Stress corrosion cracking model based on experiment and gray theory for high strength aluminum alloy

The making precrack in 3.5% NaC1 solution was used for testing the variation of the stress corrosion crack length with time for 2124 high strength aluminum alloy. The variation law of the crack growth rate with the time and the threshold stress intensity for stress corrosion cracking were obtained. The fractograph was also analyzed. According to the fundamental rules of crack propagation, the grey prediction model GM (1, 1) was used for predicting the stress corrosion crack length based on the values experimentally measured, and the predicted results were examined. The results showed that the crack growth rate reduced with the increasing of the corrosion time, and intergranular fracture could be observed. The crack resumed growth was driven by the corrosion production accumulation. It is also shown that the stress corrosion crack length prediction model GM(1, 1) realized by the MATLAB program can produce values closely approximating the measured ones, and the errors were relatively small, which indicated the practical valuation of the model. Using the model, the test time can be reduced, that is to say, the model has provided a scientific evidence for evaluating the material stress corrosion cracking sensitivity rapidly and scientifically.