当采用埋弧自动焊焊接压力容器筒节时,焊后经X射线照相,在筒节纵焊缝端部(起弧与收弧部位)有裂纹产生,尤其在终端更为多见,其特征为沿着焊缝纵向中心线开裂(图1)。焊缝终端裂纹是在高温下由焊接应力引起的。在筒节组装时,一般都要在焊道两端进行定位焊。定位焊后焊接时,焊件在电弧热的作用下,受热部分膨胀,使得焊件沿纵向发生 When submerged arc welding is used to weld the pressure vessel tube section, X-ray photography is performed after welding, and cracks are generated at the ends of arc welding and arc-closing sections of the longitudinal weld of the barrel section, which are more common at the terminal, and are characterized by Cracks along the longitudinal centerline of the weld (Figure 1). Weld terminal cracks are caused by welding stresses at high temperatures. In the tube assembly, generally have to weld at both ends of the weld. Positioning welding after welding, the weldment in the arc of the role of heat, the heated part of the expansion, making the weld occurred longitudinally