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Alloy 20

A Nickel-Iron-Chromium grade, Alloy 20 is ideal for a wide range of corrosive environments.

With the addition of Copper, Molybdenum and Niobium, Alloy 20 is the alloy of choice for sulphuric acid applications.


Product formSize range fromSize range to
Alloy 20 sheet & plate1.6 mm76.2 mm GET A QUOTE
Alloy 20 round bar10 mm279.4 mm GET A QUOTE
Alloy 20 pipe0.5 in10 in GET A QUOTE
Alloy 20 pipe fittings0.5 in10 in GET A QUOTE
Alloy 20 flanges0.5 in10 in GET A QUOTE

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Pipe Fittings

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Sheet & Plate

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Round Bar

Chemical Analysis

Min32.5192-3----8.0 x C 1.0-


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Perfect for applications in the Chemical Processing Industry

Alloy 20 can be used in a variety of applications, here are just a few examples:

  • Sulfuric acid pickling tanks, racks and heating coils
  • Phosphate coating drums and racks
  • Heat exchangers
  • Process piping
  • Tanks
  • Pumps and valves
  • Gaskets
  • Mechanical seals
  • Process equipment for manufacture of bullet-proof fibre, Kevlar

About Alloy 20

Alloy 20 contains Niobium for stabilisation which enhances its corrosion resistance. The alloy is an Iron-base, austenitic alloy with excellent corrosion resistance to a wide range of media.

With the high nickel content, Alloy 20 shows good resistance to chloride-induced stress corrosion cracking. In addition the alloy also has good resistance to pitting and crevice corrosion.

In the chemical process market, key applications of Alloy 20 are in sulphuric, phosphoric and nitric acid environments.

The alloy is also commonly used in the food industry for the manufacture of food preservatives (phosphorus oxychloride and phosphorus trichloride).


For complete list of inventory items contact us, or fill in our online quote form.


7.695 g/cm³ annealed
Melting range:
Electrical resistivity:
1.08 x 10-6 Ω⋅m
Poisson's Ratio:


UNS Number:
ASTM Standards:
A240, B366, B462, B463, B464, B468, B472, B473, B474, B475, B729, B775
ASME Standards:
SB463, SB464
Download the Alloy 20 Data Sheet Download

FAQs & Resources

Stress corrosion cracking (SCC) is the growth of a crack formation in a corrosive environment. It can lead to unexpected sudden failure of normally ductile metals subjected to a tensile stress, especially at an elevated temperature.

Chloride induced stress corrosion cracking is one of the most common reasons why austenitic stainless steel pipework and vessels deteriorate in the chemical processing and petrochemical industries. Deterioration By Chloride induced stress corrosion cracking can lead to failures that have the potential to release stored energy and/or hazardous substances.

At 33% Nickel content alloy 20 is virtually immune to Chloride induced stress corrosion cracking.

Uniform corrosion, localised corrosion pitting & crevice corrosion, intergranular corrosion and galvanic corrosion.
Alloy 20 is resistant to intergranular corrosion in the as welded condition.

Intergranular corrosion (IGC), also known as intergranular attack (IGA), is a form of corrosion where the boundaries of crystallites of the material are more susceptible to corrosion. This is created by the formation of intermetallic carbides at the grain boundaries resulting in the formation of Chromium-depleted zones adjacent to the grain boundaries. Often referred to as sensitisation of the material.

This alloy was developed specifically for hot sulphuric acid applications. It also demonstrates excellent general corrosion resistance. Niobium stabilisation allows the material to be used in corrosion environments in the as welded condition.

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