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Stress on the trench corrosion of high-frequency straight seam resistance welding pipe Business Articles | April 20 Cheap St.Louis Blues Shirts , 2016

Trench etching is generally believed that acute heat in the welding process, the results of local tissue metal and chemical change caused by quenching.



Direct roll-formed steel high-frequency resistance welding technique is a rapid production of pipeline technology, currently in many areas such as: downhole casing, oil and gas gathering pipe has been widely used. However, this pipe weld area than the base metal and the heat affected zone has higher activity, and therefore determines the pipe weld area of life. Corrosion is a trench for pipe joints special crevice corrosion phenomena, often forming a trench in the weld zone. Under natural conditions Cheap St.Louis Blues Jerseys , the formation of the trench easily inseam corrosive medium in the state of stagnation, leading to reduced oxygen concentration in the joints gradually oxygen concentration cell and outer seam formed to accelerate the corrosion of the metal seam. At the same time the corrosion process seam metal ion remaining, causing the joints to move within Cl-, someone had to observe the dip in neutral sodium chloride solution in the gap, which contains chloride of 3 to 10 times the body of the solution, with the the corrosion of corrosion products accumulate around the weld, such as Fe2 + hydrolysis tends to produce excess H inseam + Vladimir Sobotka Hat , and the role of stagnation makes the seam metal in acidic conditions, has been reported its pH value can reach 2 to 3 so keep the seam metal activation, promote corrosion will be. When its anodic corrosion rate of the base metal and weld depend mainly on its electrochemical activity. High-frequency electric resistance welded pipe (erw steel pipe) as a whole without heat treatment, to achieve circumferential weld residual stress around 350MPa, close to the yield strength of the pipe. When the weld processing into working electrode, the residual stress is reduced to 100MPa or less. Circumferential tensile stress can reduce the corrosion potential of welds, accelerated corrosion Colton Parayko Hat , corrosion sensitivity coefficient increases trench. And after the heat treatment of welded pipe products, circumferential weld residual tensile stress smaller, with 10 ~ 100MPa, after processing into working electrode not change its circumferential tensile stress. Such conventional measurement methods can not characterize the welded pipe products in the practical application of corrosion resistance, and can not distinguish between real or not heat treatment on the corrosion resistance of welded pipe.


In the high frequency resistance welding process, within the initial 0.1s, temperature was raised to 1600  Carter Hutton Hat , the integration process section MnS