16MnCr5 steel (1.7131): properties, composition, equivalents
16MnCr5 (1.7131) is the Mn-Cr case-hardening steel of EN 10084: 0.16 % C, carburized to 58–62 HRC surface with 780–1080 MPa core. Composition, heat treatment, 5115/SCr415/20MnCr5 equivalents.
What is 16MnCr5?
16MnCr5 is the standard European case-hardening steel for gears: 0.16 % carbon for a tough core, 1.15 % Mn and 0.95 % Cr for hardenability, Werkstoff number 1.7131, specified in EN 10084. After carburizing to 0.8 % surface carbon and quenching, the case reaches 58–62 HRC while the core stays at roughly 780–1080 MPa tensile in small sections.
It occupies the middle of the EN 10084 hardenability ladder: above C15/C16E and 16MnCr5's own lower-band variants, below 20MnCr5, 18CrNiMo7-6 and the Ni-bearing grades used for large, heavily loaded gears. That makes it the economical choice for automotive gearbox gears, small pinions, camshafts, piston pins, bushings and any part that needs a hard, wear-resistant surface over a ductile core.
The usual delivery condition is +A (soft annealed) or +FP (treated to ferrite–pearlite for machining). AISI 5115/5120, JIS SCr420 and GB 20CrMn are the nearest matches; none is identical, and the differences are explained in the table.
16MnCr5 chemical composition
| Element | Mass % | Note |
|---|---|---|
| C | 0.14 – 0.19 | |
| Si | ≤ 0.4 | |
| Mn | 1 – 1.3 | |
| P | ≤ 0.025 | |
| S | ≤ 0.035 | 16MnCrS5 (1.7139): S 0.020–0.040 |
| Cr | 0.8 – 1.1 |
EN 10084:2008 Table 3. Hardenability band (+H) available as 16MnCr5H; +HH / +HL for restricted upper/lower bands.
16MnCr5 mechanical properties
| Thickness / condition | Yield strength ReH / Rp0.2 MPa (ksi) | Tensile strength Rm MPa (ksi) | Elongation A % | Hardness |
|---|---|---|---|---|
| Core after carburize, quench & temper, 11 mm ref. bar | ≥ 590 (≥ 85.6) | 780–1080 (113.1–156.6) | 10 | — |
| Core, 30 mm ref. bar | ≥ 490 (≥ 71.1) | 690–890 (100.1–129.1) | 11 | — |
| Core, 63 mm ref. bar | ≥ 440 (≥ 63.8) | 640–840 (92.8–121.8) | 12 | — |
| Surface after carburizing | — | — | — | 58–62 HRC (≈ 700–780 HV) |
| +A soft annealed (delivery) | — | ≤ 700 (typ. 500–650) (≤ 101.5 (typ. 72.5–94.3)) | — | ≤ 207 HB |
| +FP ferrite-pearlite (delivery) | — | — | — | 140–187 HB |
Core values from EN 10084 Annex F (informative) for blank-hardened reference bars; the standard itself specifies only chemistry, hardenability and delivery hardness. Jominy J9 hardenability: 30–43 HRC for 16MnCr5H.
16MnCr5 equivalent grades
| Grade | System | Match | Why / differences |
|---|---|---|---|
| 5115 | AISI / SAE | Near | SAE 5115 (UNS G51150): C 0.13–0.18, Mn 0.70–0.90, Cr 0.70–0.90 — lower Mn and Cr, somewhat lower hardenability. SAE 5120 is closer on hardenability. |
| 590M17 | BS (superseded British) | Near | BS 970 590M17: C 0.14–0.20, Mn 1.00–1.30, Cr 0.60–1.00 (Cr window slightly lower). |
| 20MnCr5 | EN (European) | Near | 1.7147: C 0.17–0.22, same Mn/Cr; higher core strength (900–1200 MPa) for larger gears. |
| 16MnCrS5 | EN (European) | Near | Free-machining variant with 0.020–0.040 % S; same case/core response. |
| 16CrMn / 20CrMn | GB/T (China) | Near | GB/T 3077 20CrMn: C 0.17–0.23, Mn 0.90–1.20, Cr 0.90–1.20; 16MnCr5 sits at the low-carbon end. |
| 18KhG | GOST (Russia/CIS) | Near | GOST 4543 18KhG: C 0.15–0.21, Mn 0.90–1.20, Cr 0.90–1.20. |
| SCr415 / SCr420 | JIS (Japan) | Near | JIS G4053 SCr415: C 0.13–0.18, Mn 0.60–0.90, Cr 0.90–1.20; Mn lower than 16MnCr5. |
| 8620 | AISI / SAE | Functional | Ni-Cr-Mo case-hardening steel, better toughness and hardenability; the US default for the same parts. |
| C15 | EN (European) | Functional | Unalloyed case-hardening steel for small, lightly loaded parts. |
Identical = same composition and mechanical limits within rounding. Near = one limit differs (e.g. carbon max or impact temperature). Functional = interchangeable for most uses after an engineering check. Full cross-reference for 16MnCr5 →
Old and superseded designations
| Old name | Standard | Note |
|---|---|---|
| 16MnCr5 (1.7131) | DIN 17210 (withdrawn) | Name and number unchanged; standard replaced by EN 10084. |
| 590M17 / 527M17 | BS 970 | |
| 16MC5 | NF A 35-551 | |
| 16MnCr5 | UNI 7846 |
Product forms and tolerance standards
Product forms: round bar (hot-rolled, peeled, drawn), forgings, seamless tube, wire rod for cold heading.
