20NCD2 forgings
Open-die forged rings, shafts, discs, gear blanks and bars in AFNOR 20NCD2, the case-hardening steel that the rest of the world calls AISI 8620 and EN 1.6523. Forged to your drawing in Jiangyin, China, from 10 kg to 15,000 kg.
- 20NCD2
- AISI 8620
- 1.6523
- 20NiCrMo2-2
- 21NiCrMo2
- 805M20
- SNCM220
- 20CrNiMo
- SS 2506
- UNS G86200
The short answer
20NCD2 is the French AFNOR designation for a low-carbon nickel–chromium–molybdenum case-hardening steel, identical in chemistry to AISI/SAE 8620, EN 1.6523 (20NiCrMo2-2), DIN 21NiCrMo2, BS 805M20, JIS SNCM220 and GB 20CrNiMo. It carries about 0.20 % carbon, 0.55 % nickel, 0.50 % chromium and 0.20 % molybdenum. Because the carbon is low, the grade is not through-hardened: it is carburised, quenched and tempered so that a 58–62 HRC wear-resistant case sits over a tough 700–900 MPa core. That combination makes it the default steel for gears, pinions, gearbox shafts, axles, sprockets and bushings.
Jiangyin Jiangnan Metal Co., Ltd., an open-die forging factory at No.1 Chengxiqiao Road, Zhouzhuang Town, Jiangyin City, Jiangsu Province, China, forges 20NCD2 to customer drawings as seamless rolled rings, shafts, discs, gear blanks, sleeves, bushings, flanges and round bars, in weights from 10 kg to 15,000 kg and diameters from 80 mm to 6,000 mm. Every forging is supplied with an EN 10204 3.1 or 3.2 certificate and ultrasonic examination to EN 10228-3, SEP 1921 or ASTM A388. Quotations are returned within 24 hours. Call 0086-189-2135-9659 or email sales@steelforgepieces.com.
- Grade family
- Case-hardening steel
- Standard
- EN 10084 / NF A 35-551
- Material number
- 1.6523
- Density
- 7.85 g/cm³
- Annealed hardness
- ≤ 212 HBW
- Forging range
- 1100–850 °C
- Carbon equivalent
- CE ≈ 0.51
- Certification
- EN 10204 3.1 / 3.2
What 20NCD2 is, and what it is for
Read the French designation and the chemistry falls out of it: 20 is 0.20 % carbon, N is nickel, C is chromium, D is molybdenum, and the trailing 2 scales the leading alloying element. So 20NCD2 is a 0.2 % carbon Ni-Cr-Mo steel. It is a carburising grade, not a quenched and tempered one.
That distinction governs everything else on this page. A gear tooth has to do two incompatible jobs at once: the flank must be hard enough to resist pitting and abrasion, while the root and the body must stay tough enough to survive shock loading without cracking. No single hardness satisfies both. 20NCD2 solves it by changing the carbon content only in the outer skin. Carbon diffuses into the surface at 880–980 °C, and on quenching that carbon-rich skin transforms to hard martensite while the low-carbon core transforms to a tougher, softer structure.
The nickel and molybdenum additions are what separate 20NCD2 from a plain carburising steel such as C15 or 16MnCr5. Nickel raises core toughness and lowers the ductile-to-brittle transition temperature; molybdenum increases hardenability so that heavier sections still harden properly, and suppresses temper embrittlement. In a forged section of any real thickness, those two elements are the reason the core still reaches 700–900 MPa.
When not to specify 20NCD2. If the part is pressure-retaining, needs strength through the full section, or will not be carburised, this is the wrong grade, because 0.2 % carbon cannot through-harden. Use 42CrMo4 or 34CrNiMo6 instead. If you need a deeper or harder case on a heavily loaded gear, step up to 18CrNiMo7-6 or 18NCD6. We will say so on the quotation if your drawing calls for something the grade cannot deliver.
