Environmentally assisted cracking behavior of peak-aged 7010 aluminum alloy containing scandium

Abstract

The 7010 Al alloy with and without addition of 0.25 wt pct Sc in peak-aged condition was examined for its environmentally assisted cracking (EAC) behavior. Slow strain rate testing (SSRT) per ASTM standard G129-00 was employed to investigate EAC. The base 7010 Al alloy showed 10 pct elongation, 9.9 pct 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 pct in terms of elongation and reduction in area, respectively, when tested in 3.5 pct NaCl solution, showing its high susceptibility to EAC. On the other hand, the 0.25 wt pct Sc containing alloy showed a significant improvement in ductility not only in air but also in 3.5 pct NaCl solution, without any loss in the UTS. Thus, the 0.25 wt pct Sc containing alloy exhibited 13.4 pct elongation, 15.8 pct reduction in area, and 560 MPa UTS in air and 12.5 pct elongation, 16.4 pct reduction in area and 560 MPa UTS in 3.5 pct NaCl solution. The study for the first time shows that the high resistance to EAC of 7010 alloy can be imparted even in peak-aged condition by the addition of 0.25 wt pct Sc.