Monel 400, also known as UNS N04400, is a nickel-copper alloy renowned for its exceptional corrosion resistance, high strength, and excellent mechanical properties across a wide temperature range. This solid-solution alloy is composed primarily of nickel (63% min) and copper (28-34%), with small additions of iron, manganese, and silicon to enhance its durability and performance in harsh environments.

Monel 400 is widely used in marine, chemical processing, oil & gas, and aerospace industries due to its resistance to seawater, acids, and alkaline solutions. The alloy maintains its strength and toughness even at sub-zero temperatures, making it ideal for cryogenic applications.

The ASTM B164 standard governs the production of Monel 400 (N04400) and Monel 405 (N04405) in the form of hot-worked and cold-worked rods, bars, and wires.