Monel 405/Monel R405/N04405/W.Nr. 2.4361/Alloy 405 bar

Monel 405 bar, also known as Monel R-405, designated as UNS N04405 and W.Nr. 2.4361, is a free-machining nickel-copper alloy. It is essentially the same as Monel 400 but with the addition of sulfur to significantly improve machinability. This bar stock form is specifically engineered for high-speed automatic screw machining and other operations where excellent machinability is required to produce parts like fasteners, valve components, and pump shafts that also need the good corrosion resistance typical of nickel-copper alloys.

Introduction to Monel 405 (Alloy R-405)

Monel 405 is a variant of Monel 400, modified to achieve superior machining characteristics. The controlled addition of sulfur forms manganese sulfide inclusions in the microstructure, which act as chip breakers during machining. This allows for higher cutting speeds, longer tool life, and the production of fine, broken chips. The bar stock is ideal for manufacturing large quantities of parts on automatic screw machines and CNC lathes, where productivity and surface finish are critical, without sacrificing the alloy’s core resistance to seawater, acids, and alkalis.

Chemical Composition of Monel 405 Bar

The composition of Monel 405 bar is identical to Monel 400 except for the deliberate sulfur addition. Supplied by Shanghai NC Metal Materials Co., Ltd., the bar stock is formulated to balance machinability with corrosion resistance.

Mechanical Properties of Monel 405 Bar

Monel 405 bar offers mechanical properties very similar to Monel 400, with good strength and ductility. The sulfur addition slightly reduces ductility and impact toughness compared to 400, but it remains suitable for most structural applications.

Physical Properties of Monel 405 Bar

The physical properties of Alloy 405 are virtually identical to those of Monel 400.

Standard Specifications, Bar Forms, and Available Sizes

Shanghai NC Metal Materials Co., Ltd. supplies Monel 405 bar primarily in forms optimized for automatic machining, such as hexagonal and round bar in cold-drawn condition.

Primary Applications of Monel 405 Bar Stock

Machined components from Monel 405 bar are used where both corrosion resistance and high-volume machinability are needed: Fasteners: Nuts, bolts, screws, and studs for marine, chemical, and oil & gas applications. Valve and Pump Components: Stem, seats, bushings, and shafts in seawater and chemical handling equipment. Marine Hardware: Shafts, fittings, and other components exposed to seawater. Chemical Processing: Machined parts for equipment handling sulfuric and hydrofluoric acids, alkalies, and salts. Automatic Screw Machine Products: Any high-volume part requiring the corrosion resistance of Monel that is produced on Swiss-type or multi-spindle automatics.

Corrosion Resistance

Monel 405 offers corrosion resistance very similar to Monel 400. It has excellent resistance to seawater and salt atmospheres, dilute sulfuric and hydrochloric acids, phosphoric acid, and most alkalis. It is highly resistant to chloride-induced stress corrosion cracking. The sulfur addition for machinability does not significantly degrade its general corrosion resistance in most environments. However, it is not recommended for use in oxidizing acids (like nitric acid) or in high-temperature oxidizing conditions.

Machining Characteristics (Key Advantage)

The primary reason for selecting Monel 405 is its outstanding machinability among nickel-based alloys. The MnS inclusions cause the chips to break into small, manageable segments rather than forming long, tough, continuous strings. This leads to: higher permissible cutting speeds, improved surface finish, longer tool life, reduced power consumption during machining, and easier chip clearance from the work area. Standard practices include using sharp, positive-rake carbide tools and soluble oil coolants.

Welding and Heat Treatment

Monel 405 is generally considered not weldable by common fusion welding processes. The sulfur content can cause hot cracking (solidification cracking) in the weld metal and heat-affected zone. For applications where joining is necessary, mechanical fastening or silver brazing are the recommended methods. The alloy is typically used in the cold-worked and stress-relieved condition for machining. Full annealing can be performed but may slightly reduce machinability by altering the distribution of sulfide inclusions.

Reference Pricing and Key Purchasing Factors

The price of Monel 405 bar from Shanghai NC Metal Materials Co., Ltd. is comparable to Monel 400, with the added value of superior machinability often offsetting any slight premium.