Predicting the A356-T6 Cast Aluminum Alloy’s High-Cycle Fatigue Life with Finite Elements

Abstract

This attempt proposes an engineering framework to predict the AL-Si-Mg casting alloy’s High Cycle Fatigue (HCF) response considering the microstructural heterogeneities (Secondary Dendrite Arm Spacing (SDAS)) and its correlation with the casting defects effect. The developed approach is based on the evaluation of the highly stressed volume caused by local porosities and defined as the Affected Area (AA), using Finite Element (FE) analysis. Therefore, a 3D Representative Elementary Volume (REV) describing the defective material, was embedded to evaluate the cast aluminum alloy‘s High Cycle Fatigue behavior under various load conditions. Work hardening due to cyclic loading is considered by applying the Lemaitre-Chaboche model. The Kitagawa-Takahashi Diagrams were simulated, using the Affected Area Method, under fully reserved tension and torsion loadings for different SDAS values. The generated diagrams were compared to experimental data carried out on cast aluminium alloy A356 with T6 post heat-treatment with different microstructure (39–72 µm). The results show clearly that the proposed approach provides a good estimation of the A356-T6 fatigue limit and exhibits good ability in simulating the Kitagawa-Takahashi Diagrams for fine and coarse microstructures. The developed framework is practical tool able to generate the Kitagawa diagrams for fine and coarse microstructures, at different fatigue loads.