Effect of grain size on fatigue-crack growth in 2524 aluminium alloy

In this study, industrial 2524 aluminium alloy plates with various grain sizes (0.8–298 μm) were prepared by cold rolling and heat treatment. The fatigue-crack-growth rate was studied as a function of grain size through fatigue tests and microstructural observations. The results showed that grain refinement led to a decrease in the resistance against fatigue-crack growth. Besides, the levels of crack closure in coarse-grained samples were higher than those in fine-grained ones at low values of the range of the stress intensity factor K, ΔK. This phenomenon was predicted and explained well by the crack-deflection model.