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Resources/Materials & grades/20MnCr5

Materials & grades

20MnCr5 (1.7147) case-hardening steel: equivalents 5120, 20Mn5Cr5, SCr420 and SMnC420

20MnCr5 (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. The nearest US grade is 5120, India lists 20Mn5Cr5 in IS 4432, and Japan's closest are SCr420 and SMnC420.

Names by standard

What it is called in each region

RegionSystemDesignation規格Match
USAAISI/SAE5120Listed against 20MnCr5 by Saarstahl. 5120 has 0.70–0.90 % manganese and chromium, less than 20MnCr5.SAE J404Closest equivalent
EUEN 10027-1 name20MnCr5Carbon 0.17–0.22 %, manganese 1.10–1.40 %, chromium 1.00–1.30 %.EN 10084:2008Same material
EN 10027-2 number1.7147Material number of 20MnCr5.EN 10084Same material
EN 10027-1 name20MnCrS5 (1.7149)Same alloy with a controlled sulphur range (0.020–0.040 %) for machining.EN 10084Closest equivalent
インドIS 443220Mn5Cr5Carbon 0.17–0.22 %, manganese 1.00–1.40 %, chromium 1.00–1.30 %. Sulphur-controlled version is 20Mn5Cr5-S.IS 4432:1988Equivalent
JapanJIS G 4053SCr420Chromium 0.90–1.20 % but manganese only 0.60–0.90 %.JIS G 4053Closest equivalent
JIS G 4053SMnC420Manganese 1.20–1.50 % but chromium only 0.35–0.70 %.JIS G 4053Closest equivalent

On equivalence

  • 20MnCr5 and SAE 5120 are not equivalent in the strict sense. 5120 has 0.70–0.90 % manganese and chromium against 1.10–1.40 % manganese and 1.00–1.30 % chromium in 20MnCr5, so 20MnCr5 has much higher hardenability.
  • No British Standard grade is listed against 20MnCr5 by Saarstahl or Swiss Steel, so the UK region is left out here. UK buyers order 20MnCr5 to EN 10084. Some stockists quote 527M20 but that name could not be confirmed from a mill source.
  • India lists the grade as 20Mn5Cr5 in IS 4432, with manganese up to 1.40 % and 0.035 % maximum phosphorus against 0.025 % in EN 10084.
  • JIS G 4053 has no exact match. SCr420 has the chromium (0.90–1.20 %) but less manganese (0.60–0.90 %). SMnC420 has the manganese (1.20–1.50 %) but only 0.35–0.70 % chromium.
  • The chromium upper limit varies by source: EN 10084 gives 1.30 %, while an older Swiss Steel sheet prints 1.20 %.
  • 20MnCrS5 (1.7149) is the free-machining sulphur variant of the same alloy.
  • 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 %.

Chemical composition

Composition limits, mass %

Element5120USA · SAE J404 (as tabulated by Tubing China)20MnCr5 (1.7147)EU · EN 10084:200820MnCrS5 (1.7149)EU · EN 10084:200820Mn5Cr5インド · IS 4432:1988SCr420Japan · JIS G 4053SMnC420Japan · JIS G 4053
C0.17–0.220.17–0.220.17–0.220.17–0.220.18–0.230.17–0.23
Si—≤0.40≤0.400.15–0.350.15–0.350.15–0.35
Mn0.70–0.901.10–1.401.10–1.401.00–1.400.60–0.901.20–1.50
P≤0.035≤0.025≤0.025≤0.035≤0.030≤0.030
S≤0.040≤0.0350.020–0.040≤0.035≤0.030≤0.030
Cr0.70–0.901.00–1.301.00–1.301.00–1.300.90–1.200.35–0.70
Ni————≤0.25≤0.25

Mechanical properties

Strength and hardness

ConditionTensile strengthYield strengthElongationHardness
Soft annealed (+A), as suppliedSpecified maximum hardness, EN 10084 supply conditionSaarstahl and Swiss Steel data sheets———≤217 HB
Annealed to a hardness range (+TH)Specified hardness range, EN 10084 supply conditionSaarstahl and Swiss Steel data sheets———170–217 HB
Treated to ferrite-pearlite (+FP)Specified hardness range, EN 10084 supply conditionSaarstahl and Swiss Steel data sheets———152–201 HB
Core after hardening, tempered at 200 °CMinimum tensile strength, d ≤16 mmSaarstahl data sheet≥1200 MPa≥174 ksi———
Core after hardening, tempered at 200 °CMinimum tensile strength, d 16–40 mmSaarstahl data sheet≥1000 MPa≥145 ksi———
Core after hardening, tempered at 200 °CMinimum tensile strength, d 40–100 mmSaarstahl data sheet≥800 MPa≥116 ksi———
Blank hardened, typical (withdrawn DIN 17210 guide values)11 mm diameter, guide values onlySwiss Steel data sheet1080–1380 MPa157–200 ksi735 MPa107 ksi7 %—
Blank hardened, typical (withdrawn DIN 17210 guide values)30 mm diameter, guide values onlySwiss Steel data sheet980–1280 MPa142–186 ksi685 MPa99 ksi8 %—
Blank hardened, typical (withdrawn DIN 17210 guide values)63 mm diameter, guide values onlySwiss Steel data sheet780–1080 MPa113–157 ksi540 MPa78 ksi10 %—
Core of case-hardened test bar (20Mn5Cr5)16 mm diameter; tensile range, yield and elongation minimums; elongation on 5.65√A gaugeIS 4432:1988, Table 41000–1300 MPa145–189 ksi≥750 MPa≥109 ksi≥7 %—
Core of case-hardened test bar (20Mn5Cr5)30 mm diameter; tensile range, yield and elongation minimumsIS 4432:1988, Table 41000–1300 MPa145–189 ksi≥700 MPa≥102 ksi≥8 %—
Core of case-hardened test bar (20Mn5Cr5)63 mm diameter; tensile range, yield and elongation minimumsIS 4432:1988, Table 4800–1100 MPa116–160 ksi≥550 MPa≥80 ksi≥10 %—

