恒定磁场辅助选区激光熔化粉末自支撑悬垂成型激光深穿透抑制和成型机理研究

With the requirements of the state on lightweight equipment of low carbon, energy saving, using selective laser melting forming complex parts is increasing In the process of complex parts forming, overhang forming base on powder-self-supporting produce multiple defects. The molten pool of stress equilibrium and laser deep penetration suppression can come true with the addition of magnetic and controlling thermal energy in the molten pool. This project lay emphasis up on 1) Establishing the mechanical model of molten pool, and researching the effective matching between additional excitation load and "supporting force" to realize forming parts with arbitrary angle. 2) Constructing the overhang forming quality criterion, achieving effective matching of light and constant magnetic field, optimizing the process parameters to control the alloy microstructure and composition. 3) Using numerical simulation and experimental testing to establish the thermo-mechanical- magnetic multi-field coupling numerical calculation model, obtain the regularities of distribution of thermo-mechanical- magnetic multi-field coupling, and obtain evolution process and formation mechanism of microstructure in the forming process combined with the solidification theory. To obtain high quality, non-defective overhang parts of powder-self-supporting forming by selective laser melting through the above studies. This project will provide a new idea to selective laser melting powder-self-supporting forming parts, and is a reference to high-energy beam forming based on powder bed, so it has important theory significance and application value for selective laser melting complex parts forming quality improvement .

随着国家对装备结构轻量化的低碳、节能要求，采用选区激光熔化成型结构复杂零件日益增多。针对复杂零件加工中粉末自支撑悬垂成型多缺陷产生，提出通过外加磁力和调控熔池内能量实现熔池受力平衡和激光深穿透抑制，重点研究1）建立熔池受力模型，研究附加励磁载荷与“支撑力”的有效匹配，实现任意角度成型；2）构建悬垂成型质量判据，通过光和恒定磁场的有效匹配，优化成型工艺参数，实现合金成型组织、成分控制；3）采用数值模拟和实验检测，建立热-力-磁多场耦合数值计算模型，获得热-力-磁多场耦合分布规律，结合凝固理论掌握成型过程中微观组织演变过程及生长机制。通过以上研究获得高质量、无缺陷的选区激光熔化粉末自支撑悬垂成型零件。本研究将为选区激光熔化粉末自支撑悬垂成型提供一种新思路，对基于粉床的高能束成型有一定的参考作用，对选区激光熔化复杂零件成型质量提高具有重要的理论意义和应用价值。

针对装备结构轻量化的低碳、节能要求，本项目拟采用恒定磁场辅助SLM成型技术，通过附加磁力达到熔池力学平衡，将SLM悬垂成型转化为“有支撑”成型。通过光和恒定磁场的有效匹配，实现选区激光熔化粉末自支撑悬垂成型熔池内能量的有效控制，实现合金元素的分布的控制，达到组织、性能、应力的控制。通过实验研究恒定磁场辅助SLM粉末自支撑悬垂成型过程中微观组织演化规律和生长机理，建立典型金属SLM悬垂成型工艺规律及流程。项目发表论文10篇，申请发明专利21项，授权3项，培养研究生1人。