AL-6XN
Encyclopedia
The AL-6XN alloy
is a superaustenitic stainless steel
which was developed by Allegheny Ludlum Corporation. It exhibits far greater resistance to chloride pitting, crevice corrosion
and stress corrosion cracking
than exhibited by the standard 300 series stainless steel
s, and is less costly than the traditional nickel-base corrosion resistant alloys.
The UNS
Designation of the AL-6XN alloy is N08367.
The high nickel
(24%) and molybdenum
(6.3%) contents of the AL-6XN alloy give it good resistance to chloride stress-corrosion cracking. The molybdenum confers resistance to chloride pitting. The nitrogen
content of AL-6XN alloy serves to further increase pitting resistance and also gives it higher strength than typical 300 series austenitic stainless steels, and thereby often allows it to be used in thinner sections. The high levels of chromium
, molybdenum and nitrogen in AL-6XN alloy all serve to produce exceptional corrosion resistance for this formable and weldable stainless steel.
This metal is commonly used in lieu of 300 series stainless steels in high temperature and low ph applications in food processing. for example, tomato juice will corrode 316L stainless steel at pasteurization temperatures of 210°F. AL-6XN will better resist this corrosion while still offering the benificial properties of stainless steel.
Alloy
An alloy is a mixture or metallic solid solution composed of two or more elements. Complete solid solution alloys give single solid phase microstructure, while partial solutions give two or more phases that may or may not be homogeneous in distribution, depending on thermal history...
is a superaustenitic stainless steel
Stainless steel
In metallurgy, stainless steel, also known as inox steel or inox from French "inoxydable", is defined as a steel alloy with a minimum of 10.5 or 11% chromium content by mass....
which was developed by Allegheny Ludlum Corporation. It exhibits far greater resistance to chloride pitting, crevice corrosion
Corrosion
Corrosion is the disintegration of an engineered material into its constituent atoms due to chemical reactions with its surroundings. In the most common use of the word, this means electrochemical oxidation of metals in reaction with an oxidant such as oxygen...
and stress corrosion cracking
Stress corrosion cracking
Stress corrosion cracking is the unexpected sudden failure of normally ductile metals subjected to a tensile stress in a corrosive environment, especially at elevated temperature in the case of metals. SCC is highly chemically specific in that certain alloys are likely to undergo SCC only when...
than exhibited by the standard 300 series stainless steel
Stainless steel
In metallurgy, stainless steel, also known as inox steel or inox from French "inoxydable", is defined as a steel alloy with a minimum of 10.5 or 11% chromium content by mass....
s, and is less costly than the traditional nickel-base corrosion resistant alloys.
The UNS
Unified numbering system
The unified numbering system is an alloy designation system widely accepted in North America. It consists of a prefix letter and five digits designating a material composition. A prefix of S indicates stainless steel alloys, C for copper, brass, or bronze alloys, T for tool steels, etc...
Designation of the AL-6XN alloy is N08367.
The high nickel
Nickel
Nickel is a chemical element with the chemical symbol Ni and atomic number 28. It is a silvery-white lustrous metal with a slight golden tinge. Nickel belongs to the transition metals and is hard and ductile...
(24%) and molybdenum
Molybdenum
Molybdenum , is a Group 6 chemical element with the symbol Mo and atomic number 42. The name is from Neo-Latin Molybdaenum, from Ancient Greek , meaning lead, itself proposed as a loanword from Anatolian Luvian and Lydian languages, since its ores were confused with lead ores...
(6.3%) contents of the AL-6XN alloy give it good resistance to chloride stress-corrosion cracking. The molybdenum confers resistance to chloride pitting. The nitrogen
Nitrogen
Nitrogen is a chemical element that has the symbol N, atomic number of 7 and atomic mass 14.00674 u. Elemental nitrogen is a colorless, odorless, tasteless, and mostly inert diatomic gas at standard conditions, constituting 78.08% by volume of Earth's atmosphere...
content of AL-6XN alloy serves to further increase pitting resistance and also gives it higher strength than typical 300 series austenitic stainless steels, and thereby often allows it to be used in thinner sections. The high levels of chromium
Chromium
Chromium is a chemical element which has the symbol Cr and atomic number 24. It is the first element in Group 6. It is a steely-gray, lustrous, hard metal that takes a high polish and has a high melting point. It is also odorless, tasteless, and malleable...
, molybdenum and nitrogen in AL-6XN alloy all serve to produce exceptional corrosion resistance for this formable and weldable stainless steel.
This metal is commonly used in lieu of 300 series stainless steels in high temperature and low ph applications in food processing. for example, tomato juice will corrode 316L stainless steel at pasteurization temperatures of 210°F. AL-6XN will better resist this corrosion while still offering the benificial properties of stainless steel.