16MnCr5
EN 10083-3 · 1.7131
16MnCr5 is an engineering steel (Case-Hardening Alloy family) to EN 10083-3 (1.7131). It has a specified 0.2 % proof stress of 635 MPa and a typical tensile strength of about 880 MPa, with a uniform elongation of 10 %. Nominal carbon content is around 0.16 %. For nonlinear FEA, a bilinear model uses E = 210 GPa up to yield and a tangent modulus of 2580 MPa above it. It is designed for surface hardening — a hard, wear-resistant case over a tough core.
Bilinear material model — nonlinear FEA
Uniform elongation εu = 10.0% · conservative analysis limit ½εu = 5.0%
Bilinear (BISO) approximation. Elastic modulus E up to the 0.2% proof stress R_p0.2, then a single tangent slope Eₜ to the ultimate tensile strength: Eₜ = (Rₘ − R_p0.2) / (εu − R_p0.2/E − 0.002), where εu is the uniform elongation and Rₘ is a typical (nominal) UTS within the specified band. The half-εu figure is a conservative strain limit for the analysis. Treat these as guidance for first-pass models; for critical work use a measured true stress–strain curve for the actual product and condition.
Ratings — engineering judgement
Weldabilitymoderate
The low-carbon core is weldable, but parts are rarely welded after carburising — the hard case and residual stresses make it inadvisable. Weld before case-hardening if at all.
Formabilitymoderate
Formed and machined in the soft (annealed) condition before carburising.
Machinabilitygood
Machines well soft — the intended sequence is machine, then carburise and harden to final size (with grinding allowance).
Corrosion resistancepoor
None inherent — protect in service.
Hardenabilitygood
The Mn–Cr pair gives good core hardenability, so the core develops real strength on quench while the carburised surface reaches 58–62 HRC.
Toughnessgood
Tough, ductile core beneath the hard case — the whole point of a case-hardening steel, giving fatigue and shock resistance.
Expert notes
16MnCr5 is the workhorse European case-hardening (carburising) gear steel. The recipe is deliberate: a low base carbon so the core stays tough and machinable, with manganese and chromium for enough core hardenability to develop strength on quench. You machine it soft, carburise to enrich the surface with carbon, then harden — leaving a very hard wear- and fatigue-resistant case (58–62 HRC) over a ductile core.
The FEA subtlety is important: a case-hardened part is really two materials in one, with a hard high-strength skin, a softer core, and a beneficial residual-compressive-stress field in the case. A single bilinear card here describes the core only. For gear-tooth bending or contact (Hertzian) fatigue, work to the case hardness and the residual-stress profile, not the core yield.
Distortion during heat treatment is the practical headache — gears are often press-quenched or plug-quenched to hold form, and a grinding allowance is left for finishing after hardening.
If you need deeper hardenability for larger gears, step up to 20MnCr5 or the nickel-bearing 18CrNiMo7-6.
Mechanical properties
| Condition | Section | Yield (MPa) |
|---|---|---|
| 16MnCr5 · core (blank-hardened & tempered) | typical | 635 |
UTS 880–1180 (core, blank-hardened) MPa · Impact good (tough core) · Hardness case 58–62 HRC · core ~270–400 HB
Physical properties
| Density | 7850 | kg/m³ |
| Elastic modulus | 210 | GPa |
| Shear modulus | 81 | GPa |
| Poisson's ratio | 0.30 | |
| Thermal expansion | 11.5 | ×10⁻⁶/°C |
| Thermal conductivity | 44 | W/(m·K) |
| Specific heat | 460 | J/(kg·K) |
Chemical composition (wt %)
Available forms
Equivalent grades
| Standard | Grade | Note |
|---|---|---|
| AISI | 5115 | Nearest US case-hardening grade (approximate). |
| JIS | SCr415(H) | |
| EN 10084 | 16MnCr5 / 1.7131 |
Historical designations
| Standard | Grade | Note |
|---|---|---|
| DIN 17210 | 16MnCr5 | Long-standing German case-hardening designation. |
Common applications
- Carburised gears and pinions
- Camshafts and gudgeon pins
- Small highly-loaded shafts
- Splined and toothed components needing a hard wear surface
- Bushes and rolling contacts
History
Manganese-chromium case-hardening steels were developed to give mass-produced gears a hard, fatigue-resistant carburised surface over a tough core; 16MnCr5 became the European standard for the job.
- 1930Cr–Mn carburising steels adopted for automotive gearing
- 1986EN 10084 harmonises 16MnCr5 (1.7131) for case-hardening