Alloy Steel
8640 Alloy Steel
Higher-carbon relative of 8620, through-hardening rather than case-hardening, used where higher core strength is needed without carburizing.
Chemical Composition
| Element | Percentage (% by weight) |
|---|---|
| Mn | 0.75 - 1 |
| Ni | 0.4 - 0.7 |
| Cr | 0.4 - 0.6 |
| C | 0.38 - 0.43 |
| Si | 0.15 - 0.3 |
| Mo | 0.15 - 0.25 |
| S | max 0.04 |
| P | max 0.035 |
Physical Properties
- Density (kg/m³)
- 7700 to 8030
Also known as
Direct equivalents
DIN 1.6546
Same material sold under a different naming standard.
Typical Applications
- Gears
- Shafts requiring through-hardening rather than a carburized case
Buying This Grade in Pakistan
Chosen over 8620 when a shop wants through-hardening rather than a carburized case, relevant to the same PAAPAM-linked forging and gear shops, worth stocking as the through-hardening counterpart when quoting alongside 8620.
Related reading
- 8620 vs 8640: case-hardening vs through-hardening, which one and why
The difference between 8620 and 8640 alloy steel comes down to one question: does the part need a hard case over a tough core, or uniform hardness throughout?
Grade Family
Nickel-chromium-molybdenum alloy steel
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