Advantages and Disadvantages of Longitudinal Submerged Arc Welding

First: advantages of longitudinal submerged arc weldingIt can damage the ingot casting structure, refine the grain of steel, and eliminate the defects of microstructure, so that the steel structure is compact, mechanical properties improved. This improvement is mainly reflected in the rolling direction, so that straight stitch structural steel pipe to a certain extent is no longer isotropic; pouring the formation of bubbles, cracks and loose, but also in the high temperature and pressure under the welding.Second: defects of straight seam submerged arc welded steel pipe1, The residual stress caused by uneven cooling. Residual stress is in the absence of external force under the internal self-equilibrium stress, all kinds of cross-section of hot-rolled steel have such residual stress, the general steel cross-sectional size, the greater the residual stress although the residual stress is self - balanced, it has some effect on the performance of the steel members under external forces, such as deformation, stability, fatigue resistance and so on, which may have an adverse effect.2, After the welding, the non-metallic inclusions inside the straight seam steel pipe are pressed into the sheet, and the stratification is caused. The performance of the DSAW steel pipe in the thickness direction is greatly deteriorated and there is a possibility that the weld, the local strain induced by the weld shrinkage often reaches several times the yield point strain, much larger than the load caused by the load.