Stainless Steel Alloy 254 SMO

Chemical Analysis
C Carbon
.02 max
Mn Manganese
1.00 max
P Phosphorus
0.030 max
S Sulfur
0.010 max
Si Silicon
0.80 max
Cr Chromium
19.50 – 20.50
Mo Molybdenum
6.00 – 6.50
Ni Nickel
17.50 – 18.50
N Nitrogen
0.018 – 0.22
Cu Copper
0.50 – 1.00

General characteristics of Stainless Steel Alloy 254 SMO

This alloy has a high nickel content and about 6 percent molybdenum, together with copper and nitrogen additions. The alloy was developed, along with a series of others, to resist stress corrosion cracking in boiling chloride solutions. It is relatively easy to fabricate and weld.


The alloy is suitable for use in chemical processing industries, offshore oil and gas platform process systems and desalination equipment.


This is a highly alloyed material and the recommended forging temperature range is 2370/1920ºF (1300/1050ºC), followed by a solution anneal at 2100ºF (1150ºC) minimum temperature.

Heat treatment

Solution anneal at 2100ºF (1150ºC) minimum. Parts should be rapidly quenched following solution annealing to prevent formation of intermetallic compounds and attendant loss of impact strength.


This alloy is not easy to machine, in fact much more difficult than the ‘normal’ austenitic stainless steels such as types 304 and 316. The rule is rigid equipment, carbide tooling and low speeds and feeds. It is important to consult the product manufacturer for detailed information regarding machining parameters.


The chemical analysis of 254 SMO grade is such that both ferrite and austenite are formed on cooling from welding, giving resistance to hot cracking. A postweld anneal is recommended, as is consultation with the product manufacturer regarding welding parameters.

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