817M37 Alloy Steel Forgings (BS 970 Ni-Cr-Mo Grade)
817M37 is a through-hardening alloy steel in BS 970, the British standard. It contains about 1 % nickel, 1 % chromium and 0.2 % molybdenum, with a nominal carbon content of 0.37 %. The closest European equivalent is 36CrNiMo4, material number 1.6511. The closest American equivalent is AISI/SAE 9840. It is specified for parts that have to be hardened and tempered through a large section, such as heavy shafts, gear and pinion shafts, spindles, rolled rings and forged discs.
Jiangyin Jiangnan Metal Co., Ltd. is an open-die forging factory in Jiangyin, Jiangsu Province, China. We forge 817M37 to customer drawings as round and flat bars, seamless rolled rings, forged rings, discs, blocks, hollow bars, sleeves, cylinders, gear shafts and pinion shafts. Material is supplied with an EN 10204 3.1 certificate.
What the designation 817M37 means
Each part of a BS 970 grade number carries information. That is why 817M37, 817A37 and 817M40 are closely related grades but are not interchangeable.
817A37 is the same steel ordered against a chemical analysis rather than mechanical properties. 817M40 (EN24) is a higher-carbon, higher-alloy steel in the same family.
817M37 at a glance
- Standard
- BS 970 (United Kingdom)
- Steel type
- Ni-Cr-Mo through-hardening alloy steel
- Nominal carbon
- 0.37 % (range 0.32–0.40 %)
- European equivalent
- 36CrNiMo4 / 1.6511
- American equivalent
- AISI/SAE 9840
- Supply condition
- +QT, +N or annealed (+A)
- Annealed hardness
- 241 HBW maximum
- Certification
- EN 10204 3.1 / 3.2
817M37 equivalent grades
The grades below are the ones normally accepted as nearest equivalents. They are close but not identical. Composition ranges, permitted residuals and test requirements all differ between standards. Confirm any substitution against the current issue of your specification before material is released.
| Standard / country | Designation | Relationship |
|---|---|---|
| BS 970 (UK) | 817M37 | Reference grade on this page |
| BS 970 (UK) | 817A37 | Same steel, ordered to chemical analysis |
| EN 10083-3 / DIN (Europe) | 36CrNiMo4 (W.Nr. 1.6511) | Closest equivalent |
| AISI / SAE (USA) | 9840 | Closest equivalent |
| AISI / SAE (USA) | 4337 | Comparable, higher nickel |
| JIS (Japan) | SNCM439 | Comparable |
| AFNOR (France) | 35NCD6 | Comparable |
| GB/T 3077 (China) | 40CrNiMoA | Comparable |
| GOST (Russia) | 38KhN3MA | Comparable, higher nickel |
Chemical composition of 817M37
Percentage by mass, iron the balance. Steel is supplied from electric-arc furnace with ladle refining. Vacuum degassing is available where hydrogen and inclusion levels are critical.
| C | Si | Mn | Ni | Cr | Mo | P | S |
|---|---|---|---|---|---|---|---|
| 0.32–0.40 | 0.40 max | 0.50–0.80 | 0.90–1.20 | 0.90–1.20 | 0.15–0.30 | 0.035 max | 0.035 max |
The nickel, chromium and molybdenum content is what gives this steel its hardenability. A 300 mm forged shaft can be quenched and tempered to a consistent structure from surface to core.
Mechanical properties of 817M37 in the quenched and tempered (+QT) condition
Values are indicative for the quenched and tempered condition. They fall as section size increases, because the cooling rate at the core of a thick forging is lower. Acceptance values for a specific order are agreed before production and reported on the material certificate.
Heavy forged sections
| Property | up to 160 mm | 160–330 mm | 330–660 mm |
|---|---|---|---|
| Rm tensile strength (MPa) | 750 | 700 | 650 |
| Re yield strength, min. (MPa) | 550 | 500 | 450 |
| Elongation at fracture A, min. longitudinal (%) | 14 | 15 | 16 |
Bar and thin sections
| Property | up to 8 mm | 8–20 mm | 20–50 mm | 50–80 mm |
|---|---|---|---|---|
| Rm tensile strength (MPa) | 1100 | 1000 | 900 | 800 |
| ReH yield strength, min. (MPa) | 900 | 800 | 700 | 600 |
| Elongation at fracture A, min. longitudinal (%) | 10 | 11 | 12 | 13 |
Impact energy, transverse ductility and hardness
| Property | Condition | Value |
|---|---|---|
| Charpy V-notch impact energy KV, longitudinal | +QT, tested at +20 °C | 35–45 J |
| Charpy V-notch impact energy KV, transverse | +QT, tested at +20 °C | 25–27 J |
| Elongation at fracture A, transverse | +QT | 10–12 % |
| Brinell hardness | Annealed (+A) | 241 HBW max |
Transverse values are lower than longitudinal because the forging fibre runs along the length of the piece. If a component is loaded across the grain, for example the section of a rolled ring, state this at enquiry stage so the forging route and test-piece orientation can be planned.
