40NiMoCr10-4 forgings (W.-Nr. 1.6745, 40NiMoCr10-5, BS 970 826M40 / EN26)
Open-die forged and ring-rolled 40NiMoCr10-4 made to your drawing: melted EAF + LF + VD, quenched and tempered to BS 970 conditions U to Z, ultrasonically tested and certified to EN 10204 3.1 or 3.2.
- 400.40 % carbonCarbon content × 100
- NiMoCrAlloying elementsNickel, molybdenum, chromium
- 10-42.5 % Ni, 0.4 % MoNickel 10 ÷ 4, molybdenum 4 ÷ 10
Summary
40NiMoCr10-4 (W.-Nr. 1.6745, also written 40NiMoCr10-5) is a through-hardening alloy steel with about 0.40 % carbon, 2.5 % nickel, 0.7 % chromium and 0.5 % molybdenum. It is the European designation for the steel that BS 970 calls 826M40 and UK engineers still call EN26. Its high hardenability lets heavy forgings be quenched and tempered to 1,000–1,150 MPa (BS 970 condition V) in ruling sections up to 250 mm, and to 1,550 MPa or more (condition Z) in sections up to 100 mm. Impact energy drops as strength rises: 42 J minimum in conditions U and V, 9 J in condition Z.
Jiangyin Jiangnan Metal Co., Ltd., an open-die forging factory at No.1 Chengxiqiao Road, Zhouzhuang Town, Jiangyin City, Jiangsu Province, China, forges 40NiMoCr10-4 to customer drawings as seamless rolled rings, shafts, discs, flanges, sleeves and bars. Material is melted EAF + LF + VD, supplied annealed, normalized and tempered, or quenched and tempered, ultrasonically tested to EN 10228-3, SEP 1921 or ASTM A388, and certified to EN 10204 3.1 or 3.2. Written quotations are issued within 24 hours from sales@steelforgepieces.com or 0086-189-2135-9659.
40NiMoCr10-4 key data
- Designations
- 40NiMoCr10-4, 40NiMoCr10-5, 1.6745
- Nearest standard grade
- BS 970 826M40 (EN26)
- Steel type
- 2.5 % Ni-Cr-Mo, quench and temper
- Carbon / nickel
- 0.37–0.43 % C, 2.40–2.70 % Ni
- Q+T tensile range
- 925 to ≥ 1,550 MPa (U–Z)
- Deepest guaranteed section
- 250 mm LRS (U, V, W)
- Hardening
- 820–850 °C, oil or polymer
- Tempering
- 450–660 °C (U to Y)
- Forging range
- 1,150–1,200 °C, finish ≥ 850 °C
- Annealed hardness
- ≤ 277 HB
- Density
- 7.85 g/cm³
- Melting route
- EAF + LF + VD
- Ultrasonic testing
- EN 10228-3, SEP 1921, ASTM A388
- Certificate
- EN 10204 3.1 or 3.2
What 40NiMoCr10-4 forgings can you order?
Every part is forged to the customer's drawing with machining allowance. We choose the route by shape: open-die forging on hammers and hydraulic presses for shafts, blocks, discs and stepped parts; seamless ring rolling for rings, flanges and gear blanks; upsetting and piercing for sleeves, bushings and hollow bars.
- Seamless rolled ringsGear rings, bearing and slewing rings, flange blanks
- Forged shafts and stepped shaftsPump, compressor, gearbox and mill shafts
- Eccentric shafts and crankshaftsPlunger pumps, mills, presses
- Discs and gear blanksPinions, gear wheels, compressor and turbine discs
- Flanges and hubsHigh-strength bolted joints and couplings
- Sleeves, bushings, hollow barsRams, liners, spacer sleeves
- Bars and blocksRound, square and flat, for tooling and die holders
- Valve partsStems, seat rings, blocks and bodies
- Spindles, rolls and wheelsHeavy machinery and mill equipment
- Custom open-die forgingsTo customer drawing
See also our general pages on forged rings, forged discs, forged eccentric shafts and open-die forging parts.
What is 40NiMoCr10-4 steel?
