涡轮叶片的光内送粉变光斑高效增材制造方法及机理研究

Turbine blade is one of the key components of power equipment. The difficulties of fabrication remain a significant challenge due to the increasing demands for thinner and more complex of turbine blades at present. As one of the most promising additive manufacturing technologies, laser metal direct forming (LMDF) can be employed to directly build three-dimensional full dense metal components with excellent mechanical properties. However, the existing problems of mutual compromise between efficiency and accuracy of forming and low powder utilization have limited the further development of this technology. We propose a variable laser spot method to fabricate single-track cladding layers with unequal width by the inside-laser powder feeding. Thereby, the turbine blade can be fabricated by layer-by-layer accumulation..The combination of numerical simulation, theoretical analysis and experimental tests is used to fulfill the key research contents, described as follows..(1).To establish the theoretical model by studying the interaction law among laser beam, powder and molten pool. The model can predict geometrical morphology of cladding layers and reveal the space coupling mechanism between hollow light and powder..(2).To investigate the real-time control mechanism among process parameters according to the theoretical model. .(3).To optimize the forming process based on the internal relation of forming accuracy, structural properties and process parameters..The objective of the project is expected to provide a new fundamental and technique, supporting for manufacturing of high-performance turbine blades.

涡轮叶片是动力装备的核心部件，其日益复杂的结构及越发变薄的壁厚使得制造技术面临极大的挑战。激光金属直接成形是最具代表性的一种增材制造技术，能直接制造出全致密且力学性能优异的金属零件，是制造技术的发展方向。鉴于现有技术中存在成形效率及成形质量相互制约，粉末利用率低等问题。本项目提出基于光内送粉方式在单道工艺中实时变化激光光斑大小一次扫描而非多道搭接直接成形出不等宽熔覆层的新方法，逐层堆积直接制造出涡轮叶片。采用数值模拟、理论分析及实验检测相结合的方法，重点研究激光变斑过程中激光束、光内粉及熔池间的相互作用规律，建立能预测熔覆层几何形貌的理论模型，揭示中空光与光内粉的空间耦合机理及工艺参数实时精确调控机制，掌握成形精度、组织性能与工艺参数的内在联系，优化成形工艺，实现涡轮叶片变光斑激光金属直接成形。本课题的研究成果有望为高性能涡轮叶片制造提供新的理论方法和技术支撑。

涡轮叶片是动力装备的核心部件，其日益复杂的结构及越发变薄的壁厚使得制造技术面临极大的挑战。激光金属直接成形是最具代表性的一种增材制造技术，能直接制造出全致密且力学性能优异的金属零件，是制造技术的发展方向。研究了激光变斑过程中激光束、光内粉及熔池间的相互作用规律，建立了能预测熔覆层截面几何形貌的理论模型；研究了变光斑过程中工艺参数间的匹配规律，实现了变斑熔覆过程中工艺参数间实时精确调控机制；开发了基于激光位移传感器的熔覆层生长高度的闭环控制系统，能够实现实际增长高度及理想高度的一致性，稳态波动范围±0.02mm，层高的阶跃响应5～8层后趋于稳定，具有良好的鲁棒性；研究了激光变斑成形不等宽构件的显微组织及力学性能。在开发的变光斑激光直接成形系统平台上，采用优化的工艺变光斑成形工艺，获得了熔覆层宽度从1mm到3mm连续变化的薄壁叶片，达到了变斑直接成形薄壁零件预期的效果。本课题的研究成果有望为高性能涡轮叶片制造提供新的理论方法和技术支撑。