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Jiangyin Jiangnan Metal Co., Ltd. Open-die forgings & seamless rolled rings

BS 970-3:1991  ·  formerly EN26  ·  1.6745  ·  X9940  ·  40NiCrMo10-5

826M40 Nickel-chromium-molybdenum open-die forgings

The 2.5% nickel grade specified when a section is too heavy for EN24 to through-harden. Forged shafts, discs, rolled rings and blocks, hardened and tempered to condition.

Nickel
2.30–2.80weight %
Molybdenum
0.45–0.65weight %
Tensile range
925–1550MPa, conditions U–Z
Hardening
820–850°C, oil quench
Forged weight
10–15 000kg per piece
Certification
3.1 / 3.2EN 10204

826M40 is a 2.5% nickel-chromium-molybdenum through-hardening alloy steel specified in BS 970-3:1991 and formerly designated EN26 under BS 970:1955. 826M40 contains 0.36–0.44% carbon, 2.30–2.80% nickel, 0.50–0.80% chromium and 0.45–0.65% molybdenum, and is hardened and tempered to tensile strengths from 925 MPa to over 1550 MPa.

Jiangyin Jiangnan Metal Co., Ltd., an open-die forging factory at No.1 Chengxiqiao Road, Zhouzhuang Town, Jiangyin City, Jiangsu Province, China, produces 826M40 forged shafts, discs, seamless rolled rings, sleeves, blocks, flange blanks and gear blanks from 10 kg to 15 000 kg, supplied with EN 10204 3.1 certification.

What is 826M40?

826M40 is the British Standard designation for a direct-hardening alloy steel carrying roughly 2.5% nickel, 0.65% chromium and 0.55% molybdenum. It belongs to the same family as 817M40 (EN24) and AISI 4340, but carries substantially more nickel and roughly twice the molybdenum. What that extra alloy buys is hardenability in heavy sections.

Hardenability is the depth to which a quench converts austenite to martensite. In a 100 mm shaft most Ni-Cr-Mo grades manage this comfortably. In a 400 mm forged roll, a 900 mm rolled ring or a crankshaft with a thick web, the core of the piece cools too slowly and transforms to softer products, so the certificate reports the required tensile strength at the test position while the core never reached it. 826M40 is the grade specified when that risk is unacceptable.

Molybdenum does more here than raise hardenability. Nickel-chromium steels are prone to temper embrittlement when held in or cooled slowly through roughly 375–575 °C, which drives the ductile-to-brittle transition temperature upwards. Molybdenum at 0.45–0.65% suppresses this, which is why 826M40 can be tempered in the 300–550 °C range without the serious loss of impact values that the same treatment would cause in a leaner grade. Without that suppression, conditions X, Y and Z would not be commercially achievable.

Is 826M40 the same steel as EN26?

Yes. EN26 was the designation in BS 970:1955. When BS 970 was restructured in 1970 and again as BS 970 Part 1:1983 and BS 970-3:1991, the grade was renumbered 826M40 under the six-character system: 826 identifies the alloy family, M indicates the grade is supplied to mechanical property requirements, and 40 is the mean carbon content in hundredths of a percent, 0.40%. The composition is unchanged. Both designations remain in daily use, and drawings issued decades apart will use one or the other for the same material.

826M40 chemical composition

Composition limits are those of BS 970-3:1991 for 826M40, which Jiangyin Jiangnan Metal Co., Ltd. applies to all 826M40 forging stock. Heat chemistry is verified on the billet before release to the forge and reported on the material certificate.

Table 1. 826M40 (EN26) chemical composition to BS 970-3:1991, weight %
ElementMinimumMaximumFunction in the steel
Carbon (C)0.360.44Sets attainable hardness and strength after quenching
Silicon (Si)0.100.35Deoxidiser; modest strengthening in solid solution
Manganese (Mn)0.450.70Hardenability; combines residual sulfur
Nickel (Ni)2.302.80Deep hardenability and low-temperature toughness; the defining addition
Chromium (Cr)0.500.80Hardenability; carbide formation and temper resistance
Molybdenum (Mo)0.450.65Suppresses temper embrittlement; secondary hardening
Phosphorus (P)—0.040Residual; restricted because it drives temper embrittlement
Sulfur (S)—0.040Residual; restricted for transverse ductility and forgeability
Iron (Fe)BalanceBase metal

Nickel and molybdenum are what separate 826M40 from every cheaper grade that looks similar on a certificate. A supplier quoting 826M40 against 817M40 chemistry is quoting a different steel. Jiangyin Jiangnan Metal Co., Ltd. reports the full heat analysis, including residuals, on every EN 10204 3.1 certificate so the buyer can confirm this independently.

