1.6526 (20NiCrMoS2-2) forgings in EN 10084 case-hardening steel

Standards that cover 1.6526

1.6526 is a case-hardening steel, so the standard that governs it is EN 10084. Drawings sometimes cite EN 10083 for this grade. That reference is wrong: EN 10083 covers quenched and tempered steels, which carry more carbon and follow a different heat treatment route.

Chemical composition of 1.6526

The specified composition of 20NiCrMoS2-2 to EN 10084, in per cent by mass, together with a typical mill analysis:

The sulphur in 1.6526 is added on purpose and held within a controlled band. It forms manganese sulphide inclusions that break up the chip during machining. Balance iron.

Every heat we forge carries its own ladle analysis on the mill test certificate. If your specification restricts a residual element or narrows a range beyond EN 10084, tell us before we order the heat and we will agree the restricted analysis with the mill.

Mechanical properties of 1.6526

Two sets of numbers matter for a case-hardening steel. One is the hardness you receive the forging at, which governs how it machines. The other is the strength it develops after carburising and hardening.

Hardness in the delivery condition

Strength after hardening and tempering at 200 °C

Other reference values

• Core tensile strength in service, after case hardening: typically 700–900 N/mm².
• Surface hardness after carburising, quenching and low tempering: typically 58–62 HRC.
• Tensile strength in the spheroidised condition (+AC): about 590 N/mm².
• Reduction of area on fracture (Z): 57–62%.
• Density: approximately 7.85 g/cm³.
• Case depth (CHD) is set by the carburising cycle, and is commonly specified between 0.5 mm and 1.5 mm.

These are reference values for the grade. What a forging actually achieves depends on section size, forging reduction, where the test piece is taken and the heat treatment cycle applied. The values certified for your order are the ones measured on the delivered heat and recorded on the mill test certificate.

Forging and heat treatment route for 1.6526

Temperatures for the full route, from billet to finished carburised part:

How a 1.6526 forging is normally processed

1. Forge to shape. Open-die forging or ring rolling between 1100 °C and 850 °C, with enough reduction to close porosity and orient the grain flow along the loaded direction.
2. Normalise. 850–880 °C, air cooled, to refine the grain left coarse by finishing the forging hot and to give a uniform structure before machining.
3. Soft anneal if required. 650–700 °C with furnace cooling where the customer wants the lowest hardness for deep machining.
4. Rough machine. Carried out by the customer or by us, leaving grinding stock, because carburising distorts the part.
5. Carburise and harden. 880–980 °C carburising, then quench, then temper at 150–200 °C to relieve stress without softening the case.
6. Finish grind. Grinding after hardening restores the tolerances lost to heat-treatment distortion and takes the part to final size.

1.6526 is suitable for direct hardening from the carburising temperature. Where maximum core toughness is needed, double hardening with an intermediate anneal at 630–650 °C is used instead.

1.6526 equivalent grades worldwide

Grades used in place of 1.6526 in other standards. Equivalence is close but rarely exact, so state the governing standard on the order.

Choosing between 1.6526 and 1.6523

These two grades share the same alloy design and are often confused on drawings. The difference is sulphur, and it changes how the part behaves in service.

Choose 1.6526 when the part carries heavy machining and the loading runs mainly along the forging fibre. Gear blanks with deep tooth cutting, splined shafts and multi-feature housings all fall into this group. The manganese sulphide inclusions raise tool life and improve surface finish.

Choose 1.6523 when transverse impact toughness governs, or when a specification restricts sulphur for weldability or for cleanness. Sulphide inclusions elongate during forging and lower the notch toughness measured across the grain flow, which matters most in short, heavily loaded sections.

We forge both grades. If the drawing is ambiguous, send it over and we will tell you which grade the stated properties match.

1.6526 forged shapes we produce

Everything here is made to your drawing, sample or dimension list. We hold no fixed catalogue, so shape, machining allowance and delivery condition all come from your order.

• Forged barsRound, square, flat and rectangular, forged and turned or black
• Seamless rolled ringsPlain and contoured, radial–axial rolled
• Gear blanks and gear shaftsSpur, helical and bevel gear blanks, pinion shafts
• Shafts and spindlesStepped, flanged and eccentric shafts
• Sleeves and bushingsHollow forgings and bored hollow bar
• Discs and blocksSolid discs, hubs, plates and rectangular blocks
• Housings and shellsCup and shell forgings for gearboxes
• Tube blanksForged and bored blanks for further machining

Delivery conditions available: as forged, normalised (+N), soft annealed (+A), treated to hardness range (+TH) or treated to a ferrite-pearlite structure (+FP). Carburising normally happens after rough machining, because the case has to go onto the near-final geometry.

