805M20 at a glance
- Grade
- 805M20
- Standard
- BS 970-3:1991
- Former BS
- En362 (BS 970:1955)
- SAE / AISI
- 8620
- UNS
- G86200
- Werkstoff
- 1.6523 / 21NiCrMo2
- EN 10084
- 20NiCrMo2-2
- Steel type
- Ni-Cr-Mo case hardening
- Carbon
- 0.17–0.23 %
- Case hardness
- 58–62 HRC
- Core Rm at 63 mm
- 690–930 MPa
- Delivery hardness
- 255 HB max, annealed
- Density
- 7.85 g/cm³
- Melt route
- EAF + LF + VOD, ESR optional
- Press force
- 6,300 t max
- Piece weight
- 5 kg to 60,000 kg
- Max turned dia.
- ⌀5,000 mm
- Max turned shaft
- ⌀1,600 mm × 14 m
- Ultrasonic testing
- EN 10228-3 / SEP 1921 / ASTM A388
- Certification
- EN 10204 3.1 or 3.2
- Minimum order
- One piece, no tooling cost
- Manufacturer
- Jiangyin Jiangnan Metal Co., Ltd.
Technical page maintained by Jiangyin Jiangnan Metal Co., Ltd. Last reviewed .
What is 805M20?
805M20 is a carburising grade specified in BS 970 Part 3:1991. The designation breaks down the way every BS 970 number does. The 800 series covers nickel-chromium-molybdenum steels, M means the steel is supplied to a chemical composition requirement, and 20 is the mean carbon content in hundredths of a percent. Before the 1970 revision the same steel was called En362, and a lot of older drawings still carry that number.
The alloy content is modest by design. Around 0.5 % chromium, 0.55 % nickel and 0.2 % molybdenum give enough hardenability to quench a useful core strength into sections up to about 63 mm, without pushing the price into 17CrNiMo6 territory. The nickel is what separates 805M20 from the plain chromium carburising steels such as 16MnCr5: it raises core toughness and shock resistance rather than surface hardness.
Carbon sits at 0.17 to 0.23 %. That is the whole point of the grade. A part machines easily in the annealed condition, then carbon is diffused into the surface during carburising and only the case hardens on quenching. The result is a wear surface at 58 to 62 HRC sitting on a core that will bend before it snaps.
Where 805M20 sits among carburising steels
16MnCr5 and 20MnCr5 sit below it. They cost less and work well on small parts, but they carry no nickel and lose core strength as the section grows. 17CrNiMo6 and 18CrNiMo7-6 sit above it, with roughly three times the chromium and enough hardenability for heavy wind turbine and mill gearing. 805M20 covers the middle: light to medium stressed components where surface wear resistance matters and the core still has to take impact.
805M20 designations, equivalents and standards
805M20, En362, SAE 8620 and UNS G86200 all describe the same steel. Enquiries arrive under all four names plus the German and Japanese numbers. Jiangyin Jiangnan Metal Co., Ltd. accepts orders under any of the designations below.
| System | Designation | Notes |
|---|---|---|
| BS 970-3:1991, UK | 805M20 | Current British designation |
| BS 970:1955, UK | En362 | Superseded, still quoted on legacy drawings |
| SAE / AISI, USA | 8620 | The name most enquiries arrive under |
| UNS, USA | G86200 | Unified Numbering System |
| ASTM A29 / A29M | 8620 | Bar product standard |
| DIN / Werkstoff | 21NiCrMo2 / 1.6523 | German material number |
| EN 10084 | 20NiCrMo2-2 | European case-hardening steel standard |
| AFNOR, France | 20NCD2 | NF A35-551 |
| JIS G4052, Japan | SNCM220 / SNCM220H | H grade has guaranteed hardenability |
| GB/T 3077, China | 20CrNiMo | Closest Chinese grade |
| AS 1444, Australia | 8620 / 8620H | Follows the SAE designation |
| Equivalents are close but not identical in every requirement. Where a drawing calls up a specific national standard, state it on the enquiry and it will be quoted to that standard. | ||
Chemical composition of 805M20
Composition limits follow BS 970 Part 3:1991. The aim column is the mid-range chemistry melted to for forging stock. Every heat is analysed on a SPECTROTEST TXC25 spark spectrometer in the company laboratory and the result is printed on the mill certificate.