40NiMoCr10-4 is a medium-carbon, low-alloy steel made to be hardened and tempered. The 2.5 % nickel content gives good toughness and good impact values at low temperature. Together with molybdenum and chromium it also allows hardening through thicker sections than 1.3–2 % nickel grades such as AISI 4340 or 817M40 (EN24).
The name follows EN 10027-1: 40 is the carbon content × 100, Ni, Mo and Cr are the alloying elements, 10 is nickel × 4 and 4 is molybdenum × 10. The material number 1.6745 comes from EN 10027-2, whose 67 group covers chromium-nickel-molybdenum steels with higher molybdenum or nickel.
Mills and stockholders generally treat 40NiMoCr10-4, 1.6745 and 826M40 (EN26) as the same material. The ranges are close but not identical, so check the chemistry comparison before accepting a certificate issued under a different name.
Which grades are equivalent to 40NiMoCr10-4?
The first four designations describe the same steel. The other grades are similar Ni-Cr-Mo steels that are sometimes offered as alternatives.
| Designation | System | Relationship | Difference |
|---|---|---|---|
| 40NiMoCr10-4 | EN 10027-1 steel name | This grade | Also written 40NiMoCr10-5 |
| 1.6745 | EN 10027-2 material number (W.-Nr.) | Same steel | Quote it on drawings next to the name |
| 826M40 | BS 970-1:1983 | Near-identical chemistry | Mo 0.45–0.65 %, S ≤ 0.040 % |
| EN26, EN26W | BS 970:1955 (old) | Same as 826M40 | Letter suffix gives the tensile condition, e.g. W |
| AISI 4340 | ASTM A29 / SAE J404 | Nearest US grade, not equivalent | 1.65–2.00 % Ni, 0.20–0.30 % Mo |
| 40NiCrMo6 / 1.6565, SNCM439 | DIN, JIS | 4340-type steels | Less nickel and molybdenum |
| 817M40 (EN24) | BS 970 | One step down in alloy | About 1.5 % Ni; lower strength per section |
| 34CrNiMo6 / 1.6582 | EN 10083-3 | Different balance | Lower carbon, 1.5 % Cr, 0.15–0.30 % Mo |
| 36NiCrMo16 / 1.6773, 35NCD16 | EN 10083-3, AFNOR | Higher-nickel step up | 3.60–4.10 % Ni for the heaviest sections |
| 40CrNiMoA, 40CrNi2Mo | GB/T 3077 (China) | No direct match | Both are 4340-type steels |
What is the chemical composition of 40NiMoCr10-4?
The first column is the range we order 40NiMoCr10-4 heats to. BS 970 826M40 and AISI 4340 are shown for comparison. Shaded cells differ from our ordering range.
| Element | 40NiMoCr10-4 (our ordering range) | 826M40 / EN26 (BS 970-1) | AISI 4340 (ASTM A29) | Effect |
|---|---|---|---|---|
| Carbon (C) | 0.37–0.43 | 0.36–0.44 | 0.38–0.43 | Sets hardness after quenching and the strength ceiling |
| Silicon (Si) | 0.15–0.35 | 0.10–0.35 | 0.15–0.35 | Deoxidiser |
| Manganese (Mn) | 0.50–0.70 | 0.45–0.70 | 0.60–0.80 | Hardenability; ties up sulphur |
| Phosphorus (P) | 0.035 | 0.035 | 0.035 | Residual; embrittles grain boundaries |
| Sulphur (S) | 0.035 | 0.040 | 0.040 | Residual; sulphides cut transverse ductility |
| Chromium (Cr) | 0.60–0.80 | 0.50–0.80 | 0.70–0.90 | Hardenability and resistance to softening in tempering |
| Molybdenum (Mo) | 0.40–0.60 | 0.45–0.65 | 0.20–0.30 | Deep hardening; resists temper embrittlement |
| Nickel (Ni) | 2.40–2.70 | 2.30–2.80 | 1.65–2.00 | Toughness, low-temperature impact, section hardenability |
| Iron (Fe) | Balance | Balance | Balance | Matrix |
Ordering to 826M40 / EN26 as wellWhen a drawing requires both 40NiMoCr10-4 and 826M40 / EN26, the heat is made to the common range of the two specifications (Mo 0.45–0.60 %). Both designations are then shown on one EN 10204 certificate.
