347 Stainless Steel: The Alternative to 304 Stainless Steel

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Frequently used for the fabrication of heavy welded equipment, 347 stainless steel proves valuable in several industries, including the food and beverage industry. Yes, you read that correctly. It is true that 316 and 304 stainless steel are generally the go-to choices for food processing. However, did you know that 347 is a modification of 304? Thus, this type of steel makes the perfect solution for temperatures reaching above 800 degrees.

Here at Alliant Metals, we love keeping our customers educated. So, here is your inside look at 347.

 

The composition and properties of 347 stainless steel

347 is composed primarily of chromium and nickel. However, the following elements are also present in the steel:

  • Manganese
  • Silicon
  • Phosphorus
  • Sulfur
  • Niobium
  • Columbium
  • Tantalum
  • Carbon

With numerous elements, the properties of 347 are vast. Among the many, its high corrosion and heat resistance make it an ideal material in welding and food industries.

  • Corrosion resistance comparable to 304 stainless steel
  • Superior heat resistance
  • Eliminates intergranular corrosion.
  • Considered one of the most weldable out of all of the high alloy steels.
  • Austenitic stainless steel – prevent hardening by heat treatment and makes it non-magnetic.
  • Weldable by all fusion and resistance welding processes.
  • Annealing temperature range is 1800 – 2000 degrees Fahrenheit

 

Applications

As mentioned, with some of the best weldability and corrosion and heat resistance properties, 347 stainless steel is a forerunner in the food industry. However, as we also mentioned, this steel is versatile and highly sought after in several other applications as well. Here are a few of those:

  • High temperature chemical process
  • Heat exchanger tubes
  • Airplane exhaust stacks
  • Jet engine parts
  • Boil tubes
  • High pressure steam pipes
  • Radiant superheater
  • Refinery pipy
  • Heavy duty exhaust systems

Physical properties

Density: 0.288 lbs/in3 7.97 g/cm3 Electrical Resistivity: microhm-in (microhm-cm): 68 °F (20 °C): 28.7 (73)

Specific Heat: BTU/lb/°F (kJ/kg•K):
32 – 212 °F (0 – 100 °C): 0.12 (0.50)

Thermal Conductivity: BTU/hr/ft2/ft/°F (W/m•K):
At 212 °F (100 °C): 9.3 (16.0)
At 932 °F (500 °C): 12.8 (22.0)

Mean Coefficient of Thermal Expansion: in/in/°F (µm/m•K)
32 – 212 °F (0 – 100 °C): 9.3 x 10·6 (16.6)
32 – 1000 °F (0 – 538 °C): 10.5 x 10·6 (18.9)
32 – 1500 °F (0 – 873 °C): 11.4 x 10·6 (20.5)

Modulus of Elasticity: ksi (MPa)
28 x 103 (193 x 103) in tension
11 .2 x 103 (78 x 103) in torsion

Magnetic Permeability: H = 200 Oersteds: Annealed < 1.02 max
Melting Range: 2500 – 2550 °F (1371 – 1400 °C)

 

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As you can see, 347 stainless steel proves valuable in a range of applications. Similar to 304 but with the addition of columbium and tantalum, this stainless steel is recommended for welding jobs and others that need to operate at higher temperatures.

For more information, please contact the region’s largest supplier of stainless steel, Alliant Metals. Our experts are here to assist you in finding the perfect solution for whatever the application may be. As a nationally renowned metals distributor, our experts are known for efficiency and superior service – don’t settle for anything less. Call Alliant Metals at 800.543-1453.

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