Alloy 20 stands out among corrosion-resistant materials due to its nickel-iron-chromium based composition, offering exceptional protection in caustic environments containing sulfuric acid or other aggressive media including phosphoric acid, nitric acid and aqueous salt solutions. Stabilized with niobium (Nb), this austenitic alloy outperforms standard austenitic stainless steels when intergranular corrosion risks are present.

What is Intergranular Corrosion?

Austenitic stainless steels, such as 304 and 316, can be more susceptible to intergranular corrosion attack when exposed to aggressive media, especially at elevated temperatures. Chromium carbides precipitate at the grain boundaries and the structure becomes sensitized. Damage from grain boundary attack can lead to grain detachment, creating weak areas in the material with little visible evidence. Failing to account for potential risks caused by intergranular corrosion can result in premature material failure, making it essential for businesses to carefully consider material selection.

Alloy 20’s niobium-stabilized composition helps mitigate intergranular corrosion by producing niobium carbides instead of chromium rich carbides,  thus reducing the risk of intergranular corrosion attack. This niobium-stabilized composition enables alloy 20 to provide superior corrosion resistance performance compared to common austenitic stainless steel grades, such as 304 and 316.

Additionally, when cost savings is a factor in material selection, alloy 20 is an economical choice compared to other higher nickel-based alloys.