254SMO / UNS S31254 Seamless Stainless Steel Pipe ASTM EN GB Standard
Stainless steel grade 254 SMO 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, grade 254 SMO has been reported to be a cost-effective substitute for high nickel and titanium alloys. It is known to possess excellent workability as well.
The following sections will discuss in detail about stainless steel grade 254 SMO.
The chemical composition of stainless steel grade 254 SMO is outlined in the following table.
The physical properties of stainless steel grade 254 SMO™ are tabulated below.
The following table shows mechanical properties of stainless steel grade 254 SMO.
Modulus of elasticity
Elongation at break
The thermal properties of stainless steel grade 254 SMO™ are tabulated below.
Other designations that are equivalent to stainless steel grade 254 SMO include the following.
ASTM A182 (F44)
Fabrication and Heat Treatment
Stainless steel grade 254 SMO 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.
Welding of stainless steel grade 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 of this material should be performed at 1149-1204°C (2100-2200°F), which should be followed by a water quench.
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 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.
Stainless steel grade 254 SMO does not respond to heat treatment. Hardening is possible only through cold reduction.
Stainless steel grade 254 SMO is used in the following areas:
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