Difference between cracks in spiral submerged arc welded steel pipe and straight submerged arc welde

Submerged arc welded steel pipe, although the tensile specimen sampling direction is basically independent of the results, but the test results V Charpy impact specimen sampling direction is closely related. When sampling the maximum CVN along the rolling direction, the value of CVN in the vertical direction was the lowest.


The difference between the rupture of spiral welded pipe and straight submerged arc welded steel pipe is that the latter is the same as the initial or expanded maximum drive direction resistance minimum (axial), so that initiation and expansion must carry uranium. On the contrary, the maximum driving direction (oil) and the path of least resistance (rolling direction) of helical start or extension are inconsistent, so there are two possibilities for the initiation and propagation of cracks: one is axial exhaust and the other is along Rolling direction (ie spiral weld direction).


It is considered that the change will be determined from the rolling direction when it is generally considered that the maximum and minimum CVN are three or more.


In some cases, although the spiral fracture starts in the rolling direction and the larger crack expands in the axial direction, the rolling direction should still be considered in the calculation of the crack initiation criterion.