航空发动机叶片修复中激光与材料相互作用机理及关键技术研究

Laser re-manufacturing is energy controllable with wide range of materials, thus becomes a new method for aero-engine blade repairs. Energy, momentum and mass are transferred with laser powder flow into the bath, affecting the fusion of materials, precision, deformation, and factures after the blade is repaired. . A study on the interaction of laser and materials is conducted to analyze the scattering, diffraction, absorption, and transmission mechanism of laser in ultrafine metal powder flow, so to build a coupling model between laser and powder as well as the matrix. The laying-off 2D blade curving method is adopted to establish the defect model of the blade, the ant colony algorithm is applied to optimize the repair routes, and the orthogonal test is performed to determine the optimal processing parameters.. SHPB experiment is developed to plot material stress strain curve, and build a dynamic constitutive relationship for analyzing the deformation mechanism and mechanic behaviors of the blade, such to provide evidences for selecting repair materials. The forming of cracks and nucleation and growth effects are also studied to explore the effect of thermal shock on the development of damage.. A breakthrough is expected in the blade laser repair theory, selection of materials and the evaluation of quality and performance. Ultrafine metal powder transmission system, laser head, process monitoring and spectrum detection systems will be developed, a database for blade laser repair process parameters will be established, a quality and performance evaluation criteria will be proposed, so to provide theoretical evidence and processing references for blade laser repair applications.

激光再制造能量可控、材料选择广，成为航空发动机叶片修复发展的新方向。激光粉末流和熔池存在能量、动量和质量传输物理行为，直接影响叶片修复后材料熔合、精度、变形与裂纹。.通过激光与材料相互作用研究，分析激光在超细金属粉末流中散射、衍射、吸收和透射机理，建立激光与粉末流和基体耦合模型；采用放样2D叶型曲线方法构建叶片缺陷模型，蚁群算法优化激光修复路径，正交试验方法确定最佳工艺参数。.开展SHPB实验，建立材料应力应变曲线，构建其动态本构关系，分析叶片变形机制及其动态力学行为，为叶片修复材料选择提供依据；分析叶片裂纹形成、成核与长大效应，探讨热冲击对损伤发展的影响机理。.有望在叶片激光修复理论、材料选择和质量与性能评价方面取得突破，研制出超细金属粉末输送系统、激光工作头、过程监测与光谱检测系统，建立叶片激光修复工艺数据库，制定质量与性能评价标准，为叶片激光修复工业应用提供理论依据和工艺参考。

航空发动机叶片长时间工作在高温高压的恶劣环境下，工作中还易受到砂石、飞鸟等外物的撞击，经常出现各种损伤。叶片损伤会降低发动机效率，甚至对飞机的飞行安全产生影响，更换新叶片成本高，对具有修复价值的受损叶片进行修复具有较高的技术难度和广泛的市场需求。本项目针对航空发动机叶片修复中激光与材料相互作用物理过程及工艺进行了研究。构建了激光透过率检测实验装置，进行了不同送粉率和不同功率条件下的激光透过率检测实验。构建了激光熔池CCD检测系统，开展了不同工艺参数条件下激光熔凝、熔覆的熔池检测实验。建立了激光与损伤基体相互作用的数学模型，开展了不同缺陷形式和尺寸的修复实验。建立了叶片三维扫描平台，提出一种受损叶片数字化3D模型逆向重建方法，基于灰色GM(1,1)叶型重构算法，能够重建叶尖受损部位的叶型，从而提高了叶尖损坏叶片模型重建的准确性；采用等厚分层切片处理法及层间交叉垂直扫描法来规划叶片激光再制造修复路径，开展了多种轨迹的激光熔覆实验，表明在拐角处激光束能量和粉末容易出现聚集效应，对熔覆形状和质量产生较大影响。开展了变功率和变扫描速度的激光熔覆钛合金实验，通过熔覆层和基体的微观组织分析，硬度测量和耐摩擦磨损测试，得到了优化的工艺参数；开展了SHPB实验，得到了熔覆层材料高速应变率条件下的应力应变曲线，结果表明熔覆层强度能够达到轧制基材的80%以上。进行了裂纹形成机制分析与实验，实验表明氧化钛的含量及熔覆层中气孔和杂质的含量、熔覆层中残余应力均决定裂纹的形貌和数量。开展了实验叶片的修复实验，制作了不同损坏部位的实验叶片，进行了激光修复实验，在此基础上，进行了燃气轮机和飞机发动机叶片的修复实验，实验效果较好。