Post-heat treatment takes a key role for the enhancement of mechanical properties in selective laser melting (SLM) additive manufacturing (AM) of 6xxx series aluminum alloy. To understand the basic mechanism for changes of mechanical properties in the SLM process and the following post-heat treatment, the finite element model and the precipitate evolution (PE) model of SLM AM were established and combined. Results show that the hardness of the fabricated AM component can reach 91.47 HV at 170 °C for 18.8 h, which is 63.1% higher than the as-fabricated state. The comparison of hardness in as-fabricated AM component with experiments shows the validity of the proposed models. Further work on chemical composition shows that the selection of powder particle can greatly affect the hardness of the fabricated AM component. In the selection of 6xxx series aluminum alloy powder, higher Mg and Si contents in their solubility domains lead to higher generation of Mg₂Si nano-size precipitates and then cause higher hardness of AM specimen. After the optimal post-heat treatment, the maximum hardness can exceed 100 HV.

在 6xxx 系列铝合金的选择性激光熔化 (SLM) 增材制造 (AM) 中，后热处理对于提高机械性能起着关键作用。为了了解SLM过程和后续热处理中力学性能变化的基本机制，建立并结合了SLM AM的有限元模型和析出物演化（PE）模型。结果表明，制造的增材制造部件在 170°C 下 18.8 小时的硬度可以达到 91.47 HV，比制造状态高 63.1%。制造的 AM 部件的硬度与实验的比较表明了所提出模型的有效性。对化学成分的进一步研究表明，粉末颗粒的选择可以极大地影响制造的 AM 部件的硬度。₂ Si纳米级析出物导致AM试样硬度升高。经过优化的后热处理，最高硬度可达100HV以上。