254SMO / UNS S31254 Seamless Stainless Steel Pipe ASTM EN GB
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
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
Thermal expansion co-efficient (@20-100°C/68-212°F)
97.2 BTU in/hr.ft².°F
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
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
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