Characterization of the SCC behaviour of 8090 Al-Li alloy by means of the slow-strain-rate technique

Aluminium-lithium alloys possess a high resistance to stress corrosion cracking (SCC) compared with more conventional alloys. With traditional testing techniques and in conventional media some Al-Li alloys, such as 8090, show no susceptibility to SCC owing to the fact that such techniques and solutions are not appropriate for determining their behaviour. The slow-strain-rate technique makes it possible to detect the susceptibility to SCC in systems for which it cannot be detected with other testing techniques or takes much longer to detect. In the literature there are no unanimous criteria for establishing whether this technique permits characterization of the SCC behaviour of 8090-T8171 sheet in the L and LT directions, when used in standard solutions and at strain rates of between 10(-7) and 10(-4). In this work, a strain rate value has been found for which the fracture of alloy 8090-T8171, in 1 M NaCl + 0.3% H2O2, occurs as a consequence of an SCC process. Higher and lower strain rates lead to failure as a result of other mechanisms. (C) 1997 Elsevier Science Ltd.