Effect of Loading Conditions on Corrosion Fatigue Process of Fsw Aa6061-T6 Joint in 3.5% Nacl Studied by Electrochemical Noise

Abstract

Electrochemical noise (EN) signals arising from corrosion fatigue (CF) process of stir friction welded (FSW) AA6061-T6 joints in 3.5 wt.% NaCl solution under different loading conditions were monitored. Wavelet analysis and cumulative probability calculations showed that the increase in peak stress, stress ratio and stress frequency all lead to an increase in the incubation rate of local events. EN signal analysis combined with transmission electron microscopy (TEM) observations indicate that the coarsening of β' phase and the extensive dissolution of β'' phase are the main reasons for preferential failure in the weakest heat affected zone. The main contribution of this study is preliminary investigating the CF behavior of FSW AA6061 joints under different loading conditions. Moreover, a link between an alternative EN technique and in-situ CF behavior study was established.

Keywords: corrosion fatigue, electrochemical noise, friction stir welding, 6061-T6 aluminum alloy