Steel 20MnCrMo4-2 +A (Annealed)
Heat-treated state · default condition
EN 20MnCrMo4-2
Standard soft-annealed stock condition for general machining before carburizing.
Values for the +A condition
Other 20MnCrMo4-2 tempers and conditions
20MnCrMo4-2 is listed in 6 conditions; see the grade overview at 20MnCrMo4-2.
Compare all 6 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
Spheroidize annealed | Spheroidized carbide structure for maximum cold formability — cold extrusion, cold heading of gear blanks and pinions. | 350 | 560 | 24 | 170 HB | 8.5 % IACS |
Treated for high shearability | Softest-for-shearing delivery condition for bar that will be cold sheared to blanks or cold headed before carburizing. | 370 | 580 | 22 | 175 HB | 8 % IACS |
+ADefaultThis page Annealed | Standard soft-annealed stock condition for general machining before carburizing. | 400 | 620 | 20 | 195 HB | — |
Treated to ferrite-pearlite structure with specified hardness range | Choose when a uniform ferrite/pearlite microstructure and a narrow hardness band are needed for consistent high-speed machining and reproducible distortion. | 420 | 640 | 19 | 190 HB | 8 % IACS |
Heat treated to a specified hardness range | Supplied inside a contracted hardness band (typically ~170–217 HB) when tool life and machine loading must be predictable across lots. | 430 | 660 | 18 | 200 HB | 8 % IACS |
Hardenability-guaranteed (Jominy band); properties after carburize,… | Order +H when the Jominy hardenability band must be certified; the listed values are the finished case-hardened part (case 58–62 HRC, tempered ~180 °C, core ~11 mm section). | 950 | 1,250 | 9 | 60 HRC | — |
What is 20MnCrMo4-2 +A?
20MnCrMo4-2 +A is 20MnCrMo4-2 heat treated to +A — standard soft-annealed stock condition for general machining before carburizing. 20MnCrMo4-2 +A has a yield strength of 400 MPa (58 ksi) and a tensile strength of 620 MPa (89.9 ksi) — weaker than 60% of steel grades. Elongation at break is 20% and the elastic modulus is 210 GPa (30.5 Msi). 20MnCrMo4-2 +A has a density of 7.85 g/cm³ (0.284 lb/in³), heavier than 56% of steel grades. It melts at 1,420°C (2,588 °F).
Limitations
- Limited service temperature — 200°C (392 °F), worse than 93% of steel grades
20MnCrMo4-2 +A properties
Typical room-temperature values for 20MnCrMo4-2 +A; 12 are specific to this condition. Other listed values are 20MnCrMo4-2 reference data and may not represent this condition. Bars are the position among steel grades.
Physical3
20MnCrMo4-2 +A has a density of 7.85 g/cm³ (0.284 lb/in³), heavier than 56% of steel grades. It melts at 1,420°C (2,588 °F).
Mechanical16
20MnCrMo4-2 +A has a yield strength of 400 MPa (58 ksi) and a tensile strength of 620 MPa (89.9 ksi) — weaker than 60% of steel grades. Elongation at break is 20% and the elastic modulus is 210 GPa (30.5 Msi).
Thermal6
20MnCrMo4-2 +A is rated for continuous service to 200°C (392 °F). It conducts heat at 42 W/m·K (24.3 BTU/hr·ft·°F), worse than 56% of steel grades. Thermal expansion is 11.5 µm/m·K (6.39 µin/in·°F).
Electrical3
20MnCrMo4-2 +A conducts electricity at 8 % IACS, better than 55% of steel grades.
Chemical & Environmental3
Corrosion resistance is not recommended (12/100), worse than 53% of steel grades.
Sustainability4
Producing a kilogram of 20MnCrMo4-2 +A takes about 29 MJ of energy and emits 2.1 kg of CO₂ — less than 53% of steel grades. Typical recycled content is 25%.
Manufacturability8
20MnCrMo4-2 +A's machinability is good (55/100, better than 62% of steel grades); weldability fair (40/100); formability fair (50/100).
Common Calculations5
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with 20MnCrMo4-2 +A
Is 20MnCrMo4-2 easy to machine?
Machine fully in the soft (+A/+FP/+TH) condition with coated carbide at ~120–180 m/min; leave 0.1–0.3 mm grinding stock on gear/bearing surfaces, since after carburizing only grinding or hard turning with CBN is practical.