What are the mechanical properties of 40NiMoCr10-4?
The strength of 40NiMoCr10-4 depends on the heat-treatment condition ordered. Most drawings refer to the BS 970 826M40 table below. It defines six hardened-and-tempered conditions, U to Z, each guaranteed only up to a limiting ruling section (LRS): the largest section, at the time of heat treatment, in which those properties can be met. Where two values are shown, the first applies at 250 mm LRS and the second at 150 mm.
| Condition | LRS, mm | Tensile Rm, MPa | Yield Re, MPa | 0.2 % proof Rp0.2, MPa | Elongation, % | Impact, J | Hardness, HB |
|---|---|---|---|---|---|---|---|
| U | 250 / 150 | 925–1075 | 740 / 755 | 725 / 740 | 12 | 42 | 269–331 |
| V | 250 / 150 | 1000–1150 | 835 / 850 | 820 / 835 | 12 | 42 | 293–352 |
| W | 250 / 150 | 1075–1225 | 925 / 940 | 910 / 925 | 11 | 35 | 311–375 |
| X | 150 | 1150–1300 | 1020 | 1005 | 10 | 28 | 341–401 |
| Y | 150 | 1225–1375 | 1095 | 1080 | 10 | 21 | 363–429 |
| Z | 100 | ≥ 1550 | 1235 | 1125 | 5 | 9 | ≥ 444 |
| Annealed | – | – | – | – | – | – | ≤ 277 |
Sources: BS 970-1:1983 grade 826M40, as reproduced in UK and South African stockholder data sheets (references 1 and 11). Elongation and impact are the published values per condition; the impact test type is not stated consistently, so name Charpy V-notch to ISO 148-1 and the test temperature on your order. Values apply to bar; for forgings the test position and direction are agreed on the drawing.
UK stock bar is most often sold in condition V or W; "EN26W" simply means 826M40 in condition W. For forgings, the section at heat treatment matters more than the finished size, which is why we often rough-machine before quenching (see the worked example).
Condition selector
Enter the ruling section at heat treatment and the required minimum tensile strength. Conditions not available at that section are struck through. The lowest suitable condition is marked, as it gives the highest impact values.
Bars show the tensile range in MPa on a 900–1,600 MPa scale, with the minimum impact value.
At a 180 mm ruling section, BS 970 826M40 can be supplied in conditions U, V or W. For 1,000 MPa, specify condition V: 1,000–1,150 MPa, Rp0.2 ≥ 820 MPa, 42 J, 293–352 HB.
Which condition should you specify?
Specify the lowest condition that meets the design strength. From U to Y the tensile range rises in steps of 75 MPa, while minimum impact energy falls from 42 J to 21 J, and to 9 J in condition Z.
| Condition | Specify it when | Avoid it when | Typical parts |
|---|---|---|---|
| U | The section is large or shock loading governs | You need more than 925 MPa minimum | Heavy shafts, large rings, gear blanks |
| V | You want the usual balance of strength and toughness up to 250 mm | The section exceeds 250 mm (properties then agreed per order) | Shafts, spindles, gears, axles, hydraulic parts |
| W | 1,075 MPa is needed and the section is still up to 250 mm | More than 35 J impact is specified | Torsion bars, rams, connecting rods, heavy pins |
| X | Strength governs and the section is 150 mm or less | The section exceeds 150 mm | High-stress pins, tool holders, sockets |
| Y | 1,225 MPa is needed in 150 mm or less | Shock loading; impact is only 21 J minimum | Die holders, small highly stressed parts |
| Z | Maximum strength and hardness (≥ 444 HB) under static load, 100 mm or less | Any impact- or fatigue-critical duty not qualified by test | Small static high-strength parts |
How is 40NiMoCr10-4 forged and heat treated?
