347 Stainless Steel

UNS S34700 stainless
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Niobium-stabilised austenitic stainless steel providing superior intergranular corrosion resistance and better creep strength than 321 at temperatures above 600°C.

Applicable Standards

  • ASTM A240
  • ASTM A269
  • ASTM A312
  • EN 1.4550

Composition Ranges (wt %)

Element Min (%) Max (%) Typical Range
Fe 60.0 75.0 ~67.5
Cr 17.0 19.0 ~18.0
Ni 9.0 13.0 ~11.0
Nb 0.1 1.1 ~0.6
Mn — 2.0 ~1.0
C — 0.08 ~0.04
Fe 60.0–75.0% Cr 17.0–19.0% Ni 9.0–13.0% Nb 0.1–1.1% Mn 0.0–2.0% C 0.0–0.08%

Typical Applications

  • Aircraft exhaust ducts
  • Welded pressure vessels
  • Nuclear fuel reprocessing
  • High-temperature chemical plant
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