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-405is rapidly attacked  by nitric acid and ammonia systems.

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, %

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

· Fasteners

· 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