In this work, the Friction Stir Back Extrusion (FSBE) process of seamless Mg AZ31B tubes is investigated using numerical modeling and experiments. A Coupled Eulerian Lagrangian thermomechanical model is developed to simulate the FSBE process. Material flow, strains, strain rates, grain size, and temperature histories during the FSBE process were investigated. FSBE experiments were conducted to validate the model. It is shown that the measured reactive body force in the principal loading direction and the temperature histories at different locations of the die agree well with the modeling results. The numerical results show that a maximum strain rate of 90 s⁻¹ was attained at the inner surface of the tube. The maximum temperature in the workpiece reaches 599 °C. The optical microscopy and numerical results show that fine grains were formed at the inner surface of the tube with diminishing refinement effects as the outer surface is approached. It is revealed that the material in the central region of the workpiece rotates around the tube centerline in a behavior similar to that seen in the rotation zone in friction stir welding. The material near the outer surface of the workpiece moves upward with slight rotation about the tube centerline.

在这项工作中，使用数值模型和实验研究了无缝Mg AZ31B管的摩擦搅拌回挤出（FSBE）工艺。建立了一个耦合的欧拉拉格朗日热力学模型来模拟FSBE过程。研究了FSBE过程中的材料流动，应变，应变率，晶粒尺寸和温度历史。进行了FSBE实验以验证模型。结果表明，在主加载方向上测得的反作用力和模具不同位置处的温度历史与建模结果非常吻合。数值结果表明，最大应变率为90 s ^-1在管的内表面达到。工件的最高温度达到599°C。光学显微镜和数值结果表明，在管的内表面上形成细晶粒，随着接近外表面，细化效果减小。结果表明，工件中心区域中的材料围绕管中心线旋转，其行为类似于在搅拌摩擦焊接中在旋转区域中看到的行为。工件外表面附近的材料绕管中心线略微旋转而向上移动。