CBS-50 NiL® AMS 6278
CBS-50 NiL is a carburizing bearing and gear steel designed for service temperatures up to 600°F. It has high core fracture toughness properties compared to other bearing alloys. Because the CBS-50 NiL can be carburized, surface stresses are controlled to provide excellent rolling contact fatigue characteristics.
Stock sizes: 3.500” to 8.000” diameter
Common Specifications:
- AMS 6278
- B50TF347
- General Electric S-400 / S-SPEC-35
- Pratt & Whitney LCS F-17
Industry Trade Names:
- M50NIL
- UNS K91231
Common Applications:
- Aerospace bearings
- Aerospace gears
Macrostructure Limits:
| Class | Condition | Severity |
|---|---|---|
| 1 | Freckles | A |
| 2 | White Spots | A |
| 3 | Radial Segregation | B |
| 4 | Ring Pattern | B |
Composition
| Element | Min. | Max. |
|---|---|---|
| Carbon | 0.11 | 0.15 |
| Manganese | 0.15 | 0.35 |
| Silicon | 0.10 | 0.25 |
| Phosphorus | — | 0.015 |
| Sulfur | — | 0.010 |
| Chromium | 4.00 | 4.25 |
| Nickel | 3.20 | 3.60 |
| Molybdenum | 4.00 | 4.50 |
| Copper | — | 0.10 |
| Vanadium | 1.13 | 1.33 |
| Cobalt | — | 0.25 |
| Tungsten | — | 0.15 |
VIM-VAR Melting Practice
Average grain size of ASTM No. 5 or finer
Maximum Total Depth of Decarburization, inch/pound units:
| Nominal Diameter or Distance Between Parallel Sides Inches | Total Depth of Decarburation Inch |
|---|---|
| Up to 0.500, incl | 0.015 |
| Over 0.500 to 1.000, incl | 0.030 |
| Over 1.000 to 2.000, incl | 0.040 |
| Over 2.000 to 3.000, incl | 0.050 |
| Over 3.000 to 4.000, incl | 0.065 |
| Over 4.000 to 5.000, incl | 0.095 |