Before steel welding, to check each volume strip surface quality and geometry of the steel quality does not meet standards, not production, so as to avoid unnecessary losses.
High-frequency welded pipe(erw steel pipe) production process, that the impact factors in the production process quality steel products are raw materials, welding technology, roll adjustment, rolling seven aspects roller material, equipment failure, production environment and other reasons and so on. Wherein the raw materials accounted for 32.44%, accounting for 24.85% of welding process, the roll adjustment accounted for 22.72%, the sum of the three accounted for 80.01%, is the main link. The four elements of the roll material, equipment failure, production environment and other reasons, is the impact on the quality of steel products accounted for 19.99%, is a relatively minor part. Thus, in the steel production process, to deal with the raw materials, welding technology and roll adjusted to focus on three aspects of control.
Yield point and high tensile strength steel, will cause difficulty in molding strip, especially when thick wall, the resilience of the material is large, large deformation stress exists in pipe welding, weld cracks easily. When the tensile strength of steel more than 635MPa, elongation of less than 10%, the strip during welding seam prone to crack. When the tensile strength is less than 300MPa, steel molding process due to the material soft, wrinkled surface easily. Visible, the mechanical properties greatly influence the quality of steel, the material strength of the pipe should be effective quality control. ) Strip surface defects on steel strip surface quality defects are common camber, wavy, slitting edge bite several, camber and wavy generally appear in the cold rolled strip rolling process, by improper reduction control. In the steel molding process, camber and wavy cause deviation or flip the strip, easy to generate tack welded steel pipe welds, affecting the quality of steel. Strip bite edge (ie the strip edges jagged uneven phenomenon), generally appear in tape slitting, slitting machine disk causes is blunt or sharp edges caused. Since the strip edge bite, always partial lack of meat, so that the strip in the welding easy to crack, crack and affect the stability of the weld quality.
Strip geometry affect the quality of the steel strip width when less than the allowable deviation, the extrusion pressure welded steel pipe is reduced, so that the seam welded steel pipe is not solid, cracks or open tube; when the width of the strip greater than tolerance, the pressing force is increased when the welded steel pipe, steel pipe welds appear beak, lap welding and other welding defects or burrs. Therefore, the fluctuation width of the strip, not only affects the accuracy of the outside diameter of the steel pipe, but also seriously affect the surface quality of steel pipe. Requirements for the same section thickness difference does not exceed a predetermined value of the steel pipe, which requires a high degree of uniformity of thickness of the steel pipe, fluctuations in the thickness of the strip, the same volume will be transferred to the wall thickness of the permissible value of finished steel strip thickness difference beyond difference so that a large number of steel thickness exceeds the allowable deviation and sentenced to waste. Fluctuations in the thickness of the finished steel thickness only affects the accuracy of, and because the strip of varying thickness, the steel pipe during welding, extrusion pressure and welding temperature instability, resulting in unstable quality weld pipe welding. Further, since the interior of a steel material defects exist sandwich, impurities, such as trachoma, it is a key factor affecting the quality of steel.
Optimum efficiency control of high frequency welded pipe in welding process
In most cases, optimized welding process, power loss can be reduced 50% and can improve the welding quality, reduce downtime, increase production.
Stress on the trench corrosion of high-frequency straight seam resistance welding pipe
Trench etching is generally believed that acute heat in the welding process, the results of local tissue metal and chemical change caused by quenching.
Technology of straight seam high frequency resistance welded steel pipe
Factors that affect the raw material for the steel pipe welding quality affect the quality of raw materials are mainly steel mechanical properties unstable surface defects and strip geometry deviation big three aspects, therefore, we should focus on these three aspects of control.
