7N01铝合金电子束定点焊熔池输运现象预测

为有效改善真空电子束焊焊缝成形并抑制成形缺陷产生,本文以12 mm厚7N01铝合金为研究对象,基于CFD软件Ansys Fluent深入分析了电子束定点焊匙孔钻取过程及熔池传热和流体输运现象并进行了实验验证.为真实反映电子束流能量密度空间分布特点,建立了考虑束流活性区特征的自适应热源模型并采用VOF算法对气液界面进行实...

Prediction of transport phenomena of 7N01 aluminum alloy electron beamspot welding pool

To effectively improve weld forming and inhibit forming defects, taking 12 mm-thick 7N01 aluminum alloy as research object, the keyhole drilling process as well as the heat and fluid transport phenomena of electron beam spot welding (EBSW) were analyzed by Ansys Fluent and validated by experiments. In order to reflect the beam energy density distribution, a self-adaptive heat source model considering the characteristics of the active zone of beam was established, and VOF algorithm was used to track the gas-liquid interface in real time. Numerical analysis results show that the beam energy density distribution and the coupling between the beam and the transient pool/keyhole were the key factors to determine weld forming. When the beam was in lower focus mode, the unique energy distribution and the induced plasma insulation, metal vapor recoil pressure, Marangoni flow, and upward transportations of thermal buoyancy (maximum flow rate at about 15 m/s) led to the weld reinforcement and the extension of nailhead area. The beam energy density in the depth direction increased first and then decreased significantly, which resulted in similar evolutions for the welding in depth and width directions and might induce the spiking defects adjacent to the keyhole bottom. In addition, it was found that with the increase in keyhole depth, the energy fluctuation as well as the competition between recoil pressure and surface tension gradually increased, which promoted the periodicity of keyhole drilling process.