Effects of polarisation on mechanical properties and stress corrosion cracking susceptibility of 7050 aluminium alloy

摘要

The effects of polarisation (including cathodic and anodic polarisation) on mechanical properties and stress corrosion cracking (SCC) susceptibility (I_(SCC)) of 7050 aluminium alloy have been investigated by means of polarisation and slow strain rate test. The results of cathodic polarisation experiments showed that the I_(SCC) increased with shifting negatively the polarisation potential when the cathodic potential E_C ≥ -1100 mV(SCE), while it decreased with shifting negatively the polarisation potential when the cathodic potential E_C<-1100 mV(SCE). Anodic polarisation experiments demonstrated that the I_(SCC) increased severely with increasing the polarisation potential. In addition, the extents for the effect of polarisation potential on I_(SCC) were different among the 7050 aluminium alloy under various aging states. Polarisation was of the biggest effect on the I_(SCC) of under aged state, the smallest effect of over aged state and the middle effect of peak aged state. The SCC mechanism of aluminium alloy was a combination of anodic dissolution and hydrogen embrittlement, and the effects of hydrogen on SCC increased with increasing the hydrogen concentration.