8620 Steel
A Ni-Cr-Mo carburizing alloy steel
Typical values for the temper in the title
8620 is a low-carbon (about 0.2%) steel with small additions of nickel, chromium and molybdenum. It is the most common carburizing steel: a hard, wear-resistant surface, and a strong, tough core.
It is used for gears, shafts, cams, pins and automotive parts. Compared with a carburized carbon steel, the alloying gives a stronger core and better hardenability in thick parts.
Mechanical and physical properties
| Property | Value | Note |
|---|---|---|
| Tensile strength Rm | 530–620 MPa | |
| Yield strength Rp0.2 | 385–415 MPa | |
| Elongation A | 21% | |
| Hardness | 149–179 HB | |
| Modulus of elasticity E | 205 GPa | |
| Density ρ | 7.85 g/cm³ | |
| Machinability | 66% | relative rating in the site database |
Chemical composition (wt %)
| Element | Range | Role |
|---|---|---|
| C carbon | 0.18–0.23 | low: a ductile core |
| Ni nickel | 0.40–0.70 | toughness |
| Cr chromium | 0.40–0.60 | hardenability |
| Mo molybdenum | 0.15–0.25 | hardenability |
| Mn manganese | 0.70–0.90 | |
| Si silicon | 0.15–0.35 | |
| Fe iron | balance |
Ranges per SAE J404 and ASTM A322. P max 0.035, S max 0.040. Equivalents in other standards are close in composition, not identical.
Conditions and heat treatment
In alloy steels, chromium, molybdenum and nickel raise hardenability: thicker parts reach full hardness even at the center. Properties are set mainly by heat treatment.
| Condition | Properties | When to choose it |
|---|---|---|
| Annealed / hot rolled | for machining | delivery condition |
| Carburized | very hard surface, strong and tough core | gears, shafts and cams |
| Quenched and tempered (no carburizing) | medium strength | parts that do not need a hard surface |
Applications
- Gears
- Shafts and cams
- Pins and bushings
- Automotive and transmission parts
- Agricultural machine parts
Fabrication
Carburizing
A case of tenths of a millimeter up to about a millimeter is common, depending on the requirement.
Welding
Possible before carburizing.
Machining
Good hot rolled, normalized or annealed.
Compared with similar materials
| Material | Rm / Rp0.2 | Welding | When it is the better choice |
|---|---|---|---|
| 4620 | 520 / 365 MPa | Good | more nickel, no chromium · material page |
| 9310 | 1035–1380 / 795–1100 MPa | Good | for aerospace: more nickel and toughness · material page |
| 1018 | 400 / 220 MPa | Excellent | a cheap carbon steel, weaker core · material page |
Common mistakes
Machining after carburizing
The surface is very hard. Leave stock for grinding only.
Forgetting to mask areas that must not harden
Threads, for example. Protect them before carburizing.
Choosing 8620 without carburizing for a wear part
Without carburizing the surface is soft.
Equivalents, standards and supply
| EN | 20NiCrMo2-2 |
|---|---|
| DIN | 1.6523 |
| JIS | SNCM220 |
| Standards | ASTM A322 / AMS 6274 |
| Forms | rod · wire · forging |
| Producers | Ovako · TimkenSteel · Schmolz |
Learn more
Values are typical and for comparison only, and depend strongly on condition and diameter. For design, rely on the standard and on the mill certificate. Sources: SAE J403 and J404, ASTM A29, A322 and A519 (composition), producer data sheets, and the METAL HUB materials database.
Updated: October 31, 2026