Can 20MnCrMo4-2 be welded?
Weldable only with care — CEV ≈ 0.6–0.7 means 200–300 °C preheat, low-hydrogen consumables and prompt stress relief; never weld carburized surfaces.
Can 20MnCrMo4-2 be formed, bent or molded?
Cold heading and extrusion are done in the +AC (spheroidized) or +S condition; hot forging 1100–1150 °C with slow cooling or immediate isothermal anneal to avoid bainite in heavy sections.
What surface finishes work on 20MnCrMo4-2?
Not anodizable; typical finishes are Mn/Zn phosphate, black oxide, oil, or zinc/zinc-nickel plating — bake after plating to avoid hydrogen embrittlement in the hardened case.
20MnCrMo4-2 chemical composition (wt %)
Limits by weight percent from the governing specification, written the way the spec states them — a single maximum for impurities, a range for alloying elements, and the base element as balance. Nominal is the typical mid-range value.
| Element | Spec limit (wt %) | Nominal |
|---|---|---|
| CEN 10084; GB 20CrMnMo 0.17–0.23 | 0.17 – 0.22 | 0.2 |
| SiGB grade specifies 0.17–0.37 | ≤ 0.4 | 0.25 |
| Mn | 0.9 – 1.2 | 1.05 |
| P | ≤ 0.03 | 0.02 |
| Slower S (≤0.010) for +S/controlled-sulphur variants | ≤ 0.04 | 0.02 |
| CrGB 20CrMnMo 1.10–1.40 | 0.9 – 1.2 | 1.05 |
| Mo | 0.2 – 0.3 | 0.25 |
| Niresidual | ≤ 0.3 | — |
| Curesidual | ≤ 0.3 | — |
| Fe | balance | — |
20MnCrMo4-2 +A — frequently asked
What is 20MnCrMo4-2 +A used for?
20MnCrMo4-2 +A is typically used for gears, bearing rings and heavy-duty shafts. In short: deeper hardening than 20CrMo4; heavy-section gear steel; limited weldability.
What is the yield strength of 20MnCrMo4-2 +A?
20MnCrMo4-2 +A has a typical yield strength of 400 MPa (58 ksi) and a tensile strength of 620 MPa (89.9 ksi) — weaker than 60% of steel grades. Strength varies by condition: see the 6 listed tempers.
Is 20MnCrMo4-2 +A easy to machine?
Reasonably — machinability is rated good (55/100, better than 62% of steel grades). Machine fully in the soft (+A/+FP/+TH) condition with coated carbide at ~120–180 m/min; leave 0.1–0.3 mm grinding stock on gear/bearing surfaces, since after carburizing only grinding or hard turning with CBN is practical.
Can 20MnCrMo4-2 +A be welded?
With care — weldability is rated fair (40/100). Weldable only with care — CEV ≈ 0.6–0.7 means 200–300 °C preheat, low-hydrogen consumables and prompt stress relief; never weld carburized surfaces.
What surface finishes work on 20MnCrMo4-2 +A?
Not anodizable; typical finishes are Mn/Zn phosphate, black oxide, oil, or zinc/zinc-nickel plating — bake after plating to avoid hydrogen embrittlement in the hardened case.
Can 20MnCrMo4-2 +A be formed, bent or molded?
Cold heading and extrusion are done in the +AC (spheroidized) or +S condition; hot forging 1100–1150 °C with slow cooling or immediate isothermal anneal to avoid bainite in heavy sections.
What is the maximum service temperature of 20MnCrMo4-2 +A?
20MnCrMo4-2 +A is rated for continuous use to about 200°C (392 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
Sources
- EN 10084 — Case hardening steels: technical delivery conditions — CEN (2008)
- GB/T 3077 — Alloy structural steels (20CrMnMo) — SAC (2015)
- Stahlschlüssel (Key to Steel) — Verlag Stahlschlüssel Wegst (2019)
- ASM Handbook Vol.1 — Properties and Selection: Irons, Steels and High-Performance Alloys — ASM International (1990)
- ASM Handbook Vol.4 — Heat Treating (carburizing of alloy steels) — ASM International (1991)
- 20CrMnMo — Mysteel / 1688 (2026)
Property data is compiled from published supplier and standards handbooks and normalised for comparison. Nothing on this page is a certification — request mill certs, CoC or material test reports with your order.