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Last updated: October 1, 2015

What Does AL6XN Mean?

The AL6XN is a low carbon, high molybdenum superaustenitic stainless steel with excellent resistance to corrosion, high strength, good formability and weldability. It contains high levels of molybdenum, chromium and nitrogen, which contribute to its overall resistance to corrosion and make it suitable for a wide range of corrosive environments. The alloy is available in a wide variety of forms including sheets, plates, strips, wire, bars, and more.

The AL6XN alloy is identified as N08367 by the Unified Numbering System (UNS).


Corrosionpedia Explains AL6XN

The AL6XN alloy contains between 23.5 and 25.5% Nickel, 20 to 22% chromium, 6 to 7% Molybdenum, 0 to 0.03 % carbon, and 0.18 to 0.25% nitrogen. The other alloying elements include manganese – 0 to 2%, silicon – 0 to 1%, phosphorous – 0 to 0.04 %, Sulfur –0 to 0.03 %, Copper – 0 to 0.75%, while the iron takes the balance of about 47%.

The chromium, molybdenum and nitrogen improve the resistance to pitting corrosion while the nickel and molybdenum increase the resistance to chloride-stress corrosion. The nitrogen increases the tensile strength to a higher level compared to the common austenitic stainless steels.

The alloy has good cold formability, which makes it easy for drawing, bending, pressing or any other forming process required to produce fabricated items. However, bending over a sharp male die can cause cracking of the material.

The AL6XN is formed using the standard methods, but higher forces are required to deform it due to its elevated strength. The deforming should be followed by stress or full annealing so as to retain its mechanical and corrosion properties. Slow cooling of the AL6XN alloy reduces the corrosion resistance and it is therefore necessary to anneal and water quench the alloy after cold working.

AL6XN characteristics:

  • Excellent resistance to general corrosion, pitting corrosion and crevice corrosion in chloride solutions
  • Practical immunity to stress corrosion in sodium chloride environments
  • High strength
  • Formable and weldable
  • Lower cost than conventional high nickel alloy stainless steels

The AL6XN material is generally used in harsh conditions where good strength and excellent resistance to chloride pitting and stress-corrosion cracking are required. Common industries include pharmaceutical, food processing, biotech, chemical processing, medical, oil and gas, power generation and more. The material is used in bolts, nuts, and other fasteners, tube and pipe systems in distillation, chemical process tanks, seawater heat exchangers, and other industrial equipment.


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