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Resources/Materials & grades/8620 / 20NiCrMo2-2

Materials & grades

8620 / 20NiCrMo2-2 / SNCM220 case-hardening steel: equivalents 805M20 (EN362) and 20Ni2Cr2Mo2

8620 is a low-alloy nickel-chromium-molybdenum steel with about 0.20 % carbon, supplied for carburizing to give a hard case over a tough core in gears, shafts and pins. Its equivalents are 20NiCrMo2-2 (1.6523) in Europe, 805M20 (old EN362) in the UK, 20Ni2Cr2Mo2 in India and SNCM220 in Japan.

Names by standard

What it is called in each region

RegionSystemDesignationNormaMatch
USAAISI/SAE8620SAE J404; ASTM A29 / A322Same material
UNSG86200—Same material
UKBS 970805M20Listed against 8620 by Vulcan and Elgin. BS 970 has been withdrawn in favour of European standards.BS 970-3:1991Equivalent
BS 970 (1955 EN series)EN362Superseded 1955 name for 805M20.—Equivalent
BS 970805H20Variant with a guaranteed hardenability band. Ovako lists 805H22 for the same family.BS 970 (older parts; not in BS 970-3:1991)Closest equivalent
EUEN 10027-1 name20NiCrMo2-2Carbon 0.17–0.23 %, nickel 0.40–0.70 %, chromium 0.35–0.70 %.EN 10084:2008Equivalent
EN 10027-2 number1.6523Material number of 20NiCrMo2-2.EN 10084Equivalent
EN 10027-1 name20NiCrMoS2-2 (1.6526)Same alloy with a controlled sulphur range for machining.EN 10084Closest equivalent
DIN (legacy)21NiCrMo2Superseded German name for 1.6523, still seen on older drawings.DIN 1654-3Equivalent
IndieIS 443220Ni2Cr2Mo2Composition is essentially that of 8620. IS 4432 is the Indian case-hardening steel standard.IS 4432:1988Equivalent
JapanJIS G 4053SNCM220Carbon 0.17–0.23 %, manganese 0.60–0.90 %, nickel 0.40–0.70 %, chromium 0.40–0.60 %, molybdenum 0.15–0.25 %.JIS G 4053Equivalent
JIS G 4052SNCM220HHardenability-guaranteed version of SNCM220.JIS G 4052Closest equivalent
JIS (old designation)SNCM21Superseded Japanese name for SNCM220, still printed on older data sheets.—Equivalent

On equivalence

  • 8620 and 20NiCrMo2-2 are close equivalents, not the same specification. 20NiCrMo2-2 allows chromium 0.35–0.70 % and manganese 0.65–0.95 % against 8620's 0.40–0.60 % and 0.70–0.90 %, and EN 10084 caps phosphorus and sulphur lower (0.025 % and 0.035 % against 0.035 % and 0.040 %).
  • UK sources name 805M20 (BS 970-3:1991) and the old EN362. Saarstahl also lists 806M20, Ovako lists 805H22 and Elgin lists 805H20. The H grades add a guaranteed hardenability band. 805M20 is the most consistently cited.
  • 20NiCrMoS2-2 (1.6526) is the same alloy with a defined sulphur range for machining, so it is an equivalent for ordering purposes but not identical in sulphur.
  • IS 4432 calls this grade 20Ni2Cr2Mo2. Its limits match SAE 8620 apart from phosphorus and sulphur, which are both capped at 0.035 %.
  • SNCM220 (JIS G 4053) closely matches 8620. SNCM220H (JIS G 4052) adds a hardenability band. SNCM21 is the superseded Japanese name.
  • 16MnCr5 and 20MnCr5 are not substitutes. They are nickel-free manganese-chromium steels with a different hardenability and core strength.
  • The EN 10084 limits here are those of EN 10084:2008 (silicon ≤0.40 %). ISO 683-3:2019 gives silicon 0.15–0.40 % and copper ≤0.40 %.
  • Sources differ on 8620 silicon in the SAE J404 row: AZoM and H2ABC (ASTM A29) give 0.15–0.35 %, while Elgin and Engineering Toolbox give 0.15–0.30 %.

