Alloy 33 (UNS R20033, N08033 / W.Nr. 1.4591)

Alloy 33 (UNS R20033, N08033 / W.Nr. 1.4591) is a high-chromium austenitic alloy which combines ease of fabrication with outstanding resistance to highly oxidizing media such as concentrated sulphuric acid. Despite its low molybdenum content, it shows excellent resistance to localized corrosion in halide media. The nitrogen content ensures high mechanical properties with good ductility. Alloy 33 is a material that can be used for many applications in the chemical processing industry.

Equivalent Grades

Nicrofer 3033NS1405Alloy 33R20033
X1NiCrMoCuN 33-32-11.4591

Chemical Composition, %

Alloy 33≤0.015≤0.50≤2.00≤0.020≤0.01031.0-35.030.0-33.00.5-2.00.3-1.20.35-0.60Bal

Typical Physical and Mechanical Properties (RT, Annealed)

Density, g/cm3Melting Point, ℃Tensile Strength, MPaYield Strength, MPaELongation, %Hardness, HBW

Available Products and Specifications

Rod, Bar, Wire and ForgingsASTM B649, ASME SB649
Plate, Sheet and StripASTM B625, ASME SB625
Pipe and Tube
Welding Product


  • Excellent resistance against pitting corrosion in media containing chloride and against general corrosion in hot mineral acids, mixed acids and alkalis as well as seawater and brackish water
  • High strength and high ductility even in high temperatures
  • Good workability and welding characteristics
  • ASME approval for pressure vessels in the temperature range from -196℃ to 450℃


  • Heat recovery and distribution systems in the sulfuric acid production
  • Pipes and heat exchangers for sulfuric acids contaminated with chlorides
  • Vessels for storage and transport of nitric acid/hydrofluoric acid mixtures
  • Seawater conducting pipes, condensers, coolers, etc. with excellent resistance against pitting corrosion
  • Production and use of NaOH and KOH up to 70 wt.-% and max. 170℃
  • Urea solutions in the concentration range from 5 to 90 wt.-%
  • Components for the pulp and paper industry
  • Vessels and pipes in purified terephthalic acid (PTA) plants