Steel 20MC5 +A (Annealed)
Heat-treated state · default condition
EN 20MC5
Standard stock condition for bar and wire: best machinability and cold-forging behaviour before carburizing.
Values for the +A condition
Other 20MC5 tempers and conditions
20MC5 is listed in 9 conditions; see the grade overview at 20MC5.
Compare all 9 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
Treated for cold shearing / cold heading | Wire and bar softened for cold shearing, cold heading and cold extrusion of gear and shaft blanks. | 360 | 560 | 25 | 165 HB | 7.8 % IACS |
+ADefaultThis page Annealed | Standard stock condition for bar and wire: best machinability and cold-forging behaviour before carburizing. | 400 | 620 | 22 | 200 HB | — |
Treated to hardness range | Order when the purchase spec fixes a delivery hardness band for machining consistency rather than a microstructure. | 410 | 630 | 21 | 190 HB | 7.8 % IACS |
Treated to ferrite–pearlite structure and hardness range | Pick when a controlled, uniform FP microstructure and hardness band is needed for consistent high-speed machining. | 420 | 640 | 20 | 180 HB | 7.8 % IACS |
Normalized | Use to refine forging or hot-rolled grain and homogenize before carburizing, reducing heat-treat distortion. | 440 | 680 | 20 | 210 HB | 7.8 % IACS |
Hot rolled | Cheapest mill condition for forging stock or parts that will be fully heat treated after machining. | 450 | 700 | 18 | 215 HB | 7.8 % IACS |
Cold drawn | Choose for close-tolerance bright bar used in automatic-lathe production of pins, shafts and small gear blanks. | 600 | 750 | 11 | 20 HRC | 7.8 % IACS |
Q&T | For thin sections or non-carburized parts needing uniform medium strength and toughness rather than a hard case. | 750 | 1,050 | 12 | 34 HRC | — |
Case hardened | The service condition for gears and splines: hard wear-resistant case with a tough 30–42 HRC core; properties below are core values with case hardness given as HRC. | 800 | 1,150 | 10 | 60 HRC | — |
What is 20MC5 +A?
20MC5 +A is 20MC5 heat treated to +A — standard stock condition for bar and wire: best machinability and cold-forging behaviour before carburizing. 20MC5 +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 22% and the elastic modulus is 210 GPa (30.5 Msi). 20MC5 +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
20MC5 +A properties
Typical room-temperature values for 20MC5 +A; 10 are specific to this condition. Other listed values are 20MC5 reference data and may not represent this condition. Bars are the position among steel grades.
Physical3
20MC5 +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).
Mechanical14
20MC5 +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 22% and the elastic modulus is 210 GPa (30.5 Msi).
Thermal6
20MC5 +A is rated for continuous service to 200°C (392 °F). It conducts heat at 44 W/m·K (25.4 BTU/hr·ft·°F), better than 57% of steel grades. Thermal expansion is 11.7 µm/m·K (6.5 µin/in·°F).
Electrical2
20MC5 +A has an electrical resistivity of 2.2×10⁻⁷ Ω·m.
Chemical & Environmental2
Corrosion resistance is not recommended (10/100), worse than 86% of steel grades.
Sustainability4
Producing a kilogram of 20MC5 +A takes about 29 MJ of energy and emits 2.1 kg of CO₂ — less than 53% of steel grades. Typical recycled content is 30%.
Manufacturability8
20MC5 +A's machinability is good (55/100, better than 62% of steel grades); weldability fair (40/100); formability good (60/100).
Common Calculations5
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with 20MC5 +A
Is 20MC5 easy to machine?
Machine in the +A/+FP condition (~180–217 HB) with coated carbide; after carburizing only grinding, honing or hard turning with CBN is practical.
Can 20MC5 be welded?
Weldable with low-hydrogen consumables but CE ≈ 0.6 — preheat 200–300 °C, control interpass and temper after welding; never weld carburized surfaces.
Can 20MC5 be formed, bent or molded?
Excellent hot forging (1100–1200 °C, finish >900 °C) and good cold heading/extrusion in the soft-annealed or +S condition.
What surface finishes work on 20MC5?
No anodizing; protect with oil, manganese/zinc phosphate, black oxide or zinc plating — bake after plating to avoid hydrogen embrittlement of the hard case.
20MC5 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 | ≤ 0.4 | 0.25 |
| Mn | 1.1 – 1.4 | 1.25 |
| Cr | 1 – 1.3 | 1.15 |
| P | ≤ 0.03 | 0.02 |
| Smax; low-S or resulphurized (+S) variants exist | ≤ 0.04 | 0.02 |
| Fe | balance | — |
20MC5 +A — frequently asked
What is 20MC5 +A used for?
20MC5 +A is typically used for gears, shafts and pinions. In short: standard automotive gear steel; case hardens 58–62 HRC; nickel-free carburizing grade.
What is the yield strength of 20MC5 +A?
20MC5 +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 9 listed tempers.
Is 20MC5 +A easy to machine?
Reasonably — machinability is rated good (55/100, better than 62% of steel grades). Machine in the +A/+FP condition (~180–217 HB) with coated carbide; after carburizing only grinding, honing or hard turning with CBN is practical.
Can 20MC5 +A be welded?
With care — weldability is rated fair (40/100). Weldable with low-hydrogen consumables but CE ≈ 0.6 — preheat 200–300 °C, control interpass and temper after welding; never weld carburized surfaces.
What surface finishes work on 20MC5 +A?
No anodizing; protect with oil, manganese/zinc phosphate, black oxide or zinc plating — bake after plating to avoid hydrogen embrittlement of the hard case.
Can 20MC5 +A be formed, bent or molded?
Excellent hot forging (1100–1200 °C, finish >900 °C) and good cold heading/extrusion in the soft-annealed or +S condition.
What is the maximum service temperature of 20MC5 +A?
20MC5 +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.
What is the difference between 20MC5 +A and 20MC5 QT-DH?
+A is the default condition — standard stock condition for bar and wire: best machinability and cold-forging behaviour before carburizing. QT-DH: for thin sections or non-carburized parts needing uniform medium strength and toughness rather than a hard case. Yield strength is 400 MPa in +A versus 750 MPa in QT-DH.
Sources
- EN 10084 — Case hardening steels, technical delivery conditions (20MnCr5, 1.7147) — CEN (2008)
- NF A35-551 / AFNOR case-hardening steels (20MC5) — AFNOR (1987)
- ASM Handbook Vol.1 — Properties and Selection: Irons, Steels and High-Performance Alloys — ASM International (1990)
- ASM Handbook Vol.4 — Heat Treating (carburizing of Mn-Cr steels) — ASM International (1991)
- Engineering steel bar datasheets for 1.7147 / 20MnCr5 — Ovako / Böhler / Saarstahl (2022)
- GB/T 3077 — Alloy structural steels (20CrMn equivalent) — SAC (2015)
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.