Chemical composition

Composition limits, mass %

Element8620USA · SAE J404805M20UK · BS 970-3:1991, Table 15 (as also listed by Textron)20NiCrMo2-2 (1.6523)EU · EN 10084:200820Ni2Cr2Mo2Indie · IS 4432:1988SNCM220Japan · JIS G 4053
C0.18–0.230.17–0.230.17–0.230.18–0.230.17–0.23
Si0.15–0.350.10–0.40≤0.400.15–0.350.15–0.35
Mn0.70–0.900.60–0.950.65–0.950.70–0.900.60–0.90
P≤0.035≤0.040≤0.025≤0.035≤0.030
S≤0.040≤0.050≤0.035≤0.035≤0.030
Cr0.40–0.600.35–0.650.35–0.700.40–0.600.40–0.60
Ni0.40–0.700.35–0.750.40–0.700.40–0.700.40–0.70
Mo0.15–0.250.15–0.250.15–0.250.15–0.250.15–0.25

Mechanical properties

Strength and hardness

ConditionTensile strengthYield strengthElongationHardness
Annealed (+A), as suppliedSpecified maximum hardness, EN 10084 supply conditionSaarstahl and Ovako data sheets———≤212 HB
Annealed, typicalTypical values, not minimumsAZoM, AISI 8620 (UNS G86200)530 MPa77 ksi385 MPa56 ksi—149 HB
Normalized, 13 mm roundTypical values, not minimumsElgin Alloy Steel Grade 8620 fact sheet635 MPa92 ksi360 MPa52 ksi26 (50 mm gauge) %183 HB
Core after carburizing, hardened, tempered at 200 °C (20NiCrMo2-2)Minimum tensile strength, d ≤16 mmSaarstahl data sheet≥1100 MPa≥160 ksi———
Core after carburizing, hardened, tempered at 200 °C (20NiCrMo2-2)Minimum tensile strength, d 16–40 mmSaarstahl data sheet≥800 MPa≥116 ksi———
Core after carburizing, hardened, tempered at 200 °C (20NiCrMo2-2)Minimum tensile strength, d 40–100 mmSaarstahl data sheet≥700 MPa≥102 ksi———
Core of case-hardened test bar (20Ni2Cr2Mo2)16 mm diameter; tensile range, yield and elongation minimums; elongation on 5.65√A gaugeIS 4432:1988, Table 4850–1200 MPa123–174 ksi≥600 MPa≥87 ksi≥8 %—
Core of case-hardened test bar (20Ni2Cr2Mo2)30 mm diameter; tensile range, yield and elongation minimumsIS 4432:1988, Table 4800–1150 MPa116–167 ksi≥550 MPa≥80 ksi≥9 %—
Core of case-hardened test bar (20Ni2Cr2Mo2)63 mm diameter; tensile range, yield and elongation minimumsIS 4432:1988, Table 4750–1050 MPa109–152 ksi≥520 MPa≥75 ksi≥10 %—

In practice

Behaviour, heat treatment and uses

Characteristics

  • Low-carbon nickel-chromium-molybdenum steel meant to be carburized: the case reaches up to about 62 HRC while the core stays tough (Vulcan).
  • Ovako describes it for very highly strained parts with a core tensile strength of 700–900 MPa, and as suitable for direct hardening.
  • Swiss Steel notes that 20NiCrMo2-2 is used for many carburized automotive and general machine parts, especially in North America under the name SAE 8620.
  • Swiss Steel describes 20NiCrMo2-2 as generally weldable. Welding is normally done before carburizing.
  • Machinability is rated 65 on the scale where AISI 1212 is 100, hot rolled and cold drawn (AZoM).
  • Transformation temperatures: Ac1 about 730 °C, Ac3 about 830 °C, Ms about 440 °C (Swiss Steel); Ovako gives Ac1 723 °C, Ac3 827 °C and Ms 400 °C.

