Austenitic SMO 254

Austenitic SMO 254

Grade 254 SMO is a very high end austenitic stainless steel and cost effective substitute for high nickel and titanium alloy. Alloy 254 SMO is substantially stronger than the common austenitic grades, with strength nearly twice than that of 300 series stainless steel.

Specifications

GRADE UNS EN ASTM
SMO 254 S31254 1.4547 A 312, A213, A249

Significant additions of Mo, Ni and Cu give this alloy a good resistance to pitting and crevice corrosion. With high levels of chromium, molybdenum, and nitrogen, Alloy 254 is frequently used in high chloride environments; this is among the prime 254 SMO properties that it is known for. 

SMO 254 Chemical composition

GRADE Cr Ni Mo N Mn Nb C P S V Si Fe
UNS 31254 MIN 20.5 11.5 1.5 0.2 4 0.1 0.1
MAX 23.5 13.5 3 0.4 6 0.3 0.06 0.45 0.3 0.3 1 REMAINDER

Corrosion Resistance

Alloy 254 SMO UNS S31254 is described as a 6% Mo super austenitic stainless steel or 254 SMO stainless steel. 254 SMO material properties allow it to combine moderate mechanical strength (typically over 300 MPa yield strength) and high ductility with excellent corrosion resistance in seawater and a variety of industrial environments. You can find a lot of 254 SMO materials like 254 SMO pipe, 254 SMO sheet, 254 SMO tubing, 254 SMO plate, 254 SMO bar, and 254 SMO flanges at various 254 SMO stainless steel suppliers.

Physical Properties

Grade Density (g/cm3) Melting Range °C Elastic Modulus
(GPa)
Specific Heat
(J.kg-1.°K-1) at 20°F
Electrical Resistivity (μΩ/cm)
SMO 254 8 1350 195 500 8.5

Resistance to pitting corrosion and crevice corrosion is determined mainly by the content of chromium, molybdenum and nitrogen in the SMO 254 composition. This is often illustrated by using the pitting resistance equivalent (PRE) for the material. Typically the alloy has a PRE (Pitting Resistance Equivalent) of 42-44 which ensures that the resistance to pitting corrosion is high.

SS 254 SMO has a very low carbon content which implies that there is very little risk of carbide precipitation in connection with heating. It possesses very good resistance in water containing chlorides due to SMO 254 properties; therefore, it is suitable for use in seawater as it can be exposed to it for prolonged periods without suffering from crevice corrosion. The material of SMO 254 price is competitive; hence it is ideal for usage in many industries.  

Fabrication and Heat Treatment process

SMO 254 is readily fabricated by hot forming or cold forming process. In the hot forming process the entire work-piece has been exposed to a sufficiently high temperature. Hot forming should be carried out in the temperature range 1200-950°C.  In the case of partial heating, or cooling that is too slow, hot working should be followed by solution annealing. The temperature should be at least 1150°C to avoid residual intermetallic phases from the working.

Alloy 254 SMO composition lets it undergo heat treatment processes such as Solution annealing at a temperature range of 1140-1200º C. The Holding time for solution annealing is at a temperature of minimum 30 minutes, followed by rapid cooling in air or water. 

Weldability

254 SMO welding 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.

Applications

Alloy 254 SMO or UNS S31254 has an excellent corrosion resistance in seawater and a variety of industrial environments like various acidic medium such as hydrochloric acid, hydrofluoric acid, chloride contaminated sulphuric acid, phosphoric acid and pickling acids based on nitric acid and hydrofluoric acid solutions. 254 SMO material suppliers offer various equipment like 254 SMO round bar and alloy 254 SMO flanges. Some applications of SS 254 SMO are mentioned below:

  • Saltwater handling
  • Tall oil distillation columns
  • Fuel 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