钢衬耐磨材料矿浆管大钝边打底焊工艺研究

Research on root weldingprocess for large blunt edge of steel lined wear resistant material slurry pipeline

钢衬耐磨材料矿浆管,内衬材料焊接性差,对接时只对外层钢管进行焊接。为了保证外层钢管的内部成型,传统焊接时需加工较大的坡口尺寸、预留较大的装配间隙,导致焊接效率低、管道容易磨损失效。利用高效的活性TIG焊,研究了钢衬矿浆管外层管小间隙大钝边的打底焊接工艺。结果发现:在无装配间隙的V型坡口施焊时,本该收缩的活性焊电弧会沿坡口两侧发生“爬升”现象,导致活性TIG打底焊熔深急剧下降;预留装配间隙后,活性焊电弧中心的等离子流线向钝边内侧分布,有效改善电弧“爬升”现象,热量更容易传导至钝边处,钝边的熔合更加容易;随着装配间隙的增加,有利于活性焊熔池由边缘向中心的流动,钝边容易熔合,但成型效果降低,当预留间隙过大时,在无填充材料的情况下,钝边两侧无法熔合;钝边尺寸5 mm,装配间隙1.2 mm时,在适当工艺参数支持下,活性TIG焊小间隙大钝边打底效果显著。

When welding steel lined wear-resistant material slurry pipe pipeline,only the outer steel pipe is welded,and the lining pipe material is not weldable.In order to ensure the internal forming of the outer metal pipe,the traditional welding needs to process a large groove size and reserve a large assembly gap,which leads to low welding efficiency and easy wear and failure of the pipe.The root welding technology of the outer layer of steel lined slurry pipes with small gaps and large blunt edges was studied by high efficiency A-TIG welding.As a result,it was found that when welding on V-shaped grooves without assembly gaps,the active welding arc that should have shrunk will experience arc"climbing"along both sides of the groove,resulting in a sharp decrease in the penetration depth of the active TIG root welding.After reserving assembly gaps,the plasma flow line at the center of the active welding arc is distributed towards the inner side of the blunt edge,effectively improving the phenomenon of arc"climbing".Heat is more easily transmitted to the blunt edge,and fusion of the blunt edge is easier.With the increase of assembly gap,it is conducive to the flow of the active welding pool from edge to center,and the blunt edge is easy to fuse,but the forming effect is reduced.When the reserved gap is too large,the two sides of the blunt edge cannot fuse without filling materials.When the size of the blunt edge is 5 mm and the assembly gap is 1.2 mm,with the support of appropriate process parameters,the effect of small gap and large blunt edge is obvious.