Heat treatment

  • Hot working: about 1100–850 °C (Saarstahl, Swiss Steel); IS 4432 gives 1150–850 °C for its grades.
  • Normalizing: about 850–880 °C (Saarstahl) or 860–890 °C (Ovako), cool in air.
  • Soft annealing: about 650–700 °C, furnace cool (Saarstahl); Ovako gives 600–670 °C for 2 hours.
  • Carburizing: about 880–980 °C (Saarstahl); Swiss Steel recommends 900–950 °C and IS 4432 gives 890–940 °C.
  • Core hardening: about 860–900 °C, oil or water (Saarstahl); IS 4432 gives 830–870 °C for 20Ni2Cr2Mo2.
  • Case hardening: about 780–820 °C, oil or water (Saarstahl, IS 4432).
  • Direct hardening from carburizing: about 850–880 °C (Swiss Steel); IS 4432 gives 810–840 °C for single hardening.
  • Tempering: about 150–200 °C (Saarstahl) or 170–210 °C (Swiss Steel).

Typické použití

  • Gears, pinions and crown wheels
  • Driving bevel gears and transmission shafts
  • Camshafts, splined shafts and arbors
  • Pins, bushings, sleeves and ratchets
  • Chain pins and fasteners that need a hard surface

Alloy and case-hardening steels

Similar grades compared

JakostC %Mn %Cr %Ni %Tensile, first listed condition
8620 / 20NiCrMo2-20.18–0.230.70–0.900.40–0.600.40–0.70530 MPa
16MnCr50.13–0.180.70–0.900.70–0.90≤0.25≥1000 MPa
20MnCr50.17–0.220.70–0.900.70–0.90≤0.25≥1200 MPa
655M13 / EN36A0.08–0.130.45–0.651.00–1.403.00–3.50700–770 MPa
93100.08–0.130.45–0.651.00–1.403.00–3.501289 MPa
4130 / 25CrMo40.28–0.330.40–0.600.80–1.10≤0.25590–760 MPa
4135 / 34CrMo40.33–0.380.70–0.900.80–1.10≤0.251000–1200 MPa
4140 / 42CrMo40.38–0.430.75–1.000.80–1.10≤0.25655 MPa
4340 / EN240.38–0.430.60–0.800.70–0.901.65–2.00745 MPa
5140 / 41Cr40.38–0.430.70–0.900.70–0.90≤0.25570 MPa

Composition from the US standard where one exists, otherwise the first standard listed on each grade's page. Strength conditions differ between grades; open a grade for its full table.

Odpovědi na Vaše otázky

Common questions

What is the equivalent of 8620 steel?

20NiCrMo2-2 (1.6523) in Europe, 805M20 (old EN362) in the UK, 20Ni2Cr2Mo2 under IS 4432 in India and SNCM220 in Japan. These are close equivalents with slightly different chromium, manganese and impurity limits.

Is 8620 the same as 20NiCrMo2-2?

Not exactly. Both are carburizing nickel-chromium-molybdenum steels, but 20NiCrMo2-2 allows 0.35–0.70 % chromium and 0.65–0.95 % manganese, and EN 10084 sets tighter phosphorus and sulphur limits. They are normally treated as interchangeable.

Is 8620 weldable?

It is a low-carbon steel and is generally weldable, but welds and heat-affected zones will not carburize or harden like the parent metal. Weld first, then carburize and harden.

What hardness can 8620 reach after carburizing?

The case can reach up to about 62 HRC. The core stays much softer and tougher, with a tensile strength of roughly 700–900 MPa for typical sections according to Ovako.

What is the difference between 8620 and 4140?

8620 has about 0.20 % carbon and is carburized to harden only the surface. 4140 has about 0.40 % carbon and is hardened through its section by quenching and tempering.

