Abstract
Stress corrosion cracking (SCC) is the deterioration of mechanical and chemical properties under mutual action of corrosive environment stress and sensitive material. Aluminum alloys such as 2xxx, 6xxx, and 7xxx series are considered extremely susceptible to SCC. These alloys have significant applications in many industries, including transportation, aerospace, and military, due to their excellent mechanical properties versus weight ratio. SCC has extreme effects and a high requirement for frequent inspections and maintenance because of the incidental failure that happens in the grain boundary. These failures are considered a catastrophic failure and happen accidentally during the service. Understanding SCC behavior and processes for these alloys is very hard and challenging as it depends on the type of alloy, temper, concentration of the corrosive environment, temperature, as well as other factors. Also, it is important to know that SCC is hard to predict during the experimental process because of the involvement of other types of faster-acting corrosion. SCC sometimes needs more time to occur, otherwise it may lead to failure without warning. The mean aim of the thesis is comparing the SCC behavior for three types of conventional aluminum alloys (2024-T6, 6061-T6, and 7075-T6) under two different loads, 50% and 75% of the yield stress. The test was done per ASTM G44 regulations, which is a process dealing with alloys under stress undergoing alternate immersion in solution and letting to dry for continuous periods of time between 45-90 days for non-ferrous alloy such as aluminum. In this research, the test spanned across a 60-day period in an aqueous solution with a concentration of 3.5% salt, comparable to sea water.