PSI - Issue 53

R.F. Fernandes et al. / Procedia Structural Integrity 53 (2024) 144–150 Author name / Structural Integrity Procedia 00 (2019) 000–000

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1. Introduction Laser Powder Bed Fusion is an additive manufacturing process which enables the production of 3D components by melting metallic powder and building the components using a layer-by-layer strategy. This method allows the production of complex shapes that are challenging to achieve using conventional methods. Nevertheless, the process Nomenclature � Strain at fracture � Stress amplitude �� Reversible stress amplitude ��� maximum stress ��� Ultimate tensile stress �� Yield stress ∆ eq Equivalent stress range D Accumulated damage E Young’s modulus N e Experimental number of cycles N � Number of cycles to failure � Number of constant amplitude cycles of block � Number of cycles to failure of block N p Predicted number of cycles R Stress ratio is associated with defects, such as pores and lack of fusion, as well as residual stresses that can have a negative impact on the fatigue life of the components. Moreover, employing topology optimization enables the production of components with optimized geometries leading to an improved weight-to-strength ratio. In this sense, aluminum alloys have been used in the LPBF process due to their properties, such as excellent flowability and weldability. Among these alloys, AlSi10Mg shows great potential due to its high strength, low density, and good corrosion resistance properties, making it a compelling choice for aerospace and automotive industries (Wu, 2016; Yan, 2019). The application of LPBF in AlSi10Mg alloy results in a much finer microstructure due to the high heating and cooling rates during solidification, increasing the mechanical properties (Liu, 2019). However, these high thermal gradients also lead to residual stresses that can be detrimental to fatigue life of the components (Bagherifard, 2018). Considering this, several conventional heat treatments have been explored, including the investigation of the conventional T6 procedure (C. Zhang, 2018) and the stress relief at 300 ºC (Mfusi, 2019). It is important to note that elevated heat treatment temperatures will lead to a reduction in the mechanical properties of the material. An exothermic peak was observed within the range of 260-270 ºC, associated with Si precipitation. This precipitation affects the fine Al-Si network generated during the LPBF process, causing the reduction in the mechanical properties (Fiocchi, 2021). Consequently, the application of T6 and Stress relief at 300 ºC, as recommended by technology suppliers and already investigated, is not viable. This shows the importance of optimizing the applied heat treatment for AlSi10Mg components produced using LPBF. Considering the complex shapes and geometry variation related with topology optimization and geometry requirements, it is important to understand the notch sensitivity under demanding cyclic loads performed in aerospace and automotive industries. Regarding the fatigue under constant amplitudes, there are some results. There are several studies regarding the building orientation (Tridello, 2020; Y. Zhang, 2022), surface treatments (Maleki, 2022) and the influence of notched components in fatigue behavior under constant amplitudes loading (Konecna,