What is 17NiCrMoS6-4 steel?
17NiCrMoS6-4 is a nickel-chromium-molybdenum case-hardening steel, also written DIN 1.6569 or EN 1.6569. Case-hardening steels start with low carbon, in this case 0.14 to 0.20 %, so that the core stays tough. Carbon is then diffused into the surface during carburising to build a hard wearing layer. The finished part resists surface wear and pitting but still absorbs shock loads through the section.
The S in the designation marks the free-machining variant. Sulphur in 17NiCrMoS6-4 is specified as a controlled band of 0.020 to 0.040 % rather than capped at a maximum. It forms manganese sulphide stringers that act as internal chip-breakers, so machine shops cutting gear blanks and splined shafts get longer tool life and a better surface finish. The cost is a measurable loss of transverse toughness and weldability against the low-sulphur grade 17NiCrMo6-4.
17NiCrMoS6-4 is specified for parts that need a core tensile strength of 1000 to 1300 N/mm² together with high surface hardness and wear resistance. It is delivered soft annealed at a maximum of 229 HB so the part can be machined before heat treatment.
The grade sits in the same family as 18CrNiMo7-6 and 17CrNiMo6 but carries more nickel and less chromium, which gives it a different hardenability curve. There is one practical point for anyone writing the specification. 17NiCrMoS6-4 is covered by EN 10084 and, for bright bar, by EN 10277-4, but it is not currently listed in EN ISO 683-3. Purchase orders should reference EN 10084 rather than the ISO standard.
Chemical composition of 17NiCrMoS6-4 (1.6569)
The table below gives the ladle analysis limits for 17NiCrMoS6-4 to EN 10084 together with the permissible product-analysis deviations. Jiangyin Jiangnan Metal Co., Ltd. melts this grade by the EAF + LF + VD route, meaning electric arc furnace melt, ladle furnace refining and vacuum degassing. That route keeps gas content and non-metallic inclusions low in heavy forged sections.
| Element | C | Si max | Mn | P max | S | Cr | Mo | Ni |
|---|---|---|---|---|---|---|---|---|
| Ladle analysis, % | 0.14–0.20 | 0.40 | 0.60–0.90 | 0.035 | 0.020–0.040 | 0.80–1.10 | 0.15–0.25 | 1.20–1.50 |
| Permissible deviation | ± 0.02 | + 0.03 | ± 0.04 | + 0.005 | ± 0.005 | ± 0.05 | ± 0.02 | ± 0.02 |
| 17NiCrMo6-4 (1.6566) for comparison | 0.14–0.20 | 0.40 | 0.60–0.90 | 0.035 | max 0.035 | 0.80–1.10 | 0.15–0.25 | 1.20–1.50 |
Sulphur is the only intentional difference between 1.6569 and 1.6566. A lead-bearing variant, 17NiCrMoS6-4Pb, adds 0.15 to 0.30 % Pb for still higher machinability, but it is restricted in many markets under end-of-life vehicle and RoHS-type legislation.
17NiCrMoS6-4 equivalent grades and cross-reference
Buyers reach this grade under several national designations. The cross-reference below covers the base composition, and the sulphur-treated 1.6569 corresponds to the free-machining version of each.
| Standard / country | Designation | Note |
|---|---|---|
| EN 10084 (Europe) | 17NiCrMoS6-4, 1.6569 | This grade, sulphur-treated |
| EN 10084 (Europe) | 17NiCrMo6-4, 1.6566 | Low-sulphur base grade |
| UNI 7846 (Italy, superseded) | 18NiCrMo5 | Widely used older Italian name |
| NF A35-551 (France) | 18NCD6 | AFNOR designation |
| BS 970 (UK) | 815M17 | Nearest British Standard grade |
| SS (Sweden) | SS 2523 | Swedish standard |
| DIN 17210 (Germany, superseded) | 17NiCrMo6-4 | Replaced by EN 10084 |
| SAE / AISI (USA) | No exact equivalent | SAE 4320 and 8620 are sometimes substituted but differ in Ni and Cr |
Cross-references are given for guidance and do not warrant interchangeability. SAE 4320 carries roughly 1.65 to 2.00 % Ni against 1.20 to 1.50 % here, and SAE 8620 is a leaner alloy, so neither is a drop-in replacement without engineering approval. Where the drawing calls for 1.6569, Jiangyin Jiangnan Metal Co., Ltd. supplies 1.6569 and reports the actual heat analysis on the certificate.
