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

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

Typical Comparitive Chemistry

  Chromium Nickel Molybdenum Nitrogen Copper PREN
AL-6XN 20% 24% 6.3% 0.22% 0.25-0.75% 44.3
316L 16% 10% 2.0% 0.05% 0.40% 23.4
254 SMO® 20% 18% 6.3% 0.20% 0.80% 44.0
25-6 MO® 20% 25% 6.5% 0.20% 1.20% 44.7
1925 hMO® 20% 25% 6.5% 0.18% 0.90% 44.3

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.

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