稀土改性高强铝微桁架激光增材制造工艺调控

The lattice lightweight structure of micro-truss sandwich panels has important applications in the aerospace field. The selective laser melting (SLM) additive manufacturing technology can overcome the limitations of traditional processes and form complex lattice structures with high quality and integration. Taking the rare earth Sc-modified high-strength Al - Mg alloy as the object, the process optimization experiment was carried out on it by using the SLM process, and the research on the integrated forming process control of the micro-truss sandwich panel was carried out based on the optimization results. The research results show that the surface quality and metallurgical defects of the SLM-formed Al - Mg - Sc - Zr alloy change significantly with the laser parameters. Under the conditions of a laser power of 400W and a scanning speed of 800mm/s, a higher surface quality (roughness of 13.2μm) and density (relative density of 99.5%) are obtained. When the scanning speed is low, the primary Al3Sc precipitated phase is formed at the bottom of the specimen's molten pool, while when the scanning speed is too high, the precipitated phase decreases due to the too fast solidification speed, resulting in a decrease in the microhardness of the specimen. In the optimized process range, with the increase of the laser scanning speed, the powder sticking ratio of the SLM-formed Al - Mg - Sc - Zr micro-truss sandwich panel decreases, and the component quality is reduced accordingly; the dimensional accuracy of the component in the horizontal direction and the forming accuracy of the micro-rods of the truss both increase with the increase of the scanning speed.

微桁架夹芯板点阵轻量化结构在航空航天领域有重要应用,选区激光熔化(SLM)增材制造技术可克服传统工艺局限性,高质量一体化成形复杂点阵结构。以稀土Sc改性高强Al-Mg合金为对象,采用SLM工艺对其进行工艺优化试验,并基于优化结果对微桁架夹芯板开展一体化成形工艺调控研究。研究结果表明:SLM成形Al-Mg-Sc-Zr合金表面质量、冶金缺陷等随激光参数发生显著变化,在激光功率400W、扫描速度800mm/s的条件下获得较高表面质量(粗糙度为13.2μm)及致密度(相对密度为99.5%)。当扫描速度较低时试件熔池底部形成一次Al3Sc析出相,而当扫描速度过高时因凝固速度过快析出相减少,导致试件显微硬度降低。在优化工艺区间内,随激光扫描速度增加SLM成形Al- Mg-Sc-Zr微桁架夹芯板粘粉比例下降,构件质量随之减轻;水平方向构件尺寸精度、桁架微杆成形精度均随扫描速度增加而增加。