Advantages of lsaw steel pipe
It can destroy the ingot casting structure, refine the grain of the steel, and eliminate the defects of the microstructure, so that the steel structure is dense and the mechanical properties are improved. This improvement is mainly reflected in the rolling direction, so that the lsaw steel pipe is no longer an isotropic body to a certain extent; bubbles, cracks and looseness formed during pouring can also be welded under high temperature and pressure.
Disadvantages of lsaw steel pipe
1. Residual stress caused by uneven cooling. Residual stress is the stress of internal self-phase equilibrium under no external force. Hot rolled steel of various sections has such residual stress. The larger the section size of general steel, the greater the residual stress. Although the residual stress is self-balanced, it still has some influence on the performance of steel components under external forces. For example, it may have adverse effects on deformation, stability, and fatigue resistance.
2. After welding, the non-metallic inclusions inside the lsaw steel pipe are pressed into thin slices, and the delamination phenomenon occurs. The delamination greatly degrades the properties of the lsaw steel pipe in the thickness direction, and may shrink at the weld seam. Interlaminar tearing occurs. The local strain induced by weld shrinkage often reaches several times the yield strain, which is much larger than the strain caused by the load.