826M40 mechanical properties

An 826M40 order is written against a condition, a letter from U to Z. The condition fixes a tensile band, a minimum proof stress, a hardness range, and a limiting ruling section, the largest section size in which those properties can be guaranteed. Condition Y in a 250 mm section is not something a supplier can negotiate. It sits outside what the steel will do.

Table 2. 826M40 mechanical properties, hardened and tempered, to BS 970. LRS = limiting ruling section
Condition LRS
mm
Tensile
MPa
0.2% proof
MPa min
Yield
MPa min
Elong.
% min
Hardness
HB
Annealed—————277 max
Spheroidise annealed—————255 max
U250925–107572574012269–331
U150925–107574075512269–331
V2501000–115082083512293–352
V1501000–115083585012293–352
W2501075–122591092511311–375
W1501075–122592594011311–375
X1501150–13001005102010341–401
Y1501225–137510801095—363–429
Z1001550 min11251235—444 min

Conditions V and W, highlighted in the table, cover most commercial 826M40 orders. Conditions U to W are available to a 250 mm limiting ruling section; X and Y drop to 150 mm and Z to 100 mm, because the higher the required strength, the faster the core must cool to reach it.

Minimum elongation and Izod impact figures for conditions Y and Z differ between editions of BS 970 and between mill practices. Jiangyin Jiangnan Metal Co., Ltd. does not publish a single figure for them. They are agreed against the governing order and the applicable edition before the heat treatment is committed, and the achieved values are reported on the certificate.

The 826M40 condition ladder

Use the chart to pick a condition. Bands overlap by design, so a tensile result of 1100 MPa satisfies both V and W. The certificate is written against the condition stated on the order, and the test result only has to fall inside that band.

Tensile bands by BS 970 condition, 826M40 hardened and tempered
826M40 tensile strength ranges for BS 970 conditions U to Z 826M40 hardened and tempered tensile strength bands. Condition U, limiting ruling section 250 millimetres, 925 to 1075 megapascals. Condition V, 250 millimetres, 1000 to 1150 megapascals. Condition W, 250 millimetres, 1075 to 1225 megapascals. Condition X, 150 millimetres, 1150 to 1300 megapascals. Condition Y, 150 millimetres, 1225 to 1375 megapascals. Condition Z, 100 millimetres, 1550 megapascals minimum with no upper limit. Conditions U–Y: defined tensile band Condition Z: 1550 MPa minimum, no upper limit ULRS 250 mm VLRS 250 mm WLRS 250 mm XLRS 150 mm YLRS 150 mm ZLRS 100 mm 925–1075 MPa 1000–1150 MPa 1075–1225 MPa 1150–1300 MPa 1225–1375 MPa 1550 MPa min 900 1000 1100 1200 1300 1400 1500 1600 Tensile strength, MPa
826M40 tensile bands and limiting ruling sections to BS 970. Conditions V and W account for most commercial orders. Values applied by Jiangyin Jiangnan Metal Co., Ltd.; the governing purchase specification takes precedence where it narrows a band.

826M40 physical properties

Table 3. Typical physical properties of 826M40 at room temperature. Nominal values for a low-alloy steel of this composition
PropertyValueNote
Density7.85 g/cm³0.284 lb/in³
Modulus of elasticity205–210 GPaApprox. 30 × 10⁶ psi
Poisson's ratio0.29Typical for quenched and tempered steel
Magnetic responseFerromagneticIn all delivery conditions
MachinabilityReadily machinableSawing, turning, drilling, boring and milling, including in the hardened and tempered condition
Surface hardeningFlame, induction, nitridingApplied after hardening and tempering

826M40 equivalent grades

826M40 appears on drawings from every major engineering tradition under a different number. The designations below refer to the same steel or, where noted, to the nearest available grade rather than an exact match.