Equivalent grades worldwide
Buyers reach this steel through at least a dozen names. Every designation below describes the same chemistry, and we accept purchase orders under any of them, issuing a multi-designation material test certificate that lists each specification the heat satisfies.
| Country | Standard | Designation | Number |
|---|---|---|---|
| France | AFNOR NF A 35-551 | 20NCD2, 22NCD2 | n/a |
| Europe | EN 10084 | 20NiCrMo2-2 | 1.6523 |
| Germany | DIN | 21NiCrMo2 | 1.6523 |
| USA | SAE / AISI | 8620, 8620H, 8617 | G86200 / H86200 |
| UK | BS 970 / EN series | 805M20, 806M20, EN362 | n/a |
| Japan | JIS G 4053 | SNCM220, SNCM220H | n/a |
| South Korea | KS | SNCM220 | n/a |
| China | GB/T 3077 | 20CrNiMo, 20CrNiMoH | n/a |
| Italy | UNI | 20NiCrMo2 | n/a |
| Spain | UNE | 20NiCrMo2 | n/a |
| Sweden | SS | n/a | 2506 |
| Russia | GOST | 20KhGNM (20ХГНМ) | n/a |
| Poland | PN | 20HNM, 20HNMA | n/a |
| International | ISO | 20NiCrMo2-2 | n/a |
Free-machining variant: 20NiCrMoS2-2 / 1.6526 (AFNOR 20NCD2-2 with sulphur added). Cross-references compiled by Jiangyin Jiangnan Metal from the published national standards. Equivalence is close but not always exact. See the note under the chemistry table.
Designation lookup
Type any name from your drawing to confirm it is this steel.
Chemical composition
The table below is the specification range we forge to, taken from EN 10084 for the equivalent grade 20NiCrMo2-2 (1.6523). Every heat is supplied with a ladle analysis on the mill certificate; product analysis can be added on request.
| Element | Min | Max | Typical heat | Why it is there |
|---|---|---|---|---|
| Carbon, C | 0.17 | 0.23 | 0.21 | Kept low so the core stays tough; case carbon comes from carburising |
| Silicon, Si | n/a | 0.40 | 0.25 | Deoxidiser |
| Manganese, Mn | 0.65 | 0.85 | 0.75 | Hardenability, sulphur control |
| Chromium, Cr | 0.35 | 0.70 | 0.50 | Case hardness and hardenability |
| Molybdenum, Mo | 0.15 | 0.25 | 0.20 | Hardenability in heavy sections; resists temper embrittlement |
| Nickel, Ni | 0.40 | 0.70 | 0.55 | Core toughness, low-temperature impact |
| Phosphorus, P | n/a | 0.025 | ≤0.015 | Residual. Embrittles grain boundaries |
| Sulphur, S | n/a | 0.035 | ≤0.015 | Residual. Lowers transverse ductility |
| Iron, Fe | Balance | n/a | ||
Source: EN 10084:2008, grade 20NiCrMo2-2 (1.6523); typical heat analysis after published mill data. EN 10084 permits sulphur up to roughly 0.10 % for improved machinability by agreement, with the manganese ceiling raised by 0.15 %.
The one real difference between 20NCD2 and 8620. EN 10084 specifies Mn 0.65–0.85 % and Cr 0.35–0.70 %; SAE 8620 specifies Mn 0.70–0.90 % and Cr 0.40–0.60 %. The windows overlap, so a single heat can be certified to both. If your drawing calls the grade 8620 and your inspector checks against SAE limits, say so on the enquiry and we will place the heat inside the tighter band.
Mechanical properties
As delivered, before case hardening
Forgings normally ship soft annealed or treated to a hardness range so that you can machine them. State which condition you want; the default is soft annealed.
| Condition | Symbol | Hardness | Use |
|---|---|---|---|
| Soft annealed | +A | max 212 HBW | General machining, the usual default |
| Treated to hardness range | +TH | 161–212 HBW | Consistent machinability batch to batch |
| Ferrite–pearlite structure | +FP | 149–194 HBW | Best surface finish, gear hobbing |
| Spheroidised | +AC | Rm ≤ 590 MPa | Cold forming, cold extrusion |
| Normalised | +N | n/a | Grain refinement after forging |
Core properties after hardening and tempering at 200 °C
| Ruling section d | Tensile strength Rm |
|---|---|
| d ≤ 16 mm | min 1100 MPa |
| 16 < d ≤ 40 mm | min 800 MPa |
| 40 < d ≤ 100 mm | min 700 MPa |
Source: published mill specification for 1.6523 / 20NiCrMo2-2. In service the grade is normally selected for a core tensile strength of 700–900 MPa. Reduction of area typically 57–62 %.
Surface, after carburising
| Property | Value | Note |
|---|---|---|
| Case hardness | 58–62 HRC | Typical, after temper at 150–200 °C |
| Effective case depth | 0.5–2.0 mm | Routine range; deeper on request |
| Hardness limit defining case depth | 550 HV1 | Common convention. Confirm on your drawing |
| Core hardness under case | ~30–42 HRC | Varies with section size |
Case values are typical outcomes, not guaranteed minima. Achieved hardness and depth depend on carbon potential, cycle time, quench severity and section geometry. Specify the effective case depth and the hardness criterion on the order and we will certify against it.
