A995 4A

Grade 4A is a duplex stainless steel casting alloy specified by ASTM A995/A995M, developed for pressure-containing parts that demand a balance of high strength, toughness, and corrosion resistance. With a dual-phase microstructure composed of approximately equal parts austenite and ferrite, and alloying elements including chromium, nickel, molybdenum, and nitrogen, Grade 4A provides reliable resistance to pitting, crevice corrosion, and chloride stress corrosion cracking. It is the cast equivalent of wrought 2205 duplex stainless steel and is commonly used in applications such as pumps, valves, and manifolds in marine environments, desalination plants, and chemical processing systems. Grade 4A is valued for its performance in moderately aggressive service conditions where both mechanical integrity and corrosion resistance are required.