| Element | Symbol | Specified range | Typical aim |
|---|---|---|---|
| Carbon | C | 0.17–0.23 | 0.20 |
| Silicon | Si | 0.10–0.35 | 0.25 |
| Manganese | Mn | 0.60–0.95 | 0.80 |
| Chromium | Cr | 0.35–0.65 | 0.50 |
| Nickel | Ni | 0.35–0.75 | 0.55 |
| Molybdenum | Mo | 0.15–0.25 | 0.20 |
| Phosphorus | P | ≤ 0.035 | — |
| Sulphur | S | ≤ 0.035 | — |
| Iron | Fe | balance | ~97.5 |
| Heat-specific chemistry is reported per element on the EN 10204 certificate supplied with every order. | |||
Tighter phosphorus and sulphur limits, controlled residuals for gear duty, or a guaranteed hardenability band in the manner of 8620H can be specified at enquiry stage. Where cleanliness governs, 805M20 can be electroslag remelted on the 3 t or 6 t inert-gas ESR furnaces.
Mechanical properties of 805M20
Core properties after carburising and oil quenching from about 840 °C, tempered at 150 to 200 °C. Strength drops as the ruling section grows, so state the section size that your property requirement applies to.
| Property | 11 mm section | 30 mm section | 63 mm section |
|---|---|---|---|
| Tensile strength Rm, MPa | 980–1270 | 780–1080 | 690–930 |
| Yield strength min, MPa | 785 | 590 | 490 |
| Elongation min, % | 9 | 10 | 11 |
| Charpy V-notch min, J | — | 41 | 41 |
| Core hardness, HB | 290–375 | 235–320 | 205–275 |
| Core hardness, HRC | 31–41 | 23–35 | 16–29 |
| Typical specification values, not guaranteed minima for a particular section. Acceptance values are agreed against your drawing before production. | |||
Case and delivery condition
- Case hardness after carburising, hardening and tempering: 58 to 62 HRC.
- Effective case depth: normally 0.5 to 2.5 mm, set by carburising time and temperature.
- As-forged, normalised or annealed delivery hardness: 255 HB maximum, which keeps the part easy to machine before heat treatment.
- Machinability runs at roughly 65 to 70 % of free-cutting B1112, best in the annealed condition.
- Nitriding will raise surface hardness without a carburising cycle. Flame and induction hardening give poor results because the carbon content is too low to respond.
- Supplied uncarburised and quench-and-tempered, 805M20 works as a medium-strength engineering steel.
Design note. On a carburised part the fatigue limit is governed by the case, the residual compressive stress under it and the surface finish, rather than by the core tensile figures above. Where a gear tooth root is the critical feature, specify the effective case depth at the root and the permitted retained austenite, and treat the core values as a secondary check.
Physical properties of 805M20
| Property | Metric | Imperial |
|---|---|---|
| Density | 7.85 g/cm³ | 0.284 lb/in³ |
| Modulus of elasticity | 205 GPa | 29.7 × 106 psi |
| Poisson's ratio | 0.29 | 0.29 |
| Thermal conductivity at 100 °C | 46.6 W/m·K | 26.9 Btu/hr·ft·°F |
| Specific heat capacity | 477 J/kg·K | 0.114 Btu/lb·°F |
| Thermal expansion, 20–100 °C | 11.1 µm/m·K | 6.2 µin/in·°F |
| Magnetic response | Ferromagnetic in every delivery condition | |
| Typical published values for low-alloy carburising steel. The mill certificate governs for acceptance. | ||
805M20 forged product forms and size ranges
Jiangyin Jiangnan Metal Co., Ltd. forges 805M20 to drawing rather than from a stock list. All forming is open-die, so there is no die cost and single-piece or small-batch orders are accepted. Send a drawing and the achievable size is confirmed on the quotation.
Seamless rolled rings
Radial-axial rolled from a punched, upset blank so the grain follows the circumference. The usual choice for ring gears and bearing races.
OD 200–4,000 mm · height to 1,000 mmGear and pinion blanks
Upset or rolled blanks with the machining allowance you specify, left soft at 255 HB max for hobbing before the carburising cycle.
OD 100–3,000 mmForged rings
Press-forged and bored where the section is too heavy or the ratio too short to roll on the mill.
