Effect of grain size on the fatigue crack growth behavior of 2524-T3 aluminum alloy

2524-T3 aluminum alloy sheets with different grain sizes (13 mu m, 59 mu m, 178 mu m, 355 mu m, 126 mu m, and 87 mu m) were prepared using methods such as rolling and annealing. The microstructures and mechanical properties of the 2524-T3 aluminum alloy sheets were studied using optical microscopy (OM), scanning electron microscopy (SEM), and tensile and fatigue crack growth (FCG) rate tests. The grain size had a significant effect on the fatigue crack growth (FCG) rate. Alloys with grain sizes between 50 and 100 mu m exhibited high fatigue crack propagation resistances and the lowest FCG rates (da/dN = 1.05-1.45 x 10(-3) mm/cycle at Delta K = 30 MPa m(1/)2). Microstructural observations revealed that fatigue cracks propagated more tortuously in the alloy with grain sizes within the range of 50-100 mu m. This result is attributed to the combined effects of grain boundaries, crack deflection, fracture surface roughness-induced crack closure, and plasticity-induced crack closure. (C) 2016 Politechnika Wroclawska. Published by Elsevier Sp. z.o.o. All rights reserved.