1.6511 36CrNiMo4, nickel-chromium-molybdenum quenched and tempered alloy steel
1.6511 in brief
1.6511 is the EN material number for 36CrNiMo4, a nickel-chromium-molybdenum steel supplied in the quenched and tempered condition. It is listed in EN 10250-3 for open die forgings and in EN 10083-3 for quenched and tempered steels. Composition runs 0.32 to 0.40 % carbon with roughly 1 % nickel, 1 % chromium and 0.2 % molybdenum.
The nickel gives 1.6511 deeper hardening and higher impact values than 42CrMo4 at the same strength level. That is why it is specified for heavily loaded shafts, gears, pinions, spindles and crankshafts in large sections. The nearest American grade is AISI/SAE 9840.
Jiangyin Jiangnan Metal Co., Ltd. forges 1.6511 into bars, seamless rolled rings, shafts, discs, blocks and hollow forgings from 50 kg to 20 tonnes per piece, delivered with EN 10204 3.1 or 3.2 certificates. Send drawings to sales@steelforgepieces.com or call +86 189 2135 9659.
1.6511 at a glance
- EN material number
- 1.6511
- EN grade name
- 36CrNiMo4
- Steel class
- Alloy special steel, Ni-Cr-Mo, quench and temper
- Forging standard
- EN 10250-3:2000
- Bar and semi-finished standard
- EN 10083-3
- Tube standard
- EN 10297-1:2003
- Nearest US grade
- AISI/SAE 9840
- Delivery conditions
- +A soft annealed, or +QT
- Annealed hardness
- max 241 HBW (+A)
- Density
- 7.85 g/cm³
- Weldability
- Difficult, preheat and PWHT required
- Surface hardening
- Nitriding, flame or induction after +QT
What 1.6511 steel is
1.6511 (36CrNiMo4) is a medium carbon low alloy engineering steel. It is hardened by quenching and then tempered back to whatever strength the drawing calls for. Three elements do the work. Chromium and molybdenum raise hardenability and hold hardness through tempering. Nickel improves toughness and keeps impact values up as temperature falls.
What this buys you is section size. Quench a 400 mm diameter shaft in 42CrMo4 and the core will not transform fully, so centre properties fall well below the surface values. The nickel in 1.6511 slows transformation enough that the same section still hardens through to a usable core structure. That is why the grade turns up on large forgings rather than on small machined parts.
Molybdenum matters for a second reason. Components in this grade are often tempered between 550 and 650 °C, and nickel-chromium steels without molybdenum are prone to temper embrittlement in exactly that range.
Chemical composition of 1.6511 (36CrNiMo4)
| Element | Symbol | Min % | Max % | Function in this steel |
|---|---|---|---|---|
| Carbon | C | 0.32 | 0.40 | Sets attainable hardness and strength after quenching |
| Silicon | Si | — | 0.40 | Deoxidiser, small strengthening effect |
| Manganese | Mn | 0.50 | 0.80 | Hardenability, binds residual sulfur |
| Nickel | Ni | 0.90 | 1.20 | Core toughness and low-temperature impact strength |
| Chromium | Cr | 0.90 | 1.20 | Hardenability and tempering resistance |
| Molybdenum | Mo | 0.15 | 0.30 | Deep hardening, suppresses temper embrittlement |
| Phosphorus | P | — | 0.035 | Residual, kept low for toughness |
| Sulfur | S | — | 0.035 | Residual, lower values available on request |
We can supply 1.6511 to tightened residual limits, for example P and S each at 0.015 % maximum, where the drawing or the end application calls for better transverse toughness. Ask for it at enquiry stage so it goes into the steel-making order.
Mechanical properties of 1.6511 after quenching and tempering
Properties in this grade depend on ruling section. The two tables below separate the cases that come up in practice: heavy open die forgings, and smaller quenched and tempered sections.