OD 100–3,000 mmShafts and spindles
Straight, stepped, flanged and eccentric shafts and pinion shaft blanks drawn under the press with full-length grain flow.
⌀ 60–1,600 mm · length to 14 mRound bars
Drawn under the press, straightened, then peeled or turned as required and cut to the lengths your machining programme needs.
⌀ 20–1,200 mm · length to 12 mDiscs and disks
Upset discs for closures, blanks, coupling plates and gear blanks.
⌀ 100–2,500 mmForged flanges
Weld-neck, blind, slip-on and special profiles, forged and rough machined.
50–3,000 mmSleeves and bushings
Hollow forgings, trepanned or deep-hole bored to cut down the machining loss on a bored part.
OD 100–2,000 mmHollow bars and forged tubes
Thick-wall forged and bored hollows for cylinders, housings and long bored components.
OD 100–1,500 mm · bored to 10 mSingle-piece forged weight: 5 kg to 60,000 kg. Also produced in 805M20: valve stems, valve seat rings, blocks, nozzles, manifolds, crankshafts, forged wheels and rolls, and forged tube sheets. See forged and rolled rings, forged pipes and forging pieces for the full product range.
How 805M20 forgings are produced
Steps 1 to 6 are carried out on one site at Jiangyin. Carburising happens after machining, so it sits with the gear cutter rather than with the forge; see the note below step 6.
- Melting: 25 t EAF + LF + VODElectric arc melting, then 25 or 50 t ladle furnace for desulphurisation and composition trimming, then 30 or 60 t vacuum oxygen decarburisation for degassing and hydrogen control. Hydrogen matters on heavy 805M20 sections because it causes flake during cooling.
- Electroslag remelting, optional3 t or 6 t inert-gas protected ESR where the cleanliness requirement is severe. Remelting cuts non-metallic inclusions and centreline segregation, both of which show up in ultrasonic inspection to the tighter EN 10228-3 quality classes.
- Open-die forging: 1,100–1,150 °CSoak, then forge on the 6,300 t, 4,000 t or 2,000 t press with a reduction ratio of at least 3:1 to break down the as-cast structure. Finishing stops above about 850 °C. Small sections such as valve stems and seat rings go on the 750 kg to 5 t hammers instead, which gives better reduction and less material loss.
- Ring rolling or profilingRing blanks are punched, upset and rolled on the radial-axial mill. Bars, shafts and discs are drawn or upset under the press to the rough-machining envelope, then cooled slowly to avoid flake.
- Normalising 870–900 °C, annealing 860–900 °CBoth sit inside the range of the sixteen 950 °C-class furnaces on site. The largest bogie hearth measures 8.0 × 2.0 × 2.0 m. Long shafts go into the two RJ-9-850KW well-type furnaces, 15 m deep by ⌀1.5 m, hanging vertically so they do not sag. Annealing brings the forging to 255 HB maximum.
- MachiningTurned, bored or milled to your drawing with the test-piece material and the ultrasonic scanning surface left on. Vertical lathes reach ⌀5,000 mm, horizontal lathes ⌀1,600 mm × 14 m, and the CNC deep-hole drilling machine ⌀1,600 mm × 10 m.
- Testing and certificationSpark spectrometry, tensile, Charpy impact, hardness, grain size and metallography in the company laboratory. Ultrasonic testing to EN 10228-3, SEP 1921 or ASTM A388, magnetic particle inspection on request. Released with an EN 10204 3.1 mill certificate, or EN 10204 3.2 witnessed by TUV, BV, SGS or Lloyd's Register.
About carburising. Carburising, core refining, case hardening and tempering are done after the teeth are cut, so on a gear they belong with the gear cutter or the customer's own heat treater. 805M20 forgings leave Jiangyin as forged, normalised or annealed at 255 HB maximum, which is the condition the part has to be in for hobbing and turning. If you would rather buy the finished carburised part, say so at enquiry and the cycle is arranged by subcontract and written into the quotation.
