A mid-ranged corrosion resistant 6Mo alloy with good strength

• Good corrosion resistance to moderate acids & sea-water 
• 50% stronger than stainless steel
• Usable temperature limit of 1000°F
• AL6XN chemistry & specifications
• Torx screw features and benefits
• AL6XN Datasheet

Originally developed to combat sea water corrosion, AL6XN has expanded its role as being good mid-range corrosion resistant alloy. AL6XN torx screws are a low carbon, high purity, nitrogen-bearing "super-austenitic" stainless alloy. Also considered a 6Moly alloy, AL6XN screws are similar in chemistry and capabilities to Alloy 926 and SMO 254. With a higher nickel and molybdenum content than Duplex 2205 and Super Duplex 2507, it delivers better corrosion resistance while giving a more cost effective alternative to nickel super alloys like Inconel or Hastelloy in moderately corrosive conditions.

Corrosion Resistance
o  Moderate general corrosion resistance
o  Excellent chloride / salt water protection
o  Good performance in phosphoric acid
o  Moderate resistance to nitric acid

Chemical Resistance
In chemical processes which utilize chlorides, such as paper mills and waste water, stress corrosion cracking (SCC) is a common culprit for 316L stainless failures. Duplex alloys will outlast environments that will cause SCC in 316 stainless, but for more severe low PH environments, torx screws made from higher nickel content alloys like AL6XN will generally work better. For the most extreme situations, alloys with >45% nickel content like Hastelloy are often considered.

Outstanding Resistance to Salt Water
Seawater is where AL6XN torx screws outperform so many alloys providing protection to stress corrosion cracking, pitting and crevice corrosion in a broad range of marine applications. AL6XN torx screws contain a minimum of 6% molybdenum content and it is this addition of molybdenum that provides the greatest protection against pitting and crevice corrosion.

Mechanical Properties
Electrical Resistivity: 535 Ohm-circ mil/ft
Ultimate Tensile Strength: 108 ksi
0.2% Yield Strength: 53 ksi
Density: 0.291 lb/in 3

Chemistry
o  High molybdenum content provides enhanced corrosion protection in chloride environments.
o  Carbon helps to prevent sensitization during welding
o  Chromium enhances pitting and crevice corrosion resistance
o  The interstitial strengthening effect of nitrogen gives AL6XN torx screws good high strength properties

AL6XN Applications
o  Desalination plants depend on AL6XN torx screws for the salt water corrosion protection
o  Pulp bleaching equipment and piping 
o  The power industry uses AL6XN torx screws where salt water and chlorides are present such as steam surface condensers, supercritical, high pressure, feed water heaters, steam surface condensers, flue-gas desulfurization equipment and in nuclear power water piping 
o  Offshore 
o  Chemical Processing - processing tanks, vessels and pipes as well as plate and frame heat exchangers.

Resources: AL6XN Torque Specs

AL6XN Screw Types: 12 Point Screws, Button Head Cap Screws, Flat Head Screws, Hex Cap Screws, Pan Head Screws, Set Screws, Socket Head Cap Screws, Tamper Resistant Security Screws, Torx Screws

AL6XN Torx Screw Features and Benefits

AL6XN Torx screws are characterized by a 6-point star-shaped pattern, also called a star drive, spined socket or hexalobular (ISO 10664). Where Phillips heads were designed to cause the driver to cam-out (prevent overtightening), Torx screws were designed resist cam-out. This feature allows AL6XN Torx screws to provide increased torque as well as better torque transfer between driver and fasteners. This feature also helps to reduce wear on driver bits.

AL6XN Torx Screw Advantages

• Resistant to cam out (process by which a screwdriver slips out of the head)
• AL6XN Torx screws are more difficult to strip
• Increased tamper resistance as a star driver isn’t as common
• Driver insert is less susceptible to damage when over torqued than Allen head

AL6XN Chemical Composition & Specifications

AL6XN Specifications: UNS N08367, ASTM A 240, ASTM B 688, ASME SA-240, ASME SB-688, ASTM B690, ASTM B691, ASTM A240, ASTM B688, ASME SA-240, ASME SB-688

AL6XN Mechanical Data

 Corrosion Curves for AL6XN