Temperature ranges for forging and heat treatment. Bar colours correspond approximately to the glow colour of steel at each temperature.
| Operation | Temperature | Hold and cooling | Purpose and notes |
|---|---|---|---|
| Forging | Heat to 1,150–1,200 °C; do not forge below 850 °C | Soak through; cool slowly after forging | Slow cooling protects heavy Ni-Cr-Mo sections from cracking and hydrogen flakes |
| Annealing | 790–840 °C | Hold until uniform; furnace cool | Softens to ≤ 277 HB for rough machining |
| Normalizing | About 850–880 °C (typical practice) | Air cool, then temper | Refines coarse as-forged grain before hardening; thin sections can partly harden in air, so a temper always follows |
| Hardening | 820–850 °C | Oil or polymer quench; water only for simple heavy sections under a qualified procedure | Through-hardens to the LRS in Table 3 |
| Tempering | 450–660 °C for U to Y; lower for Z | At least 1 h per 25 mm; still air | Higher temperature gives lower strength and higher toughness |
| Stress relieving | 640–660 °C on annealed or normalized parts; 30–50 °C below the tempering temperature on Q+T parts | 1 h per 25 mm; still air | Relieves machining and straightening stresses without changing the condition |
| Nitriding | 490–530 °C | Slow cool, no quench | Surface up to about 60 HRC; nickel slows nitrogen diffusion, so cycles run longer |
| Induction or flame hardening | Surface to 820–850 °C | Immediate oil or water quench, then a low temper | Case above 50 HRC on a quenched and tempered core |
Temper embrittlement. Nickel-chromium steels without molybdenum can lose impact strength when tempered or slowly cooled between about 300 and 550 °C. The 0.4–0.6 % molybdenum in 40NiMoCr10-4 greatly reduces this effect, so heavy sections can be cooled slowly after tempering.
Parameters are typical guidance drawn from published 826M40 / EN26 data (reference 11) and general practice. For each order we set the actual cycle from the section size and the specified properties, and heat-treatment records are available with the certificate.
Can 40NiMoCr10-4 be welded, machined and surface hardened?
Welding
40NiMoCr10-4 is not recommended for welding. At mid-range chemistry the IIW carbon equivalent is about 0.91: 0.40 + 0.60/6 + (0.70 + 0.50)/5 + 2.55/15. Preheat is normally required from about 0.40–0.45. Where a weld cannot be avoided, use a qualified procedure with high preheat and interpass temperature, low-hydrogen consumables, slow cooling and post-weld stress relief or re-tempering. Welding a quenched and tempered forging will soften or re-harden the heat-affected zone.
Machining
Rough-machine in the annealed condition (≤ 277 HB). Parts in conditions U to W (269–375 HB) machine well with carbide tooling. Above about 400 HB, finishing is usually by grinding or hard turning. Because properties depend on the section at heat treatment, rough-machining a forging before quenching raises the properties you can guarantee.
Surface hardening and low temperature
Quenched and tempered 40NiMoCr10-4 can be nitrided at 490–530 °C to about 60 HRC with little distortion, because the core has already been tempered above that temperature. Induction or flame hardening gives a case above 50 HRC. The 2.5 % nickel keeps impact values good at sub-zero temperatures.
40NiMoCr10-4 vs 4340, EN24, 34CrNiMo6 and 36NiCrMo16
All five grades are Ni-Cr-Mo steels for quenching and tempering. The main difference is the nickel and molybdenum content, which determines hardenability in large sections and toughness.
| Grade | C | Ni | Mo | Compared with 40NiMoCr10-4 |
|---|---|---|---|---|
| 40NiMoCr10-4 / 826M40 (1.6745) | 0.37–0.43 | 2.40–2.70 | 0.40–0.60 | Reference |
| AISI 4340 | 0.38–0.43 | 1.65–2.00 | 0.20–0.30 | Same carbon, less nickel and about half the molybdenum. Lower hardenability, so heavy sections reach lower properties |
| 817M40 (EN24) | 0.36–0.44 | 1.30–1.70 | 0.20–0.35 | Lower-alloy BS 970 grade. EN26 is used where EN24 cannot reach the required strength in the section |
| 34CrNiMo6 (1.6582) | 0.30–0.38 | 1.30–1.70 | 0.15–0.30 | Common EN 10083-3 grade for heavy shafts. Lower carbon and 1.5 % chromium; better toughness, lower maximum strength |
| 36NiCrMo16 (1.6773) | 0.32–0.39 | 3.60–4.10 | 0.25–0.45 | Higher nickel for very large sections and higher toughness; higher alloy cost |
How does Jiangnan Metal forge 40NiMoCr10-4?
