Steel 20MnNiCrMo3-2-CH (Carburized and hardened)
Heat-treated state
EN 20MnNiCrMo3-2
Final in-service condition of gears and bearing races: 58–62 HRC case over a tough 30–42 HRC core.
Values for the CH condition
Other 20MnNiCrMo3-2 tempers and conditions
20MnNiCrMo3-2 is listed in 8 conditions; see the grade overview at 20MnNiCrMo3-2.
Compare all 8 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
Spheroidize annealed | Choose for cold extrusion, cold heading and deep upsetting of gear blanks and pinion bodies. | 330 | 520 | 25 | 165 HB | — |
+ADefault Annealed | Standard stock condition for bar and forging stock: softest state for rough machining before carburizing. | 350 | 560 | 22 | 180 HB | — |
Guaranteed hardenability class (Jominy band), supplied soft annealed | Specify when the Jominy end-quench band must be guaranteed so that case/core hardness is reproducible batch to batch on large gears. | 350 | 560 | 22 | 42 HRC | 7.8 % IACS |
Treated for shearability | Coil/bar condition for cold shearing of blanks in high-volume cold-forming lines. | 380 | 600 | 20 | 185 HB | 7.8 % IACS |
Treated to ferrite-pearlite structure with specified hardness range | Pick when consistent chip formation and surface finish on automatic lathes/hobbing machines matter more than minimum hardness. | 390 | 620 | 20 | 175 HB | — |
Normalized | Used on forgings to refine grain and homogenize structure before machining and carburizing. | 430 | 680 | 20 | 14 HRC | 7.8 % IACS |
Heat treated to a specified hardness range | Order when a narrow as-delivered hardness band is needed for stable CNC turning/broaching before carburizing. | 450 | 700 | 18 | 205 HB | — |
CHThis page Carburized and hardened | Final in-service condition of gears and bearing races: 58–62 HRC case over a tough 30–42 HRC core. | 900 | 1,200 | 10 | 60 HRC | — |
What is 20MnNiCrMo3-2-CH?
20MnNiCrMo3-2-CH is 20MnNiCrMo3-2 heat treated to CH — final in-service condition of gears and bearing races: 58–62 HRC case over a tough 30–42 HRC core. 20MnNiCrMo3-2-CH has a yield strength of 900 MPa (131 ksi) and a tensile strength of 1,200 MPa (174 ksi) — stronger than 90% of steel grades. Elongation at break is 10% and the elastic modulus is 210 GPa (30.5 Msi). 20MnNiCrMo3-2-CH 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; CH is available on request or by drawing note.
Advantages
- Polishes to a fine finish — 80/100, better than 97% of steel grades
- Low embodied carbon — 1.9 kg CO₂/kg, better than 92% of steel grades
- High strength — 900 MPa (131 ksi), better than 90% of steel grades
Limitations
- Difficult to machine — 12/100, worse than 99% of steel grades
- Difficult to weld — 10/100, worse than 99% of steel grades
- Limited formability — 5/100, worse than 99% of steel grades
- Limited service temperature — 180°C (356 °F), worse than 98% of steel grades
- Limited ductility — 10%, worse than 91% of steel grades
20MnNiCrMo3-2-CH properties
Typical room-temperature values for 20MnNiCrMo3-2-CH; 18 are specific to this condition. Other listed values are 20MnNiCrMo3-2 reference data and may not represent this condition. Bars are the position among steel grades.
Physical3
20MnNiCrMo3-2-CH 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
20MnNiCrMo3-2-CH has a yield strength of 900 MPa (131 ksi) and a tensile strength of 1,200 MPa (174 ksi) — stronger than 90% of steel grades. Elongation at break is 10% and the elastic modulus is 210 GPa (30.5 Msi).
Thermal6
20MnNiCrMo3-2-CH is rated for continuous service to 180°C (356 °F). It conducts heat at 44 W/m·K (25.4 BTU/hr·ft·°F), better than 57% of steel grades. Thermal expansion is 11.5 µm/m·K (6.39 µin/in·°F).
Electrical3
20MnNiCrMo3-2-CH conducts electricity at 7.8 % IACS, worse than 57% of steel grades.
Chemical & Environmental3
Corrosion resistance is not recommended (10/100), worse than 86% of steel grades.
Sustainability4
Producing a kilogram of 20MnNiCrMo3-2-CH takes about 25 MJ of energy and emits 1.9 kg of CO₂ — less than 82% of steel grades. Typical recycled content is 30%.
Manufacturability7
20MnNiCrMo3-2-CH's machinability is not recommended (12/100, worse than 99% of steel grades); weldability not recommended (10/100); formability not recommended (5/100).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with 20MnNiCrMo3-2-CH
Is 20MnNiCrMo3-2 easy to machine?
