Comprehensive Guide to Nickel-Based Alloys: Monel 400 (UNS N04400)
What is Monel 400?
UNS N04400 or DIN W.Nr. 2.4360/2.4361, Monel 400 (also known as "Alloy 400") is a solid solution nickel-copper alloy that has high strength and excellent resistance in a range of media including seawater, hydrofluoric acid, sulfuric acid, and alkalis. Alloy 400 also has strong resistance to stress corrosion cracking and pitting in most freshwater and industrial waters. Monel 400 is widely used in offshore engineering, chemical and hydrocarbon processing equipment, valves, forgings, shafts, flanges, pipe fittings, fasteners, and heat exchangers.
Weldability, Machinability, and Heat Treatment
Monel 400 can be easily joined by welding processes including stick metal arc welding (SMAW), gas tungsten arc welding (GTAW), and gas metal arc welding (GMAW). The corresponding filler or electrode should be selected. Since alloy 400 is softer than most steels, it can be hot-formed or cold-formed into almost any shape during machining. Generally speaking, Monel Alloy 400 products should be annealed (fully annealed) at 1470°F, and pickling is usually required to produce a bright and clean surface on the alloy.
Effect of Processing Rate and Heat Treatment System on UNS N04400 Alloy Steel Pipe
UNS N04400 is a nickel-copper alloy with chemical composition (wt.%), Ni≥63%, Cu 28%～34%, Mn≤2.0%, Fe≤2.5%, Si<0.5%, C<0.3%, S≤0.024%. The alloy has high strength, high corrosion resistance and high wear resistance, is more resistant to reducing medium corrosion than pure nickel, and is more resistant to oxidizing medium corrosion than pure copper; it has good resistance to sulfuric acid and phosphoric acid corrosion, especially good resistance to chloric acid corrosion, and also has excellent corrosion resistance to hot concentrated alkali. Therefore, it is widely used in cutting-edge industrial fields such as petrochemical industry, nuclear industry, and defense industry.
