Aluminum alloys with magnesium content greater than three weight percent, such as the 5xxx alloy family, are susceptible to a process called sensitization when exposed to temperatures in excess of 150°C for extended periods of time.  β-phase precipitates, which are rich in magnesium, tend to migrate to the grain boundaries when enough thermal energy is available.   As a continuous network of β-phase precipitates at the grain boundaries is formed the material becomes sensitized.  β-phase precipitates are brittle and anodic to the aluminum-based matrix material; therefore sensitization can lead to increased susceptibility to stress corrosion cracking, exfoliation, decreased ductility, and reduced useable life.  Several ships with aluminum deckhouse structures have exhibited sensitization and subsequent stress corrosion cracking on deck plates and bulkheads that were in service for less than 15 years.  As a result of in-service failures and the Navy’s interest in using aluminum as a structural material, sensitization has become a major issue.  The objective of this study was to visualize a large amount of sensitization data in a way that makes trends clear, showing the effects of different variables accurately.  This type of analysis allows for actions which may include changing construction materials, design of sensitization resistant alloys, or replacing existing components.  Analysis was performed to correlate the degree of sensitization, as determined by ASTM G67 or volume fraction/amount of β-phase, and thermal exposure for varied amounts of time.  Correlation of different measurement techniques used in the laboratory and on ships in service gives an effective approach to estimating degree of sensitization resulting from an actual ship operating environment.  Sensitization damage predictions ultimately feed a ship life damage accumulation model that can be used to influence design decisions on future platforms and maintenance or repair practices for current ships.