Effects of Aging Treatment on Intergranular Corrosion and Stress Corrosion Cracking Behavior of AA7003

Abstract

In order to study the effects of aging treatment on the intergranular corrosion (IGC) and stress corrosion cracking (SCC) of 7003 aluminum alloy (AA7003), the intergranular corrosion test, electrochemical test and slow strain rate test (SSRT), combined with optical microscopy (OM) and scanning electron microscopy (SEM) as well as transmission electron microscopy (TEM) observations have been carried out. The IGC and electrochemical test results showed that the IGC resistance of AA7003 for peak aged (PA) temper is the lowest, with double peak aged (DPA) the moderate, and retrogression and re-aging (RRA) the highest among three tempers, which is attributed to the continuous feature of precipitation on grain boundary of PA temper and the interrupted feature of precipitation on grain boundary of DPA and RRA tempers, as well as the wide precipitation free zones (PFZ) of RRA temper. In addition, the SSRT results indicated that all three tempers AA7003 are susceptible to SCC in IGC solution, and the change tendency of SCC susceptibility (I _SCC) of AA7003 for three tempers follows the order: I _SCC(RRA)<I _SCC(DPA)<I _SCC(PA).

Keywords

AA7003 / aging treatment / intergranular corrosion / stress corrosion cracking