20MnCr5
20MnCr5 Case Hardening Alloy Bright Bar
Higher carbon, higher chromium — for heavier loads and larger sections.
Also known as 1.7147 · AISI 5120 · SCr420
Overview
What 20MnCr5 is, and where it belongs
20MnCr5 is the heavier-duty member of the Mn-Cr case hardening family. Carbon rises to 0.17–0.22% and chromium to 1.00–1.30% compared with 16MnCr5, and both changes point in the same direction: more core strength and deeper hardenability.
Higher base carbon means the core transforms to a stronger structure after quenching — core tensile typically reaches 1000–1300 MPa against 780–1080 MPa for 16MnCr5. Higher chromium means that strength develops properly even in thicker sections, where a leaner alloy would not harden through.
Choose 20MnCr5 where the tooth root or the shaft core is genuinely highly loaded, or where section size is large enough that 16MnCr5 would leave a soft centre. Choose 16MnCr5 where loads are moderate and maximum core toughness is preferred — the extra core strength of 20MnCr5 is bought with some ductility.
Both grades share the same carburising route and the same processing discipline in our plant, and both ship with the heat number carried through to the delivery challan.
Chemistry
Chemical composition
As per EN 10084 / DIN 1.7147, certified per mill test certificate. Values are percentage by weight.
| Element | Symbol | Min % | Max % |
|---|---|---|---|
| Carbon | C | 0.170 | 0.220 |
| Silicon | Si | — | 0.400 |
| Manganese | Mn | 1.100 | 1.400 |
| Phosphorus | P | — | 0.035 |
| Sulphur | S | — | 0.040 |
| Chromium | Cr | 1.000 | 1.300 |
A dash in the minimum column means only an upper limit applies to that element.
Properties
Mechanical properties
Typical values in the Cold Drawn / Annealed (supplied soft for machining) condition. Certified values for your consignment appear on the test certificate.
- Hardness as supplied
- ≤ 217 HBAnnealed / soft, for machining
- Case hardness after carburising
- 58 – 62 HRC
- Core Tensile Strength
- 1000 – 1300 MPaAfter case hardening
- Core Yield Strength
- 700 MPa min
- Elongation (A5)
- 7 – 9%Core, after case hardening
Availability
Sizes and tolerances
We draw 20MnCr5 across the range below. Exact availability for a given size is confirmed on enquiry.
Round bar
8 – 65 mm
Nominal diameter
Hex bar
10 – 46 mm
Across flats (AF)
Tolerance bands
All bands are ISO 286 ‘h’ — the bar is never above nominal size. See exact values for your size.
Where it is used
Typical applications
- Heavily loaded gears and pinions
- Automotive transmission and differential parts
- Larger section carburised shafts
- Splined shafts and drive components
- Heavy duty bushes, pins and levers
Application guides
Cross reference
International equivalents
Nearest designations under other standards. Equivalents are close but rarely identical — check the specific requirement that matters for your part.
Full equivalents chart| Standard | Designation |
|---|---|
| DIN / EN (Germany) | 20MnCr5 / 1.7147 |
| AISI / SAE (USA) | 5120 |
| JIS (Japan) | SCr420 |
| BS (UK) | 527M20 |
| IS (India) | 20Mn5Cr5 |
Processing
Heat treatment guidelines
Indicative parameters. Actual cycles depend on section size, furnace and the properties your drawing calls for.
- 01Soft annealing650 – 700 °C, furnace cool — gives ≤ 217 HB for machining
- 02Normalising880 – 920 °C, cool in still air
- 03Carburising880 – 980 °C in a carburising atmosphere
- 04HardeningDirect or reheat quench from 820 – 860 °C in oil
- 05Tempering150 – 200 °C, air cool
Index relative to AISI 1212 = 100. Higher is faster to machine.
Slightly harder to machine than 16MnCr5 because of higher carbon and chromium. Machined soft before carburising; rigid setups, sharp tooling and good coolant flow are worth the attention on larger components.
Weldability: Limited
Related grades
Chemical composition and mechanical properties shown are as per the applicable standard and are indicative. Actual values for your consignment are certified in the Mill Test Certificate supplied with each dispatch. Available sizes and tolerances are confirmed at the time of enquiry.
Need 20MnCr5?
Send us the size and quantity — Round 8–65 mm · Hex 10–46 mm. We will confirm availability and come back with a price.