论文部分内容阅读
Zr-4合金广泛用作大多数压水堆和反应堆的燃料包壳材料,因此针对其焊接的研究有非常重要的现实意义。论文采用数值模拟方式研究Zr-4合金电子束焊接的瞬态过程,采用双椭球热源模型,结合接触及辐射等边界条件,采用变密度六面体网格,耦合温度场和应力场,建立了Zr-4合金管电子束焊接的有限元瞬态数学模型,采用自适应时间步,计算了Zr-4合金管真空电子束焊接的三维瞬态温度场和应力场。数值模拟结果表明:在电子束功率相对较小的条件下,焊缝深宽比较小,采用双椭球热源模型进行数值模拟,所获熔池形状与实验所得焊缝成形吻合良好,证明了该数学模型的合理性,从而可为制定实际焊接工艺提供理论指导。在所设定的计算条件下,筒盖和筒体均变形均匀,主要表现形式为沿径向突出,且筒盖变形大于筒体,和实际焊接现象基本一致;焊后最大整体变形约0.02 mm。
Zr-4 alloy is widely used as a fuel cladding material for most PWRs and reactors. Therefore, research on its welding has very important practical significance. In this paper, the transient process of electron beam welding of Zr-4 alloy was studied by means of numerical simulation. By using the dual ellipsoidal heat source model and the boundary conditions of contact and radiation, the density and the field of hexagonal mesh were used to establish the Zr -4 alloy tube electron beam welding finite element transient mathematical model, the use of adaptive time step, calculated the vacuum tube electron beam welding of Zr-4 alloy three-dimensional transient temperature and stress field. The numerical simulation results show that under the conditions of relatively small electron beam power, the weld width is relatively small, and the shape of the weld pool obtained by the experiment is well simulated by the dual ellipsoidal heat source model. Mathematical model is reasonable, which can provide theoretical guidance for the development of the actual welding process. Under the set calculation conditions, both the cylinder cover and the cylinder body deform uniformly, the main form of the cylinder cover protrudes in the radial direction, and the deformation of the cylinder cover is larger than that of the cylinder body, which is basically consistent with the actual welding phenomenon. The maximum overall deformation after welding is about 0.02 mm .