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6 Moly: 254 SMO

Penn Stainless offers 254 SMO (UNS S31254) in welded pipe and tube.

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General Properties
Alloy 254 SMO (UNS S31254) is a molybdenum and nitrogen alloyed super austenitic stainless steel with low carbon content. Super-austenitic stainless steels exhibit great resistance to chloride pitting and crevice corrosion due to their high molybdenum content (>6%) and nitrogen additions. Additionally, their higher nickel content allows superior resistance to stress-corrosion cracking compared to the 300 series. Alloy 254 SMO is almost two times as strong as 300 series grades, and is noted for its high ductility and impact strength. This grade is often used in high chloride environments, such as brackish water, seawater, pulp mill bleach plants, and other chloride process streams. Even though its higher alloy content makes for higher costs, Alloy 254 can sometimes be a cost-effective substitute for high nickel and titanium alloys.

Applications

  • Petroleum production
  • Saltwater handling
  • Food and chemical processing equipment
  • Pulp mill bleach systems
  • Flue gas desulphurization scrubbers
  • Tall oil distillation columns
  • Offshore oil and gas production equipment
  • Desalination equipment

Specifications

  • ASTM/ASME: UNS S31254
  • EURONORM: FeMi35Cr20Cu4Mo2
  • DIN: 2.4660

Resistance

  • 6 Moly alloys show superior resistance to many different chemicals, and therefore are great choices for use in high chloride environments like brackish water, seawater, and pulp mill beach plants.
  • Great resistance to pitting and crevice corrosion because of its high chromium, molybdenum, and nitrogen content
  • Low carbon content allows for very little risk of carbide precipitation during heating

Weldability

  • Possesses good weldability
  • No pre-heating or subsequent heat treatment
  • Welding with filler metal is recommended

Machinability

  • This grade is difficult to machine
  • Slow speeds, sharp tools, positive feeds, over-powered machine tools, and ample lubrication offer the best results

Chemical Properties:

% C Cr Mn Mo N Ni P Si S
254 SMO 0.02 max min: 19.5
max:20.0
1.00 max min: 6.0
max: 6.5
min: 0.18
max: 0.20
min: 17.5
max: 18.0
0.03 max 0.80 max 1.01 max

Mechanical Properties:

Grade

Tensile Strength ksi (MPa) min

Yield Strength 0.2%
Offset ksi (MPa) min
Elongation -
% in
50 mm (min.)
Hardness
(Brinell) MAX
Hardness
(Rockwell B) MAX
254 SMO Sheet & Strip 100 (690) 45 (310) 35 223 96
254 SMO Plate 95 (655) 45 (310) 35 223 96

Physical Properties:

Grade:

Alloy 254

Density

8.0 kg/dm3

Modulus of Elasticity

195 GPa

Linear Expansion
at 68to 212oF
(20 to 100oC)

16.5 X10-6/oC

Thermal Conductivity

 14 w/moC

Thermal Capacity

 500 J/kgoC

Electrical Resitivity

 0.85 μΩm

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