Heat treatment of 817M37
Typical route for 817M37 forgings. Exact temperatures and soak times depend on section thickness, the required strength band and the furnace charge. They are set by our heat-treatment procedure for each order.
- Forging. Heat to 1150–1180 °C; finish forging above 850 °C, then cool slowly in still air or in a cooling pit for heavy sections.
- Normalizing. 850–880 °C, soak through section, cool in air. Refines the as-forged grain before hardening.
- Annealing. 650–700 °C, cool slowly in the furnace, giving a machinable structure at 241 HBW maximum.
- Hardening. Austenitize at 830–860 °C, soak through section, quench in oil.
- Tempering. 540–660 °C to the required strength band, then cool in air. Avoid tempering in the 250–450 °C range, where this steel family is prone to temper embrittlement.
- Stress relieving. 550–650 °C after heavy machining or welding, cooled slowly, to release residual stress before final machining.
Nitriding and induction hardening can both be applied to 817M37 after the core has been quenched and tempered, where a hard running surface is needed on a shaft or journal.
817M37 forged products we manufacture
All shapes below are open-die forged to customer drawings at our Jiangyin factory, then heat treated, machined and inspected in house. We do not work to catalogue sizes.
| Forged shape | Also called | Typical parts |
|---|---|---|
| Round bars | Rods, forged shafts | Shaft blanks, machined shafts |
| Square, rectangular and flat bars | Blocks, flats, hexagon bars | Die blocks, machine bases, levers |
| Seamless rolled rings | Rolled rings, ring blanks | Bearing races, gear rims, flange blanks |
| Forged rings | Mandrel-forged rings | Slewing rings, retaining rings |
| Hollow bars and sleeves | Bushings, bushes, pipes, tubes, barrels, casings, shells, cylinders | Cylinder bodies, bushings, housings |
| Discs, blocks and plates | Disks, forged plate, hubs, housings | Gear blanks, hubs, cover plates |
| Gear shafts and pinion shafts | Spindles, stepped shafts, rotor shafts | Gearbox shafts, mill pinions, spindles |
| Forged flanges | Flange forgings, ring blanks | Pipeline and vessel flanges |
Surface condition: as-forged (black), shot-blasted, rough turned or finish machined. Non-standard shapes, stepped shafts and near-net-shape forgings are quoted from a drawing or a 3D model.
817M37 compared with 817M40 (EN24) and AISI 4340
These three grades are often confused with one another. The practical difference is hardenability and the strength that can be reached in a heavy section. Carbon and nickel both rise from 817M37 to 817M40 to 4340, and with them the limiting section that can still be hardened through.
| Element / attribute | 817M37 | 817M40 (EN24) | AISI 4340 |
|---|---|---|---|
| Carbon, % | 0.32–0.40 | 0.36–0.44 | 0.38–0.43 |
| Nickel, % | 0.90–1.20 | 1.30–1.70 | 1.65–2.00 |
| Chromium, % | 0.90–1.20 | 1.00–1.40 | 0.70–0.90 |
| Molybdenum, % | 0.15–0.30 | 0.20–0.35 | 0.20–0.30 |
| Closest EN grade | 36CrNiMo4 / 1.6511 | 34CrNiMo6 / 1.6582 | 34CrNiMo6 / 1.6582 |
| Relative hardenability | Good | Higher | Highest of the three |
| Choose it when | Section is moderate and cost matters | A heavy section must be hardened through | The drawing calls out a US specification |
Composition figures are indicative and taken from the respective standards. Confirm against the current issue before substituting one grade for another.
Typical applications for 817M37 forgings
817M37 is used for parts under heavy repeated load that are too large to rely on a case-hardened surface:
- Heavy transmission shafts, rotor shafts and line shafts
- Gear shafts, pinion shafts and gear blanks
- Machine tool spindles and quills
- Crankshafts and connecting rods
- Mining, crushing and rolling-mill components
- Hydraulic cylinder bodies, piston rods and end caps
- Wind turbine gearbox and main shaft components
- Drilling and downhole tool bodies
Open-die forging capability at Jiangyin Jiangnan Metal
Our factory is at No.1 Chengxiqiao Road, Zhouzhuang Town, Jiangyin City, Jiangsu Province, China, in the Yangtze River Delta. Shanghai Port is about two hours away by road.
| Process | What we do |
|---|---|
| Open-die forging | Hydraulic open-die presses, upsetting, drawing out, punching and mandrel work |
| Ring rolling | Seamless rolled rings from pierced and expanded blanks |
| Heat treatment | Normalizing, annealing, quenching and tempering; oil and water quench tanks; recorded furnace charts |
| Machining | CNC turning, boring and milling; rough machined and finish machined forgings |
| Testing | Spectrometer chemical analysis, tensile, impact and hardness testing, ultrasonic testing, magnetic particle inspection |
| Certification | EN 10204 3.1 as standard, 3.2 with third-party witness |
Inspection, testing and certification
Every 817M37 forging is traceable to its heat number. Standard supply includes an EN 10204 3.1 inspection certificate covering ladle analysis, heat-treatment condition, mechanical test results and dimensional report. Third-party witnessed inspection to EN 10204 3.2 by TÜV, SGS, BV, Lloyd's Register or a customer's own inspector is available on request, and must be arranged before heat treatment begins.