Machine in +A/+FP/+TH at 150–220 HB with coated carbide (Vc ≈ 120–200 m/min); leave 0.1–0.3 mm grinding stock on carburized surfaces since the 60 HRC case must be finish-ground.
Can 20MnNiCrMo3-2 be welded?
Weldable before carburizing with low-hydrogen consumables, 150–250 °C preheat and stress relief; welding on the carburized case is not recommended (high-carbon HAZ cracking).
Can 20MnNiCrMo3-2 be formed, bent or molded?
Best cold-headed/extruded in the +AC spheroidized condition; hot forge at 1100–1180 °C, finish above 900 °C, then normalize or soft anneal before machining.
What surface finishes work on 20MnNiCrMo3-2?
Carburize 900–930 °C to the required case depth, direct or single quench in oil, temper 160–200 °C; grind, shot-peen for bending fatigue, and protect with oil, manganese phosphate, black oxide or Zn-Ni plating (bake to avoid hydrogen embrittlement).
20MnNiCrMo3-2 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 |
|---|---|---|
| Ccase-hardening carbon level | 0.17 – 0.23 | 0.2 |
| Si | 0.1 – 0.4 | 0.25 |
| Mndesignation digit 3 ⇒ ≈0.75 % | 0.6 – 0.95 | 0.75 |
| P | ≤ 0.03 | — |
| Smax; S-modified (+S) versions run 0.020–0.040 | ≤ 0.04 | — |
| Crhardenability | 0.35 – 0.7 | 0.5 |
| Nidesignation digit 2 ⇒ ≈0.50 %; gives core toughness | 0.4 – 0.7 | 0.55 |
| Mosuppresses temper embrittlement, deepens hardenability | 0.15 – 0.25 | 0.2 |
| Curesidual max | ≤ 0.3 | — |
| Febalance; Chinese cross-reference 20CrMnMo (GB/T 3077) runs higher Mn 0.90–1.20 and Cr 1.10–1.40 — confirm heat analysis before substitution | balance | — |
20MnNiCrMo3-2-CH — frequently asked
What is 20MnNiCrMo3-2-CH used for?
20MnNiCrMo3-2-CH is typically used for carburized gears, bearing components and transmission shafts. In short: deep-hardening carburizing steel; hard case, tough core; heavier sections than 8620.
What is the yield strength of 20MnNiCrMo3-2-CH?
20MnNiCrMo3-2-CH has a typical yield strength of 900 MPa (131 ksi) and a tensile strength of 1,200 MPa (174 ksi) — stronger than 90% of steel grades. Strength varies by condition: see the 8 listed tempers.
Is 20MnNiCrMo3-2-CH easy to machine?
Not especially — machinability is rated not recommended (12/100, worse than 99% of steel grades). Machine in +A/+FP/+TH at 150–220 HB with coated carbide (Vc ≈ 120–200 m/min); leave 0.1–0.3 mm grinding stock on carburized surfaces since the 60 HRC case must be finish-ground.
Can 20MnNiCrMo3-2-CH be welded?
Not readily — weldability is rated not recommended (10/100). Weldable before carburizing with low-hydrogen consumables, 150–250 °C preheat and stress relief; welding on the carburized case is not recommended (high-carbon HAZ cracking).
What surface finishes work on 20MnNiCrMo3-2-CH?
Carburize 900–930 °C to the required case depth, direct or single quench in oil, temper 160–200 °C; grind, shot-peen for bending fatigue, and protect with oil, manganese phosphate, black oxide or Zn-Ni plating (bake to avoid hydrogen embrittlement).
Can 20MnNiCrMo3-2-CH be formed, bent or molded?
Best cold-headed/extruded in the +AC spheroidized condition; hot forge at 1100–1180 °C, finish above 900 °C, then normalize or soft anneal before machining.
What is the maximum service temperature of 20MnNiCrMo3-2-CH?
20MnNiCrMo3-2-CH is rated for continuous use to about 180°C (356 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
What is the difference between 20MnNiCrMo3-2 +A and 20MnNiCrMo3-2-CH?
+A is the default condition — standard stock condition for bar and forging stock: softest state for rough machining before carburizing. CH: final in-service condition of gears and bearing races: 58–62 HRC case over a tough 30–42 HRC core. Yield strength is 350 MPa in +A versus 900 MPa in CH.
Sources
- EN 10084 — Case hardening steels: technical delivery conditions — CEN (2008)
- GB/T 3077 — Alloy structural steels (20CrMnMo) — SAC (2015)
- ASM Handbook Vol.1 — Properties and Selection: Irons, Steels and High-Performance Alloys — ASM International (1990)
- ASM Handbook Vol.4A — Steel Heat Treating Fundamentals and Processes (carburizing) — ASM International (2013)
- Case-hardening steel bar datasheets (Ni-Cr-Mo grades) — European long-products producers (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.