Understanding fatigue crack growth in aluminum alloys by in situ X-ray synchrotron tomography

In situ 3D X-ray synchrotron tomography of fatigue crack growth was conducted in a 7075-T6 aluminum alloy. Local measurements of da/dN were possible with the 3D data sets obtained from tomography. In situ measurements of crack opening displacement (COD) were obtained, illustrating the possibilities for quantifying fatigue crack closure. Quantitative microstructural analysis enabled an assessment of the role of brittle inclusions on fatigue crack propagation. A significant increase in preferential crack growth through the inclusions was observed.