- Melt. Electric arc furnace, ladle refining and vacuum degassing (EAF + LF + VD) to the ordering range in Table 2. Degassing lowers dissolved hydrogen, the cause of internal flakes in heavy Ni-Cr-Mo forgings.
- Heat. Ingot or bloom soaked through at 1,150–1,200 °C.
- Forge or roll. Open-die forging on 1 t to 9 t hammers and 4,500 t and 5,000 t hydraulic presses, or seamless ring rolling, finishing above 850 °C with the reduction ratio agreed for the part.
- Cool and anneal. Controlled slow cooling and post-forge annealing, to prevent cracking and soften the part for machining.
- Rough machine. Reduces the ruling section before heat treatment and gives a surface fit for ultrasonic testing.
- Heat treat. Quench from 820–850 °C and temper to the ordered condition, or anneal or normalize and temper as ordered.
- Test. Tensile, impact and hardness on test pieces from the agreed position; UT to EN 10228-3, SEP 1921 or ASTM A388; magnetic particle or penetrant testing on request.
- Finish and certify. Machining to drawing, marking with heat number, EN 10204 3.1 or 3.2 certificate, export packing.
What can Jiangnan Metal forge in 40NiMoCr10-4?
The size range below applies to all grades. For 40NiMoCr10-4 the properties that can be guaranteed at a given size follow the ruling-section limits in Table 3, so please state the required properties together with the dimensions.
- Single-piece weight
- 10 kg to 15,000 kg
- Forged diameter
- 100 mm to 6,000 mm
- Forged length
- Up to 12,000 mm
- Seamless rolled rings
- To 2,500 mm OD on radial-axial mills; larger on the 6 m ring line
Forging
1 t, 3 t, 5 t and 9 t open-die hammers; 4,500 t and 5,000 t hydraulic presses; radial-axial ring mills and a 6 m ring line.
Heat treatment and machining
In-house annealing, normalizing and quench-and-temper furnaces with water and oil quench, plus rough and finish machining.
Inspection
Optical emission spectrometer, tensile and Charpy impact testing, hardness testers, ultrasonic flaw detection, magnetic particle and penetrant testing, metallographic microscope.
People
460 employees, including 9 senior and 32 intermediate engineers.
Which standards and certificates apply?
Material and documents
- 40NiMoCr10-4 / 1.6745 to the ordering range in Table 2
- BS 970 826M40 (EN26) chemistry and U–Z conditions on request
- Customer specifications and drawings
- EN 10204 3.1 as standard; 3.2 with third-party witness
Testing
- Ultrasonic: EN 10228-3, SEP 1921, ASTM A388
- Magnetic particle: ISO 9934, ASTM E1444
- Penetrant: ISO 3452, ASTM E165
- Tensile: ISO 6892-1, ASTM E8; impact: ISO 148-1, ASTM E23
- Hardness: ISO 6506-1, ASTM E10; grain size: ASTM E112
Quality management is certified to ISO 9001:2015. Third-party certificates are issued through the inspection body you nominate, such as Lloyd's Register, DNV, Bureau Veritas, ABS, TÜV or SGS, and customers may witness any production stage.
Where are 40NiMoCr10-4 forgings used?
Pumps and compressors
Plunger-pump crankshafts and eccentric shafts, chemical-pump shafts, compressor shafts and discs, nitrogen-generator and air-compressor parts.
Power transmission
Gear rings, pinions, gear shafts, gearbox and turbine shafts, couplings and spindles.
Oil and gas equipment
Valve stems, seat rings and blocks, wellhead and offshore components in sweet service, where strength per section is the limit.
Mining, cement and sugar mills
Mill shafts, crankshafts, rolls, heavy wheels and mixer shafts.
Hydraulics and heavy machinery
Rams, piston rods, cylinder sleeves, press parts, die holders and torsion bars.
Shipbuilding, paper and pulp
Heavy shafts, forged wheels and rolls.
Sour service and welded pressure partsISO 15156-2 / NACE MR0175 pre-qualifies carbon and low-alloy steels for H₂S service only below 1 % nickel and at 22 HRC maximum, so 40NiMoCr10-4 is not a pre-qualified sour-service material. For sour duty choose a low-nickel Cr-Mo grade such as AISI 4130 at controlled hardness. Welded pressure-retaining parts likewise call for a weldable grade.
