Effect of Raw Material on Quality of ERW Carbon Steel Pipe

In the production process of erw carbon steel pipe, how to ensure that the product quality in line with the requirements of technical standards and customer needs, the steel pipe production process should be the impact of product quality factors. In the production process affect the quality of welded pipe products are raw materials, welding technology, roll adjustment, roll material, equipment failure, production environment and other reasons. Of which 32.44% of raw materials, welding process accounted for 24.85%, roll adjustment accounted for 22.72%, the three accounted for 80.01%, is the main link. The impact of the roll material, equipment failure, production environment and other reasons, the impact of steel products on the quality of 19.99%, is a relatively minor link. Therefore, in the steel pipe production process, should deal with raw materials, welding technology and roll adjustment of three links to focus on control.

The mechanical properties of steel strip on the quality of steel pipe commonly used steel welded steel for the carbon structural steel. The yield point and the tensile strength of the steel strip are too high, which will cause the steel strip to be difficult to be formed. Especially when the wall is thick, the material has high elasticity, and the steel pipe has large deformation stress during welding. When the tensile strength of steel strip more than 635MPa, elongation less than 10%, the strip in the welding process is prone to crack. When the tensile strength of less than 300MPa, the strip in the molding process due to soft materials, the surface easy to wrinkle. It can be seen that the mechanical properties of the material have great influence on the quality of the steel pipe, and the quality of the steel pipe should be effectively controlled from the material strength. Steel strip surface defects on the quality of the steel pipe surface defects are common sickle bend, wave-shaped, longitudinal gripping edge, etc., sickle and wave shape generally appear in the cold-rolled strip rolling process, by the pressure Under the amount of improper control caused. In the process of forming steel pipe, sickle bending and wavy shape will cause the strip deviation or flip, easy to make welding seam welded steel pipe, affecting the quality of steel. The edge of the strip (that is, the edge of the strip showing jagged rugged phenomenon), generally appear in the longitudinal belt, the reason is the slitter disc blade blunt or not caused by sharp. As the steel side of the chewing edge, there are local lack of meat, so that the steel strip in the easy to produce cracks, cracks and affect the quality of the stability of the weld.

Effect of geometrical dimensions on the quality of the steel pipe when the width of the steel strip is less than the allowable deviation, the squeezing force of the welded steel pipe is reduced, so that the welding of the steel pipe is not strong, the crack or the opening pipe appears. When the width of the steel strip When the deviation is greater than the allowable deviation, the squeezing force is increased when the steel pipe is welded, and the welding defects such as tip, welding or burr appear at the weld of the pipe. Therefore, the fluctuation of the strip width not only affects the accuracy of the outer diameter of the steel pipe, but also seriously affects the surface quality of the steel pipe. The steel pipe thickness of the steel pipe with the same thickness of the steel pipe, which requires the same thickness of the steel pipe with the same thickness is required to be transferred to the wall thickness difference of the finished steel pipe, so that a large number of steel pipe thickness exceeds the allowable deviation and waste.

Thickness fluctuations not only affect the thickness of the finished steel pipe accuracy, at the same time, due to the thickness of the steel strip, so that the steel pipe in the welding, the extrusion pressure and welding temperature instability, resulting in welded steel welding quality is not stable. In addition, due to the existence of steel within the sandwich, impurities, trachoma and other material defects, but also affect the quality of an important factor in steel. Therefore, in the steel strip before welding, to check the surface quality of each coil and geometric size, the quality of the strip does not meet the standard requirements, do not carry out production, so as to avoid unnecessary losses.