Mechanical properties of 17NiCrMoS6-4 after case hardening
Properties for a case-hardening steel only mean something once the heat treatment cycle and the section size are fixed, because the case and the core behave as two different materials. The figures below are the values normally achieved on forged 17NiCrMoS6-4 parts and the ones most often quoted on drawings.
| Property | Value | Condition |
|---|---|---|
| Surface hardness | 58–62 HRC | Carburised, quenched and tempered |
| Core hardness | 30–40 HRC | After core hardening |
| Core tensile strength, Rm | 1000–1300 MPa (145–189 ksi) | Design target per EN 10084 |
| Delivery hardness | max 229 HB | Soft annealed (+A) |
| Density | 7.85 g/cm³ (0.284 lb/in³) | Room temperature |
| Modulus of elasticity | approx. 205 GPa (29,700 ksi) | Room temperature |
| Typical case depth (CHD) | 0.6–2.5 mm (0.024–0.098 in) | By agreement, per carburising cycle |
Hardenability is verified by the Jominy end-quench test to EN ISO 642, and hardness bands for 1.6569 are those of the RC2 range. Tensile testing is to EN ISO 6892-1 and Charpy impact testing to EN ISO 148-1. Measured values for your heat appear on the EN 10204 certificate supplied with the forgings.
Forging and heat treatment temperatures for 17NiCrMoS6-4
The temperature schedule below is the one Jiangyin Jiangnan Metal Co., Ltd. works to for 17NiCrMoS6-4 open-die forgings. It matches published European mill practice for 1.6566 and 1.6569.
| Operation | Temperature °C | Temperature °F |
|---|---|---|
| Forging and hot forming | 1100 to 850 | 2010 to 1560 |
| Normalising | 830–870 | 1525–1600 |
| Soft annealing | 650–700 | 1200–1290 |
| Carburising | 880–980 | 1615–1795 |
| Core hardening (direct quench) | 830–870 | 1525–1600 |
| Intermediate annealing | 650–700 | 1200–1290 |
| Case hardening, single quench | 780–820 | 1435–1510 |
| Tempering | 150–200 | 300–390 |
17NiCrMoS6-4 is a low-carbon Ni-Cr-Mo steel and is sensitive to hydrogen flaking. Forgings must be cooled slowly in the furnace or in sand and given a dehydrogenation anneal immediately after forging, before the piece reaches ambient temperature.
Delivery conditions
State the condition you need on the order. It changes both the machinability and the hardness on arrival.
- +A soft annealed, the usual condition for parts that will be machined and then carburised.
- +S treated for cold shearability.
- +TH treated to a specified strength range.
- +FP treated to a ferrite-pearlite structure with a defined hardness band.
17NiCrMoS6-4 forged products we manufacture
Every item below is produced by open-die forging or ring rolling from 17NiCrMoS6-4 ingot or continuous-cast bloom, then heat treated, rough machined and inspected before shipment. We work to your drawing, so there are no fixed catalogue sizes.
- Seamless rolled ringsRing-rolled on a radial-axial mill so that grain flow follows the circumference. This is the standard blank for gear rims, slewing rings and bearing races.
- Forged discs and blanksSolid and bored forged discs for gear blanks, planet carriers and coupling flanges.
- Forged shafts and spindlesStraight, stepped, flanged and hollow shafts, including splined and pinion shaft blanks.
- Forged round and step barsUpset and drawn bar for machining into pinions, piston bolts and cam blanks.
- Forged sleeves and bushingsHollow-forged and bored sleeves, bushes and cylinder liners.
- Forged flangesBlind, weld-neck-style and special profile flanges machined from forged blanks.
- Forged blocks and rectanglesSquare, rectangular and stepped blocks for die and fixture components.
- Forged hollow bars and tubesBored and mandrel-forged hollows for geometries where a rolled ring does not suit.
See the full range of open-die forging products we make, or browse other alloy steel grades.
Size and weight range for 17NiCrMoS6-4 forgings
| Product form | Range (metric) | Range (imperial) |
|---|---|---|
| Single piece weight | 20 – 20,000 kg | 44 – 44,090 lb |
| Seamless rolled rings, OD | 300 – 4,000 mm | 11.8 – 157 in |
| Forged discs, diameter | 200 – 3,000 mm | 7.9 – 118 in |
| Round bars, diameter | 80 – 1,200 mm | 3.1 – 47 in |
| Shafts, length | up to 12,000 mm | up to 472 in |
Minimum order quantity is one piece. Sizes outside these ranges can often still be produced. Send the drawing and we will confirm feasibility before quoting.