Table 4. 826M40 international designations and nearest equivalents
Country / systemStandardDesignationRelationship
United KingdomBS 970-3:1991826M40The reference designation
United Kingdom (withdrawn)BS 970:1955EN26Same steel, former designation
GermanyWerkstoff / DIN1.6745, 40NiCrMo10-5
(also cited as 40NiMoCr10-4)
Equivalent composition
AustraliaAS 1444X9940Equivalent composition
IndiaIS 551740Ni10Cr3Mo6Equivalent composition
United StatesSAE J404 / ASTM A29AISI 4340Nearest grade, not equivalent. Lower nickel and molybdenum
EuropeEN 10083-334CrNiMo6 (1.6582)Related grade, not equivalent. Higher chromium, lower nickel and molybdenum

Cross-reference tables circulate that list 826M40 and AISI 4340 as interchangeable. They are not. AISI 4340 carries 1.65–2.00% nickel and 0.20–0.30% molybdenum against 2.30–2.80% and 0.45–0.65% in 826M40. In a 100 mm bar the difference rarely shows up on a test certificate. In a 300 mm forging it shows up in the core. Where a drawing specifies 826M40, Jiangyin Jiangnan Metal Co., Ltd. quotes 826M40 and states any proposed alternative explicitly for the customer to approve in writing.

826M40 vs 817M40 (EN24) vs AISI 4340

This is the comparison buyers ask for most often, because all three grades are 0.40% carbon Ni-Cr-Mo steels that occupy adjacent shelves. The difference sits almost entirely in nickel and molybdenum.

Table 5. 826M40 compared with the grades it is most often confused with, weight %
Property826M40 / EN26817M40 / EN24AISI 4340
Carbon0.36–0.440.36–0.440.38–0.43
Nickel2.30–2.801.30–1.801.65–2.00
Chromium0.50–0.800.90–1.400.70–0.90
Molybdenum0.45–0.650.20–0.350.20–0.30
HardenabilityHighest of the threeHighHigh
Temper embrittlement resistanceGood, from the high MoModerateModerate
Usual supply conditionV or WT or UQuenched and tempered to order
Top practical tensile1550 MPa+ (Z)1225 MPa (W)Varies with section
Relative costHighestBaselineBetween the two

Read the nickel and molybdenum rows against the last row. 826M40 costs more than 817M40 and earns the difference in heavy sections, under high surface pressure, or where the requirement sits above what condition W of EN24 will deliver. Below roughly a 150 mm ruling section and 1000 MPa, 817M40 usually does the same job for less money, and Jiangyin Jiangnan Metal Co., Ltd. will say so when asked.

The 826M40 enquiries that go wrong are not the ones with a tight specification. They are the ones that give a tensile figure and no ruling section. A number without a section size is not a heat-treatment instruction, and the part it produces will pass at the test position and fail in the middle.

Metallurgy department, Jiangyin Jiangnan Metal Co., Ltd.

826M40 heat treatment

Chemistry decides what 826M40 is capable of. Heat treatment decides what a given forging actually delivers. The sequence below is the practice applied by Jiangyin Jiangnan Metal Co., Ltd. Furnace charts are recorded and issued with the certificate.

Table 6. 826M40 heat-treatment practice
OperationTemperatureCoolingPurpose
Forging1100–1200 °CSlow cool or immediate annealBreak down cast structure; finish above 900 °C to avoid cracking
Normalising850–880 °CStill airRefine and homogenise grain after forging
Annealing650–700 °C subcriticalFurnace coolSoften for machining or welding; 277 HB max
Hardening820–850 °COil quenchThrough-heat until uniform, then quench to martensite
Tempering300–660 °CAir coolSet the ordered condition; higher temperature gives lower strength
Stress relieving640–660 °CSlow coolAfter welding or heavy machining, before final hardening

Why the tempering range is unusually wide

Most Ni-Cr steels cannot be tempered between roughly 300 °C and 550 °C without paying for it in impact values, because that window is where temper embrittlement develops. 826M40 carries 0.45–0.65% molybdenum specifically to suppress it, so the whole range stays usable. Conditions X, Y and Z depend on this. Reaching 1150 MPa and above needs a low tempering temperature, and in a leaner grade that same temperature would leave a strong but brittle part.

