---
title: "805M20 Forgings (SAE 8620) | Forged Rings, Bars, Gears & Shafts"
description: "805M20 (SAE 8620 / En362) forgings: 6,300 t open-die press, EAF+LF+VOD melted, 15 m well-type furnaces for long shafts. Rings, bars, gear blanks, shafts to 60 t."
canonical: https://www.steelforgepieces.com/Alloy-Steel/805M20.html
publisher: Jiangyin Jiangnan Metal Co., Ltd.
grade: 805M20
equivalents: SAE 8620, En362, 1.6523, 21NiCrMo2, 20NiCrMo2-2, 20NCD2, SNCM220, 20CrNiMo, G86200
standard: BS 970-3:1991
updated: 2026-09-12
---

# 805M20 Forgings: Forged Rings, Bars, Gear Blanks & Shafts

*Carburising Ni-Cr-Mo steel, open-die forged to drawing from 5 kg to 60 t*

Case-hardening alloy steel · BS 970-3:1991 805M20 · SAE 8620 · En362 · 1.6523

**805M20 is the BS 970 designation for a low nickel-chromium-molybdenum case-hardening steel, the
British equivalent of SAE 8620.** Carburised, oil quenched and tempered it carries a 58 to 62 HRC
case over a core that stays tough enough for shock loading, which is why gear makers have used it
for decades.

**Jiangyin Jiangnan Metal Co., Ltd.** is an open-die forging factory in Jiangyin, Jiangsu Province,
China that produces 805M20 as seamless rolled rings, forged rings, gear and pinion blanks, round
bars, shafts, flanges, discs, sleeves, bushings and tube sheets, made to customer drawing. The plant
melts this grade on a 25 t electric arc furnace with 25 and 50 t ladle furnaces and 30 and 60 t
vacuum oxygen decarburisation, forges on 6,300 t, 4,000 t and 2,000 t open-die presses, normalises
and anneals in its own 950 °C-class furnaces including two 15 m well-type furnaces for long shafts,
and tests in-house to EN 10228-3, SEP 1921 or ASTM A388 with EN 10204 3.1 or 3.2 certification.

| Key figure | Value |
| --- | --- |
| Case hardness after carburising and tempering | 58–62 HRC |
| Single-piece forged weight range | 5 kg – 60 t |
| Largest open-die press on site | 6,300 t |
| Well-type furnace depth for long shafts | 15 m |

---

## 805M20 at a glance

| Field | Value |
| --- | --- |
| 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 diameter | ⌀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., Jiangyin, Jiangsu, China |

Technical page maintained by Jiangyin Jiangnan Metal Co., Ltd. Last reviewed 12 September 2026.

---

## 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. 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 |

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.

| 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**.
- 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.

| Form | Description | Size range |
| --- | --- | --- |
| Seamless rolled rings | Radial-axial rolled from a punched, upset blank so the grain follows the circumference | OD 200–4,000 mm · height to 1,000 mm |
| Gear and pinion blanks | Left soft at 255 HB max for hobbing before the carburising cycle | OD 100–3,000 mm |
| Forged rings | Press-forged and bored where the section is too heavy or the ratio too short to roll | OD 100–3,000 mm |
| Shafts and spindles | Straight, stepped, flanged and eccentric shafts with full-length grain flow | ⌀ 60–1,600 mm · length to 14 m |
| Round bars | Drawn under the press, straightened, peeled or turned as required | ⌀ 20–1,200 mm · length to 12 m |
| Discs and disks | Upset discs for closures, blanks, coupling plates and gear blanks | ⌀ 100–2,500 mm |
| Forged flanges | Weld-neck, blind, slip-on and special profiles, forged and rough machined | 50–3,000 mm |
| Sleeves and bushings | Hollow forgings, trepanned or deep-hole bored to cut machining loss | OD 100–2,000 mm |
| Hollow bars and forged tubes | Thick-wall forged and bored hollows | OD 100–1,500 mm · bored to 10 m |

**Single-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.

---

## How 805M20 forgings are produced

Steps 1 to 7 are carried out on one site at Jiangyin. Carburising happens after machining, so it sits
with the gear cutter rather than with the forge.

1. **Melting: 25 t EAF + LF + VOD.** Electric 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.
2. **Electroslag remelting, optional.** 3 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.
3. **Open-die forging: 1,100–1,150 °C.** Soak, then forge on the 6,300 t, 4,000 t or 2,000 t press
   with a reduction ratio of at least 3:1. 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.
4. **Ring rolling or profiling.** Ring 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.
5. **Normalising 870–900 °C, annealing 860–900 °C.** Both 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.
6. **Machining.** Turned, bored or milled to your drawing with test-piece material and the UT
   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.
7. **Testing and certification.** Spark spectrometry, tensile, Charpy impact, hardness, grain size and
   metallography in the company laboratory. Ultrasonic testing to **EN 10228-3, SEP 1921 or
   ASTM A388**. 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

| 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

| 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.

| 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 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. What matters 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.

### 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 furnaces available 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.

### Machining

| 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

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, USM35XS, CTS-22 flaw detectors, for EN 10228-3, SEP 1921 and ASTM A388 |
| Magnetic particle testing | CYE-3A multipurpose crack detector |
| Chemical analysis | SPECTROTEST TXC25 spark spectrometer, X-Mwt3000TX handheld analyser, HIR-9440D infrared carbon and sulphur analyser, HC-II, TG328A balance |
| Tensile testing | WE-600B 600 kN hydraulic universal testing machine, WDW-300 electronic universal testing machine |
| Impact testing | JBN-300 pendulum impact tester, DWC-60 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 |
| Hardness | TH140 Leeb hardness tester |
| Bore and cavity inspection | DNJ industrial video endoscope |
| Specimen preparation | DK7720 CNC wire EDM, MYS7120 surface grinder, GJ-I 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

1. **Send the geometry.** A drawing in PDF, DWG or STEP is ideal. For rings, a size list of
   OD × ID × height is enough to quote.
2. **State quantity and delivery condition.** As forged, normalised, annealed, quenched and tempered,
   rough machined or finish machined.
3. **State testing and certification.** Which ultrasonic standard and acceptance class, and whether
   you need EN 10204 3.1 or a third-party 3.2 certificate.
4. **Name any governing specification.** If 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.
5. **Say whether you want it carburised.** Most buyers carburise after cutting the teeth. If you want
   the finished hardened part instead, say so and the cycle is arranged and priced in.
6. **Receive a quotation.** Enquiries 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.

### 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.

---

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Last reviewed 12 September 2026 by Jiangyin Jiangnan Metal Co., Ltd.