MaterialsSteels

16MnCr5 — 1.7131 case-hardening steel

The manganese-chromium case-hardening steel 16MnCr5: designations, chemical composition, hardness in the delivery conditions, carburizing and hardening temperatures, weldability and machining — and why its core strength has no single value.

LiveUpdated 11 October 20263 min read

16MnCr5: hard case on a tough core

Carbon content, EN ISO 683-3: 0.14–0.19% C
Carburizing temperature: 880–980°C
Surface hardness after case hardening (Lucefin): 57–64HRC
Approximate AISI/SAE equivalent: 5115

16MnCr5 is a low-carbon manganese-chromium steel made to be case hardened. Carburizing adds carbon to a thin surface layer, which then hardens on quenching, while the low-carbon core stays tough. The result is a hard, wear-resistant surface on a tough core.

Designations

Name	Number	Note
16MnCr5	1.7131	Base grade
16MnCrS5	1.7139	Specified sulphur range 0.020–0.040 %; described by Deutsche Edelstahlwerke as particularly suitable for machining

Approximate equivalent: AISI/SAE 5115. No JIS equivalent could be confirmed.

The current standard is EN ISO 683-3:2022. It replaced the 2019 and 2018 editions and, before them, EN 10084:2008. Many mill data sheets still cite EN 10084.

Chemical composition

Heat analysis, % by mass, EN ISO 683-3:

C	Si	Mn	P max	S max	Cr	Cu max
0.14–0.19	0.15–0.40	1.00–1.30	0.025	0.035	0.80–1.10	0.40

16MnCrS5 has S 0.020–0.040 %. The silicon minimum of 0.15 % appears in the EN ISO 683-3 based sheets of Ovako and Lucefin; EN 10084 gave only a maximum of 0.40 %.

Hardness in the delivery conditions

Condition	Hardness (HB)
+A, soft annealed	max 207
+FP, treated to ferrite-pearlite and hardness range	140–187
+N, normalized	138–187
+TH, treated to hardness range	156–207 (Deutsche Edelstahlwerke)

Heat treatment

Step	Temperature (°C)	Notes
Carburizing	880–980
Core hardening	860–900	Oil or polymer
Case hardening	780–820	Saarstahl and DEW; Lucefin gives 810–840
Tempering	150–200
Soft annealing	650–700	Ovako 670–710

Heat treatment temperatures from the table above. The thick bar is the range this page uses; thin bars are the values individual makers print. Hover a bar to read it.

Lucefin gives a surface hardness of about 57–64 HRC after carburizing and hardening.

Weldability

Deutsche Edelstahlwerke rates 16MnCr5 as generally weldable. Lucefin recommends welding before carburizing, a preheat of 150–350 °C and stress relieving at about 600 °C.

Machining

Machining is normally done before carburizing, in the +A, +FP or +N condition, so the hardness ranges above are what the tool sees. Where machinability matters, 16MnCrS5 with its controlled sulphur, or Ovako’s calcium-treated version, is offered. After case hardening, finishing is done by grinding or hard turning. In ISO 513 the soft steel belongs to group P and the hardened case to group H.

1Delivery condition
- +A max 207 HB
- +FP 140–187 HB
- +N 138–187 HB
2Machining
- in the soft condition
- ISO 513 group P
- 16MnCrS5 for machinability
3Carburizing
- carbon into the surface layer
880–980 °C
4Hardening
- core 860–900 °C
- case 780–820 °C
- oil or polymer
780–900 °C
5Tempering
- surface about 57–64 HRC
- (Lucefin)
150–200 °C
6Finishing
- grinding or hard turning
- ISO 513 group H

The route of a case-hardened part in the order described on this page, with the temperatures and hardness values from the tables above.

Sources (7)

Every value and quotation on this page comes from the documents below.