Description
Stainless steel grade 254 SMO™, UNS S31254, 1.4547, 6MO, F44
What is S31254?
Stainless steel 254SMO ( UNS S31254 ) is a very high end austenitic stainless steel. It is designed with a combination of impact toughness resistance to chloride stress corrosion cracking, and pitting and crevice corrosion with strength that is twice that of the stainless steel 300 series.
For certain applications, stainless steel 254SMO ( 1.4547 ) has been reported to be a cost-effective substitute for high nickel and titanium alloys. It is known to possess excellent workability as well.
UNS S31254 Chemical Composition
| Element | Content (%) |
| Iron, Fe | 55.69 |
| Chromium, Cr | 20 |
| Nickel, Ni | 18 |
| Molybdenum, Mo | 6.1 |
| Nitrogen, N | 0.20 |
| Carbon, C | 0.010 |
254 smo stainless steel Properties
| Properties | Metric | Imperial |
| Density | 8 g/cm3 | 0.289 lb/in3 |
UNS S31254 Mechanical Properties
| Properties | Metric | Imperial |
| Tensile strength | 680 MPa | 98600 psi |
| Yield strength | 300 MPa | 43500 psi |
| Modulus of elasticity | 195 GPa | 28300 ksi |
| Shear modulus | 75 GPa | 10900 ksi |
| Poisson’s ratio | 0.30 | 0.30 |
| Elongation at break | 50 % | 50 % |
| Hardness, Brinell | 210 | 210 |
Thermal Properties
| Properties | Metric | Imperial |
| Thermal expansion co-efficient (@20-100°C/68-212°F) | 16.5 µm/m°C | 9.17 µin/in°F |
| Thermal conductivity | 14 W/mK | 97.2 BTU in/hr.ft².°F |
254 smo stainless steel Machinability
254 SMO stainless steel is quite tough to machine due to the extremely high work hardening rate and lack of sulfur content; however using sharp tools, overpowered machine tools, positive feeds, good amount of lubrication, and slow speeds tend to provide good machining results.
How do you weld a SMO 254?
Welding of stainless steel type 254 SMO requires filler material without which it results in poor strength properties. Filler metals such as AWS A5.14 ERNiCrMo-3, and alloy 625 are recommended. Electrodes used in the process, have to match with AWS A5.11 ENiCrMo-12.
Annealing
Annealing of this material should be performed at 1149-1204°C (2100-2200°F), which should be followed by a water quench.
Hot Working
Forging, upsetting and other operations relating to this material can be performed at 982 – 1149°C (1800 – 2100°F). It is recommended that temperatures do not exceed this range as it would result in scaling and reduction in the workability of the material. To re-attain maximum corrosion resistant properties, it is advisable to perform post-process annealing.
Cold Working
Cold working can be carried out using all the traditional methods; however the process would be tough due to its high work hardening rate. The result will provide the material with increased strength and toughness.
254SMO | F44 Heat treatment
Stainless steel grade 254 SMO™ does not respond to heat treatment. Hardening is possible only through cold reduction.
1.4547 | S31254 Applications
Stainless steel grade 254 SMO™ is used in the following areas:
- Saltwater handling
- Tall oil distillation columns
- Flue gas desulfurization scrubbers
- Components used in petroleum production
- Food processing equipment
- Process equipment in chemical industry
- Bleaching equipment in the pulp and paper industry
- Flue-gas cleaning
- Desalination
- Heat exchangers
