Enhancing Stress Corrosion Cracking Resistance in Al-Zn-Mg-Cu Alloy through Inhibiting Recrystallization

摘要

In this work, the effect of recrystallization inhibition in Al-Zn-Mg-Cu (7010) alloy towards the stress corrosion cracking (SCC) behavior was studied. For this purpose, Sc addition (0.25 wt.%) was made to Al-Zn-Mg-Cu alloy and the SCC behavior of the base and Sc-bearing alloys in peak-aged condition was examined using slow strain rate testing (SSRT). The base 7010 Al alloy showed 10% elongation, 9.9% reduction in area and 561 MPa ultimate tensile strength (UTS), when tested in air. The ductility of the base alloy dropped to 3% and 3.3% in terms of elongation and reduction in area, respectively, when tested in 3.5% NaCl solution, showing its high susceptibility to SCC. On the other hand, the 0.25 wt.% Sc containing alloy showed a significant improvement in ductility not only in air but also in 3.5% NaCl solution, without any loss in the UTS. Thus, the 0.25 wt.% Sc containing alloy exhibited 13.4% elongation, 15.8% reduction in area and 560 MPa UTS in air and 12.5% elongation, 16.4% reduction in area and 560 MPa UTS in 3.5% NaCl solution. The study shows that inhibiting recrystallization in 7010 alloy through Sc addition, improves the SCC resistance substantially even in the peak aged condition.