Designation
- Grade
- 4140
- UNS
- G41400
- Standard
- SAE J404 / AISI 4140 (cast: ASTM A732 Gr. 8Q)
- Density
- ≈ 7.85 g/cm³
- Usual delivery condition
- Quenched (or normalised) and tempered
Chemical composition
| Element | Mass fraction, % |
|---|---|
| C | 0.38–0.43 |
| Mn | 0.75–1.00 |
| Si | 0.15–0.35 |
| Cr | 0.80–1.10 |
| Mo | 0.15–0.25 |
| Fe | bal. |
Main elements only. Phosphorus, sulphur and residual-element limits are specified in the standard and are not reproduced here.
Mechanical properties
Mechanical properties depend on the heat-treatment condition and the ordering specification and are therefore not listed as single values. They are agreed per project.
Characteristics
- Corrosion and oxidation behaviour
- Not corrosion resistant; coating or other protection required in corrosive environments
- Weldability
- Limited; crack-sensitive, welding only by agreement
- Machinability
- Good in the appropriate heat-treatment condition
- Typical applications
- Gears and drives Automotive Structural parts General engineering
International cross-reference
| System | Designation | Relationship |
|---|---|---|
| EN (wrought) | 1.7225 (42CrMo4) | Similar composition |
| EN (cast) | 1.7231 (G42CrMo4), EN 10293 | Comparable properties |
| JIS | SCM440 | Similar composition |
Casting and processing considerations
Good castability and moderate pouring temperatures. Surface decarburisation from the reaction between metal, shell and atmosphere has to be considered on heat-treated and wear surfaces; machining allowance or a controlled furnace atmosphere are common countermeasures. Section-size sensitivity of quenched and tempered grades should be reflected in the drawing requirements.
Reference data compiled from the cited standards for orientation. Always work from the current edition of the governing specification; values are not a guaranteed LOSTWAX delivery specification.