Achieving superior mechanical properties of selective laser melted AlSi10Mg via direct aging treatment

For additive manufactured aluminum alloys, the inferior mechanical properties along the building direction have been a serious weakness. In this study, an optimized heat treatment was developed as a simple and effective solution. The effects of direct aging on microstructure and mechanical properties along the building direction of AlSi10Mg samples produced via selective laser melting (SLM) were investigated. The results showed that, compared with the conventional heat treatment at elevated temperatures, direct aging at temperatures of 130-190 degrees C could retain the fine grain microstructure of SLM samples and promote further precipitation of Si phase, however, the growth of pores occurred during direct aging. With increasing aging temperature, while finer cell structures were obtained, more and larger pores were developed, resulting in decreased density of the samples. Two types of pore formation mechanisms were identified. Considering the balance between the refinement of cell structure and the growth of pores, aging at 130 degrees C was determined as the optimized heat treatment for SLM AlSi10Mg samples. The tensile strength along the building direction of the 130 degrees C aged sample was increased from 403 MPa to 451 MPa, with relatively high elongation of 6.5%. (C) 2022 Published by Elsevier Ltd on behalf of The editorial office of Journal of Materials Science & Technology.

Automated summary

This study investigates the issue of inferior mechanical properties along the building direction in additive manufactured aluminum alloys and develops an optimized heat treatment method. The results show that direct aging treatment can retain the fine grain microstructure and promote Si phase precipitation, but it also leads to pore growth. By balancing the refinement of cell structure and pore growth, aging at 130 degrees C is determined to be the optimal treatment, resulting in improved tensile strength and elongation of the samples.