A mid-ranged corrosion resistant alloy with good strength
- Good corrosion resistance to moderate acids & sea-water
- 50% stronger than stainless steel
- Usable temperature limit of 1000°F
- AL-6XN chemistry & specifications
- Set screw features and benefits
Originally developed to combat sea water corrosion, AL6XN has expanded its role as being good mid-range corrosion resistant alloy. AL-6XN set screws are a low carbon, high purity, nitrogen-bearing "super-austenitic" stainless alloy. 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.
• Moderate general corrosion resistance
• Excellent chloride / salt water protection
• Good performance in phosphoric acid
• Moderate resistance to nitric acid
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, set 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 AL-6XN set screws outperform so many alloys providing protection to stress corrosion cracking, pitting and crevice corrosion in a broad range of marine applications. AL-6XN set 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.
Electrical Resistivity: 535 Ohm-circ mil/ft
Ultimate Tensile Strength: 108 ksi
0.2% Yield Strength: 53 ksi
Density: 0.291 lb/in 3
• High molybdenum content provides enhanced corrosion protection in chloride environments.
• Carbon helps to prevent sensitization during welding
• Chromium enhances pitting and crevice corrosion resistance
• The interstitial strengthening effect of nitrogen gives AL-6XN set screws good high strength properties
• Desalination plants depend on AL-6XN set screws for the salt water corrosion protection
• Pulp bleaching equipment and piping
• The power industry uses AL-6XN set 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
• Chemical Processing - processing tanks, vessels and pipes as well as plate and frame heat exchangers.
Resources: Al-6XN Torque Specs
AL-6XN set screws are unique in that they have no screw head, meaning that they have no protruding part past the threaded shaft. They are thread only and are available with a socket or slotted driver insert at one end. Set screws are used to secure an object within or against another object. Typically they secure a rotating part such as a gear or shaft. AL-6XN set screws are driven through a threaded hole in the rotating part until it is tight against the inner object, preventing from moving relative to the outer object. Set screws are available with various points depending on the application.
This is the most commonly used set screw and is identified by a cup-shaped indentation on one end. AL-6XN cup points are typically used for a quick, semi-permanent or permanent applications where it is acceptable to cut the cup point edge of the screw.
A cone point is easily identifiable by its sharp cone-shaped point – just like an ice cream cone. AL-6XN cone point set screws deliver the strongest clamping force due to the deep penetration of the point. As a result they are used for permanent assembly.
The cheapest and simplest of the set screw point styles, this screw has a flat surface on the bottom of the screw. This type is used when you need the ability to frequently change parts and require minimal shaft deformation.
AL-6XN 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