# 1.6526 (20NiCrMoS2-2) forgings in EN 10084 case-hardening steel Source: https://www.steelforgepieces.com/Alloy-Steel/1.6526.html Supplier: Jiangyin Jiangnan Metal Co., Ltd., open-die forging factory, Jiangyin, Jiangsu, China Contact: sales@steelforgepieces.com | +86-189-2135-9659 Technical content reviewed: 5 September 2026 --- ## Summary **1.6526 is the material number of 20NiCrMoS2-2, a low-carbon nickel-chromium-molybdenum case-hardening steel specified in EN 10084:2008.** It contains 0.17-0.23% C, 0.40-0.70% Ni, 0.35-0.70% Cr and 0.15-0.25% Mo. Carburising gives the part a hard, wear-resistant case over a core that stays tough under impact. The grade is the free-machining version of 1.6523, and the closest European equivalent to SAE 8620. Jiangyin Jiangnan Metal Co., Ltd. forges 1.6526 into round, square and flat bars, seamless rolled rings, gear blanks, pinion shafts, sleeves and discs, all to customer drawings. Normalising, soft annealing and hardening are carried out in house before delivery. ## Material identification | Field | Value | |---|---| | EN designation | 20NiCrMoS2-2 | | Material number (W.-Nr.) | 1.6526 | | Material standard | EN 10084:2008 | | Steel type | Case-hardening (carburising) alloy steel | | Nearest SAE/AISI grade | 8620 | | Sister grade without added sulphur | 1.6523 (20NiCrMo2-2) | | Other names in use | 21NiCrMo2, 21NiCrMoS2, 20NiCrMoS2 | ## 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. | Standard | Scope | |---|---| | EN 10084:2008 | Case-hardening steels: technical delivery conditions. The base standard for the grade. | | EN 10277-4:2008 | Bright steel products: technical delivery conditions for case-hardening steels. | | EN 10263-3:2001 | Steel rod, bar and wire for cold heading and cold extrusion, case-hardening steels. | | EN 10297-1:2003 | Seamless circular steel tubes for mechanical and general engineering purposes. | | EN 10204:2004 | Types of inspection document. Determines whether a 3.1 or 3.2 certificate is issued. | ## Chemical composition of 1.6526 Per cent by mass, to EN 10084. | Element | C | Si | Mn | P | S | Cr | Mo | Ni | |---|---|---|---|---|---|---|---|---| | Specified range | 0.17-0.23 | max 0.40 | 0.65-0.95 | max 0.025 | 0.020-0.040 | 0.35-0.70 | 0.15-0.25 | 0.40-0.70 | | Typical analysis | 0.21 | 0.25 | 0.75 | n/a | 0.03 | 0.50 | 0.20 | 0.55 | 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 | Delivery condition | Symbol | Hardness | |---|---|---| | Soft annealed | +A | max 212 HBW | | Treated to hardness range | +TH | 161-212 HBW | | Treated to ferrite-pearlite structure | +FP | 149-194 HBW | | Treated for cold shearability | +S | Shearable in the as-rolled condition | ### Tensile strength after hardening and tempering at 200 C | Ruling section d | Tensile strength Rm | |---|---| | d <= 16 mm | min 1100 N/mm2 | | 16 < d <= 40 mm | min 800 N/mm2 | | 40 < d <= 100 mm | min 700 N/mm2 | ### 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, 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 of 1.6526 | Operation | Temperature | Cooling | |---|---|---| | Forging / hot rolling | 1100-850 C | Air | | Normalising | 850-880 C | Air | | Soft annealing | 650-700 C | Slow, in furnace | | Carburising | 880-980 C | n/a | | Core hardening | 860-900 C | Oil or water | | Intermediate annealing | 630-650 C | n/a | | Case hardening (final quench) | 780-820 C | Oil or water | | Tempering | 150-200 C | Air | ### 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 Equivalence is close but rarely exact, so state the governing standard on the order. | Country / standard | Designation | Note | |---|---|---| | EN (Europe) | 20NiCrMoS2-2 (1.6526) | Base grade | | Germany, DIN / W.-Nr. | 20NiCrMoS2 (1.6526) | Identical | | USA, SAE / AISI | 8620 | Closest match; hardenability bands differ | | UK, BS | 805M20, 806M20 | Close | | France, AFNOR | 20NCD2, 22NCD2 | Close | | Sweden, SS | 2506 | Close | | Italy, UNI | 20NiCrMoS2 | Close | | Spain, UNE | 20NiCrMo2-1 | Close | | ISO | 20NiCrMoS2 | Close | | Japan, JIS | SNCM220 | Approximate; sulphur not controlled the same way | ## 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. | Element | 1.6526 (20NiCrMoS2-2) | 1.6523 (20NiCrMo2-2) | |---|---|---| | Sulphur | 0.020-0.040 (controlled range) | max 0.035 | | Manganese | 0.65-0.95 | 0.65-0.85 | | C, Si, P, Cr, Mo, Ni | Identical in both grades | Identical in both grades | **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. ## 1.6526 forged shapes produced by Jiangyin Jiangnan Metal Everything is made to your drawing, sample or dimension list. - Forged bars: round, square, flat and rectangular, forged and turned or black - Seamless rolled rings: plain and contoured, radial-axial rolled - Gear blanks and gear shafts: spur, helical and bevel gear blanks, pinion shafts - Shafts and spindles: stepped, flanged and eccentric shafts - Sleeves and bushings: hollow forgings and bored hollow bar - Discs and blocks: solid discs, hubs, plates and