Heavy open die forgings, +QT
| Property | Up to 160 mm | 160 to 330 mm | 330 to 660 mm |
|---|---|---|---|
| Tensile strength Rm, MPa | 750 | 700 | 650 |
| Upper yield strength Re, MPa | 550 | 500 | 450 |
| Elongation A, longitudinal, % | 14 | 15 | 16 |
| Elongation A, transverse, % | 10 to 12 | ||
| Impact energy KV at +20 °C, longitudinal, J | 35 to 45 | ||
| Impact energy KV at +20 °C, transverse, J | 25 to 27 | ||
Smaller quenched and tempered sections
| Property | Up to 8 mm | 8 to 20 mm | 20 to 50 mm | 50 to 80 mm |
|---|---|---|---|---|
| Tensile strength Rm, MPa | 1100 | 1000 | 900 | 800 |
| Minimum yield strength ReH, MPa | 900 | 800 | 700 | 600 |
| Elongation A, longitudinal, % | 10 | 11 | 12 | 13 |
Note on the thickness bands. Current editions of EN 10083-3 use different band boundaries from those shown above and express Rm as a range rather than a single minimum. Check the requirement against the edition of the standard named on your drawing and agree the final acceptance values in the purchase order.
Hardness in the soft annealed condition is 241 HBW maximum. After quenching and tempering, delivered hardness for general engineering work usually sits between 260 and 320 HBW, set by the tempering temperature to hit the strength band you need.
Physical properties
| Property | Value |
|---|---|
| Density | 7.85 g/cm³ |
| Modulus of elasticity | approx. 210 GPa |
| Thermal conductivity | approx. 42 W/(m·K) |
| Coefficient of thermal expansion, 20 to 200 °C | approx. 11.5 × 10⁻⁶ /K |
| Specific heat capacity | approx. 460 J/(kg·K) |
| Magnetic | Yes, ferromagnetic |
Heat treatment and forging parameters
| Operation | Temperature | Cooling and notes |
|---|---|---|
| Forging | 1100 to 1200 °C start | Finish above about 850 °C, then slow cool in furnace or insulated pit |
| Normalising | 850 to 880 °C | Air cool, refines the as-forged structure before hardening |
| Soft annealing | 650 to 700 °C | Furnace cool, gives max 241 HBW for machining |
| Hardening | 830 to 870 °C | Quench in oil or polymer. Water quenching is not recommended on heavy sections |
| Tempering | 540 to 680 °C | Higher temperature gives lower strength and higher toughness. Hold, then air cool |
| Stress relieving | 600 to 650 °C | After rough machining, below the final tempering temperature |
| Nitriding | 500 to 530 °C | Optional, after +QT. Gives a hard wear-resistant case without distorting the core |
Welding 1.6511
1.6511 is classed as difficult to weld. Carbon at up to 0.40 % plus around 3 % total alloy content gives a high carbon equivalent and a hardenable heat-affected zone. Where welding cannot be avoided, weld in the soft annealed condition, preheat to roughly 200 to 300 °C, hold the interpass temperature, use low-hydrogen consumables and apply a post-weld heat treatment below the final tempering temperature. Welding on a finished quenched and tempered forging will locally soften and re-harden the heat-affected zone, so it needs to be agreed in writing before production.
1.6511 international equivalents
| Standard or country | Designation | Note |
|---|---|---|
| EN, Europe | 36CrNiMo4, W.Nr. 1.6511 | The reference grade on this page |
| ISO | 36CrNiMo4 | Same designation |
| AISI / SAE, USA | 9840 | Nearest American match on Ni, Cr and Mo |
| AISI / SAE, USA | 4340 | Widely quoted but loose. AISI 4340 carries about 1.65 to 2.00 % Ni |
| JIS, Japan | SNCM439 | Comparable service grade, higher nickel |
| BS, United Kingdom | 817M37, 817A37 | Also cross-referenced to 816M40 in some tables |
| AFNOR, France | 40NCD3 | Also listed as 35NCD4 |
| UNI, Italy | 38NiCrMo4 (KB) | Also 35NiCrMo4 |
| PN, Poland | 36HNM | — |
| CSN, Czechia | 16341 | — |
| GOST, Russia | 40KhN2MA | — |
| GB, China | 40CrNiMoA | Nearest Chinese national grade |
If your drawing calls out one designation and your supply chain offers another, send us both. We will compare the composition and property limits line by line and confirm in writing whether the substitution works for your section size before you commit to an order.