In practice

Behaviour, heat treatment and uses

Characteristics

  • Nickel-free manganese-chromium steel for wear-loaded parts that need a core tensile strength of about 1000–1300 MPa (Saarstahl).
  • A widely used steel for gear parts and machine components that are machined first and carburized afterwards (Swiss Steel).
  • Higher hardenability than 16MnCr5, so it suits larger sections or higher core strength.
  • Swiss Steel describes it as generally weldable. Weld before carburizing.
  • Density 7.75 g/cm³, elastic modulus 210 GPa, thermal conductivity 42.0 W/(m·K) at 20 °C (Swiss Steel).
  • Transformation temperatures: Ms about 410 °C, Ac1 about 740 °C, Ac3 about 840 °C (Swiss Steel).

Heat treatment

  • Hot working: about 1100–850 °C (Saarstahl, Swiss Steel).
  • Normalizing: about 840–870 °C, cool in air (Saarstahl).
  • Soft annealing: about 650–700 °C, furnace cool (Saarstahl, Swiss Steel).
  • 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 (Saarstahl); Swiss Steel gives 850–880 °C for single hardening.
  • Case hardening: about 780–820 °C, oil (Saarstahl); IS 4432 gives 790–830 °C.
  • Tempering: about 150–200 °C (Saarstahl) or 170–210 °C (Swiss Steel).

主な用途

  • Gears, pinions and gearbox shafts
  • Camshafts and control parts
  • Piston pins, bushes and spindles
  • Transmission and general machine components under wear

Alloy and case-hardening steels

Similar grades compared

グレードC %Mn %Cr %Ni %Tensile, first listed condition
20MnCr50.17–0.220.70–0.900.70–0.90≤0.25≥1200 MPa
16MnCr50.13–0.180.70–0.900.70–0.90≤0.25≥1000 MPa
655M13 / EN36A0.08–0.130.45–0.651.00–1.403.00–3.50700–770 MPa
8620 / 20NiCrMo2-20.18–0.230.70–0.900.40–0.600.40–0.70530 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.

よくあるご質問

Common questions

What is the equivalent of 20MnCr5?

SAE 5120 is the nearest US grade, India lists 20Mn5Cr5 in IS 4432, and Japan's closest are SCr420 and SMnC420. None is exact: 5120 and SCr420 have lower manganese, and SMnC420 has much lower chromium.

Is 20MnCr5 the same as 5120?

No. 5120 has 0.70–0.90 % manganese and 0.70–0.90 % chromium, while 20MnCr5 has 1.10–1.40 % and 1.00–1.30 %. 20MnCr5 is the more hardenable steel.

What is the difference between 20MnCr5 and 16MnCr5?

20MnCr5 has more carbon, manganese and chromium. After case hardening its core reaches roughly 1000–1300 MPa, against about 800–1100 MPa for 16MnCr5.

What is 20MnCr5 used for?

Carburized gears, pinions, shafts, camshafts, piston pins and other transmission parts that need a hard surface and a strong core.

Is 20MnCr5 weldable?

It is generally weldable because of its low carbon content, but welding is best done before carburizing. A welded zone will not carburize and harden like the parent steel.

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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.8620 / 20NiCrMo2-28620 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.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.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.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. 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.
  2. Kobelco: wire rod and bar standard tables (JIS G 4053 alloy steels for machine structure) — JIS G 4053 composition tables (2008 revision).
  3. Saarstahl data sheet: 20MnCr5 / 20MnCrS5 — International designations, typical analysis, heat treatment, minimum tensile strength after hardening.
  4. Swiss Steel (Deutsche Edelstahlwerke) data sheet: 1.7147 / 1.7149 (20MnCr5 / 20MnCrS5) — Composition (2008 sheet), designations, supply hardness, typical core properties (from DIN 17210), heat treatment.
  5. Tubing China: chemical analysis of alloy steel (SAE J404 table) — 5120 limits; silicon not used because editions differ.
  6. ASM Alloy Digest SA-294: AISI 5120 chromium carburizing steel — Identifies 5120 as a low-carbon, low-chromium carburizing steel (abstract only).

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