What 805M20 forgings are used for
805M20 is specified where a surface has to resist wear and contact fatigue while the body of the part still has to survive impact. That puts it into gearing first, then into any rotating or reciprocating component that runs against another.
| Industry | Forged components | Why 805M20 |
|---|---|---|
| Power transmission | Ring gears, gear and pinion blanks, planet carriers, gearbox shafts, splined couplings | Hard case for tooth flank wear over a core that takes shock loading |
| Oil, gas and offshore | Drilling equipment, wellhead and Christmas tree parts, valve stems, seat rings, valve bodies | Wear resistance with a tough core, and a machinable annealed condition |
| Mining and cement | Mill pinions, crusher shafts, kiln roller shafts, conveyor and drive components | Survives abrasive duty and repeated impact without through-hardened brittleness |
| Pumps and compressors | Pump shafts, sleeves, wear rings, compressor gears and spacer bushings | Case depth can be tuned to the contact stress at each bearing position |
| Marine and shipbuilding | Reduction gear blanks, rudder stock components, winch and deck machinery parts, shaft couplings | Nickel content keeps core toughness at low service temperature |
| Bearings and rotating equipment | Seamless rolled rings, races, spacer rings, cam followers | Circumferential grain flow from ring rolling plus a carburised raceway |
| Heavy machinery | Forged wheels, rolls, eccentric shafts, crankshafts, press and mixer components | Cost-effective carburising grade for light to medium stressed parts |
805M20 compared with 16MnCr5, 20MnCr5, 18CrNiMo7-6 and 42CrMo4
805M20 usually comes up in one of two comparisons. Against the plain chromium carburising steels, the question is whether the extra nickel is worth paying for. Against 18CrNiMo7-6, the question is whether the section is heavy enough to need that much hardenability.
| Grade | C % | Cr % | Ni % | Mo % | Where it fits |
|---|---|---|---|---|---|
| 805M20 / SAE 8620 | 0.20 | 0.50 | 0.55 | 0.20 | Light to medium sections, good core toughness, moderate cost |
| 16MnCr5 / 1.7131 | 0.16 | 1.00 | — | — | Small parts, cheapest route, core strength falls away in thick sections |
| 20MnCr5 / 1.7147 | 0.20 | 1.15 | — | — | Higher core strength than 16MnCr5, still no nickel for shock duty |
| 17CrNiMo6 / 1.6587 | 0.17 | 1.60 | 1.50 | 0.30 | Heavy gearing, high hardenability, noticeably more expensive |
| 18CrNiMo7-6 / 1.6587 | 0.18 | 1.65 | 1.50 | 0.28 | Wind turbine and mill gears, large modules, heaviest sections |
| 42CrMo4 / 1.7225 | 0.42 | 1.05 | — | 0.22 | Through-hardening alternative where no carburised case is wanted |
| Composition figures are nominal and given for orientation. Grade selection for a gear or a safety-critical part should be made against the applicable design code and the rating calculation rather than from a summary table. | |||||
Machining, carburising and welding notes
Machining
Machine 805M20 in the annealed or normalised condition at 255 HB maximum, before any carburising cycle. It cuts predictably at roughly 65 to 70 % of free-cutting B1112. Leave the grinding stock you need on every carburised surface and keep the allowance uniform, because an uneven allowance grinds through a thin case at the high spots. Anything that must stay soft, such as a bore that will be press-fitted, needs copper plating or stop-off paint before the part goes into the furnace.
Carburising
Carburise at 900 to 930 °C. Time at temperature sets the case depth, and surface carbon should land near 0.8 % for the best combination of hardness and toughness. Push surface carbon higher and retained austenite and carbide networks start to appear, which cost fatigue strength. On deep cases, sub-zero treatment after quenching converts retained austenite and adds a few points of hardness. Specify the effective case depth and the hardness value that defines it, usually 550 HV, rather than a total case depth.
Welding
805M20 welds without difficulty in the annealed or normalised condition using low-hydrogen consumables. Preheat to 150 to 200 °C on heavy sections and stress relieve afterwards. Do not weld a carburised part: the high-carbon case cracks. Any welding has to be finished before the part goes for carburising.
Hot working
Forge between 1,100 and 1,150 °C and stop above about 850 °C. Cool slowly from the forging heat, then normalise before machining. Heavy sections benefit from a slow furnace cool rather than a pile cool.
