外拘束对接管-安全端焊接接头残余应力和变形的影响

Influence of Restraining Control on Residual Stress and Distortion about Nozzle Safe-end Welded Joints

接管与安全端的连接是核岛一回路相关设备中典型的焊接接头,利用有限元法探究了外拘束对焊接接头残余应力分布和变形的影响。结果表明,由于接管侧固定,安全端侧的拘束状态明显影响残余应力,若焊接过程中安全端不受外拘束,则接头轴向弯曲明显,焊缝根部由于弯曲效应发生应变硬化,导致根部存在较大的轴向拉伸残余应力;若焊接中安全端进行固定且焊完去除拘束,则可有效抑制焊接接头的弯曲效应,降低焊缝根部的轴向拉伸应力,而环向残余应力仅略有增大,且主要集中在管壁中间位置,同时近外壁和近内壁区域的峰值环向应力也没有明显增大。

Based on the finite element model,the restraining condition affecting residual stress and distortion of nozzle safe-end welded joints has been discussed. The results show that the hoop residual stress and the axial residual stress change obviously under different restraining conditions. Under the condition that restrain the side and free the other side,the axial bending effect of pipe is obvious and the tensile stress at weld root is very high due to strain hardening. Under the condition that restrain the two sides during welding and removing the restrain after welding,the axial bending is controled and the tensile stress at weld root is weakened effectively,just the hoop residual stress increases slightly and focus on the middle of pipe thickness.