used interchangeably in India, but C45 has a little more carbon (about 0.45% against 0.40%). Name the grade on the drawing if it matters.
What is the hardness of C45?: About 170–220 HB normalised; induction hardening can give a surface of about 55–58 HRC.
What is CK45?: An older German name for the low-sulphur, cleaner version of C45, now C45E (1.1191).

The figures on this page are typical values for guidance, written by Diemeco from standard engineering practice. They are not a specification: confirm grades and properties with the relevant standard or the supplier's mill test certificate, and tolerances with your workshop. Last checked 8 October 2026.