Steel 20MnCr4-2 +AC (Spheroidize annealed)
Heat-treated state
EN 20MnCr4-2
Pick for cold extrusion, cold heading or deep-drawing of blanks that will later be carburized.
Values for the +AC condition
Other 20MnCr4-2 tempers and conditions
20MnCr4-2 is listed in 6 conditions; see the grade overview at 20MnCr4-2.
Compare all 6 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
+ACThis page Spheroidize annealed | Pick for cold extrusion, cold heading or deep-drawing of blanks that will later be carburized. | 320 | 500 | 26 | 165 HB | — |
Heat treated to a specified hardness range | Order when uniform bar-to-bar hardness is needed for automatic machining lines and predictable tool life. | 350 | 570 | 21 | 170 HB | — |
+ADefault Annealed | Standard stock condition for bar and tube: softest general-purpose state before machining and carburizing. | 360 | 590 | 22 | 180 HB | — |
Supplied with specified hardenability | Specify when the case/core hardness after carburizing must be guaranteed; mechanical properties as delivered are those of the annealed bar. | 360 | 590 | 22 | 41 HRC | 8.5 % IACS |
Treated for high shearability | Choose for wire/bar that is cold-sheared into slugs: hardness held in a band that gives clean, burr-free cut faces. | 400 | 630 | 18 | 190 HB | — |
Carburized, hardened and low-temperature tempered | The in-service condition: hard 58–62 HRC case over a tough 30–40 HRC core for bearing raceways, gears and pins. | 660 | 950 | 11 | 60 HRC | — |
What is 20MnCr4-2 +AC?
20MnCr4-2 +AC is 20MnCr4-2 heat treated to +AC — pick for cold extrusion, cold heading or deep-drawing of blanks that will later be carburized. 20MnCr4-2 +AC has a yield strength of 320 MPa (46.4 ksi) and a tensile strength of 500 MPa (72.5 ksi) — weaker than 81% of steel grades. Elongation at break is 26% and the elastic modulus is 207 GPa (30 Msi). 20MnCr4-2 +AC has a density of 7.85 g/cm³ (0.284 lb/in³), heavier than 56% of steel grades. It melts at 1,425°C (2,597 °F). +A is the default condition FabDigit quotes; +AC is available on request or by drawing note.
Advantages
- Forms and bends easily — 75/100, better than 90% of steel grades
- Ductile — tolerates forming and impact — 26%, better than 82% of steel grades
- Polishes to a fine finish — 65/100, better than 78% of steel grades
Limitations
- Low strength — 320 MPa (46.4 ksi), worse than 81% of steel grades
20MnCr4-2 +AC properties
Typical room-temperature values for 20MnCr4-2 +AC; 13 are specific to this condition. Other listed values are 20MnCr4-2 reference data and may not represent this condition. Bars are the position among steel grades.
Physical3
20MnCr4-2 +AC has a density of 7.85 g/cm³ (0.284 lb/in³), heavier than 56% of steel grades. It melts at 1,425°C (2,597 °F).
Mechanical16
20MnCr4-2 +AC has a yield strength of 320 MPa (46.4 ksi) and a tensile strength of 500 MPa (72.5 ksi) — weaker than 81% of steel grades. Elongation at break is 26% and the elastic modulus is 207 GPa (30 Msi).
Thermal6
20MnCr4-2 +AC is rated for continuous service to 400°C (752 °F). It conducts heat at 44 W/m·K (25.4 BTU/hr·ft·°F), better than 57% of steel grades. Thermal expansion is 12.3 µm/m·K (6.83 µin/in·°F).
Electrical3
20MnCr4-2 +AC conducts electricity at 8.5 % IACS, better than 63% of steel grades.
Chemical & Environmental3
Corrosion resistance is not recommended (11/100), worse than 73% of steel grades.
