347/347H – 1.4550

347/347H – 1.4550

(South America offer) Niobium Stabilized Austenitic Stainless Steel with corrosion resistance at high temperatures.

Main features

Due to the stabilization with niobium, this grade has the corrosion resistance at high temperatures as its main characteristic. When submitted to temperatures ranging from 450-900 ºC, some grades tend to form chromium carbide precipitate in the grain boundary region, and the material becomes susceptible to intergranular corrosion. The stabilization with niobium inhibits the formation of chromium carbide, and consequently increases the resistance to this type of corrosion. Grade AISI 347 has excellent weldability, a characteristic common to austenitic steels, as well as high mechanical properties, which guarantees good ductability, and it s recommended for some cold forming processes.


Equipment for the aeronautical industry, such as turbine collector rings and exhaust systems, expansion joints and also for high temperature chemical process equipment. It also finds application in the oil industry, especially during refining, in the form of tubes, connections or flat plates.


  • ASTM 347/347H
  • UNS S34709
  • EN 1.4550

Chemical composition

Typical values

  • C=0.044
  • Si=0.42
  • Mn=1.84
  • Cr=17.31
  • Ni=9.02
  • P=0.025
  • S=0.001

Dimensional range

Coils & Sheets

  • Thickness: from 0.40 to 8 mm
  • Width: from 1,000 to 1,00 mm


  • Diameter: from 8 to 2,032 mm
  • Thickness: from 0.50 to 6.35 mm

Heavy Plates

  • Thickness: from 9 to 50 mm
  • Width: from 1,000 mm to 1,500 mm

Surface aspect

  • Hot rolled & Cold rolled
  • NR1/1D, 2D, 2B

According to forms & dimensions.

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