A Study on the Correlation between Heat-Treatment Microstructure and Mechanical Properties of Additive Manufactured Al-Si-Mg Alloy with Bulk and Lattice Structure for Weight Reduction of Vehicle Parts and Application of Shock Absorbing Regions 2024-01-2574

This study delves into the microstructural and mechanical characteristics of AlSi10Mg alloy produced through the Laser Powder Bed Fusion (L-PBF) method. The investigation identified optimal process parameters for AlSi10Mg alloy based on Volume Energy Density (VED). Manufacturing conditions in the L-PBF process involve factors like laser power, scan speed, hatching distance, and layer thickness. Generally, high laser power may lead to spattering, while low laser power can result in lack-of-fusion areas. Similarly, high scan speeds may cause lack-of-fusion, and low scan speeds can induce spattering. Ensuring the quality of specimens and parts necessitates optimizing these process parameters. To address the low elongation properties in the as-built condition, heat treatment was employed. The initial microstructure of AlSi10Mg alloy in its as-built state comprises a cell structure with α-Al cell walls and eutectic Si. Heat treatment caused the collapse of the eutectic Si cell walls, and a needle-shaped Mg2Si precipitated phase formed within α-Al. These changes became more prominent with higher heat treatment temperatures and times. Interestingly, increasing heat treatment temperature and time resulted in lower strength but higher ductility in the mechanical properties. Thus, finding optimal heat treatment conditions is crucial to achieving the desired material properties. Furthermore, the study explored the microstructural properties, compression behavior, and energy absorption properties of lattice structures fabricated using the L-PBF method. Leveraging the previously derived optimal process parameters for L-PBFed AlSi10Mg alloy improved internal and surface quality even in thin lattice structures. Analyzing shock absorption characteristics with the application of lattice structures revealed that the L-PBF method's advantage lies in its ability to create complex shapes. This versatility enables incorporating both bulk geometry and lattice structure in a single part using AlSi10Mg alloy. Applying this technique to a shock absorber housing demonstrated excellent durability and achieved a 27% reduction in weight.