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93109310 is a nickel-chromium-molybdenum carburizing steel with about 0.10 % carbon and 3.25 % nickel, used for highly stressed aerospace gears and shafts.16MnCr516MnCr5 (1.7131) is a manganese-chromium case-hardening steel with 0.14–0.19 % carbon, used for gears, shafts and camshafts that are carburized and hardened.20MnCr520MnCr5 (1.7147) is a manganese-chromium case-hardening steel with 0.17–0.22 % carbon and a higher core strength than 16MnCr5, used for gears, shafts and cam parts.655M13 / EN36A655M13, formerly EN36A, is a UK case-hardening steel with about 3.25 % nickel and 0.8 % chromium, used for heavily loaded gears and shafts in large sections.4140 / 42CrMo4AISI 4140 is a medium-carbon chromium-molybdenum alloy steel, normally used hardened and tempered for shafts, gears and high-strength bolts.4340 / EN24AISI 4340 is a medium-carbon nickel-chromium-molybdenum alloy steel, used hardened and tempered where high strength and toughness are needed in large sections.10181018 is a low-carbon, non-alloy steel with 0.15–0.20 % carbon and 0.60–0.90 % manganese, widely used as cold-drawn bar for machined and case-hardened parts.Quenching and temperingQuenching and tempering hardens steel by cooling it rapidly from the austenite range to form martensite, then reheats it below Ac1 to trade some hardness for toughness.AnnealingAnnealing heats steel to a set temperature, holds it and cools it slowly to make it softer, more ductile and easier to machine or cold form.NormalizingNormalizing heats steel above its upper critical temperature and lets it cool in still air to give a fine, uniform ferrite–pearlite structure.SAE / AISI numbersA four-digit SAE/AISI number such as 1045 or 4140 names a carbon or alloy steel by its chemistry: the first two digits identify the steel family and the last two give the nominal carbon content in hundredths of a percent.EN 10027 names and numbersEuropean steels carry two identifiers under EN 10027: a steel name (Part 1) such as S235JR, C45 or 42CrMo4 that describes the steel's use or chemistry, and a material number (Part 2) such as 1.0503 or 1.7225.BS 970 and the EN seriesBS 970 names steels with a six-character code such as 080M40, in which the first three digits give the steel type, the letter says how the steel is specified and the last two digits give the carbon content.IS 1570 and Indian designationsIndian steel names follow the letter-symbol code in IS 1762 (Part 1), which the IS 1570 schedules use: 45C8 means about 0.45% carbon, C for carbon steel and about 0.8% manganese, while alloy names such as 40Cr4Mo3 list each element with a multiplied content figure.JIS steel designationsJapanese JIS steel symbols start with S for steel and add letters for the steel family or its use, but the number means different things in different standards.

References

Sources

  1. SAE J404: Chemical compositions of SAE alloy steels — Governs the 8620 composition limits; values here as tabulated by AZoM.
  2. IS 4432:1988 Case hardening steels (public copy) — Grades, composition (Table 1), core properties of case-hardened test bars (Table 4) and heat-treatment guidance.
  3. Kobelco: wire rod and bar standard tables (JIS G 4053 alloy steels for machine structure) — JIS G 4053 composition tables (2008 revision).
  4. Saarstahl data sheet: 20NiCrMo2-2 / 20NiCrMoS2-2 — International designations, typical analysis, heat treatment, minimum tensile strength after hardening.
  5. Swiss Steel (Deutsche Edelstahlwerke) data sheet: 1.6523 / 1.6526 — EN 10084 composition, supply hardness, transformation temperatures, heat treatment.
  6. Ovako Steel Navigator: 20NiCrMoS2-2 (similar designations include 20NiCrMo2-2 and SAE 8620) — Sulphur-controlled variant; similar designations, core strength guidance and heat treatment.
  7. AZoM: AISI 8620 alloy steel (UNS G86200) — Composition, annealed properties, machinability and cross-references.
  8. ASM Alloy Digest SA-879: SAE 8620, 8620H, 8620RH, CEN ISO 20NiCrMo2-2 — Groups 8620, 20NiCrMo2-2 and SNCM220 as carburizing steels (abstract only).
  9. Elgin: Alloy Steel Grade 8620 fact sheet — Normalized properties and cross-references (BS 805M20 and 805H20, JIS SNCM21, DIN 1.6523).
  10. Vulcan Engineering Steels: case hardening steels (8620) — Lists 805M20, EN362, SNCM220H, composition and uses. Its silicon and sulphur limits for 805M20 differ from BS 970-3:1991 (see the BS 970-3 and Textron entries).
  11. BS 970-3:1991 Table 15, alloy case hardening steels (BSI) — 805M20 silicon 0.10–0.40 %, phosphorus 0.04 % max and sulphur 0.05 % max.
  12. Textron Steel Alloys: 805M20 round bars — 805M20 composition to BS 970-3:1991 (silicon up to 0.40 %, phosphorus 0.040 % max, sulphur 0.050 % max).

Values summarize published limits and typical data. The governing standard and the current edition control; check them before specifying.