805M20 forging capability
For 805M20 the limiting factor is the ingot from the electric arc route rather than press force, and for long shafts it is the well-type furnace rather than the lathe. Both limits are given below with the equipment that sets them.
| Parameter | Capability | Set by |
|---|---|---|
| Ingot weight | to 60,000 kg | 25 t EAF, 25/50 t LF, 30/60 t VOD |
| Single-piece forged weight | approx. 5 kg – 60,000 kg | Ingot size, less top and bottom discard |
| Open-die press force | 6,300 t / 4,000 t / 2,000 t | Three hydraulic open-die presses |
| Hammer forging | 750 kg – 5 t hammers | Five hammers, for small and medium sections |
| Normalising and annealing | 860 – 900 °C | Sixteen 950 °C-class bogie-hearth and well-type furnaces |
| Largest heat-treated part | 8,000 × 2,000 × 2,000 mm | RTX-9-810KW bogie-hearth furnace |
| Longest shaft heat treated | 15 m deep × ⌀1.5 m | Two RJ-9-850KW well-type furnaces, hung vertically |
| Max turned diameter | ⌀5,000 mm | ⌀5000 vertical lathe |
| Max turned shaft | ⌀1,600 mm × 14,000 mm | CW61160 × 14 m horizontal lathe |
| Max deep-hole bored length | ⌀1,600 mm × 10,000 mm | CNC deep-hole drilling machine |
| Minimum order quantity | One piece | Open-die forging, no dedicated tooling required |
| Delivery conditions | As-forged · normalised · annealed · quenched and tempered · rough machined · finish machined | |
| Figures are the capability envelope of the plant. The achievable size and weight for a specific 805M20 part depend on its geometry, the forging reduction ratio and the acceptance class of the ultrasonic test. This is confirmed at enquiry. | ||
Melting and refining
805M20 is an air-melted low-alloy steel, so the electric arc route carries it. Vacuum induction melting is reserved for the aluminium and titanium bearing superalloys, where those elements would oxidise in air. What matters for 805M20 is the ladle furnace for sulphur control and the VOD for hydrogen, because hydrogen left in a heavy section causes flake as the forging cools.
| Process | Installed capacity | Role for 805M20 |
|---|---|---|
| EAF, electric arc furnace | 25 t | Primary melt |
| LF, ladle furnace | 25 t and 50 t | Desulphurisation, temperature and composition trimming |
| VOD, vacuum oxygen decarburisation | 30 t and 60 t | Degassing, hydrogen and sulphur removal |
| ESR, inert-gas electroslag remelting | 3 t and 6 t | Optional remelt where gear-quality cleanliness is specified |
| IF, medium-frequency induction | 2 t, 8 t, 25 t | Supporting melt capacity |
| VIM, vacuum induction melting | 3 t | Not used for 805M20; reserved for Al and Ti bearing superalloys |
| VAR, vacuum arc remelting | 6 t | Not used for 805M20 |
| Twelve melting and remelting furnaces in total. State on the enquiry whether your specification requires an ESR remelt. | ||
Open-die forging equipment
| Machine | Force | Qty |
|---|---|---|
| Hydraulic open-die press | 6,300 t | 1 |
| Hydraulic open-die press | 4,000 t | 1 |
| Hydraulic open-die press | 2,000 t | 1 |
| Forging hammer | 5 t | 1 |
| Forging hammer | 3 t | 1 |
| Forging hammer | 2 t | 1 |
| Forging hammer | 1 t | 1 |
| Forging hammer | 750 kg | 1 |
| Small 805M20 sections such as valve stems and seat rings are forged on the hammers rather than the presses, which gives better forging reduction and less material loss. | ||
Heat treatment: why the well-type furnaces matter for 805M20
805M20 normalises at 870 to 900 °C and anneals at 860 to 900 °C, both comfortably inside the 950 °C-class furnaces. The three 1200 °C furnaces are not needed for this grade, which leaves sixteen furnaces available for it. The pair of 15 m well-type furnaces is the useful part: a long 805M20 pinion shaft hangs vertically and comes out straight, instead of sagging across a bogie hearth and needing straightening afterwards.
