Evaluation of fracture toughness and Charpy V-notch test correlations for selected Al alloys

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This research experimentally compared the correlations on the fracture toughness using Charpy V-notch tests. The fracture toughness tests are expensive, complex, and unreliable. Therefore, researchers developed correlations using Charpy V-notch tests to estimate fracture toughness, thereby structural integrity assessment. For the current work, nine different fracture toughness correlations were selected using the existing literature and most common Al alloys, including 2024-T4, 6061-T6, and 7075-T6, were chosen as testing materials.. Tensile tests were utilized to determine the deformation behavior of the tested alloys. Also, Charpy V-notch tests were carried out to obtain absorbed energy during the low impact conditions. Rupture strain, yield, and ultimate tensile strengths of the alloys were determined by tensile testing. Charpy V-notch test results revealed that the energy absorption ability of the 6061-T6 Al alloy is roughly two times higher than the 2024-T4 and roughly four times higher than the 7075-T6 Al alloy. The fracture toughness estimations resulted in a broad range of values in which the highest and lowest values were obtained when the equations of Li et al. and Roberts and Newton were employed, respectively. The experimentally obtained fracture toughness values attained from the literature were used to define the error of each correlation. The correlation developed by Lucan et al. yielded the lowest average error with an error percentage of 15.6%. Lastly, the ductile fracture of the 6061-T6 Al alloy tensile test specimens executed at the quasi-static conditions was attributed to having a higher fracture toughness.