Effect of Travel Speed on the Stress Corrosion Behavior of Friction Stir Welded 2024-T4 Aluminum Alloy

Abstract

The effect of travel speed on stress corrosion cracking (SCC) behavior of friction stir welded 2024-T4 aluminum alloy was investigated by slow strain rate tensile test. Microstructure and microhardness of the welded joint were studied. The results showed that the size of second phase particles increased with increasing travel speed, and the distribution of second phase particles was much more homogeneous at lower travel speed. The minimum microhardness was located at the boundary of nugget zone and thermomechanically affected zone. In addition, the SCC susceptibility of the friction stir welded joint increased with the increase of travel speed, owing to the size and distribution of second phase particles in the welds. The anodic applied potentials of −700, −650, −600 mV, and cathodic applied potential of −1200 mV facilitated SCC while the cathodic applied potential of −1000 mV improved the SCC resistance. The SCC behavior was mainly controlled by the metal anodic dissolution at the open circuit potential, and hydrogen accelerated metal embrittlement.