254 SMO Stainless Steel

Material Grade: 254 SMo Super Austenitic Stainless Steel

American Grade: UNS S31254

DIN/EN Grade: 1.4547

Chinese Grade: 00Cr20Ni18Mo6CuN

Forging Grade: F44

What is 254 SMO Stainless Steel

A lot of people think 254 SMO is a steel grade, but actually 254 SMO is trademark owned by Outokumpu OY, one of the biggest steel company in the word. But the grade has developed by other companies, you can think it is steel grade, it is equivalent to UNS S31254, it is a super austenitic stainless steel.

254SMo (S31254.F44, 1.4547) belongs to super austenitic stainless steel. Due to its high content of molybdenum, it has excellent performance on the resistance of pitting and crevice corrosion. This kind of stainless steel is developed for use in halogenated environments such as sea water. Besides, 254SMo also performs well in uniform corrosion. Especially in halogenated acid, the steel is superior to ordinary stainless steel. And its carbon content is below 0.03%, which is called pure austenitic stainless steel (The Carbon content below 0.019% will be called super austenitic stainless steel).

Super stainless steel is a kind of special stainless steel. First, the difference between it and ordinary stainless steel is shown on the chemical composition. For super stainless steel, it is a kind of high alloy stainless steel containing high nickel, high chromium, high molybdenum, and 254SMo with the content of 6% Mo is one of the most famous high alloy stainless steels. For this stainless steel, it has very good local corrosion resistance, pitting resistance (PI240) and stress corrosion resistance under seawater, gas, crack and low speed scour conditions, which is an ideal material for Ni-alloy and Ti-alloy. Second, it also shows a better performance on high temperature resistance and lameness resistance, which cannot be replaced by 304 stainless steel. In addition, judging from the classification of stainless steel, the metallographic structure of special stainless steel is a kind of stable austenitic metallographic structure. Because 254SMo (S31254, F44, 1.4547) is a kind of high alloy material, its processing technology is very complicated. Generally, people can only use traditional processes to produce this kind of special stainless steel, such as pouring, forging, and rolling. It can also be produced through cold rolling or cold drawing.

254 SMO Stainless Steel Equivalent

254 SMO stainless steel is equivalent to EN 1.4547, ASTM A312 UNS S31254 (pipe), the forged grade is ASTM A182 F44, and the casting number is ASTM A351 CK3MCuN, it is also callded 6Mo Alloy.

Alloy 6Mo Stainless Steel

What is alloy 6mo material? In fact, 6Mo is another name of 254 SMO. Because the composition of Mo is 6 -7%, so the people call it 6mo alloy.

II. Chemical Compositions of 254 SMo Stainless Steel

III. Physical Performance of 254 SMo (S31254, F44, 1.4547)

a) Density: 8.24g/cm3;

b) Melting point: 1320-1390 °C;

c) Magnetic: No.

IV. Mechanical properties of 254 SMo Stainless Steel

a) Tensile strength: AB ≥ 650MPa;

b) Yield strength OB ≥310Mpa;

c)Elongation: 8>409%;

d) Hardness: 182-223 (HB).

V. Corrosion Resistance of 254 SMo (S31254, F44, 1.4547)

254SMo is a kind of super austenitic stainless steel with high corrosion resistance. It is developed for halide and acid environment, and is widely used in high concentration of chloride ion media, seawater and other harsh conditions. In some industrial environment with acidic medium, especially with halogenated acid, 254SMo performs much better than other stainless steels, which can be like Hastelloy alloy and titanium in some circumstance. With low carbon content and high molybdenum, it has good pitting and crevice corrosion resistance as well as excellent intergranular corrosion resistance. It is a kind of cost-effective stainless steel, which is widely used in chemical industry, desulfurization and environmental protection at home and abroad.

VI. Welding materials of 254 SMo (S31254.F44, 1.4547)

Welding material for 254SMo includes ErniCrMo-3, and welding rod includes EnicCrMo-3.

VII. Application of 254 SMo (S31254.F44, 1.4547)

a) Marine: marine structures; seawater desalination; marine culture; seawater heat exchange, etc.

b) Environmental protection field: flue gas desulfurization device of thermal power generation; waste water treatment, etc.

c) Energy field: atomic power generation; utilization of coal; tidal power generation, etc.

d) Petrochemical field: oil refining; chemical equipment, etc.

e) Food field: salt production; soy sauce brewing, etc.

f) High concentration ammonia ion environment: paper industry; all kinds of bleaching equipment.

VIII. Corrosion Properties of 254 SMo (S31254, F44, 1.4547)

a) A lot of field tests and experiences have shown that 254SMo has very high crevice corrosion resistance in seawater even when the temperature goes slightly higher. Only a few types of stainless steels can perform such resistance.

b) The corrosion resistance of 254SMo in acidic and oxidizing halide solutions performs similarly to that of the most corrosion-resistant nickel-based and titanium alloys, such as those needed in paper bleaching.

c) Due to the high nitrogen content in 254SMo, its mechanical strength decline is higher than that of other kinds of austenitic stainless steels. In addition, 254SMo has high ductility, impact strength and weldability.

d) The high aluminum content of 254SMo enables itself to oxidize faster when annealing, which can bring a rougher surface after pickling compared with ordinary stainless steels. And this will not produce any adverse effects on its corrosion resistance.

IX. Specifications and Supply Status of 254 SMo (S31254.F44, 1.4547)

a) Variety: 254SMo seamless pipe; 254SMo steel plate; 254SMo round steel; 254SMo forgings; 254SMo flange; 254SMo ring; 254SMo welded pipe; 254SMo steel strip; 254SMo wire and 254SMo supporting welding materials.

b) Delivery Status: Seamless tube will delivered with solid solution and acid white, and length can be fixed; Plate will delivered with solution, pickling, and edge cutting; Welding pipe will delivered with solution acid white and RT% flaw detection; Forgings will delivered with annealing and car light, and the bar will be in the state of forging and rolling as well as polished or turned smooth surface; Fei material will be delivered after cold rolling, solution soft state, and descaling; Wire will be delivered in the state of solid solution pickling disk or straight strip and fine polishing of solid solution straight strip.