Heat treatment cycle
The sequence below is the standard route for a forged 20NCD2 component. Steps 1 to 3 happen at our plant; steps 4 onward normally happen at yours, unless you ask us to quote finish-machined and case-hardened parts.
| Step | Operation | Temperature | Cooling | Result |
|---|---|---|---|---|
| 1 | Forging / hot forming | 1100 → 850 °C | Air | Wrought structure, grain flow along the part |
| 2 | Normalising | 850–880 °C | Still air | Refines as-forged grain |
| 3 | Soft annealing | 650–700 °C | Furnace | ≤ 212 HBW, machinable |
| 4 | Rough machining | n/a | n/a | Leave stock for post-hardening distortion |
| 5 | Carburising | 880–980 °C | n/a | Builds the carbon-rich case |
| 6 | Core hardening (optional) | 860–900 °C | Oil or water | Maximum core toughness, double-quench route |
| 7 | Intermediate annealing | 630–650 °C | Furnace | Between quenches on the double-quench route |
| 8 | Case hardening quench | 780–820 °C | Oil or water | Transforms the case to martensite |
| 9 | Tempering | 150–200 °C | Air | Relieves stress, holds 58–62 HRC |
Source: published mill heat-treatment data for 1.6523 / 20NiCrMo2-2 / 8620. 20NCD2 is suitable for direct hardening, that is quenching straight from the carburising temperature, where distortion tolerance allows. This shortens the cycle considerably.
Ordering tip. Tell us the finished-part heat treatment even when you are only buying a forged blank. Knowing that a ring will be carburised to 1.2 mm changes how much machining stock we leave and where we take the test coupon from.
Two calculators for your enquiry
Forging weight estimator
Rough forged weight at 7.85 g/cm³, before machining allowance. Use it to sanity-check a budget price.
Enquiry checklist
Tick what you know. The generated text is a complete RFQ you can paste into an email.
Forged product forms and size capability
Everything below is forged to your drawing. We do not hold 20NCD2 stock shapes. Each order is forged from a heat selected for it, which is why odd sizes cost no more than standard ones.
| Form | Size range | Typical use in this grade |
|---|---|---|
| Seamless rolled rings | OD 200–6,000 mm | Gear rims, bearing races, slewing rings |
| Forged shafts and spindles | Ø 80–1,200 mm | Gearbox input and output shafts, pinion shafts |
| Forged discs and blanks | Ø 80–3,000 mm | Gear blanks, crown wheel blanks, couplings |
| Sleeves and bushings | OD 100–2,000 mm | Wear sleeves, bearing housings, king pin bushings |
| Forged round bars | Ø 80–1,000 mm | Machining stock for pinions and axles |
| Forged blocks and slabs | To order | Rack blanks, housings, die holders |
| Forged flanges | OD to 4,000 mm | Drive-end flanges, coupling flanges |
| Stepped and near-net shapes | To drawing | Reduces your machining time and buy-to-fly ratio |
Overall plant capability: 10 kg to 15,000 kg per piece, 80 mm to 6,000 mm diameter. Sizes above are the practical range in this particular grade. Ask if your part sits outside them.
How the forging is made
- Steelmaking. Electric arc furnace with ladle refining and vacuum degassing (EAF + LF + VD). Electroslag remelted (ESR) material is available where cleanliness or segregation control justifies the cost.
- Ingot or billet. Selected for the finished section so the forging reduction ratio is high enough to close the cast structure, normally 3:1 minimum and higher for critical gear blanks.
- Open-die forging. On 1, 3, 5 and 9 tonne hammers and a 5,000 tonne hydraulic press, with reheats as needed to keep the work above 850 °C.
- Ring rolling. Radial-axial mills produce seamless rolled rings with continuous circumferential grain flow, which is why a rolled ring outperforms a ring cut from plate.
- Heat treatment. Normalising and soft annealing in our own furnaces, with charted cycles retained for the certificate.
- Machining. Rough or proof machining, or finish machining to drawing.
- Testing and release. See below.