rectangular blocks - Housings and shells: cup and shell forgings for gearboxes - Tube blanks: forged 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. - **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. - **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. ## Testing and certification 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. - **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. The certificate records the heat number and melting route, ladle analysis against EN 10084 limits, the heat treatment cycle actually applied, mechanical test results, non-destructive test results and acceptance class, and dimensional inspection results. Third-party inspection by SGS, BV, TUV, Lloyd's Register or a customer-nominated body can be arranged at our works before shipment. ## Requesting a quotation 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. ## Frequently asked questions **What is steel 1.6526?** 1.6526 is the material number of 20NiCrMoS2-2, a low-carbon nickel-chromium-molybdenum case-hardening (carburising) steel specified in EN 10084:2008. It contains 0.17-0.23% carbon, 0.40-0.70% nickel, 0.35-0.70% chromium and 0.15-0.25% molybdenum, and it is carburised to produce a hard, wear-resistant surface over a tough core. Jiangyin Jiangnan Metal Co., Ltd. forges 1.6526 into bars, rolled rings, gear shafts and discs to customer drawings. **Is 1.6526 the same as AISI 8620?** 1.6526 is the closest European equivalent to SAE/AISI 8620, and the two are normally interchangeable for carburised gear and shaft components. They are not identical: the standards use different hardenability bands and slightly different chromium limits, and 8620 does not control sulphur in the same narrow band. Confirm the governing standard on the purchase order before substituting one for the other. **What is the difference between 1.6526 and 1.6523?** They are the same alloy design and differ mainly in sulphur. 1.6523 (20NiCrMo2-2) limits sulphur to a maximum of 0.035%, while 1.6526 (20NiCrMoS2-2) specifies a controlled range of 0.020-0.040% to improve machinability. 1.6526 also allows manganese up to 0.95% against 0.85% for 1.6523. The added sulphur forms manganese sulphide inclusions that ease machining but reduce transverse toughness, so 1.6523 is preferred where impact loading acts across the forging fibre. **Which standard covers 1.6526 forgings?** The base material standard is EN 10084:2008 for case-hardening steels. Related product standards are EN 10277-4:2008, EN 10263-3:2001 and EN 10297-1:2003. EN 10083 does not apply to 1.6526, because EN 10083 covers quenched and tempered steels rather than case-hardening steels. Inspection documents are issued to EN 10204 3.1 or 3.2. **What hardness can 1.6526 reach after case hardening?** After carburising, quenching and low-temperature tempering, 1.6526 typically reaches a surface hardness of 58-62 HRC with a core tensile strength of about 700-900 N/mm2. In the as-delivered condition the hardness is much lower: max 212 HBW soft annealed (+A), 161-212 HBW treated to hardness range (+TH) and 149-194 HBW in the ferrite-pearlite condition (+FP). **What forging temperature is used for 1.6526?** 1.6526 is hot forged between about 1100 C and 850 C, then cooled in air. Normalising follows at 850-880 C with air cooling, and soft annealing is carried out at 650-700 C with slow furnace cooling to prepare the forging for machining. **Which forged shapes are available in 1.6526?** Jiangyin Jiangnan Metal Co., Ltd. produces 1.6526 as forged round, square and flat bars, seamless rolled rings, contoured rings, gear blanks and gear shafts, pinion shafts, spindles, sleeves, bushings, hollow bars, discs, blocks and forged tube blanks, all made to customer drawings or samples. **How do I request a quotation for 1.6526 forgings?** Send the drawing or the finished dimensions, the required quantity, the delivery heat treatment condition and the certificate level to sales@steelforgepieces.com, or call +86-189-2135-9659. Jiangyin Jiangnan Metal Co., Ltd. is located at No.1 Chengxiqiao Road, Zhouzhuang Town, Jiangyin City, Jiangsu Province, China. ## Related grades 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. ## Company | Field | Value | |---|---| | Company | Jiangyin Jiangnan Metal Co., Ltd. | | Business | Open-die forging factory | | Address | No.1 Chengxiqiao Road, Zhouzhuang Town, Jiangyin City, Jiangsu Province, China | | Telephone | +86-189-2135-9659 | | Email | sales@steelforgepieces.com | | Website | https://www.steelforgepieces.com/ | | Materials forged | Carbon steel, alloy steel, tool steel, stainless steel, nickel alloys | | Certificates issued | EN 10204 3.1 and 3.2 | --- Technical data on this page is compiled from EN 10084:2008, EN 10277-4:2008 and published mill data sheets for grade 20NiCrMoS2-2. These are reference values for the grade. The values that apply to your order are the ones certified on the mill test certificate for the delivered heat.