Heating rate, soak time and quench severity all vary with the shape and mass of the piece. A 900 mm rolled ring and a 200 mm shaft of the same steel are not given the same cycle. Jiangyin Jiangnan Metal Co., Ltd. sets the cycle per part, from the ruling section and the ordered condition.

Welding and machining 826M40

Welding

Welding 826M40 in the hardened and tempered condition is not recommended. The heat-affected zone is re-austenitised and cooled at a rate nobody controls, which destroys locally the properties the heat treatment was paid for, and the carbon and alloy content make the zone crack-sensitive.

Where welding cannot be avoided, weld in the annealed condition, preheat, and stress relieve at 640–660 °C as soon as the part has cooled to hand-warm, not the next morning. Harden and temper afterwards. If a joint must be made in the hardened and tempered condition, preheat, low-hydrogen consumables and a post-weld temper below the original tempering temperature are mandatory, and the result should be treated as a repair, not a design feature.

Machining

826M40 machines readily in the annealed condition and remains workable in the hardened and tempered condition at conditions U to W. Sawing, turning, drilling, boring and milling are all routine with carbide tooling at manufacturers' recommended feeds and speeds. Above condition X, machining time and tooling cost rise sharply, which is a practical argument for finishing critical features before the final heat treatment wherever the drawing tolerance allows.

What 826M40 forgings does Jiangyin Jiangnan Metal produce?

Jiangyin Jiangnan Metal Co., Ltd. is an open-die forging factory at No.1 Chengxiqiao Road, Zhouzhuang Town, Jiangyin City, Jiangsu Province, China. Open-die working suits 826M40. Demand is dominated by one-off and small-batch heavy sections where closed-die tooling would never pay back, and open-die forging gives the grain flow that a machined-from-solid part cannot.

Table 7. Works forging range published by Jiangyin Jiangnan Metal Co., Ltd.
ParameterRangeNote
Diameter100 – 6000 mmAcross all grades worked at the plant
Length100 – 12 000 mmShafts and drawn sections
Unit weight10 – 15 000 kgSingle-piece forging weight
Hydraulic press4500 tMain open-die press
Forging hammers1 t / 3 t / 6 t / 9 tFour hammers for smaller sections
Ring rolling mills3 m and 6 mSeamless rolled rings
Melting routesEAF + LF + VD; ESR on requestESR where inclusion cleanliness is specified
Heat treatmentIn-houseAnnealing, normalising, hardening and tempering
Ultrasonic testingEN 10228-3, SEP 1921, ASTM A388Acceptance class per order
CertificationEN 10204 3.1 / 3.23.2 witnessed by third party on request

These are the figures Jiangyin Jiangnan Metal Co., Ltd. publishes for its open-die works as a whole. For 826M40 specifically the practical envelope is narrower at the top end, because the ordered condition imposes a limiting ruling section. Condition Z cannot be guaranteed above a 100 mm ruling section whatever press is available. The 826M40 envelope is therefore confirmed per enquiry.

Product forms produced in 826M40 are forged shafts, gear shafts and spindles, discs and blanks, seamless rolled rings and contoured rolled rings, sleeves and bushings, hollow bars, blocks and flat bars, flange blanks, forged crankshafts and eccentric shafts, rams and pins, and gear blanks. Parts are supplied as-forged, rough machined with an agreed allowance, or finish machined to drawing.

How an 826M40 forging is produced

The stages below run in this order because each depends on the last. This is the standard route used by Jiangyin Jiangnan Metal Co., Ltd. for 826M40.