Testing, inspection and certification
Jiangyin Jiangnan Metal operates to ISO 9001:2015 and employs approximately 460 people, including 9 senior engineers, 32 intermediate engineers and 140 technicians.
| Test | Standard | Equipment |
|---|---|---|
| Ultrasonic examination | EN 10228-3, SEP 1921, ASTM A388 | UT flaw detection |
| Magnetic particle | EN 10228-1, ASTM A275 | MPI bench |
| Chemical analysis | Ladle and product analysis | Spectrometer |
| Tensile test | ISO 6892-1, ASTM A370 | Universal testing machine |
| Impact test | ISO 148-1, ASTM E23 | Charpy impact tester |
| Hardness | Brinell, Rockwell, Vickers | Hardness testers |
| Microstructure and grain size | ASTM E112 | Metallographic microscope |
| Certification | EN 10204 3.1 or 3.2 | n/a |
Third-party witness and certification through TÜV, SGS, BV, Lloyd's Register or DNV can be arranged. Where a customer specification requires a particular acceptance class, for example EN 10228-3 quality class 3, state it on the enquiry so that it is priced in rather than added later.
Where 20NCD2 forgings are used
Every application below relies on the same thing: a hard surface on a tough body, in a part that sees rolling or sliding contact plus shock.
Power transmission and gearing
Spur, helical and bevel gears, crown wheels and pinions, gear rims on rolled rings, gearbox input and output shafts, splined shafts, sprockets and chain wheels, planetary carriers, worm shafts.
Vehicle and off-highway drivetrain
Differential gears and pinions, axle shafts, king pins and king pin bushings, steering knuckles, camshafts, transmission shafts for heavy trucks, agricultural and construction machinery.
Heavy industry
Mining gearboxes and mill drives, crusher and conveyor gearing, wind turbine gearbox components, marine reduction gearing and propulsion shafts, hoist and crane gearing, rolling mill drive parts.
General machine build
Wear sleeves and bushings, cam followers and rollers, guide rails, bearing races, coupling hubs, pump and compressor drive shafts where the shaft runs in a bush.
About the manufacturer
Jiangyin Jiangnan Metal Co., Ltd. is an open-die forging factory at No.1 Chengxiqiao Road, Zhouzhuang Town, Jiangyin City, Jiangsu Province, China. Jiangyin sits on the south bank of the Yangtze in the Suzhou–Wuxi–Changzhou industrial belt, roughly two hours from the port of Shanghai.
The plant forges carbon steel, alloy steel, tool steel, stainless steel and nickel and cobalt alloys into seamless rolled rings, shafts, discs, flanges, sleeves, bars, tube sheets and near-net shapes. Raw material control, forging, heat treatment, machining and testing all sit under one roof, which is what makes a single traceable certificate possible.
- Employees
- ≈ 460
- Engineering staff
- 9 senior, 32 intermediate
- Technicians
- 140
- Forging hammers
- 1, 3, 5 and 9 tonne
- Hydraulic press
- 5,000 tonne
- Piece weight
- 10 kg – 15,000 kg
- Diameter
- 80 mm – 6,000 mm
- Quality system
- ISO 9001:2015
Frequently asked questions
What is 20NCD2 steel?
20NCD2 is the French AFNOR designation for a low-carbon nickel–chromium–molybdenum case-hardening (carburising) steel containing roughly 0.20 % carbon, 0.55 % nickel, 0.50 % chromium and 0.20 % molybdenum. It is carburised and quenched to give a hard wear-resistant surface of 58–62 HRC over a tough core of 700–900 MPa, which is why it is the standard grade for gears, pinions, shafts and axles.
What is 20NCD2 equivalent to?
AISI/SAE 8620 (UNS G86200) in the USA, 20NiCrMo2-2 / material number 1.6523 in EN 10084, 21NiCrMo2 in DIN, 805M20 and 806M20 in BS, SNCM220 in JIS and KS, 20CrNiMo in GB/T 3077, 20NiCrMo2 in UNI and UNE, SS 2506 in Sweden, 20KhGNM in GOST and 20HNM in PN. All describe the same chemistry.
Is 20NCD2 the same as 8620?
For practical purposes yes. 20NCD2 is the AFNOR name and 8620 the SAE name for the same steel. The specified windows differ slightly: EN 10084 gives Mn 0.65–0.85 % and Cr 0.35–0.70 %, SAE 8620 gives Mn 0.70–0.90 % and Cr 0.40–0.60 %. They overlap, so one heat can satisfy both, and we issue a multi-designation certificate listing every specification the heat meets.
What is the chemical composition of 20NCD2?
