Grade Designations.
| BS EN 10084:2008 | 20NiCrMo2-2 / 1.6523 |
| BS 970:1991 (withdrawn) | 805M20 |
| AISI/SAE | 8620 / 8617 |
| DIN | 21NiCrMo2-2 / 1.6523 |
| Alt. designation | 21NiCrMo2-2 / 1.6543 (some suppliers) |
| JIS | SNCM220 |
Availability & Supply Condition.
Bright Rounds: 16–100mm | Black Rounds: 40–200mm
Supply condition: Bright Drawn or Hot Rolled Black. Typically supplied in the normalised or annealed condition.
Cut to length from 1 piece — −0/+2mm standard tolerance — 2–3 day turnaround — Cutting service details ›
Chemical Analysis.
Values shown as percentages by weight (% wt). Values are ranges unless stated as maxima.
| Designation | C | Si | Mn | P max | S max | Cr | Ni | Mo |
|---|---|---|---|---|---|---|---|---|
| 805M20 | 0.17–0.23 | 0.10–0.35 | 0.60–0.95 | 0.04 | 0.04 | 0.35–0.65 | 0.35–0.75 | 0.15–0.25 |
| 20NiCrMo2-2 | 0.17–0.23 | 0.17–0.37 | 0.65–0.95 | 0.025 | 0.035 | 0.35–0.65 | 0.40–0.70 | 0.15–0.25 |
For full chemical analysis with heat number, request an EN 10204 3.1 material test certificate when ordering — available on all alloy grades. Certificate types explained ›
Mechanical Properties.
Values shown for standard supply condition. Properties vary by section size and heat treatment condition.
| Condition | Core Tensile (N/mm²) | Core Yield (N/mm²) | Case HRC | Core HB |
|---|---|---|---|---|
| After case hardening | ~620–800 | ~375–550 | 58–62 | ~180–235 |
Hardness values: see our hardness conversion table to convert between HRC, HB, HV and tensile strength.
Typical Applications.
- Automotive gears and pinions
- Camshafts and tappets
- Transmission shafts
- Aerospace sub-critical components
- Hydraulic and pneumatic components
- Fasteners and bolts
Key Benefits.
- Good combination of case hardness and core toughness
- Better weldability than higher-alloy case hardening grades
- More cost-effective than EN36 for moderate-duty applications
- Recognised globally as SAE 8620 — ideal for international supply chains
- Consistent carburising response
Remarks & Guidance.
Carburise at 880–930°C. Oil quench directly from carburising temperature or pot-cool for double hardening. Temper at 150–200°C. For heavily shock-loaded applications requiring higher core toughness, specify EN36 (655M13) or EN36C (832M13).
Relevant Heat Treatment Processes.
This grade responds to the following heat treatment processes. Click any card for temperatures, cooling methods and expected hardness values.