Dimensional tolerances: hot-rolled round: EN 10060; bright bar: EN 10278; forgings: EN 10250-3.
Key property values
16MnCr5 core strength
After carburizing and hardening, core tensile is about 780–1080 MPa in an 11 mm reference bar, 690–890 MPa at 30 mm and 640–840 MPa at 63 mm (EN 10084 Annex F). Core hardness ≈ 25–35 HRC.
16MnCr5 surface hardness
Carburized case: 58–62 HRC (700–780 HV) at a typical case depth (CHD) of 0.6–1.5 mm. Carbonitriding gives similar hardness at shallower depth for small parts.
Delivery hardness
+A soft-annealed max 207 HB; +FP 140–187 HB; +S (treated for shearability) max 255 HB.
Heat treatment
Carburize 880–980 °C; direct or single quench from 820–860 °C in oil; core-refine at 860–900 °C where required; temper 150–200 °C. Normalize 880–920 °C; soft anneal 650–700 °C. Ac1 ≈ 740 °C, Ac3 ≈ 840 °C.
Hardenability
Jominy end-quench (16MnCr5H): J1.5 = 39–47 HRC, J9 = 30–43 HRC, J15 = 22–37 HRC. Sufficient for gears up to roughly module 5 / 50 mm section.
Weldability
Weldable in the soft-annealed condition with preheat 150–250 °C and low-hydrogen consumables (CEV ≈ 0.50 %). Carburized surfaces must be removed or masked before welding. Post-weld stress relief 550–650 °C. Welding is uncommon; parts are usually machined from bar or forged.
Machining, forming and heat treatment
Machinability is good in the +FP or +A condition (index ≈ 65–70 %); 16MnCrS5 with controlled S is preferred for high-volume turning and hobbing. Machine to finish size allowing for carburizing distortion (grinding stock 0.1–0.3 mm on gear flanks). Cold heading and cold extrusion are possible after spheroidize annealing (+AC). Hot forging 1100–850 °C then normalize.
Typical applications
- Automotive gearbox gears, synchronizer rings and shafts
- Small pinions, worms and sprockets
- Camshafts and rocker arms
- Piston pins, bushings and sleeves
- Ball-screw nuts, guide rails and cam followers
- Cold-headed parts requiring a hard case (rivets, pins)
Frequently asked questions
What is 16MnCr5 equivalent to in AISI?
The nearest SAE grades are 5115 and 5120 (Cr steels with 0.15–0.20 % C). 8620 is the functional US equivalent in gear practice because it is what American mills stock, but it is a Ni-Cr-Mo steel with different hardenability.
What hardness does 16MnCr5 reach after case hardening?
Surface 58–62 HRC with a case depth of typically 0.6–1.5 mm; core around 25–35 HRC (780–1080 MPa in thin sections).
What is the difference between 16MnCr5 and 20MnCr5?
20MnCr5 (1.7147) has 0.17–0.22 % carbon versus 0.14–0.19 %, giving a stronger core (about 900–1200 MPa) and slightly higher hardenability. Choose 20MnCr5 for larger gears and higher torque.
Can 16MnCr5 be through-hardened instead of carburized?
Not usefully. With 0.16 % C the as-quenched hardness is only about 40–45 HRC. Use 42CrMo4 or C45 if you need a through-hardened part.
Related grades
Verified against EN 10084:2008; EN 10084:2008 Tables 3, 6 and Annex F; EN ISO 642 (Jominy). Last checked: September 2026.