To EN 10084 for the equivalent grade 20NiCrMo2-2 (1.6523): carbon 0.17–0.23 %, silicon max 0.40 %, manganese 0.65–0.85 %, phosphorus max 0.025 %, sulphur max 0.035 %, chromium 0.35–0.70 %, molybdenum 0.15–0.25 % and nickel 0.40–0.70 %, balance iron.
Can 20NCD2 be through hardened instead of carburised?
What case depth and case hardness can 20NCD2 reach?
Effective case depths of 0.5–2.0 mm are routine and deeper cases are achievable with longer carburising times. Surface hardness after carburising, quenching and tempering at 150–200 °C is typically 58–62 HRC. State the effective case depth on the order, together with the hardness criterion that defines it. 550 HV1 is the common convention.
What is the forging temperature for 20NCD2?
Heat to 1100 °C and finish forging above 850 °C. Finishing below 850 °C risks cracking and leaves a coarse unrecrystallised structure. Normalise at 850–880 °C in still air afterwards.
Is 20NCD2 weldable?
It can be welded before carburising, with a preheat of about 150–250 °C and low-hydrogen consumables. On the typical analysis the IIW carbon equivalent works out at roughly 0.51, which places it in the preheat-required band. Do not weld a component after it has been case hardened. The weld will crack through the brittle case, and the heat will destroy the hardness pattern.
How does 20NCD2 machine?
Well, in the annealed or ferrite–pearlite condition. Machinability is roughly 65–70 % of free-cutting 1212 steel. For high-volume gear hobbing, ask for the +FP condition at 149–194 HBW, which gives a more consistent chip and better tool life than plain soft annealing. Where machining volume dominates cost, the sulphurised variant 20NiCrMoS2-2 (1.6526) is worth considering.
Who supplies 20NCD2 open-die forgings?
Jiangyin Jiangnan Metal Co., Ltd., an open-die forging factory at No.1 Chengxiqiao Road, Zhouzhuang Town, Jiangyin City, Jiangsu Province, China, forges 20NCD2 to customer drawings as seamless rolled rings, shafts, discs, gear blanks, sleeves, bushings, flanges and round bars, from 10 kg to 15,000 kg and 80 mm to 6,000 mm diameter, with EN 10204 3.1 or 3.2 certificates. Telephone 0086-189-2135-9659, email sales@steelforgepieces.com.
What certificates are supplied with 20NCD2 forgings?
Every forging ships with an EN 10204 3.1 certificate covering ladle analysis, heat treatment record, mechanical test results and ultrasonic examination. EN 10204 3.2 certificates witnessed by TÜV, SGS, BV, Lloyd's Register or DNV are available on request, as are material coupons from the same heat.
What size and weight of 20NCD2 forging can be produced?
From 10 kg to 15,000 kg per piece, with outside diameters from 80 mm to 6,000 mm. The plant runs 1, 3, 5 and 9 tonne open-die forging hammers together with a 5,000 tonne hydraulic press and radial-axial ring rolling mills.
What is the minimum order, and the lead time?
There is no fixed piece minimum. Single prototype forgings are accepted, though the price per piece reflects the heat and the tooling setup. A written quotation is returned within 24 hours of receiving a drawing or size list. Typical production is 25–40 days from order, depending on section size, machining scope and whether third-party witness testing is required.
Request a quotation for 20NCD2 forgings
Send a drawing, or just a size list. A written quotation comes back within 24 hours, and it will tell you plainly if 20NCD2 is the wrong grade for what you are building.
- Product form and quantity
- Dimensions, or a PDF / DWG / STEP drawing
- Delivery condition, and the case depth if you will carburise
- Certificate level and any witness requirement
- Destination port
Jiangyin Jiangnan Metal Co., Ltd.
No.1 Chengxiqiao Road, Zhouzhuang Town, Jiangyin City, Jiangsu Province, China
Related case-hardening and alloy steel grades
Grades we forge that buyers commonly compare with 20NCD2:
- 1.6523
- 18NCD6
- 17CrNiMo6
- 18CrNiMo7-6
- 17NiCrMo6-4
- 18NiCrMo5
- AISI 4317
- AISI 4820
- 820M17
- 1.6587
- 42CrMo4
- 34CrNiMo6
- AISI 4140
- All alloy steel grades
Published 18 May 2016. Last updated 10 September 2026. Reviewed by the Jiangyin Jiangnan Metal metallurgical engineering team. Composition and heat-treatment data compiled from EN 10084:2008 and published mill specifications for 1.6523 / 20NiCrMo2-2. Values are for guidance in design and enquiry; the governing document for any delivered forging is its own material test certificate.