1.6511 compared with 42CrMo4 and 34CrNiMo6
These three grades cover most heavy engineering forgings and buyers regularly ask which one to specify. The difference between them is nickel, and what nickel buys is hardenability and toughness in thick sections.
| Criterion | 42CrMo4 (1.7225) | 1.6511 (36CrNiMo4) | 34CrNiMo6 (1.6582) |
|---|---|---|---|
| Carbon, % | 0.38 to 0.45 | 0.32 to 0.40 | 0.30 to 0.38 |
| Nickel, % | — | 0.90 to 1.20 | 1.30 to 1.70 |
| Chromium, % | 0.90 to 1.20 | 0.90 to 1.20 | 1.30 to 1.70 |
| Molybdenum, % | 0.15 to 0.30 | 0.15 to 0.30 | 0.15 to 0.30 |
| Hardenability | Good | Better | Best of the three |
| Core toughness in heavy sections | Moderate | Good | Very good |
| Relative material cost | Lowest | Medium | Highest |
| Typical section limit | Up to about 250 mm | Up to about 400 mm | Above 400 mm |
| US cross-reference | AISI 4140 | AISI 9840 | AISI 4340 |
As a working rule, specify 42CrMo4 when the section is moderate and cost matters. Move to 1.6511 once the ruling section passes roughly 250 mm or impact requirements tighten. Move to 34CrNiMo6 for the largest and most critical shafts. Section limits shift with the quench medium and the required core properties, so treat these figures as a starting point and confirm with a hardenability assessment.
1.6511 forged product forms
We produce the following shapes in 1.6511 (36CrNiMo4), rough machined or finish machined to drawing:
Forged bars
Round, square, rectangular, flat and hexagonal bar in 1.6511, cut to length, saw cut or flame cut.
Seamless rolled rings
Radial-axial ring rolled 1.6511 rings for bearings, gear rims, flanges and slew rings.
Shafts and spindles
Stepped shafts, gear shafts, pinion shafts, spindles and crankshaft blanks in 1.6511.
Discs, blocks and plates
Forged discs, gear blanks, rectangular blocks and forged plate in 1.6511.
Hollow forgings
Bored and trepanned 1.6511 sleeves, bushes, cylinders, casings, housings, hubs and shells.
Forged flanges
Custom 1.6511 flanges and forged blanks made to customer drawing rather than catalogue dimensions.
Size range and forging capability
| Parameter | Range |
|---|---|
| Single-piece forged weight | 50 kg to 20,000 kg |
| Round bar diameter | 80 to 1,200 mm |
| Maximum forged length | up to 12,000 mm |
| Seamless rolled ring outside diameter | 200 to 3,000 mm |
| Ring wall thickness | 30 to 400 mm |
| Forged disc and block thickness | 50 to 800 mm |
| Delivery condition | As forged, +N, +A, +QT, rough machined or finish machined |
| Steel-making route | EAF + LF + VD, ESR available where specified |
| Typical lead time | 25 to 45 days depending on size and heat treatment |
| Minimum order | Single prototype pieces accepted |
Testing, inspection and certification
Every 1.6511 order leaves the works with documentation traceable to the heat number stamped on the forging. Standard scope covers:
- Chemical analysis. Ladle analysis and, on request, product analysis by spectrometer.
- Mechanical testing. Tensile, yield, elongation, reduction of area and Charpy V-notch impact on test pieces cut from prolongations in the delivered heat-treatment condition.
- Hardness survey. Brinell readings at agreed positions on the forging.
- Ultrasonic examination. Normally to EN 10228-3, or to ASTM A388 or SEP 1921 where the customer specifies.
- Magnetic particle inspection. To EN 10228-1 on machined surfaces when required.
- Grain size and microstructure. Reported when the specification calls for it.
- Dimensional report. Against the customer drawing, with machining allowance recorded.
- Inspection certificate. EN 10204 type 3.1 as standard. Type 3.2 with third-party witness on request.
Third-party or customer witness inspection at our works in Zhouzhuang Town, Jiangyin is welcome. Tell us at order stage which hold points you want so they go into the manufacturing plan rather than getting added late.
Typical applications
1.6511 gets specified where a component is large, dynamically loaded and expensive to replace. Common uses include:
- Power transmission. Gear blanks, gear rims, pinion shafts, worm shafts and heavy-duty couplings.
- Wind and hydro energy. Gearbox shafts, planetary carriers, main shaft components and rotor parts.
- Mining and quarrying. Crusher eccentric shafts, mill pinions and conveyor drive shafts.
- Oil, gas and drilling. Drill collars, pump shafts, valve bodies and pressure-containing forged blocks.
- Heavy vehicles and construction machinery. Crankshafts, axle shafts, king pins, track and roller components.
- Steel plant and rolling mills. Mill rolls, roll necks, spindles, gear couplings and press components.
- Marine. Propeller shafts, intermediate shafts and rudder stocks where classification society approval is agreed in advance.
How to get a quotation
- Send the drawing or the dimensions. A PDF, STEP or DWG file is ideal. With no drawing, give outside diameter, inside diameter, length or thickness, and the machining allowance you expect.
