Natural Steels

Other common names: Alloy 400

Monel 400 is a nickel-copper alloy (about 67% Ni - 23% Cu) that is resistant to sea water and steam at high temperatures as well as to salt and caustic solutions. Alloy 400 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 alloy is particularly resistant to hydrochloric and hydrofluoric acids when they are de-aerated. As would be expected from its high copper content, alloy 400 is rapidly attacked by nitric acid and ammonia systems.

Monel 400 has great mechanical properties at subzero temperatures, can be used in temperatures up to 1000 F, and its melting point is 2370-2460 F. However, alloy 400 is low in strength in the annealed condition so, a variety of tempers may be used to increase the strength.

In what forms is Monel 400 Available at Natural Steels?

• Sheet
• Plate
• Bar
• Pipe & Tube (welded & seamless)
• Fittings (i.e. flanges, slip-ons, blinds, weld-necks, lapjoints, long welding necks, socket welds, elbows, tees, stub-ends, returns, caps, crosses, reducers, and pipe nipples)
• Wire

What are the characteristics of Monel 400?

• 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 at 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
• Good mechanical properties from sub-zero temperatures up to 1020 F
• High resistance to alkalis

Chemical Composition, %

Corrosion Resistant Monel 400

Alloy 400 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.

This nickel alloy is attacked in sulfur-bearing gases above approximately 700 F and molten sulfur attacks the alloy at temperatures over approximately 500F.

Monel 400 offers 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.

• Yellowish brown in color
• Resistant against corrosion
• Dimensionally accurate

We are the leading supplier of Monel Tubesmade available to our clients at competitive prices. It is composed of carbon, chromium, copper iron, manganese, molybdenum, nickel phosphorus, silicon, & sulfur. 
Monel Tube Specification; ASTM B163, ASTM B730
Monel Tube Schedule; SCH20, SCH 30, SCH40, STD, SCH80, XS, SCH60, SCH120, SCH140, SCH160, XXS
Monel Tube Type; Monel Seamless Tube, Monel Welded Tube, Monel ERW Tube, Monel Fabricated Tube
Monel Tube End; Plain End, Beveled End, Threaded
Monel Grades; Monel 400, Monel 401, Monel 404, Monel 405, Monel K-500

Other common names: Alloy K500

Monel K500 is a precipitation-hardenable nickel-copper alloy that combines the excellent corrosion resistance characteristic of Monel 400 with the added advantage of greater strength and hardness. These amplified properties, strength and hardness, are obtained by adding aluminum and titanium to the nickel-copper base and by a thermal processing used to effect precipitation, typically called age hardening or aging. When in the age-hardened condition, Monel K-500 has a greater tendency toward stress-corrosion cracking in some environments than Monel 400. Alloy K-500 has approximately three times the yield strength and double the tensile strength when compared with alloy 400. Plus, it can be further strengthened by cold working prior to precipitation hardening. The strength of this nickel steel alloy is maintained to 1200° F but stays ductile and tough down to temperatures of 400° F. Its melting range is 2400-2460° F.

In what forms is Monel K500 Available at Natural Steels?

• Bar
• Rod

Corrosion Resistant Monel K-500

The corrosion resistance of alloy K-500 is substantially equivalent to that of alloy 400 except that when in the age-hardened condition, nickel alloy K-500 has a greater tendency toward stress-corrosion cracking in some environments. Monel K-500 has been found to be resistant to a sour-gas environment. The combination of very low corrosion rates in high-velocity sear water and high strength make alloy K-500 particularly suitable for shafts of centrifugal pumps in marine service. In stagnant or slow-moving sea water, fouling may occur followed by pitting but this pitting slows down after a fairly rapid initial attack.

What are the characteristics of Monel K500?

• Corrosion resistance in an extensive range of marine and chemical environments. From pure water to non-oxidizing mineral acids, salts and alkalis.
• Excellent resistance to high velocity sea water
• Resistant to a sour-gas environment
• Excellent mechanical properties from sub-zero temperatures up to about 480C
• Non-magnetic alloy

  Chemical Composition, %

  Ni	Cu	Al	Ti	C	Mn	Fe	S	Si
  63.0-70.0	Remainder	2.30-3.15	.35-.85	.25 max	1.5 max	2.0 max	.01 max	.50 max

  In what applications is Monel K-500 used?

• Sour-gas service applications
• Oil and gas production safety lifts and valves
• Oil-well tools and instruments like drill collars
• Oil well industry
• Doctor blades and scrapers
• Chains, cables, springs, valve trim, fasteners for marine service
• Pump shafts and impellers in marine service

In what forms is Monel R-405 Available at Natural Steels?

• 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.

Chemical Composition, %