17CrNi6-6 Forgings (DIN 1.5918)

What is 17CrNi6-6 steel?

17CrNi6-6 is a chromium-nickel case hardening steel listed in EN 10084 under material number 1.5918. It carries about 0.17 % carbon with roughly 1.55 % chromium and 1.55 % nickel, which is where the two sixes in the name come from. The carbon is deliberately low, so the part is carburized: the surface takes on 58-62 HRC while the core stays at 900-1200 MPa.

That split is the reason the grade exists. A gear tooth needs a face that resists pitting and abrasion, but a tooth root that shatters on the first shock load is no use to anyone. Chromium raises hardenability and gives a hard, wear-resistant carburized layer. Nickel keeps the core ductile and holds impact values down at low temperature. There is no molybdenum, which makes the grade cheaper than 18CrNiMo7-6 but limits how deep it will harden in a thick section.

Parts in this grade are forged rather than cut from plate whenever they carry alternating or impact loads. Open-die forging closes internal porosity and lays the grain flow along the shape of the part. That is why a forged 17CrNi6-6 pinion shaft survives fatigue loading that the same shaft machined from stock bar will not.

Designations and spellings for 17CrNi6-6

The same steel arrives in enquiries under several spellings. 17CrNi6-6, 17CrNi66, 17 CrNi 6-6, 17CrNi6.6 and DIN 1.5918 are all the one EN 10084 case hardening steel. Older German drawings may show the former brand name RECNW, or group it with 15CrNi6 (1.5919).

17CrNi6-6 chemical composition (EN 10084)

17CrNi6-6 contains 0.14-0.20 % C, 0.50-0.90 % Mn, max 0.40 % Si, 1.40-1.70 % Cr and 1.40-1.70 % Ni, with phosphorus capped at 0.025 % and sulphur at 0.035 %. There is no specified molybdenum. Jiangyin Jiangnan Metal Co., Ltd. re-checks every heat by spectrometer against these limits before the billet goes into the furnace.

Molybdenum is a residual here, not an addition. If the drawing calls for guaranteed Mo, specify 18CrNiMo7-6 (1.6587) instead. Tighter internal limits on P, S and oxygen can be agreed at order stage for aerospace and wind gearbox work.

Mechanical properties of 17CrNi6-6

Carburized and hardened, 17CrNi6-6 gives a core tensile strength of 900-1200 MPa with a yield point around 635 MPa and roughly 11 % elongation, and a carburized surface of 58-62 HRC. In the annealed delivery condition hardness sits at or below 217 HB so the forging can be machined.

Why large forgings fall short of the data sheet

Published EN 10084 properties come off a 16 mm test sample. Most forgings are nothing like that thin. In a 300 mm shaft the core cools far more slowly during quenching, so core strength lands below the 16 mm figure. That is the mass effect, and because 17CrNi6-6 has no molybdenum the drop-off starts earlier than it does in 18CrNiMo7-6.

We supply Jominy end-quench data for each 17CrNi6-6 heat on request, so your design engineer can work out real core properties at the actual section size using DIN 50190 or SAE J406. Above roughly 100 mm section, where the core has to harden through, we normally suggest moving to 18CrNiMo7-6.

17CrNi6-6 heat treatment and forging temperatures

17CrNi6-6 is forged at 1100-850 °C, normalised at 850-880 °C in air, soft annealed at 650-700 °C in the furnace, carburized at 880-980 °C, core hardened at 830-870 °C in oil, case hardened at 780-820 °C in oil and tempered at 150-200 °C.

Direct hardening straight from carburizing temperature works but leaves coarser grain. Double hardening, core quench then case quench, is the route used where fatigue strength decides the part, such as aerospace and wind gearbox work. State the intended cycle on the purchase order so the delivery condition suits your heat treater.

17CrNi6-6 equivalent and comparable grades

The nearest international grades to 17CrNi6-6 (1.5918) are AFNOR 16NC6, SAE 3115 and, more loosely, AISI 4320 and 4320H. None of them is a drop-in substitute. Composition ranges and hardenability differ, so any substitution needs approval from the design authority first.

17CrNi6-6 or 18CrNiMo7-6

If you are not sure which grade the drawing needs, send us the part weight, section thickness and required case depth at sales@steelforgepieces.com and our metallurgist will recommend one before we quote.

17CrNi6-6 forged product forms we make

Jiangyin Jiangnan Metal Co., Ltd. open-die forges 17CrNi6-6 into six product families: solid bars, hollow bars and sleeves, seamless rolled rings, forged rings, discs and blocks, and gear or pinion shafts. Every shape is forged to a customer drawing rather than cut from stock, and supplied rough machined or finish machined as required.

Bars: round, square, flat and hexagonal

Forged 17CrNi6-6 round bars, rods, square bars, rectangular and flat bars and hex bars, supplied black, peeled, rough turned or ground. These go out as blanks for pinions, spindles, piston bolts and camshafts.

Hollow bars, sleeves, bushes and cylinders

Forged 17CrNi6-6 hollow bars, sleeves, bushings, bushes, tubes, barrels, casings, cases, shells, cylinders, hubs and housings. Forging a hollow section instead of drilling out a solid bar removes the centre segregation zone and takes a lot of machining time off a thick-walled part.

