20NiCrMo2-2
1.6523Nickel-chromium-molybdenum case-hardening steel — the base grade of the 8620 family. Good weldability, toughness, and machinability. Case hardness up to HRC 60–63 with core strength 700–1100 MPa after carburizing and quenching. Used for gears, shafts, pinions, piston pins, and camshafts in automotive, gearbox, and general mechanical engineering. Equivalent to AISI 8620 and BS 805M20.
International equivalents
| Flag | Standard | Country | Grade | Number | Match |
|---|---|---|---|---|---|
| 🇺🇸 | AISI | USA | AISI 8620 | H86200 | REF |
| 🇬🇧 | BS | United Kingdom | 805M20 | — | 95% |
| 🇫🇷 | AFNOR | France | 20NCD2 | — | 95% |
Sources: ASTM A29, BS 970, NF EN 10084
Chemical composition comparison (wt%)
Side-by-side: 20NiCrMo2-2 (EN) (EN 10084:2008) vs 805M20 (BS)
| Element | 20NiCrMo2-2 (EN) | 805M20 (BS) | Overlap |
|---|---|---|---|
| C | 0.17–0.23% | — | — |
| Si | ≤ 0.4% | — | — |
| Mn | 0.65–0.85% | — | — |
| P | ≤ 0.025% | — | — |
| S | ≤ 0.035% | — | — |
| Cr | 0.35–0.7% | — | — |
| Mo | 0.15–0.25% | — | — |
| Ni | 0.4–0.7% | — | — |
Mechanical properties
Case Hardened
| Property | Value | Unit |
|---|---|---|
| Tensile Strength | 700–1100 | MPa |
| Yield Strength | ≥ 500 | MPa |
| Elongation | ≥ 10 | % |
| Hardness HRC | 60–63 | HRC |
| Density | ≥ 7.85 | g/cm3 |
| Elastic Modulus | ≥ 210 | GPa |
Heat treatment
| Process | Temperature | Medium | Holding Time | Notes |
|---|---|---|---|---|
| carburizing | 880–920 °C | furnace | — | Case depth 0.5-1.5 mm typical |
| quenching | 810–840 °C | oil | — | After carburizing |
| tempering | 150–200 °C | air | — | Low-temperature temper to maintain case hardness |
| annealing | 640–670 °C | furnace | — | Soft annealing max 212 HB |
Compatibility verdict
20NiCrMo2-2 and 805M20: 95% composition match
Close equivalents but NOT identical.
Related materials
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