Abstract
Long-term aged [343 K (70 C) for 30 months and natural exposure for over 10 years] Al 5456
H116 samples were characterized using electron backscatter diffraction (EBSD), scanning
transmission electron microscopy (STEM), state-of-the-art energy-dispersive X-ray spectroscopy
(EDS) systems, and small-angle neutron scattering (SANS). ASTM G-67 mass loss
tests of the sensitized Al 5456 alloy samples were conducted. Intragranular Mg-rich precipitates,
such as Guinier–Preston (GP) zones, were confirmed in Al 5456 H116 aged at 343 K (70 C) for
30 months, and the volume of these precipitates is 1.39 pct. b¢ phase is identified at the grain
boundary of a navy ship sample, while high-resolution STEM results reveal no intragranular
precipitates. Intergranular corrosion (IGC) of Al 5456 was found to be related to the continuity
of intergranular precipitates.