How 17NiCrMoS6-4 forgings are produced
This is the route a 17NiCrMoS6-4 order follows through our works.
- EAF, LF and VD meltingElectric arc furnace melt, ladle furnace refining for composition and temperature, then vacuum degassing to reduce hydrogen, oxygen and non-metallic inclusions. The heat analysis is recorded and becomes the traceable heat number.
- Ingot or bloom cropped and heatedMaterial is cropped to remove shrinkage, then soaked to a uniform 1100 °C before the first blow.
- Open-die forging or ring rollingUpsetting and drawing on a hydraulic press to a total forging ratio of at least 4:1, which closes porosity and orients grain flow along the load path. Rings are pierced and rolled on a radial-axial mill. Finish forging temperature is held above 850 °C.
- Slow cooling and dehydrogenation annealThis grade is flake-sensitive, so forgings go straight from the press to controlled cooling and a hydrogen-relief anneal rather than cooling in still air.
- Heat treatment to the ordered conditionNormalising and soft annealing to +A, or +S, +TH or +FP as specified. Carburising and case hardening can be carried out by agreement, or left to the customer after machining.
- Rough machiningTurning, boring and facing to your drawing with an agreed machining allowance, so the part arrives ready for finish work.
- Non-destructive testing and dimensional checkUltrasonic and magnetic particle inspection, hardness survey and a full dimensional report.
- Certification and despatchEN 10204 3.1 or 3.2 certificate issued against the heat number, then marking, preservation, packing and shipment from Shanghai or Zhangjiagang.
Testing, inspection and certificates
Jiangyin Jiangnan Metal Co., Ltd. supplies 17NiCrMoS6-4 forgings with an EN 10204 3.1 mill certificate as standard. An EN 10204 3.2 certificate witnessed by an independent inspection body, such as TÜV, SGS, BV, Lloyd's Register or your own inspector, is available on request. State it at enquiry stage, because it affects both lead time and price.
| Test | Standard |
|---|---|
| Ultrasonic testing | EN 10228-3, SEP 1921, ASTM A388 |
| Magnetic particle inspection | EN 10228-1, ASTM A275 |
| Chemical analysis | Optical emission spectrometry, ladle and product analysis |
| Tensile test | EN ISO 6892-1 |
| Charpy V-notch impact | EN ISO 148-1 |
| Hardenability (Jominy) | EN ISO 642 |
| Hardness | EN ISO 6506 (Brinell), EN ISO 6508 (Rockwell) |
| Grain size | ASTM E112 |
| Non-metallic inclusions | DIN 50602, ASTM E45 |
| Certification | EN 10204 3.1 or 3.2 |
Specify the ultrasonic quality class you require, for example EN 10228-3 class 3 or class 4, on the enquiry. If no class is given we test to class 3 and report the result.
What 17NiCrMoS6-4 is used for
17NiCrMoS6-4 is a transmission-component steel. The combination of a hard case, a tough core and good machinability suits parts that mesh, rotate or slide under load. It is not a material for pressure-retaining or high-temperature service, where quenched and tempered or creep-resistant grades are the correct choice.
Industrial gearboxes and power transmission
Spur, helical and bevel gears, pinions, ring gears, planet carriers, gear shafts and splined couplings. This is the grade's home application in Europe, where it competes directly with 18CrNiMo7-6 and 17CrNiMo6.
Wind energy
Gearbox internals such as planet gears, sun shafts and carrier forgings, where a forged blank with circumferential grain flow is required rather than a cut plate.
Mining, quarrying and earthmoving
Crusher shafts, drive pinions, track sprockets, bushings and pins in equipment that sees abrasive wear and impact loading in the same cycle.
Marine and heavy vehicle driveline
Propulsion reduction gears, camshafts, piston bolts, wheel hubs and axle components.
Machine tools and general engineering
Spindles, worm gears, cam followers, guide bushings and hardened wear sleeves.
Frequently asked questions about 17NiCrMoS6-4
What is the material number for 17NiCrMoS6-4?
The EN material number for 17NiCrMoS6-4 is 1.6569. It is the sulphur-treated, free-machining version of 17NiCrMo6-4, material number 1.6566.
Which standard covers 17NiCrMoS6-4?