Worked example: can 40NiMoCr10-4 reach 1,000 MPa in a 320 mm shaft?
Given. A stepped pump shaft with a largest diameter of 320 mm. The drawing asks for Rm ≥ 1,000 MPa, Rp0.2 ≥ 820 MPa and 40 J impact.
Check. BS 970 guarantees condition V (1,000–1,150 MPa, Rp0.2 ≥ 820 MPa, 42 J) only up to a 250 mm ruling section. At 320 mm the part is outside the table.
Options.
- Rough-machine the steps and, if the design allows, bore the centre before quenching, so the ruling section falls to 250 mm or less.
- Keep the 320 mm section and agree the properties at mid-radius, proven on a test prolongation. Shaft stresses peak at the surface, where the quenched properties are highest, so mid-radius values are often enough.
- If the full section must meet condition V everywhere, move to 36NiCrMo16 with 3.6–4.1 % nickel.
Weight check. A finished ring of 1,200 mm OD × 900 mm ID × 300 mm height weighs about 1,165 kg at 7.85 g/cm³; the rough forging, with 20–35 % machining stock, is about 1,400–1,575 kg. The calculator below does this for any shape.
How do you specify a 40NiMoCr10-4 forging?
- Name the material. Write "40NiMoCr10-4 (1.6745)". Add "826M40 / EN26" only if your specification requires it; the heat is then made to Mo 0.45–0.60 %.
- State the condition. Annealed, normalized and tempered, or quenched and tempered to a BS 970 condition (for example V), or to explicit Rm, Rp0.2, impact and hardness values.
- Give the test location. For example "tests at mid-radius from a prolongation, longitudinal". Above 250 mm this decides what can be guaranteed.
- Define the NDT and its acceptance class. For example "UT to EN 10228-3, quality class 3".
- Choose the certificate. EN 10204 3.1, or 3.2 with the inspection body named.
- Send the drawing and quantity. Rough or finished dimensions, machining allowance and number of pieces.
- State delivery. Required date, Incoterm (EXW Jiangyin, FOB Shanghai, CIF) and destination.
Example material note for drawings
MATERIAL: 40NiMoCr10-4 (W.-Nr. 1.6745)
[if required: also BS 970 826M40 / EN26, Mo 0.45-0.60 %]
MELTING: EAF + LF + VD
CONDITION: Hardened and tempered to BS 970 condition V
Rm 1000-1150 MPa, Rp0.2 >= 835 MPa, 293-352 HB
ruling section at heat treatment <= 150 mm
TESTS: Tensile ISO 6892-1, Charpy V ISO 148-1 (state temperature),
mid-radius, longitudinal
UT: EN 10228-3 quality class 3 (or SEP 1921 / ASTM A388)
CERTIFICATE: EN 10204 3.1 (3.2 with third-party witness if stated on PO)
MARKING: Heat number and part number, low-stress stamp
Forging weight calculator
Net weight at 7.85 g/cm³, with the usual 20–35 % allowance for the rough forging.
Request a 40NiMoCr10-4 quotation
Send the drawing (PDF, DWG or STEP) or rough dimensions to sales@steelforgepieces.com, call 0086-189-2135-9659, or message us on WhatsApp. We reply within 24 hours with price, lead time and the standards we will certify to.
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Glossary
- Ruling section
- The section that controls cooling rate during quenching. For a solid round it is the diameter at the time of heat treatment, not the finished size.
- Limiting ruling section (LRS)
- The largest ruling section for which BS 970 guarantees a given tensile condition; 250 mm for U, V and W in 826M40.
- Condition U to Z
- BS 970 letter codes for tensile ranges after hardening and tempering, rising in 75 MPa steps from U (925–1,075 MPa) to Y, with Z at 1,550 MPa minimum.
- Hardenability
- How deep a steel hardens on quenching. Nickel, molybdenum and chromium raise it; it is why 40NiMoCr10-4 suits heavy sections.
- Temper embrittlement
- Loss of impact toughness after tempering in, or slow cooling through, roughly 300–550 °C. Molybdenum reduces it.