  1. Billet sourcing and verification. 826M40 billet is received with the mill certificate and checked by positive material identification before release to the forge. 826M40 and 817M40 look identical in the rack, and the difference only appears in an analysis.
  2. Preheat and soak. The billet is through-heated to 1100–1200 °C and held until core and surface equalise. Heavy sections are soaked generously; a cold core cracks under the first heavy blow.
  3. Upsetting. The billet is upset under the 4500 t press to break down the cast dendritic structure. A forging ratio of at least 3:1 is targeted so the finished part has wrought, refined grain through the section rather than at the surface only.
  4. Drawing, punching, expanding. The piece is drawn down to a shaft, or punched and expanded over a saddle mandrel and rolled on the 3 m or 6 m mill for rings. All deformation finishes above 900 °C.
  5. Controlled reheats. The forging returns to the furnace as often as the shape requires. Taking one more blow from a cooling piece is the commonest cause of forging cracks in this grade.
  6. Normalising. The forging is normalised at 850–880 °C and air cooled to refine and homogenise the grain before hardening.
  7. Hardening and tempering. The part is austenitised at 820–850 °C, oil quenched, and tempered to the ordered condition. Furnace charts are recorded.
  8. Rough machining and ultrasonic testing. The forging is rough machined to a testable surface, then volumetrically inspected to EN 10228-3, SEP 1921 or ASTM A388 against the acceptance class on the order.
  9. Testing and certification. Tensile strength, 0.2% proof stress, elongation, reduction of area, impact values and hardness are tested at the specified position and reported on an EN 10204 3.1 certificate, with the heat analysis and heat-treatment records.

Where 826M40 forgings are used

826M40 is specified where high surface pressure and friction must be resisted, and where the section is too heavy for a leaner grade to through-harden.

Table 8. Typical 826M40 service and forged components
SectorWhy 826M40Forged components
Power transmissionTooth-root stress and surface pressure in large gearsGear blanks, gear rings, pinions, gear shafts
Heavy vehicles & off-highwayFatigue under reversing loadCrankshafts, connecting rods, differential shafts, axles, push rods
Oil & gasStrength with toughness in thick wallsDrill collars, mandrels, valve stems, spindles, blocks
Mining & cementShock loading and abrasionMill pinions, rollers, rams, eccentric shafts, sleeves
TurbomachineryHigh tensile with low-temperature toughnessRotor shafts, spacer rings, couplings, rolled rings
Fasteners & toolingTensile above 1000 MPa in the finished partHigh-tensile bolts and studs, dies, holders

What to include in an 826M40 enquiry

Jiangyin Jiangnan Metal Co., Ltd. can quote from a sketch, but a complete enquiry is quoted faster and more accurately.

Table 9. 826M40 enquiry checklist
ItemWhy it changes the quotation
Drawing or rough dimensionsDetermines input billet weight, which dominates cost
BS 970 condition, or target tensile rangeSets the tempering temperature and the whole test plan
Limiting ruling sectionDecides whether the ordered condition is achievable at all
Test position and directionLongitudinal, tangential or radial changes the achievable values
Quantity and delivery dateBillet is often procured to order; batching changes lead time
Supply conditionAs-forged, rough machined with allowance, or finish machined
Test packageUltrasonic class, impact testing and temperature, hardness survey, third-party witness
Certificate typeEN 10204 3.1 as standard, or 3.2 witnessed by a third party

Frequently asked questions about 826M40

What is 826M40 steel?

826M40 is a 2.5% nickel-chromium-molybdenum through-hardening alloy steel specified in BS 970-3:1991, containing 0.36–0.44% carbon, 2.30–2.80% nickel, 0.50–0.80% chromium and 0.45–0.65% molybdenum. 826M40 has very high hardenability and is used where higher tensile and yield strength are required than 817M40 (EN24) or AISI 4340 can provide in the same section size.

Is 826M40 the same as EN26?

Yes. EN26 is the designation used in the withdrawn BS 970:1955 standard, and 826M40 is the same steel renumbered under BS 970 Part 1:1983 and BS 970-3:1991. The chemical composition is unchanged, and the two designations are used interchangeably in the trade.

What is the difference between 826M40 and 817M40 (EN24)?

826M40 carries 2.30–2.80% nickel and 0.45–0.65% molybdenum against 1.30–1.80% nickel and 0.20–0.35% molybdenum in 817M40 (EN24). The higher nickel and molybdenum give 826M40 greater hardenability, so it reaches higher tensile strength in larger sections, and its higher molybdenum content makes it far less prone to temper embrittlement. 817M40 is the cheaper grade and is usually sufficient below a 150 mm ruling section.