| Furnace | Working chamber | Rating | Qty |
|---|---|---|---|
| RTX-9-810KW bogie hearth | 8.0 × 2.0 × 2.0 m | 950 °C | 2 |
| RTX-9-900KW bogie hearth | 6.0 × 3.5 × 2.3 m | 950 °C | 1 |
| RTX-9-720 bogie hearth | 5.5 × 3.0 × 1.8 m | 950 °C | 2 |
| RTX-9-530KW bogie hearth | 8.0 × 1.5 × 1.2 m | 950 °C | 2 |
| RTX-9-430 bogie hearth | 6.5 × 1.5 × 1.1 m and 5.5 × 1.5 × 1.1 m | 950 °C | 2 |
| RJ-9-850KW well type, vertical | 15 m deep × ⌀1.5 m | 950 °C | 2 |
| RTX-12-350KW bogie hearth | 3.5 × 1.3 × 1.1 m | 1200 °C | 3 |
| Nineteen furnaces in total. The 1200 °C units are listed for completeness; 805M20 does not need them, so furnace availability for this grade is not affected by superalloy work. | |||
Machining
805M20 forgings can be supplied rough machined or finish machined. Buying the part rough machined keeps the machining allowance predictable and means the ultrasonic scanning surface is prepared before the forging leaves.
| Machine | Capacity | Qty |
|---|---|---|
| Vertical lathe | ⌀5,000 mm | 1 |
| Vertical lathe | ⌀3,500 mm | 1 |
| Vertical lathe | ⌀2,500 mm | 4 |
| Horizontal lathe CW61180 | ⌀1,800 mm × 8 m | 3 |
| Horizontal lathe CW61140 | ⌀1,400 mm × 8 m | 2 |
| Horizontal lathe CW61160 / CW61125 | ⌀1,600 mm × 14 m and ⌀1,250 mm × 10 m | 1 |
| CNC lathe | ⌀2,000 mm × 10,000 mm | 1 |
| CNC lathe | ⌀2,000 mm × 8,000 mm | 1 |
| CNC lathe | ⌀1,600 mm × 3,300 mm | 3 |
| CNC deep-hole drilling machine | ⌀1,600 mm × 10,000 mm | 1 |
| Eighteen machines. The deep-hole drilling machine is used for long hollow sleeves, bushings and bored shafts, which avoids the material loss of trepanning. | ||
In-house testing laboratory
Chemistry, mechanical testing, metallography and non-destructive testing are all carried out in the company's own laboratory. Results do not wait on an outside lab, and a non-conforming part is found before it ships. For 805M20 the metallurgical microscope matters more than usual, because it is what measures austenitic grain size and, on a carburised sample, the effective case depth.
| Discipline | Equipment and standard |
|---|---|
| Ultrasonic testing | PXUT-3300 full-digital flaw detector, USM35XS digital flaw detector, CTS-22 flaw detector, for EN 10228-3, SEP 1921 and ASTM A388 |
| Magnetic particle testing | CYE-3A multipurpose crack detector |
| Chemical analysis | SPECTROTEST TXC25 mobile spark spectrometer, X-Mwt3000TX handheld alloy analyser, HIR-9440D infrared carbon and sulphur analyser, HC-II high-speed digital analyser, TG328A analytical balance |
| Tensile testing | WE-600B 600 kN hydraulic universal testing machine, WDW-300 microcomputer-controlled electronic universal testing machine |
| Impact testing | JBN-300 pendulum impact tester, DWC-60 low-temperature bath to −60 °C, CST-50 Charpy projector, VU-2D notch broaching machine |
| Metallography | XJP-6A microscope, XQ-2B mounting press, M-2 pre-grinder, P-2 polisher, for grain size to ASTM E112 and case depth measurement |
| Hardness | TH140 Leeb hardness tester |
| Bore and cavity inspection | DNJ industrial video endoscope |
| Specimen preparation | DK7720 CNC wire EDM, MYS7120 surface grinder, GJ-I sealed sample grinder, 101-2A drying oven, QZLRY-3000 calorimeter |
| Twenty-six instruments. If your specification requires witnessed testing, name the inspection body on the purchase order and an EN 10204 3.2 certificate is issued against their endorsement. | |
How to request an 805M20 quotation
- Send the geometryA drawing in PDF, DWG or STEP is ideal. For rings, a size list of OD × ID × height is enough to quote.
- State quantity and delivery conditionAs forged, normalised, annealed, quenched and tempered, rough machined or finish machined.
- State testing and certificationWhich ultrasonic standard and acceptance class, and whether you need EN 10204 3.1 or a third-party 3.2 certificate.
