C45

The everyday medium-carbon machine steel: quenched and tempered Rp0.2 490 MPa and Rm 700–850 MPa up to 16 mm, less in larger sections.

For shafts, pins, bolts and gear parts that need more strength than structural steel but no alloying. Hardens only in thin sections; induction or flame hardening gives a hard surface. Welding needs preheat because of the carbon content.

Thicknessmm

Yield strength Re / Rp0.2: ≥ 490 MPa2guaranteed minimum
Tensile strength Rm: 700–850 MPa2guaranteed range
Elongation after fracture A: ≥ 14 %1guaranteed minimum
Brinell hardness HB: ≤ 255 HB1guaranteed maximum · treated for cold shearability (+S); ≤ 207 HB1guaranteed maximum · soft annealed (+A)

How we know these values · 31 values from 3 sources

Corroborated: 18
Single source: 13

Click any value under “All values” to see the sources that state it, with dates.
How we rate evidence

What to watch

Not yet sourced: +QT values above 100 mm (EN 10083-2 gives none for C45: it does not harden through); Impact energy KV +QT; Physical values (E, λ, α) from a producer sheet.

All values

Identity and composition 8
Mechanical 23
Physical not yet
Thermal not yet
Electrical and magnetic not yet
Chemical and durability not yet

Mechanical

Strength

Yield strength Re / Rp0.2

Minimum yield strength, or 0.2 % proof strength when there is no marked yield point.

Condition	Value	Evidence
	≥ 490MPa	Corroborated
	≥ 430MPa	Corroborated
	≥ 370MPa	Corroborated
	≥ 340MPa	Single source
	≥ 305MPa	Single source
	≥ 275MPa	Single source

Tensile strength Rm

Ultimate tensile strength. Product standards give a range or a minimum.

Condition	Value	Evidence
	700–850MPa	Corroborated
	650–800MPa	Corroborated
	630–780MPa	Corroborated
	≥ 620MPa	Single source
	≥ 580MPa	Single source
	≥ 560MPa	Single source

Brinell hardness HB

Resistance to indentation by a hard ball; for castings and bearings.

Condition	Value	Evidence
	≤ 255HB	Single source
	≤ 207HB	Single source

Ductility

Elongation after fracture A

Minimum elongation; depends on gauge length and test direction.

Condition	Value	Evidence
	≥ 14%	Single source
	≥ 16%	Corroborated
	≥ 17%	Corroborated
	≥ 14%	Single source
	≥ 16%	Single source
	≥ 16%	Single source

Reduction of area Z

Minimum necking at fracture of a tensile test piece, relative to its cross-section.

Condition	Value	Evidence
	≥ 35%	Single source
	≥ 40%	Corroborated
	≥ 45%	Corroborated

Chemical composition

Show on the periodic table

Cast analysis, %

Element	Applies to	Range %	Evidence
C	all thicknesses	0.42–0.5	Corroborated
Si	all thicknesses	0.40	Corroborated
Mn	all thicknesses	0.5–0.8	Corroborated
P	all thicknesses	0.045	Corroborated
S	all thicknesses	0.045	Corroborated
Cr	all thicknesses	0.40	Corroborated
Mo	all thicknesses	0.10	Corroborated
Ni	all thicknesses	0.40	Corroborated

Cr + Mo + Ni ≤ 0.63 % (Saarstahl). Ovako's ISO 683-1 row also sets Si ≥ 0.10 % and Cu ≤ 0.30 %.

Compare side by side

With any other grade

Sources here are public pages that reproduce EN 10083-2. For design and acceptance, the standard edition named in your specification and the inspection certificate (EN 10204 3.1) of the delivered product take precedence. Design factors are recommended values; your National Annex may set others.