What is 20MnCr5 used for?

Case-hardened parts that need a hard surface and a tough core: mainly gears, pinions, shafts and pins.

Can 20MnCr5 be through hardened?

Its carbon is low, so through hardening gives only modest hardness. It is meant to be carburised (case hardened).

Is 16MnCr5 the same as 20MnCr5?

No. 16MnCr5 has a little less carbon and gives a slightly softer core; both are case-hardening steels used for gears.

20MnCr5 steel: case hardening, properties and uses

20MnCr5 is a low-carbon manganese-chromium steel made for case hardening. After carburising and quenching it has a hard, wear-resistant surface (about 58–62 HRC) and a tough core. It is one of the most common gear steels in European and Indian drawings.

Quick facts

Type: Low-carbon alloy case-hardening steel
Main alloys: Manganese and chromium
Case hardness: About 58–62 HRC after carburising and hardening
Core: Tough, about 30–40 HRC depending on section
Machinability: Good in the annealed or normalised condition
As supplied: Annealed, normalised or 'BG' (for machining)

Equivalent grades

Standard	Grade
EN 10084 / DIN	20MnCr5, 1.7147
SAE / AISI	5120 (close)
Similar case-hardening steels	16MnCr5, EN353, SAE 8620

Equivalents are close, not identical. Name the grade and standard on the drawing.

Typical chemical composition

Element	%
Carbon (C)	About 0.17–0.22
Manganese (Mn)	About 1.10–1.40
Chromium (Cr)	About 1.00–1.30
Silicon (Si)	Up to about 0.40

Values are typical. The exact limits depend on the standard and supplier; ask for the mill test certificate when it matters.

Heat treatment

Carburise at about 880–950 °C to the case depth wanted
Quench in oil, directly or after reheating to about 820–860 °C
Temper at about 150–200 °C
Grind critical sizes after hardening

Typical uses

Gears and pinions
Shafts, spindles and camshafts
Piston pins and bushes
Splined shafts and couplings

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Questions

What is 20MnCr5 used for?: Case-hardened parts that need a hard surface and a tough core: mainly gears, pinions, shafts and pins.
Can 20MnCr5 be through hardened?: Its carbon is low, so through hardening gives only modest hardness. It is meant to be carburised (case hardened).
Is 16MnCr5 the same as 20MnCr5?: No. 16MnCr5 has a little less carbon and gives a slightly softer core; both are case-hardening steels used for gears.

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 9 October 2026.