Type 347 Stainless Steel

347 stainless steel is variant of the basic austenitic 18/8 Grade 304 with added Columbium – the introduction of Columbium stabilizes the steel and eliminates carbide precipitation which subsequently causes intergranular corrosion.

The steel has excellent forming and welding qualities and excellent toughness even at cryogenic temperatures.

Benefits of 347 Stainless Steel

  • Higher creep stress and rupture properties when compared with 304
  • Ideal for high temperature service
  • Overcomes sensitization and intergranular corrosion concerns
  • Can be used in elevated temperature applications for ASME Boiler and Pressure Vessel Code applications
  • Due to stabilisation the material offers better overall corrosion resistance when compared to 304/304L
  • Excellent mechanical properties
  • A high carbon version (347H) is also available

Typical Uses

  • Heat exchangers
  • High temperature steam service
  • High temperature chemical process

Both 347/347H are used primarily in elevated temperature applications.

Mechanical Properties of Type 347

Description Type 347
Proof Stress 0.2% (MPa) 205
Tensile strength (MPa) 515
Elongation A5 (%) 40
Hardness HB: 201
HRB: 92

Chemical Composition of Type 347

UNS No S34700
EN 1.4550
AISI 347
Carbon (C) 0.08
Silicon (Si) 0.75
Manganese (Mn) 2.00
Phosphorus (P) 0.045
Sulphur (S) 0.030
Chromium (Cr) 17.00 – 19.00
Molybdenum (Mo)
Nickel (Ni) 9.00 – 13.00
Nitrogen (N)
Other Cb:10xC1.00