The Effect of Sensitization on the Stress Corrosion Cracking of Aluminum Alloy 5456
NAVAL POSTGRADUATE SCHOOL MONTEREY CA
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This work examines the effect of sensitization on the stress corrosion cracking behavior of marine grade aluminum alloys Al-Mg. These alloys can be sensitized during operation, promoting their susceptibility to intergranular stress corrosion cracking IGSCC. Aluminum alloy 5456-H116 also identified as Al-Mg5.1 samples were sensitized at 175 C for varying durations of time and then mechanically tested in salt water. Mass loss tests quantified the degree of sensitization DOS as a function of sensitization time. Dual cantilever beam tests were used to measure the SCC growth rate and cyclic fatigue tests were conducted to determine the corrosion fatigue behavior. DOS increased as sensitization time increased with little difference in mass losses above 336 hours. Stress corrosion crack growth rate increased as sensitization time increased. Although the sensitization rates for AA5456-H116 were higher than for AA5083, the stress corrosion crack growth rates were significantly lower. The stress corrosion fracture surfaces showed clear showed a clearly intergranular fracture path with extensive crack branching and delamination in the transverse direction.
- Properties of Metals and Alloys