激光预热/流体冷却辅助激光金属沉积AlSi10Mg成形

铝合金导热率高、激光吸收率低、热累积效应显著，难以稳定形成激光金属沉积（LMD）。为实现自动精确预热、消除热累积、分析预热影响并提升AlSi10Mg铝合金LMD成形能力，采用“光内送粉”Ar送气保护式激光金属沉积技术，设计激光预热与流体冷却温控系统并建立预热与冷却温控模型，进行AlSi10Mg 铝合金LMD成形实验研究，系统分析预热对激光吸收率、表面质量、截面形貌、温度场和材料组织性能的影响。结果表明:激光预热与流体冷却温控系统可实现精确预热并消除热累积，获得表面粗糙度Ra为2.6 μm的单熔道，实现AlSi10Mg搭接、块体和薄壁的高精高效稳定LMD成形。预热提高激光吸收率，使熔道扁平化，增大了晶粒尺寸。该辅助系统和方法能够有效解决铝合金LMD成形稳定性差的难题，为成形质量控制与熔池温控提供了新思路新工艺。

Laser preheating/fluid cooling assisted laser metal deposition of AlSi10Mg

It is difficult to form aluminum alloy stablely by laser metal deposition(LMD) due to high thermal conductivity, low laser absorptivity, and significant heat accumulation effect. To realize automatic and accurate preheating, eliminating heat accumulation, analyzing the effect of preheating and improving the forming ability of AlSi10Mg aluminum alloy LMD, the technology of laser metal deposition with "internal powder feeding" and Ar supply protection was adopted, the laser preheating and fluid cooling temperature control system was designed and the preheating and cooling temperature control model was established, LMD forming experiments of AlSi10Mg aluminum alloy was carried out, the effects of preheating on laser absorptivity, surface quality, cross-section morphology, temperature field, microstructure and properties of aluminum alloy were systematically analyzed. The results show that the laser preheating and fluid cooling temperature control system can realize accurate preheating and eliminate heat accumulation, obtain a single track with a surface roughness Ra of 2.6 μm. High precision, high efficiency and stable LMD forming of AlSi10Mg overlap, block and thin-wall are realized. Preheating can improve the laser absorptivity, flatten the track and increase the grain size. The assist system and method can effectively solve the problem of insufficient forming stability of aluminum alloy LMD, and provide a new idea and process for forming quality control and molten temperature controlling.