- EAF + LF + VD
- Electric arc furnace melting, ladle-furnace refining and vacuum degassing, which lowers hydrogen and inclusions.
- Carbon equivalent (CE IIW)
- C + Mn/6 + (Cr + Mo + V)/5 + (Ni + Cu)/15; a guide to weldability. About 0.91 for 40NiMoCr10-4.
- EN 10204 3.1 / 3.2
- Inspection certificates. 3.1 is issued by the manufacturer's independent inspection; 3.2 is also signed by a third party or the buyer's inspector.
40NiMoCr10-4 frequently asked questions
What is 40NiMoCr10-4 steel?
40NiMoCr10-4 (W.-Nr. 1.6745) is a through-hardening nickel-chromium-molybdenum alloy steel with about 0.40 % carbon, 2.5 % nickel, 0.7 % chromium and 0.5 % molybdenum. It is supplied quenched and tempered for heavily loaded shafts, gears, rings and other forgings that need high strength in large sections.
Is 40NiMoCr10-4 the same as 1.6745, 40NiMoCr10-5 and EN26 (826M40)?
1.6745 is the material number of 40NiMoCr10-4, and 40NiMoCr10-5 is an alternative spelling of the same name. BS 970 826M40, still called EN26, is the British equivalent with almost the same chemistry; its molybdenum range is 0.45–0.65 % against 0.40–0.60 %, and its sulphur limit is 0.040 %. A heat made to the overlap of both ranges can be certified to both names.
What is the chemical composition of 40NiMoCr10-4?
Jiangyin Jiangnan Metal orders 40NiMoCr10-4 to C 0.37–0.43 %, Si 0.15–0.35 %, Mn 0.50–0.70 %, P 0.035 % max, S 0.035 % max, Cr 0.60–0.80 %, Mo 0.40–0.60 % and Ni 2.40–2.70 %, balance iron.
What tensile strength can 40NiMoCr10-4 forgings reach?
Using the BS 970 826M40 conditions, quenched and tempered 40NiMoCr10-4 ranges from 925–1,075 MPa (condition U) to 1,550 MPa minimum (condition Z). Conditions U, V and W are guaranteed up to a 250 mm ruling section, X and Y up to 150 mm, and Z up to 100 mm. Condition V, 1,000–1,150 MPa with Rp0.2 of at least 820 MPa, is the most common choice.
What is the hardness of 40NiMoCr10-4?
Annealed 40NiMoCr10-4 is 277 HB maximum. Quenched and tempered, it ranges from 269–331 HB in condition U, through 293–352 HB in condition V, to at least 444 HB in condition Z. Nitriding raises the surface to about 60 HRC and induction hardening gives a case above 50 HRC.
How is 40NiMoCr10-4 heat treated?
Harden from 820–850 °C with an oil or polymer quench, then temper at 450–660 °C for conditions U to Y, allowing at least one hour per 25 mm of section. Anneal at 790–840 °C with furnace cooling. Forge between 1,200 °C and 850 °C and cool slowly after forging.
Is 40NiMoCr10-4 equivalent to AISI 4340?
No. AISI 4340 is the nearest US grade but has 1.65–2.00 % nickel and 0.20–0.30 % molybdenum against 2.40–2.70 % and 0.40–0.60 % in 40NiMoCr10-4. The extra alloy gives 40NiMoCr10-4 higher hardenability, so it reaches higher properties in heavy forgings.
Can 40NiMoCr10-4 be welded?
Only with difficulty. Its carbon equivalent (IIW) is about 0.91 at mid-range chemistry, so welding needs a qualified procedure with high preheat and interpass temperature, low-hydrogen consumables and post-weld stress relief or re-tempering. It is better to design forgings in this grade without structural welds.
Is 40NiMoCr10-4 suitable for sour (H₂S) service?
Not without qualification. ISO 15156-2 / NACE MR0175 pre-qualifies carbon and low-alloy steels only when they contain less than 1 % nickel and are 22 HRC or softer. With 2.4–2.7 % nickel, 40NiMoCr10-4 falls outside that route; a low-nickel Cr-Mo grade such as AISI 4130 is the usual choice for sour duty.
Who manufactures 40NiMoCr10-4 forgings in China?
