ThePipingMart Blog Grades Alloy 20 – Properties, Uses, and Composition

Alloy 20 – Properties, Uses, and Composition

Alloy 20 - Properties, Uses, and Composition

Alloy 20, also known as Carpenter 20, is a nickel-chromium-molybdenum stainless steel alloy. This type of steel is austenitic, which means it cannot be hardened through heat treatment. It is corrosion-resistant and has excellent mechanical properties at low and high temperatures. Let’s take a closer look at the composition, mechanical properties, and uses of alloy 20.

What is Alloy 20?

Alloy 20 is a nickel-iron-chromium alloy that is highly resistant to corrosion and other harmful elements. It can easily withstand extreme temperature fluctuations, so it is commonly used in machinery and equipment such as tanks and pumps. The alloy possesses excellent strength and toughness qualities, making it a favorite among personnel looking for strong but cost-effective materials. Furthermore, the alloy’s good ductility properties mean it can be formed or manipulated into any required shape. All of these noteworthy attributes make Alloy 20 an extremely practical choice when manufacturing products that will come into contact with corrosive substances or high temperatures.

Alloy 20 chemical composition

Alloy 20 contains a balanced composition of nickel (30%), chromium (19-22%), molybdenum (2-3%), manganese (1.5%), iron (balance), silicon (.75%), sulfur (.035%) and carbon (.07%). The balance of these elements results in a steel alloy with good strength and excellent corrosion resistance to both acidic and alkaline environments. It has greater resistance to stress corrosion cracking than most other alloys.

Element Content (%)
Iron, Fe 35
Nickel, Ni 32-38
Chromium, Cr 19-21
Copper, Cu 3-4
Manganese, Mn ≤2
Molybdenum, Mo 2-3
Niobium, Nb ≤1
Silicon, Si ≤1
Carbon, C ≤0.07
Phosphorous, P ≤0.045
Sulfur, S ≤0.035

Alloy 20 properties

Alloy 20 is an amazing metal alloy with tantalizing properties and a wide range of applications. It is a nickel-iron-chromium stainless steel most commonly used in the chemical, food and pharmaceutical industries. Notable features of Alloy 20 are its acid resistance and excellent formability, making it ideal for a variety of high temperature uses, including heat exchangers, pressure vessels, condensers and valves. It also contains molybdenum for enhanced corrosion resistance at elevated temperatures. High work hardening ability makes it well suited for manufacturing components that require higher yields and stronger tensile strengths. In addition to its unique combination of mechanical traits, Alloy 20 is also highly resistant to stress corrosion cracking and sulfur compounds such as sulfuric acid. For these reasons and more, you can trust that alloy 20 has all the advantageous properties you need for any industrial application.

Mechanical Properties

mechanical properties of alloy 20 include a tensile strength ranging from 80ksi minimum to 145ksi maximum and an 0.2% yield strength ranging from 40ksi minimum to 95ksi maximum. The elongation ranges from 30% to 40% maximum in 2 inches for hot rolled product forms or annealed condition; cold finished product forms may range from 50% minimum to 60% maximum in 2 inches for all conditions.

Properties Metric Imperial
Tensile strength (annealed) 620 MPa 89900 psi
Yield strength (annealed) 300 MPa 43500 psi
Elongation at break (annealed) 41% 41%

Uses of Alloy 20

Alloy 20 finds use in many industries, including pharmaceuticals, chemical processing, power generation, pulp & paper production, food processing, oil & gas exploration & production, waste treatment systems, and nuclear fuel reprocessing plants due to its excellent corrosion resistance qualities combined with good mechanical strength over a wide temperature range. It can be used for many applications such as pumps, valves & fittings; pickling equipment; fasteners; flanges; heat exchanger’s; pressure vessels; tanks; piping systems & components; nuclear fuel element spacers; condensers & evaporators; piping systems components & supports; centrifuges & agitators; hydrocracking reaction vessels/towers/piping systems; trays & baskets for handling corrosive materials.

  • Production of plastics and synthetic fibers
  • Chemical and petroleum processing equipment
  • Mixing tanks
  • Heat exchangers
  • Process piping

Alloy 20 equivalent material

  • ASME SB-462 – SB-464
  • ASME SB-468
  • ASTM B 462 – B 464
  • ASTM B 468
  • ASTM B 472 – B 474
  • ASTM B 751


Alloy 20 is austenitic stainless steel that offers excellent corrosion resistance against both acidic and alkaline environments, combined with good mechanical properties over a wide temperature range. It contains a balanced composition of nickel (30%), chromium (19-22%), molybdenum (2-3%), manganese (1.5%), iron (balance), silicon (.75%), sulfur (.035%) and carbon (.07%) which make it ideal for use in many industries such as pharmaceuticals processing, chemical processing, power generation, pulp & paper production, etc., where it can be used for pumps, valves & fittings, pickling equipment, fasteners, flanges, heat exchanger’s, pressure vessels, tanks, piping systems & components, etc. If you are looking for an alloy that offers excellent corrosion resistance while maintaining strong mechanical performance in various demanding industrial environments, then alloy 20 should be your top choice!

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Alloy 20 – Properties, Uses, and Composition

by Piping Mart time to read: 3 min