Quantification of pitting in two tempers of 7075 aluminium alloy by non-destructive evaluation

An attempt was made to use the damage parameter, beta obtained from non-linear ultrasonic assessment, to quantify pitting damage in 7075 aluminium alloy. beta values were found to be different for the two tempers, T6 and T73. beta reflected the pitting damage quite well in the initial stages of pitting, during which the non-linearity change in the lattice was mostly governed by the creation of free surfaces due to pitting. However, on prolonged pitting, the beta values showed anomalous behaviour. The findings are explained by the operation of counteracting microstructural influences on lattice non-linearity. (C) 2010 Elsevier Ltd. All rights reserved.