The metallurgical properties of spiral steel pipe materials

Spiral steel pipe is hot-rolled coil production. Unit hot strip rolling process has a series of advantages of having access to production quality pipeline steel metallurgy process capability. For example, the output bench equipped with a water cooling system to accelerate cooling, which allows the use of low alloy composition to achieve special grade strength and low temperature toughness to improve the weld ability of the steel. However, this system is the basic steel production plant no. Coil alloy content (carbon equivalent) is often lower than similar grades of steel plate, which also improves the weld ability of spiral steel pipe.

The process according to the provisions of the submerged arc welding, each weld should have the arc and at the extinction at each Longitudinal but when welding girth, unable to meet the conditions, thereby extinction may have more at welding defects. Since the coil spiral steel pipe rolling direction is not perpendicular to the axial direction from the welding process, the welding method is consistent with the spiral steel pipe joints straight, but straight pipe joints will inevitably have a lot of T-weld, so there is welding the probability of defects also greatly improved, and the larger weld metal T welds are often in a three dimensional stress state, increasing the possibility of cracks.