selective Laser Melting (SLM), as one of additive manufacturing method, is an advanced technology for the rapid production of metallic components with complex geometries. This rapidly evolving technology has also enabled the production of certain aluminum alloys. Given the widespread application of SLM-manufactured components in various industries, eva‎luating their fatigue behavior is of significant importance. This is particularly crucial for aluminum alloys such as AlSi10Mg, which are widely used in sectors like automotive and aerospace. Despite its importance, studies indicate that no comprehensive research has been conducted domestically on the fatigue behavior of AlSi10Mg produced by SLM, and sufficient data on this topic is lacking. Therefore, in this research, the high-cycle fatigue behavior of AlSi10Mg alloy produced by SLM was investigated under rotary bending conditions. Due to its outstanding mechanical properties, including high strength-to-weight ratio, good weldability, and excellent corrosion resistance, this alloy has extensive applications in the mentioned fields. The objective of this study was to obtain comprehensive insights into the fatigue performance of AlSi10Mg alloy in the high-cycle fatigue regime, in both as-built and T6 heat-treated conditions, which are among the common post-processing treatments for this alloy. Additionally, the obtained results were compared with the fatigue behavior of a similar aluminum alloy produced by sand casting, one of the conventional manufacturing methods. Rotary bending fatigue tests were conducted for both categories of samples at stress levels of 195 MPa and 234 MPa (equivalent to 75% and 90% of the yield strength of the heat-treated SLM-manufactured material). The results demonstrated that the as-built SLM samples exhibited the highest fatigue life among the three investigated groups, which was attributed to their silicon-rich network structure and high dislocation density. In contrast, the cast samples showed the poorest fatigue performance due to the presence of shrinkage defects, coarser dendritic structures, and stress concentrations induced by silicon platelets. The heat-treated SLM samples exhibited an intermediate fatigue performance between the other two groups. Although microstructural changes caused by heat treatment, such as the breakdown of the silicon-rich network, spheroidization of silicon particles, and reduced dislocation density, led to a reduction in fatigue life compared to the as-built condition, they still outperformed the cast samples. Fractographic analysis of the fracture surfaces using scanning electron microscopy (SEM) revealed that crack initiation and propagation mechanisms were influenced by factors such as surface roughness, lack of fusion defects, and microstructural variations. Additionally, the presence of parabolic striations, resulting from the coalescence of small cracks with the main fatigue crack, provided insight into the crack growth direction.

محسن بدرسماي , علي مالكي

احسان فروزمهر

عليرضا فدائي تهراني , عباس قائي