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

• 2524 alloy plates with grain sizes (0.8–300 μm) were prepared by conventional cold rolling and heat treatment.
• Crack-growth rate was studied as function of grain size by fatigue and microstructure evaluation.
• Grain refinement led to a decrease in the resistance against fatigue-crack growth in 2524 alloy.
• The crack closure levels in coarse-grain samples were higher than those in fine-grain ones at low ΔK.

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.

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