Sustainability4
Producing a kilogram of 20MnCr4-2 +AC takes about 30 MJ of energy and emits 2.2 kg of CO₂ — more than 56% of steel grades. Typical recycled content is 30%.
Manufacturability8
20MnCr4-2 +AC's machinability is good (58/100, better than 75% of steel grades); weldability good (55/100); formability very good (75/100).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with 20MnCr4-2 +AC
Is 20MnCr4-2 easy to machine?
Machine in the +A/+AC/+TH soft condition (~60 % of 1212) and finish-grind after carburizing; expect gummy chips — use sharp positive geometry and coolant.
Can 20MnCr4-2 be welded?
Weldable before carburizing with low-hydrogen consumables and 150–250 °C preheat; welding after case hardening is not recommended.
Can 20MnCr4-2 be formed, bent or molded?
Spheroidized (+AC) bar cold-heads and cold-extrudes well; hot forge at 1100–850 °C followed by controlled cool or annealing.
What surface finishes work on 20MnCr4-2?
No anodizing — protect with phosphate + oil, black oxide, or zinc/Zn-Ni plating (bake to avoid hydrogen embrittlement); raceways are hard-turned or ground and honed.
20MnCr4-2 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 |
|---|---|---|
| C | 0.17 – 0.22 | 0.2 |
| Si | 0.15 – 0.4 | 0.25 |
| Mn | 0.9 – 1.2 | 1.05 |
| Cr | 0.3 – 0.6 | 0.45 |
| P | ≤ 0.03 | — |
| Smax; bearing-quality orders often ≤0.015 | ≤ 0.04 | — |
| Moresidual | ≤ 0.1 | — |
| Niresidual | ≤ 0.3 | — |
| Curesidual | ≤ 0.3 | — |
| Fe | balance | — |
20MnCr4-2 +AC — frequently asked
What is 20MnCr4-2 +AC used for?
20MnCr4-2 +AC is typically used for carburized bearing rings, rollers and small gears. In short: case-hardening bearing steel; weldable before carburizing; good cold-heading formability.
What is the yield strength of 20MnCr4-2 +AC?
20MnCr4-2 +AC has a typical yield strength of 320 MPa (46.4 ksi) and a tensile strength of 500 MPa (72.5 ksi) — weaker than 81% of steel grades. Strength varies by condition: see the 6 listed tempers.
Is 20MnCr4-2 +AC easy to machine?
Reasonably — machinability is rated good (58/100, better than 75% of steel grades). Machine in the +A/+AC/+TH soft condition (~60 % of 1212) and finish-grind after carburizing; expect gummy chips — use sharp positive geometry and coolant.
Can 20MnCr4-2 +AC be welded?
Yes — weldability is rated good (55/100). Weldable before carburizing with low-hydrogen consumables and 150–250 °C preheat; welding after case hardening is not recommended.
What surface finishes work on 20MnCr4-2 +AC?
No anodizing — protect with phosphate + oil, black oxide, or zinc/Zn-Ni plating (bake to avoid hydrogen embrittlement); raceways are hard-turned or ground and honed.
Can 20MnCr4-2 +AC be formed, bent or molded?
Spheroidized (+AC) bar cold-heads and cold-extrudes well; hot forge at 1100–850 °C followed by controlled cool or annealing.
What is the maximum service temperature of 20MnCr4-2 +AC?
20MnCr4-2 +AC is rated for continuous use to about 400°C (752 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
Sources
- EN ISO 683-17 — Heat-treatable steels, alloy steels: ball and roller bearing steels — ISO/CEN (2014)
- EN 10084 — Case hardening steels: technical delivery conditions — CEN (2008)
- ASM Handbook Vol.1 — Properties and Selection: Irons, Steels and High-Performance Alloys — ASM International (1990)
- ASM Handbook Vol.4 — Heat Treating (carburizing) — ASM International (1991)
- Case-hardening / bearing steel bar datasheets (1.3515, 20MnCr5 class) — European long-product mills (2023)
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.