Designation
- Grade
- CK3MCuN
- UNS
- J93254
- EN designation
- ≈ 1.4557 (GX2CrNiMoCuN20-18-6)
- Commonly associated designations
- 6Mo type (254 SMO®)
Type designations and trade names are given for orientation only. Trade names are trademarks of their respective owners; the cast grade and its standard remain the specification. - Standard
- ASTM A351/A351M, A743/A743M, A744/A744M
- Density
- ≈ 8.00 g/cm³
- Usual delivery condition
- Solution annealed and quenched
Chemical composition
| Element | Mass fraction, % |
|---|---|
| C | ≤ 0.025 |
| Mn | ≤ 1.20 |
| Si | ≤ 1.00 |
| Cr | 19.5–20.5 |
| Ni | 17.5–19.5 |
| Mo | 6.0–7.0 |
| Cu | 0.50–1.00 |
| N | 0.18–0.24 |
| Fe | bal. |
Main elements only. Phosphorus, sulphur and residual-element limits are specified in the standard and are not reproduced here.
Mechanical properties
| Condition | Tensile strength Rm, min. (MPa) | Yield strength Rp0.2, min. (MPa) | Elongation, min. (%) |
|---|---|---|---|
| Solution annealed and quenched | 550 | 260 | 35 |
Minimum values (or ranges) for separately cast test bars as specified in ASTM A351/A351M, A743/A743M, A744/A744M.
Characteristics
- Corrosion and oxidation behaviour
- Very good resistance in seawater and chloride-bearing media
- Weldability
- Possible with qualified procedure; preheat and/or post-weld heat treatment as specified
- Machinability
- Difficult; rigid set-ups, low cutting speeds or grinding
- Typical applications
- Valves Pumps Marine Offshore Chemical processing
International cross-reference
| System | Designation | Relationship |
|---|---|---|
| EN | 1.4557 (GX2CrNiMoCuN20-18-6), EN 10283 | Similar composition |
| UNS (wrought) | S31254 | Comparable properties |
Casting and processing considerations
Castings are normally solution annealed and rapidly cooled to dissolve carbides and restore corrosion resistance. Low-carbon grades are preferred where castings will be welded without subsequent heat treatment. High shrinkage requires adequate feeding of heavy sections; surface finish and pickling or passivation requirements should be agreed in advance.
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 TR delivery specification.
Other grades in this family
CF8 GX5CrNi19-10 (1.4308) CF3 CF8C GX2CrNi19-11 (1.4309) CF8M GX5CrNiMo19-11-2 (1.4408) CF3M GX2CrNiMo19-11-2 (1.4409) CG8M CN7M CN3MN GX2NiCrMoCu25-20-5 (1.4584)