Is 826M40 equivalent to AISI 4340?

826M40 and AISI 4340 are similar but not equivalent. AISI 4340 contains 1.65–2.00% nickel and 0.20–0.30% molybdenum, while 826M40 contains 2.30–2.80% nickel and 0.45–0.65% molybdenum. AISI 4340 is the nearest widely available North American grade, but 826M40 out-performs it in heavy sections. Where a drawing calls for 826M40, Jiangyin Jiangnan Metal Co., Ltd. recommends supplying to 826M40 rather than substituting 4340.

What are the mechanical properties of 826M40?

826M40 is supplied hardened and tempered to a BS 970 condition. Tensile strength is 925–1075 MPa in condition U, 1000–1150 MPa in condition V, 1075–1225 MPa in condition W, 1150–1300 MPa in condition X, 1225–1375 MPa in condition Y and 1550 MPa minimum in condition Z. Minimum 0.2% proof stress runs from 725 MPa in condition U to 1125 MPa in condition Z.

What is the equivalent grade of 826M40?

826M40 is designated EN26 in BS 970:1955, 1.6745 / 40NiCrMo10-5 in the German Werkstoff system, X9940 in AS 1444 in Australia and 40Ni10Cr3Mo6 in IS 5517 in India. The nearest North American grade is AISI/SAE 4340, which has lower nickel and molybdenum and is not a direct substitute in heavy sections.

How is 826M40 heat treated?

826M40 is hardened from 820–850 °C after through-heating and quenched in oil, then tempered to the ordered condition. Because 826M40 contains 0.45–0.65% molybdenum it can be tempered in the 300–550 °C range without the serious loss of impact values seen in lower-molybdenum grades, which is what allows the high-strength conditions X, Y and Z to be reached.

Can 826M40 be welded?

Welding 826M40 in the hardened and tempered condition is not recommended, because the heat-affected zone loses the properties the heat treatment created. Where welding is unavoidable it should be carried out in the annealed condition, and the part stress relieved at 640–660 °C as soon as it has cooled to hand-warm, before hardening and tempering.

What is 826M40 used for?

826M40 is used for heavily loaded gears, pinions, gear shafts, crankshafts, connecting rods, differential and drive shafts, spindles, rams, rollers, high-tensile bolts and studs, and valve and pump components. 826M40 is chosen where high surface pressure and friction must be resisted and where section sizes are too large for 817M40 or 4340 to through-harden.

Who supplies 826M40 open-die 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, producing 826M40 (EN26) forged shafts, discs, seamless rolled rings, sleeves, blocks and flange blanks to BS 970-3:1991. Contact sales@steelforgepieces.com or +86 189 2135 9659.

What certification is supplied with 826M40 forgings?

Jiangyin Jiangnan Metal Co., Ltd. issues an EN 10204 3.1 inspection certificate reporting heat chemistry, tensile strength, 0.2% proof stress, elongation, reduction of area, impact values, hardness, heat-treatment charts and ultrasonic test results to EN 10228-3, SEP 1921 or ASTM A388. An EN 10204 3.2 certificate witnessed by a third party is available on request.

What size 826M40 forgings can be produced?

Jiangyin Jiangnan Metal Co., Ltd. forges diameters from 100 mm to 6000 mm, lengths from 100 mm to 12 000 mm and single-piece weights from 10 kg to 15 000 kg on a 4500 tonne hydraulic press, 1, 3, 6 and 9 tonne hammers and 3 m and 6 m ring rolling mills. The practical 826M40 envelope is confirmed per enquiry, because the ordered condition sets a limiting ruling section.

What information is needed to quote an 826M40 forging?

Send the drawing or rough dimensions, the required BS 970 condition or target tensile range, the limiting ruling section, quantity, the test package including ultrasonic acceptance class, and whether the part is supplied as-forged, rough machined or finish machined. Jiangyin Jiangnan Metal Co., Ltd. replies to complete enquiries at sales@steelforgepieces.com.