Seamless rolled rings and forged rings

17CrNi6-6 seamless rolled rings and open-die forged rings for bearing races, gear rims, slewing rings and flanged assemblies. Ring rolling puts the grain flow around the circumference, which is what a ring under hoop stress needs.

Discs, blocks and plates

Forged 17CrNi6-6 discs, disks, blocks and plates for gear blanks, end covers, die holders and tooling plates, upset forged so the through-thickness properties hold up.

Gear shafts, pinion shafts and crankshafts

17CrNi6-6 forged gear shafts, pinion shafts, spindles, bevel gear blanks, crown wheel blanks and crankshaft forgings. This is where most of the grade goes: heavily loaded drivetrain parts that have to take surface contact stress and bending fatigue at the same time.

Other forged components

Flanges, couplings, forks, levers, connecting rods and near-net-shape forgings in 17CrNi6-6, made to drawing, sample or 3D model.

Available sizes and forging capability

Jiangyin Jiangnan Metal Co., Ltd. forges 17CrNi6-6 round bars from 80 mm to 1200 mm diameter, rings from 300 mm to 4000 mm outside diameter, discs and blocks to 1500 mm and shafts up to 8000 mm long, at single piece weights from 20 kg to 20 tons.

• Surface condition: black forged, shot blasted, rough turned, proof machined or finish machined to drawing.
• Machining allowance: usually 5-15 mm per side depending on section, agreed at order stage.
• Minimum forging ratio: 3:1, recorded on the certificate.
• Minimum order: single prototype pieces are accepted. There is no minimum tonnage on 17CrNi6-6.
• Lead time: typically 20-35 days from drawing approval, subject to billet availability.

Testing, inspection and certificates

Every 17CrNi6-6 order from Jiangyin Jiangnan Metal Co., Ltd. ships with an EN 10204 3.1 mill test certificate covering chemical analysis, mechanical properties, hardness, the heat treatment record, forging ratio, grain size and ultrasonic testing to EN 10228. Third-party witnessed EN 10204 3.2 certification through SGS, BV, TUV or Lloyd's Register can be arranged on request.

Each forging is stamped with its heat number so it traces back to the certificate and to the original steel melt. We keep the records for ten years.

What 17CrNi6-6 forgings are used for

17CrNi6-6 goes into parts that need a hard, wear-resistant face over a core tough enough to take impact: driving bevel gears, crown wheels, gears, pinion shafts, camshafts, piston bolts, spindles and heavy-duty transmission shafts in automotive, truck, aerospace and general mechanical engineering.

How 17CrNi6-6 forgings are made

Jiangyin Jiangnan Metal Co., Ltd. runs 17CrNi6-6 through eight stages, from billet verification to packing. Typical time from drawing approval to shipment is 20 to 35 days.

1. Steel supply and verification. 17CrNi6-6 billet arrives with a mill certificate. We re-check the chemistry by spectrometer against EN 10084 before the billet goes into the furnace.
2. Heating. The billet is heated to 1180-1220 °C. The furnace chart is kept with the job file.
3. Open-die forging. Forging runs between 1100 °C and 850 °C on a hydraulic press, at a forging ratio of 3:1 or better.
4. Controlled cooling. Parts cool slowly in still air or in sand depending on section size. Cr-Ni grades crack if they are cooled too fast off the press.
5. Normalising or soft annealing. Normalise at 850-880 °C or soft anneal at 650-700 °C to bring hardness down to about 217 HB so the part can be machined.
6. Machining. Turned, bored or milled to the agreed allowance. Finish machining is available where the drawing calls for it.
7. Testing and certification. Chemical analysis, tensile and impact testing, hardness, grain size, ultrasonic testing to EN 10228 and a dimensional report go onto an EN 10204 3.1 or 3.2 certificate.
8. Preservation and shipment. Shot blasted, oiled, stamped with the heat number and packed in fumigation-free wooden cases.

How to order 17CrNi6-6 forgings

Send a drawing, sketch or 3D model to sales@steelforgepieces.com, or call +86-189-2135-9659. Quotations normally go back within 24 hours on working days.

Send these eight items and the quotation comes back complete instead of with questions attached:

1. Grade and standard. 17CrNi6-6, 1.5918, EN 10084, plus any customer specification.
2. Shape and dimensions. Drawing in PDF, DWG or STEP, with tolerances and machining allowance.
3. Quantity. Prototype, batch size and expected annual volume.
4. Delivery condition. As forged, normalised, annealed, rough turned or finish machined.
5. Heat treatment. Tell us if you carburize and harden in house, or want it included in our scope.
6. Case depth and surface hardness if we are doing the carburizing.
7. Testing and certificate. EN 10204 3.1 or 3.2, UT acceptance class, impact test temperature.
8. Destination port and Incoterms. FOB Shanghai, CIF or DDP.

Frequently asked questions about 17CrNi6-6

Related grades and forged products

Other case hardening and alloy steel grades we open-die forge:

• 18CrNiMo7-6
• 17CrNiMo6
• 1.6587
• AISI 4317
• AISI 4820
• 18NCD6
• 820M17
• 822M17
• 42CrMo4
• AISI 4140
• AISI 4340
• 34CrMo4
• SCM440
• Inconel 617
• Waspaloy
• 17-4PH

Figures on this page are taken from EN 10084:2008 and published steel mill data sheets and are given for guidance. They do not replace the material certificate supplied with your order. Last reviewed 9 September 2026.