Alloy 20 (1) is an iron-based austenitic alloy developed to resist sulfuric acid corrosion. It has excellent resistance to sulfuric acid corrosion; Phosphoric acid, nitric acid and chloride environment, chloride stress corrosion, resistance to point corrosion and crack corrosion are very strong. Therefore, alloy 20 has the name of corrosion resistant alloy; It has a wide range of applications: such as: chemistry, food, medicine, electricity production and plastics industry will use it. Resistance to point corrosion and chloride corrosion, stress corrosion cracking problems, etc., often choose alloy 20.