Jiangyin Jiangnan Metal Co., Ltd. is an open-die forging factory at No.1 Chengxiqiao Road, Zhouzhuang Town, Jiangyin City, Jiangsu Province, China. It forges 40NiMoCr10-4 (1.6745 / EN26) seamless rolled rings, shafts, discs, flanges, sleeves and bars to customer drawings, with EN 10204 3.1 or 3.2 certificates. Contact sales@steelforgepieces.com or 0086-189-2135-9659 for a quotation within 24 hours.
What sizes of 40NiMoCr10-4 forgings can Jiangnan Metal supply?
Jiangyin Jiangnan Metal forges single pieces from 10 kg to 15,000 kg, diameters from 100 mm to 6,000 mm and lengths up to 12,000 mm, with seamless rolled rings to 2,500 mm outside diameter on radial-axial ring mills. The properties guaranteed at a given size follow the BS 970 ruling-section limits.
Which tests and certificates come with the forgings?
Every 40NiMoCr10-4 forging from Jiangyin Jiangnan Metal is supplied with an EN 10204 3.1 certificate showing heat analysis, heat treatment, tensile, impact and hardness results, and ultrasonic testing to EN 10228-3, SEP 1921 or ASTM A388. EN 10204 3.2 certificates with Lloyd's Register, DNV, Bureau Veritas, ABS, TÜV or SGS witness are available on request.
What information is needed for a quotation?
Send the drawing or rough dimensions, quantity, required condition or properties, test location, ultrasonic testing standard and acceptance class, certificate type and delivery term. Jiangyin Jiangnan Metal replies within 24 hours from sales@steelforgepieces.com.
References
- BS 970-1:1983, Wrought steels for mechanical and allied engineering purposes, grade 826M40 (formerly EN26 in BS 970:1955). Chemistry, conditions U–Z and limiting ruling sections.
- EN 10027-1, Designation systems for steels. Part 1: Steel names, and EN 10027-2, Part 2: Numerical system.
- EN 10083-3, Steels for quenching and tempering. Part 3: Technical delivery conditions for alloy steels (34CrNiMo6, 36NiCrMo16).
- ASTM A29/A29M, Standard Specification for General Requirements for Steel Bars, Carbon and Alloy, Hot-Wrought (AISI 4340 chemistry).
- EN 10228-3, Non-destructive testing of steel forgings. Part 3: Ultrasonic testing of ferritic or martensitic steel forgings.
- SEP 1921, Ultrasonic testing of forgings and bars, Stahl-Eisen-Prüfblatt.
- ASTM A388/A388M, Standard Practice for Ultrasonic Examination of Steel Forgings.
- EN 10204, Metallic products. Types of inspection documents.
- ISO 6892-1 (tensile testing) and ISO 148-1 (Charpy pendulum impact testing).
- ISO 15156-2 / NACE MR0175, Materials for use in H₂S-containing environments. Part 2: Cracking-resistant carbon and low-alloy steels, clause A.2.1.2.
- West Yorkshire Steel, 826M40 alloy steel data sheet (forging, annealing, hardening, tempering, typical properties by condition).
Standards are cited by number; always work to the revision in force at your contract date.
About Jiangyin Jiangnan Metal Co., Ltd.
Jiangyin Jiangnan Metal Co., Ltd. is an open-die forging factory in Jiangyin, Jiangsu Province, China, with 460 employees including 9 senior and 32 intermediate engineers. The plant runs 1 t to 9 t open-die hammers, 4,500 t and 5,000 t hydraulic presses and radial-axial ring mills, with in-house heat treatment, machining, mechanical testing and non-destructive examination. Besides 40NiMoCr10-4 it forges carbon, alloy, tool and stainless steels and nickel alloys. Quality management is certified to ISO 9001:2015, and material is supplied with EN 10204 3.1 certification as standard, 3.2 with third-party witness on request.
Reference: Jiangyin Jiangnan Metal Co., Ltd. (2026). 40NiMoCr10-4 (1.6745 / EN26) forgings: composition, properties, heat treatment and ordering guide. Updated 11 September 2026. https://www.steelforgepieces.com/Alloy-Steel/40NiMoCr10-4.html