- State the grade and standard. Tell us whether the callout is 1.6511, 36CrNiMo4, 9840, 40CrNiMoA or another equivalent, and which standard edition governs acceptance.
- Confirm the delivery condition and testing. Soft annealed or quenched and tempered, target hardness or strength band, ultrasonic class, and certificate type.
- Give quantity and destination port. Quantity changes the tooling and heat-treatment batching, and the port lets us quote FOB, CFR or CIF rather than ex-works only.
- Receive the quotation. We reply within one working day with price, weight, lead time and the proposed manufacturing route.
Send everything to sales@steelforgepieces.com or message +86 189 2135 9659 on WhatsApp or WeChat.
Frequently asked questions about 1.6511 steel
Is 1.6511 the same as 36CrNiMo4?
Yes. 1.6511 is the EN material number and 36CrNiMo4 is the EN name for the same nickel-chromium-molybdenum quenched and tempered alloy steel. Both designations refer to one steel and can be used interchangeably on drawings and purchase orders.
What is the American equivalent of 1.6511 steel?
AISI/SAE 9840 is the nearest American grade to 1.6511 (36CrNiMo4). The grade is also often cross-referenced to AISI 4340, but that comparison is loose. AISI 4340 carries roughly 1.65 to 2.00 % nickel against 0.90 to 1.20 % in 1.6511, so the closer EN match for 4340 is 34CrNiMo6 (1.6582). Treat all cross-references as nearest equivalents rather than identical materials.
What is the chemical composition of 1.6511 steel?
To EN 10250-3, 1.6511 (36CrNiMo4) contains 0.32 to 0.40 % carbon, maximum 0.40 % silicon, 0.50 to 0.80 % manganese, 0.90 to 1.20 % nickel, 0.90 to 1.20 % chromium, 0.15 to 0.30 % molybdenum, maximum 0.035 % phosphorus and maximum 0.035 % sulfur, balance iron.
What strength can 1.6511 reach after quenching and tempering?
In open die forgings to EN 10250-3 in the +QT condition, 1.6511 meets a minimum tensile strength of 750 MPa and a minimum upper yield strength of 550 MPa up to 160 mm thickness. Those figures fall to 650 MPa and 450 MPa in the 330 to 660 mm band. In small sections the grade can be tempered to 1100 MPa tensile. Strength always drops as the ruling section rises, so state the section thickness at enquiry.
Can 1.6511 be welded?
1.6511 is difficult to weld because of its carbon and alloy content. Weld in the soft annealed condition where possible, preheat to roughly 200 to 300 °C, use low-hydrogen consumables and apply a post-weld heat treatment. Welding on a quenched and tempered forging will soften the heat-affected zone and should be agreed with the buyer before production starts.
What sizes of 1.6511 forgings can Jiangyin Jiangnan Metal supply?
Jiangyin Jiangnan Metal Co., Ltd. produces 1.6511 (36CrNiMo4) open die forgings from 50 kg to 20,000 kg single-piece weight, in round bar diameters of 80 to 1,200 mm, lengths up to 12,000 mm, and seamless rolled rings up to 3,000 mm outside diameter. Contact sales@steelforgepieces.com or +86 189 2135 9659 to confirm the current maximum for a given drawing.
Which standards cover 1.6511 forgings?
EN 10250-3 covers open steel die forgings in alloy special steels including 36CrNiMo4 (1.6511). EN 10083-3 covers quenched and tempered alloy steels in bar and semi-finished form. EN 10297-1 covers seamless tubes in the grade. Inspection documents are issued to EN 10204 type 3.1 or 3.2, and ultrasonic examination is normally carried out to EN 10228-3.
In which condition is 1.6511 normally delivered?
1.6511 forgings are normally delivered either soft annealed (+A) at a maximum of 241 HBW for further machining, or quenched and tempered (+QT) to an agreed strength or hardness band. Rough machined, stress relieved and ultrasonically tested conditions are also available on request.
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. The works produces forged bars, seamless rolled rings, shafts, discs, blocks, hollow forgings and forged flanges in carbon steel, alloy steel, tool steel, stainless steel and nickel alloys, and supplies 1.6511 (36CrNiMo4) forgings to machinery, energy, mining, oil and gas and steel plant customers internationally.
Enquiries in English or Chinese: sales@steelforgepieces.com, telephone and WhatsApp +86 189 2135 9659.