Ultrasonic testing to an agreed acceptance class, magnetic particle inspection, grain size, inclusion rating and low-temperature impact testing can all be added to the test plan at enquiry stage.
Frequently asked questions about 817M37
What is 817M37 steel?
817M37 is a British Standard BS 970 through-hardening alloy steel with about 1 % nickel, 1 % chromium and 0.2 % molybdenum, and a nominal 0.37 % carbon. It is supplied hardened and tempered and is used for heavily loaded components such as shafts, gears, spindles and forged rings.
What is the equivalent of 817M37 in European and American standards?
The closest European equivalent is 36CrNiMo4, material number 1.6511, under EN 10083-3. The closest American equivalent is AISI/SAE 9840; AISI 4337 is comparable but carries more nickel. In Japan the comparable grade is SNCM439, in France 35NCD6, and in China 40CrNiMoA. These are nearest equivalents rather than exact substitutes.
What does the M in 817M37 mean?
In the BS 970 numbering system the middle letter states how the steel is ordered. M means the steel is supplied against mechanical property requirements, A means it is supplied against a chemical analysis, and H means it is supplied against hardenability requirements. So 817M37 and 817A37 are the same steel bought two different ways.
What is the chemical composition of 817M37?
Carbon 0.32–0.40 %, silicon 0.40 % maximum, manganese 0.50–0.80 %, nickel 0.90–1.20 %, chromium 0.90–1.20 %, molybdenum 0.15–0.30 %, phosphorus 0.035 % maximum and sulphur 0.035 % maximum, with iron the balance.
How is 817M37 heat treated?
Forge at 1150–1180 °C and finish above 850 °C. Normalize at 850–880 °C and air cool. Harden by austenitizing at 830–860 °C followed by an oil quench, then temper at 540–660 °C to the required strength band. Annealing at 650–700 °C with a slow furnace cool gives a machinable structure at 241 HBW maximum. Avoid tempering between 250 °C and 450 °C, where this steel family is susceptible to temper embrittlement.
What is the difference between 817M37 and 817M40 (EN24)?
They belong to the same BS 970 nickel-chromium-molybdenum family, but 817M40 carries more carbon (0.36–0.44 % against 0.32–0.40 %) and more nickel (1.30–1.70 % against 0.90–1.20 %). That gives 817M40 higher strength and better hardenability, so it holds its properties through a thicker section. 817M37 is the lower-cost choice where the section is moderate.
Can 817M37 be welded?
It is difficult to weld and welding is not recommended in the hardened and tempered condition. Where welding is unavoidable, weld in the annealed condition with preheat around 250–300 °C, low-hydrogen consumables and interpass control, then apply a full post-weld heat treatment and re-qualify the mechanical properties. In most cases a one-piece forging is preferable to a fabrication.
What certification is supplied with 817M37 forgings?
Standard supply is an EN 10204 3.1 inspection certificate with the heat number, ladle analysis, heat-treatment condition, mechanical test results and dimensional report. EN 10204 3.2 certification witnessed by TÜV, SGS, BV, Lloyd's Register or a customer inspector is available if it is requested at order stage.
Who supplies 817M37 forgings from China?
Jiangyin Jiangnan Metal Co., Ltd., an open-die forging factory at No.1 Chengxiqiao Road, Zhouzhuang Town, Jiangyin City, Jiangsu Province, China, manufactures 817M37 forgings to drawing, including bars, seamless rolled rings, discs, blocks, hollow sections, gear shafts and pinion shafts. Enquiries: sales@steelforgepieces.com or +86 189 2135 9659.
What information do you need to quote an 817M37 forging?
A drawing or dimensioned sketch, the quantity, the supply condition and strength band you need, whether you want as-forged or machined, any testing beyond the standard certificate, and your destination port. With those we can normally return a quotation within one to two working days.
Request a quotation for 817M37 forgings
Send a drawing and we will quote a price, a forged weight and a delivery date. If the grade is not settled yet, send the duty and the section size and we will advise between 817M37, 817M40 and 42CrMo4.
Open-die forging factory
Jiangyin City, Jiangsu Province, China
Related alloy steel grades
Data sources and revision
Published by Jiangyin Jiangnan Metal Co., Ltd., open-die forging factory, Jiangyin, Jiangsu, China. Reviewed by our technical department. Last reviewed .
Composition and mechanical data on this page are compiled from BS 970, from EN 10083-3 for the equivalent grade 36CrNiMo4 (1.6511), and from our own works test records. Figures are indicative and given to assist material selection. They do not replace the current issue of the relevant standard or an order-specific acceptance specification.