High Alloy Materials
Monel R-405

MONEL® R-405

UNS N04405

Monel R405 is the free machining version of Monel 400. It is a nickel-copper alloy with a controlled amount of sulfur added to provide sulfide inclusions that act as chip breakers during machining. Like Monel 400, alloy R-405 is resistant to sea water and steam at high temperatures as well as to salt and caustic solutions. Monel R405 is a solid solution alloy that can only be hardened by cold working. This nickel alloy exhibits characteristics like good corrosion-resistance, good weldability and high strength. A low corrosion rate in rapidly flowing brackish or seawater combined with excellent resistance to stress corrosion cracking in most freshwaters, and its resistance to a variety of corrosive conditions led to its wide use in marine applications and other non-oxidizing chloride solutions. This nickel steel alloy is particularly resistant to hydrochloric and hydrofluoric acidswhenthey are de-aerated. As would be expected from its high copper content, alloy R-405 is rapidly attacked by nitric acid and ammonia systems.


In what forms is Monel R405 Available ?

Round Bar (ASTM specification B 164)
Hex Bar

Corrosion Resistant Monel R-405

As with alloy 400, Monel R-405 is virtually immune to chloride ion stress corrosion cracking in typical environments. Generally, its corrosion resistance is very good in reducing environments, but poor in oxidizing conditions. It is not useful in oxidizing acids, such as nitric acid and nitrous. Nevertheless, it is resistant to most alkalis, salts, waters, food products, organic substances and atmospheric conditions at normal and elevated temperatures.

Monel 400 and R-405 offer about the same corrosion resistance as nickel but with higher maximum working pressures and temperatures and at a lower cost due to its superior ability to be machined.


What are the characteristics of Monel R405?

Characteristics are essentially the same as those of Monel 400 such as:

Good machinability and is recommended for use with automatic screw machines
Resistant to seawater and steam at high temperatures
Excellent resistance to rapidly flowing brackish water or seawater
Excellent resistance to stress corrosion cracking in most freshwaters
Particularly resistant to hydrochloric and hydrofluoric acids when they are de-aerated
Offers some resistance to hydrochloric and sulfuric acids a modest temperatures and concentrations, but is seldom the material of choice for these acids
Excellent resistance to neutral and alkaline salt
Resistance to chloride induced stress corrosion cracking
High resistance to alkalis

Chemical Composition, %

Ni Cu Fe S Mn C Si
63.0 min 28.0-34.0 2.5 max .025-.060 2.0 max .3 max .5 max


In what applications is Monel R-405 used?

Alloy R-405 is chiefly used for automatic-screw-machine stock and it not generally recommended for other applications. Screw machine stock for fasteners and similar high production run items.

Meter and valve parts
Screw machine products

Fabrication with Monel R-405

Monel R-405 is fabricated, pickled and heat-treated by the same procedures as for alloy 400. It is not recommended for forging. However, R-405 alloy was especially developed for good machinability and is recommended for use with automatic screw machines. The nickel –copper sulfides resulting from the sulfur in its composition act as chip breakers.

This nickel alloy also has the same procedures and processes as alloy 400 and can be joined by standard welding, brazing and soldering techniques. Just as with alloy 400, R-405 can easily be welded by gas – tungsten arc, gas metal arc, or shielded metal arc processes using appropriate filler metals. There is no need for post weld heat treatment, however, thorough cleaning after welding is critical for optimum corrosion resistance, otherwise there is the risk of contamination and embrittlement.


Mechanical Properties 
Nominal Mechanical Property Range of Monel Alloy R-405 Rod and Bar

Condition Tensile (ksi) .2% Yield (ksi) Elongation % Hardness Brinell (3000 kg) Hardness Rockwell B
Annealed 70-85 25-40 50-35 110-140 60-76
Hot-Finished 75-90 35-60 45-30 130-170 72-86
Cold-Drawn, As-Drawn 85-115 50-105 35-15 160-245 85-23C

The ranges shown are composites for various product sizes and therefore are not suitable for specification purposes.

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