Slow strain rate testing of high‐strength aluminium alloy plate in an aqueous solution of 3% NaCl + 0.3% H2O2

Abstract

AbstractThe stress corrosion cracking (SCC) behaviour of aluminium alloy plate materials was investigated in the short transverse direction using the slow strain rate (SSR) testing technique. The synthetic environment used was an aqueous solution of 3% NaCl + 0.3% H2O2. Reference tests under constant deformation and alternate immersion conditions according to ASTM G44 were performed, too. Both static and dynamic loading tests indicate high SCC susceptibility with the alloys 2024‐T351, 2091‐T8X51, 7050 T651 and 7475‐T651. For the alloy 8090‐T8171, a low SCC resistance is found in the alternate immersion tests, whereas a rather moderate sensitivity is observed performing SSR tests. The SSR testing technique fails to indicate the SCC sensitivity of the more resistant alloys 2024‐T851 and 7050‐T7651. As demonstrated by pre‐exposure tests, the reduction of fracture energy observed with the latter alloys as well as with the immune alloys 7050‐T7351 and 7475‐T7351 is caused by pitting and intergranular corrosion. Using an aqueous solution of 3% NaCl + 0.3% H2O2, the SSR testing technique is a useful rapid method to screen wrought aluminium alloys which are quite sensitive to environmentally assisted cracking. Because chloride‐peroxide solutions are also conducive to corrosion processes independent of stress, pre exposure tests are required to be incorporated into such sorting tests.