ATI 20™ alloy (UNS N08020) has been available for many years and has found applications in many environments, such as in chlorides and in sulfuric and sulfurous acids.

Although ATI 20 alloy was developed for improved resistance to corrosion by sulfuric acid, it finds wide use throughout the chemical industry. It is used extensively in the manufacture of solvents, explosives, plastics, synthetic fibers, organic chemicals, pharmaceuticals, and food-processing equipment. Containment of acid mixtures and chloride stress corrosion resistance are examples of successful applications for ATI 20 alloy. Where purity must be maintained in the processing of products such as foodstuffs or dyes, ATI 20 alloy is used to protect end products from the danger of contamination by metallic ions through corrosion.

ATI 20 alloy has been applied economically in many areas where other materials may provide the necessary corrosion resistance, but are either higher in initial cost or more expensive to install and maintain. Important advantages of ATI 20 alloy are its excellent mechanical properties and comparative ease of fabrication. The presence of columbium in the alloy minimizes the precipitation of carbides in heat-affected zones during welding so that assemblies can usually be placed in service in the as-welded condition. Welds with matching filler metal will be slightly less corrosion resistant than the base alloy.

ATI 20 alloy is readily available in a wide range of product forms, and is covered by a wide variety of ASTM and ASME specifications having assigned maximum design stresses to 1000°F (540°C). The alloy is familiar to many fabricators and the weldability of this alloy contributes to its use in many engineered applications. Weld filler metal is readily available and welding procedures are well established.