AL-6XN Properties

Physical Properties of AL-6XN
Property Value Units
Density 0.291
8.06		 lb/in3
g/cm3
Modulus of Elasticity 28.3 x 106
195 		psi
Gpa
Melting Range 2410 to 2550
1320 to 1400		 °F
°C
Thermal Conductivity
68 to 212 °F
20 to 100°C
6.8
11.8
Btu/hr • ft • °F
W/mK
Coefficient of Expansion
68 to 212 °F
20 to 100°C
8.5
15.3
10-6/°F
10-6/°C
Specific Heat Capacity 0.11
500		 Btu/lb • °F
J/kg • K
Electrical Resistivity 535
0.89		 Ohm • circ mil/ft
µΩm
Magnetic Permeability
Fully annealed 0.5" plate
65% cold-worked plate
1.0028
1.0028
Oersted
(µ at 200H)
Sealing Temperature 1885
1030		 °F
°C

Chemical Composition

Element Typical Allowable
Carbon 0.02 0.03 maximum
Manganese 0.40 2.00 maximum
Phosphorus 0.020 0.040 maximum
Sulfer 0.001 0.030 maximum
Silicon 0.40 1.00 maximum
Chromium 20.5 20.00 / 22.00
Nickel 24.00 23.50 / 25.50
Molybdenum 6.20 6.00 / 7.00
Nitrogen 0.22 0.18 / 0.25
Copper 0.2 0.75
Iron Balance Balance

Temperature Stability

AL-6XN alloy is metallurgically stable to 1000 °F (540 °C) and has no phase transformation even after extensive deformation. When exposed to temperatures in the range of 1200-1800° F the opportunity for chi phase formations exists. Chi phase, a chromium-iron-molybdenum compound (sometimes incorrectly referred to as sigma phase), forms along the grain boundaries depleting the area of molybdenum and chromium reducing the corrosion resistance of the material. In order to help combat chi phase formation, nitrogen was added to the AL-6XN alloy to minimize this formation, improving corrosion resistance and increasing strength over a broad range of temperatures, while maintaining the good formability of austenitic stainless steel.

Chromium Carbides

Above: Example of chromium carbides formed along the grain boundaries depleting the surrounding areas of chromium and molybdenum


Comparative chemistry for AL-6XN alloy vs. 316L stainless
steel and other 6% Molybdenum containing products is as follows:

Typical Comparitive Chemistry

  UNS # Chromium Nickel Molybdenum Nitrogen PREN
AL-6XN N08367 20-22% 23.5-22.5% 6-7% 0.18-0.25% 45.89
316L S31603 16-20% 10-15% 2-3% 0.05% 27.05
254 SMO® S31254 20% 18% 6.3% 0.20% 43.83
904L N08904 20% 25% 6.5% 0.20% 35.85
2205 S31803 20% 25% 6.5% 0.18% 34.14

Low copper content gives resistance against chloride corrosion. Cu above 0.75% tends to corrode in high chloride environments. For seawater pitting resistance PREN must be greater than 32.