- Name any governing specificationIf the drawing calls up SAE 8620, En362, 1.6523, 20NiCrMo2-2 or SNCM220 rather than 805M20, say so and it will be quoted to that standard.
- Say whether you want it carburisedMost buyers carburise after cutting the teeth. If you want the finished hardened part instead, say so and the cycle is arranged and priced in.
- Receive a quotationEnquiries sent to sales@steelforgepieces.com are normally answered within one working day.
Frequently asked questions about 805M20
What is 805M20 steel?
805M20 is a low nickel-chromium-molybdenum case-hardening alloy steel specified in BS 970 Part 3:1991. It carries nominally 0.20 % carbon, 0.50 % chromium, 0.55 % nickel and 0.20 % molybdenum. Carburised, quenched and tempered it gives a wear-resistant case of 58 to 62 HRC over a core that stays tough, which is why it is a standard grade for gears, pinions, shafts and bearing components.
What is 805M20 equivalent to?
805M20 is equivalent to SAE/AISI 8620 and UNS G86200 in the American system, En362 under the older BS 970:1955, 21NiCrMo2 and Werkstoff 1.6523 in the German system, 20NiCrMo2-2 in EN 10084, 20NCD2 in French AFNOR, SNCM220 and SNCM220H in JIS G4052, and 20CrNiMo in Chinese GB/T 3077. These are nearest equivalents and the composition limits differ slightly between standards.
What is the chemical composition of 805M20?
To BS 970-3:1991, 805M20 contains 0.17 to 0.23 % carbon, 0.10 to 0.35 % silicon, 0.60 to 0.95 % manganese, 0.35 to 0.65 % chromium, 0.35 to 0.75 % nickel and 0.15 to 0.25 % molybdenum, with phosphorus and sulphur each held to 0.035 % maximum. Iron is the balance.
Is 805M20 a case-hardening or a through-hardening steel?
805M20 is a case-hardening grade. At 0.17 to 0.23 % carbon it will not through-harden to high hardness. It can be supplied uncarburised in the hardened and tempered condition as a medium-strength engineering steel, and it will take a nitrided surface. It responds poorly to flame and induction hardening because the carbon content is too low.
What case hardness can 805M20 reach?
Carburised at 900 to 930 °C, oil quenched and tempered at 150 to 200 °C, 805M20 reaches a case hardness of 58 to 62 HRC. Core tensile strength falls with section size, running about 980 to 1270 MPa at an 11 mm ruling section, 780 to 1080 MPa at 30 mm and 690 to 930 MPa at 63 mm.
Do you carburise 805M20 forgings?
Carburising is carried out after machining, so it normally sits with the gear cutter or the customer's heat treater rather than with the forge. Jiangyin Jiangnan Metal Co., Ltd. supplies 805M20 forgings as forged, normalised or annealed at 255 HB maximum, which is the condition the part needs to be in for hobbing and turning. Carburising, core refining, case hardening and tempering can be arranged by subcontract if you would rather buy the finished part.
What is the maximum size and weight of an 805M20 forging?
Single-piece forged weight runs from about 5 kg up to 60,000 kg. The ingot comes from a 25 t electric arc furnace with 25 and 50 t ladle furnaces and 30 and 60 t vacuum oxygen decarburisation. Forging is on 6,300 t, 4,000 t and 2,000 t open-die presses plus five hammers from 750 kg to 5 t. Machining reaches ⌀5,000 mm turned diameter, shafts of ⌀1,600 mm by 14 m and deep-hole boring of ⌀1,600 mm by 10 m.
The achievable size for a specific part depends on its geometry, the forging reduction ratio and the ultrasonic acceptance class, and is confirmed at enquiry. See forging capability.
Can you heat treat long 805M20 shafts?
Yes. 805M20 normalises at 870 to 900 °C and anneals at 860 to 900 °C, both inside the range of the sixteen 950 °C-class furnaces on site. Two RJ-9-850KW well-type furnaces take shafts up to 15 m long by ⌀1.5 m hanging vertically, which avoids the distortion a long shaft picks up lying in a bogie-hearth furnace. The largest bogie hearth measures 8.0 × 2.0 × 2.0 m.
Is testing of 805M20 forgings done in-house?