Where 1.6526 forgings are used

1.6526 is a carburising steel. It suits parts that have to resist surface wear and contact fatigue while absorbing shock in the core. It is not a pressure-containing grade, so it does not go into pressure-vessel shells or valve bodies. Those call for quenched and tempered or dedicated pressure-vessel steels.

• Gearboxes and power transmission. Gear blanks, ring gears, pinion shafts, bevel and crown wheels, splined shafts and couplings, where tooth flanks need a hard case and the shaft needs a tough core.
• Automotive and off-highway drivetrains. Differential pinions, transmission shafts, king pins, camshafts and sprockets.
• Mining, crushing and cement plant. Pinion shafts for mills and kilns, eccentric shafts for crushers, pulley and roller shafts subject to abrasive wear.
• Bearings and rolling contact parts. Bearing races, slewing-ring blanks, rollers and cam followers, where contact fatigue resistance is the design driver.
• Sleeves, bushings and guide components. Wear sleeves, guide pins, piston pins and bushes running against a mating surface.
• General machinery. Press and conveyor shafts, ratchets, arbors and tool holders needing wear resistance with dimensional stability.

If the duty involves pressure retention, elevated temperature or corrosive service, a case-hardening steel is the wrong family. Tell us what the part has to do and we will point you to a suitable grade from the carbon, alloy, tool and stainless steels and nickel alloys we forge.

Testing and certification of 1.6526 forgings

Every 1.6526 forging leaves our factory with a mill test certificate to EN 10204 3.1, or to 3.2 countersigned by a third-party inspection body when the order requires it.

Testing carried out

• Chemical analysis. Ladle analysis, with product analysis on request.
• Mechanical testing. Tensile, hardness and Charpy V-notch impact, on test pieces taken in the location and orientation your specification requires.
• Ultrasonic testing. To EN 10228-3, SEP 1921 or ASTM A388, at the acceptance class stated on the order.
• Magnetic particle or dye penetrant inspection. For surface indications, where specified.
• Dimensional inspection. Against the drawing, with a recorded measurement report.
• Grain size and microstructure. On request. This matters for carburising grades, because grain coarsening during carburising drives distortion.

What the certificate records

• Heat number, melting route and the traceability marking stamped on the part.
• Ladle analysis against the EN 10084 limits.
• Heat treatment cycle actually applied, with temperatures and holding times.
• Mechanical test results and hardness readings.
• Non-destructive test results and acceptance class.
• Dimensional inspection results and any concessions agreed.

Third-party inspection by SGS, BV, TÜV, Lloyd's Register or a customer-nominated body can be arranged at our works before shipment.

Request a quotation for 1.6526 forgings

Send us the following and we can price the job accurately. A drawing on its own is usually enough to start.

1. Drawing, sketch or finished dimensions, and whether the price should include machining allowance.
2. Grade as you specify it (1.6526, 20NiCrMoS2-2, 21NiCrMoS2, 8620 or 805M20) and the governing standard.
3. Quantity and whether this is a prototype, a repeat order or an annual requirement.
4. Delivery condition: as forged, +N, +A, +TH or +FP.
5. Testing scope and certificate level: EN 10204 3.1 or 3.2.
6. Destination port and required delivery date.

Email sales@steelforgepieces.com or call +86 189 2135 9659. Drawings are treated as confidential and are not shared outside our engineering and production team.

Frequently asked questions about 1.6526

Related grades we forge

Same case-hardening family

• 1.6523
• 20NiCrMo2-2
• 21NiCrMo2
• AISI 8620
• AISI 8620H
• 805M20
• 20NCD2
• SNCM220
• SNCM 21

Higher-hardenability carburising grades

• 18CrNiMo7-6
• 1.6587
• 17CrNiMo6
• 17NiCrMo6-4
• 1.6566
• 20NiCrMoS6-4
• 1.6571
• AISI 4320
• AISI 4820

Quenched and tempered alternatives

• 42CrMo4
• AISI 4140
• 34CrNiMo6
• AISI 4340
• 30CrNiMo8
• 1.6582

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About Jiangyin Jiangnan Metal Co., Ltd.

Jiangyin Jiangnan Metal Co., Ltd. is an open-die forging factory in Zhouzhuang Town, Jiangyin City, Jiangsu Province, China, in the Yangtze River delta industrial belt and within reach of Shanghai port. We forge components to customer drawings in carbon steel, alloy steel, tool steel, stainless steel and nickel alloys, and we run our own heat treatment and inspection.

Most of our 1.6526 work is transmission components: gear blanks, pinion shafts, rolled rings and wear sleeves. Parts are delivered in whichever heat treatment condition suits your machining route, and certified to EN 10204.