束流品质表征及其对电子束选区熔化成形质量的影响机制

Electron beam selective melting (EBSM) is an ideal rapid manufacturing technology of high performance and complex metal parts. Forming quality is the foundation issue to be resolved for the promotion and application of EBSM, and the electron beam quality is most important factor for the forming quality. This project fully will test the drift space transmission electron beam using electron beam quality testing system, study the effects of the parameters of the electron gun such as the acceleration voltage, beam current and focus current on the electron beam quality, and propose the characteristic parameters of electron beam quality. A real heat source model of EBSM based on the electron beam power density distribution will be established by means of the nonlinear multi peak surface fitting to the test data. The process testing and numerical simulation based on the real heat source of EBSM will be carried out for the beams with different quality characteristic parameters, and the influence law of the beam quality on microstructure, mechanical properties, surface roughness and temperature distribution and geometry of the molten pool will be analyzed. The study solved the issue about characterization of the electron beam quality and its relation with the forming quality, to lay the theoretical basis for the forming quality control of EBSM.

电子束选区熔化（EBSM）成形是高性能复杂金属件的理想快速制造技术，成形质量是EBSM推广应用需要解决的基础问题，而电子束流品质是成形质量最重要的影响因素。本项目利用已研发的电子束流品质测试系统全面测试漂移空间传输的电子束流，研究电子枪的加速电压、束流大小、聚焦电流等参数变化对电子束流品质的影响规律，提出表征电子束品质的特征参数；对测试数据进行非线性多峰曲面拟合，建立基于束流功率密度分布的EBSM真实热源模型；针对具有不同的束流品质特征参数的电子束开展EBSM成形工艺试验和真实热源数值模拟计算，分析束流品质对EBSM成形构件显微组织、力学性能、表面粗糙度、熔池温度分布、熔池几何形状的影响规律。该项研究解决了电子束流品质的表征及其与EBSM成形质量关系问题，为EBSM成形质量控制奠定理论基础。

电子束选区熔化增材是高性能复杂金属件的理想快速制造技术，而电子束流品质是电子束选区熔化成形质量最重要的影响因素。本项目研制了电子束高速电子偏转扫描及微信号传感采集系统和多维图形显示软件，实现了电子束流三维重构空间任意两点距离的测量和束腰仿真，建立了电力束流功率密度分布规律和特征参数的模型，通过有线方法模拟多级电子枪空间传输过程，形成了双峰椭圆高斯分布的电子束选区熔化热源模型，开展了钛/钢电子束选区熔化工艺试验研究，建立了束流功率特征分布的电子束选区熔化钛/钢梯度过渡接头模型，为钛/钢连接提供有效的实现方法，同时为电子束选区熔化设备的性能调整和成形质量的控制提供先进的测试评价手段。