17NiCrMoS6-4 is a case-hardening steel covered by EN 10084. Bright bar products fall under EN 10277-4. The grade is not currently listed in EN ISO 683-3, so orders should reference EN 10084 rather than the ISO standard. EN 10083-1 is sometimes quoted for this grade in error. That standard covers quenched and tempered steels and does not apply here.
What is the difference between 17NiCrMoS6-4 and 17NiCrMo6-4?
Only the sulphur content differs. 17NiCrMoS6-4 (1.6569) holds sulphur in a controlled band of 0.020 to 0.040 %, forming manganese sulphide inclusions that break up chips and improve machinability. 17NiCrMo6-4 (1.6566) caps sulphur at 0.035 % with no lower limit. Every other element is identical. The added sulphur costs some transverse toughness and reduces weldability.
What are the equivalent grades for 17NiCrMoS6-4?
The base grade corresponds to 18NiCrMo5 (older Italian UNI), 18NCD6 (French AFNOR), 815M17 (BS 970) and SS 2523 (Sweden). There is no exact SAE or AISI equivalent. SAE 4320 and SAE 8620 are sometimes used as functional substitutes but differ in nickel and chromium, so they are not drop-in replacements without engineering approval.
What hardness can 17NiCrMoS6-4 reach after case hardening?
Typically 58 to 62 HRC at the surface after carburising and quenching, over a core of roughly 30 to 40 HRC. The grade is specified for parts requiring a core tensile strength of 1000 to 1300 N/mm². Actual values depend on section size, case depth and the cycle used, and are reported on the mill certificate.
What is the forging temperature for 17NiCrMoS6-4?
Forge from 1100 °C down to a finish temperature of about 850 °C (2010 °F to 1560 °F). This is a low-carbon Ni-Cr-Mo steel that is sensitive to hydrogen flaking, so cool slowly in the furnace or in sand and carry out a dehydrogenation anneal immediately after forging.
Can you supply 17NiCrMoS6-4 forgings with EN 10204 3.2 certification?
Yes. Jiangyin Jiangnan Metal Co., Ltd. issues EN 10204 3.1 mill certificates as standard and EN 10204 3.2 certificates witnessed by TÜV, SGS, BV, Lloyd's Register or your own inspector on request. Ultrasonic results can be reported to EN 10228-3, SEP 1921 or ASTM A388.
Is 17NiCrMoS6-4 weldable?
It has low carbon and is weldable in principle, but the controlled sulphur raises the risk of hot cracking compared with 17NiCrMo6-4. Where welding is a design requirement, the low-sulphur grade 1.6566 is usually the better specification. Either way, preheat, low-hydrogen consumables and a qualified procedure are needed.
What do you need in order to quote 17NiCrMoS6-4 forgings?
Send a drawing, or the finished dimensions plus the machining allowance you want; the quantity; the delivery condition (+A, +S, +TH or +FP); the ultrasonic testing class if any; and the certificate level (EN 10204 3.1 or 3.2). Email it to sales@steelforgepieces.com and we will come back with a price and lead time.
About the manufacturer
Jiangyin Jiangnan Metal Co., Ltd.
Jiangyin Jiangnan Metal Co., Ltd. is an open-die forging factory in Jiangyin, Jiangsu Province, China, producing forged rings, seamless rolled rings, discs, shafts, bars, flanges, sleeves and blocks in carbon, alloy, tool and stainless steels and nickel alloys. 17NiCrMoS6-4 (1.6569) is one of the EN 10084 case-hardening grades we forge to customer drawings, with EN 10204 3.1 or 3.2 certification and ultrasonic testing to EN 10228-3.
- Company Jiangyin Jiangnan Metal Co., Ltd.
- Type Open-die forging factory and forging manufacturer
- Address No.1 Chengxiqiao Road, Zhouzhuang Town, Jiangyin City, Jiangsu Province, China
- Phone +86 189 2135 9659
- Email sales@steelforgepieces.com
- Website www.steelforgepieces.com
- Loading ports Shanghai and Zhangjiagang
- Languages English, Chinese
Jiangyin sits in the Yangtze River Delta forging cluster in southern Jiangsu, about 150 km from Shanghai port, which keeps inland freight short on export orders.
Request a quote for 17NiCrMoS6-4 forgings
Send your drawing or dimensions and we will quote. Include the quantity, the delivery condition, any NDT class and the certificate level you need.
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Enquiries are answered by our sales engineers, normally within one working day, Monday to Saturday, China Standard Time (UTC+8).