Monel 400 Round Bar

Monel 400 is a nickel-copper alloy, UNS N04400 and Werkstoff 2.4360. Material is furnished to ASTM B164, the standard covering nickel-copper alloy rod, bar and wire, with ASME SB-164 for pressure equipment.

The composition is simple: nickel 63% minimum with 28-34% copper and little else. That binary nickel-copper system is close to a solid solution across the whole composition range, which gives the alloy unusually uniform properties and no phase changes to worry about.

Its defining application is hydrofluoric acid. Monel 400 is one of very few materials that performs reliably in HF across a wide concentration and temperature range, and much of the world’s HF alkylation plant is built from it. It also resists seawater, brine, alkalis and reducing acids, and handles flowing seawater far better than copper alloys.

The limitation is oxidising conditions. Nitric acid, ferric chloride, cupric chloride and oxidising salts attack it rapidly, so it is not a general-purpose corrosion alloy.

One property catches people out: Monel 400 has a Curie temperature near room temperature, so it can be weakly magnetic at ambient depending on composition and temperature. It is not a reliably non-magnetic material.

Bar is supplied annealed, hot-finished, or cold drawn and stress relieved, and the three conditions carry different mechanical requirements, so the condition belongs on the order.

The modulus of elasticity at 179 GPa is noticeably below the roughly 200 GPa of steels, which matters for deflection-limited design and for bolted joints where stiffness affects load distribution.

Sizes span 6 mm to 250 mm, either random or cut to length.

Typical work is HF alkylation hardware, marine shafting, pump and valve components, heat exchangers and fasteners.