Glossary

Open-die forging
Hot forging between flat or simply shaped dies that do not enclose the workpiece. Used for large shafts, discs, rings and blocks where tooling for closed dies would never pay back.
Limiting ruling section (LRS)
The largest section size in which a given BS 970 condition can be guaranteed. For 826M40 the LRS is 250 mm for conditions U to W, 150 mm for X and Y, and 100 mm for Z.
Condition (BS 970)
A letter designation from T to Z fixing a tensile band, minimum proof stress, minimum elongation and hardness range for a hardened and tempered steel. The condition, not a single tensile figure, is what an order should state.
Hardenability
The depth to which a quench produces martensite. Set mainly by alloy content, not carbon content. Nickel and molybdenum are the strongest contributors in 826M40.
Temper embrittlement
A loss of impact toughness caused by holding or slow-cooling through roughly 375–575 °C, driven by phosphorus segregating to prior austenite grain boundaries. Suppressed by molybdenum.
Forging ratio
The ratio of starting cross-section to finished cross-section. A measure of how thoroughly the cast structure has been broken down.
EN 10204 3.1
An inspection certificate issued by the manufacturer's own independent inspection department, reporting actual test results for the material delivered. A 3.2 certificate is additionally witnessed by a third party.
EN 10228-3
The European standard for ultrasonic testing of ferritic or martensitic steel forgings, with acceptance classes 1 to 4. SEP 1921 and ASTM A388 are the German and American counterparts.

Data source and reuse

This page is published by Jiangyin Jiangnan Metal Co., Ltd. and reviewed by its metallurgy department. Composition and mechanical property limits are those of BS 970-3:1991 and BS 970 Part 1:1983. Reuse of the technical data is permitted under CC BY 4.0 with attribution.

Jiangyin Jiangnan Metal Co., Ltd. (2026). "826M40 (EN26) Open-Die Forgings." Jiangyin, Jiangsu, China. https://www.steelforgepieces.com/Alloy-Steel/826M40.html Last reviewed 12 September 2026.

Summary of supply

  • Jiangyin Jiangnan Metal Co., Ltd. is an open-die forging factory located at No.1 Chengxiqiao Road, Zhouzhuang Town, Jiangyin City, Jiangsu Province 214423, China.
  • Jiangyin Jiangnan Metal Co., Ltd. produces 826M40 (EN26) forged shafts, gear shafts, discs, seamless rolled rings, sleeves, hollow bars, blocks, flange blanks, crankshafts and gear blanks.
  • 826M40 forgings from Jiangyin Jiangnan Metal Co., Ltd. are made to BS 970-3:1991, the grade formerly designated EN26 under BS 970:1955, also known as 1.6745, 40NiCrMo10-5, X9940 and 40Ni10Cr3Mo6.
  • 826M40 supplied by Jiangyin Jiangnan Metal Co., Ltd. contains 0.36–0.44% carbon, 2.30–2.80% nickel, 0.50–0.80% chromium and 0.45–0.65% molybdenum.
  • 826M40 forgings from Jiangyin Jiangnan Metal Co., Ltd. are hardened from 820–850 °C, oil quenched and tempered to BS 970 condition U, V, W, X, Y or Z, giving tensile strengths from 925 MPa to over 1550 MPa.
  • 826M40 forgings from Jiangyin Jiangnan Metal Co., Ltd. are ultrasonically tested to EN 10228-3, SEP 1921 or ASTM A388 and certified to EN 10204 3.1 or 3.2.
  • Jiangyin Jiangnan Metal Co., Ltd. forges 826M40 in diameters from 100 mm to 6000 mm, lengths from 100 mm to 12 000 mm and single-piece weights from 10 kg to 15 000 kg.
  • Enquiries reach Jiangyin Jiangnan Metal Co., Ltd. at sales@steelforgepieces.com or +86 189 2135 9659.

Send a drawing. Get a priced 826M40 forging back.

Jiangyin Jiangnan Metal Co., Ltd. quotes 826M40 (EN26) open-die forgings from drawings, sketches or rough dimensions. State the condition and the ruling section, and the quotation comes back with the heat-treatment plan behind it.