Yes. Chemistry, mechanical testing, metallography and NDT are all in the company's own laboratory: three ultrasonic flaw detectors (PXUT-3300, USM35XS and CTS-22) for EN 10228-3, SEP 1921 and ASTM A388, CYE-3A magnetic particle testing, SPECTROTEST TXC25 spark spectrometry, a 600 kN WE-600B universal testing machine, a JBN-300 pendulum impact tester with a DWC-60 bath for testing to −60 °C, and an XJP-6A metallurgical microscope for grain size and case depth measurement.
Is 805M20 weldable?
805M20 welds without difficulty in the annealed or normalised condition using low-hydrogen consumables. Preheat to 150 to 200 °C on heavy sections and stress relieve afterwards. Do not weld a carburised part, because the high-carbon case will crack. Any welding has to be completed before the carburising cycle.
What certification comes with 805M20 forgings?
Every 805M20 forging is released with an EN 10204 3.1 mill test certificate covering heat number, chemistry, mechanical properties and heat-treatment records. EN 10204 3.2 certification witnessed by a third party such as TUV, BV, SGS or Lloyd's Register is available on request, as is ultrasonic testing to EN 10228-3, SEP 1921 or ASTM A388.
What is the density of 805M20?
The density of 805M20 is approximately 7.85 g/cm³, which is 0.284 lb/in³. Modulus of elasticity is about 205 GPa, thermal conductivity about 46.6 W/m·K, and the steel is ferromagnetic in every delivery condition.
How do I get a price for an 805M20 forging?
Send the drawing or the finished dimensions, the quantity, the delivery condition and any test or certification requirements to sales@steelforgepieces.com, or call +86 189 2135 9659. Jiangyin Jiangnan Metal Co., Ltd. is at No.1 Chengxiqiao Road, Zhouzhuang Town, Jiangyin City, Jiangsu Province, China. Because forging is open die there is no tooling cost and single-piece orders are accepted.
About the manufacturer
Jiangyin Jiangnan Metal Co., Ltd. is an open-die forging works at No.1 Chengxiqiao Road, Zhouzhuang Town, Jiangyin City, Jiangsu Province, China, producing forgings in carbon steel, alloy steel, tool steel, stainless steel and nickel-based superalloys including 805M20. The works sits on the south bank of the Yangtze between Shanghai and Nanjing, in the centre of China's forging and special-steel industry.
Melting, forging, heat treatment, machining and testing are carried out on one site rather than subcontracted. For 805M20 this keeps the melt record, the forging reduction and the heat treatment record under a single certificate.
| Area | Installed |
|---|---|
| Melting and remelting | 12 furnaces: 25 t EAF, 25/50 t LF, 30/60 t VOD, 3 t VIM, 6 t VAR, 3 t and 6 t inert-gas ESR, 2/8/25 t induction |
| Forging | 8 machines: 6,300 t, 4,000 t and 2,000 t presses; 5 t, 3 t, 2 t, 1 t and 750 kg hammers |
| Heat treatment | 19 furnaces, including two 15 m well-type furnaces and three 1200 °C-rated high-temperature furnaces |
| Machining | 18 machines: vertical lathes to ⌀5,000 mm, CNC to ⌀2,000 × 10,000 mm, deep-hole boring to ⌀1,600 × 10,000 mm |
| Testing laboratory | 26 instruments: 3 UT flaw detectors, MPI, spark and XRF spectrometry, 600 kN tensile, impact to −60 °C, metallography |
| Because forging is open die rather than closed die, there is no tooling cost and single-piece orders are accepted. Full equipment list available on request. | |
Data source and citation
Technical data on this page is published by the manufacturer and may be quoted with attribution. Suggested citation:
Jiangyin Jiangnan Metal Co., Ltd. “805M20 Forgings (SAE 8620 / En362): composition, properties, forged product forms and plant capability.” steelforgepieces.com, Jiangyin, Jiangsu, China. Updated 12 September 2026.
https://www.steelforgepieces.com/Alloy-Steel/805M20.html
Supplier of record: Jiangyin Jiangnan Metal Co., Ltd., No.1 Chengxiqiao Road, Zhouzhuang Town, Jiangyin City, Jiangsu Province, China. Tel +86 189 2135 9659. Email sales@steelforgepieces.com. Composition and property ranges follow published BS 970-3:1991 and SAE 8620 data. The mill certificate supplied with each forging governs for acceptance.