Device and method of pulse current assisting lsaw pipe welding process

Abstract

The invention relates to a pulse current assisted LSAW pipe welding process device and its use method, which includes a nut, a graphite electrode, a base, a beam, a first bracket, a second bracket, a servo motor, a gear, a mounting ring and a mounting arm, the The nut and the graphite electrode are coaxially installed on the base, and a spring is installed between the graphite electrode and the base. Two groups of nuts, graphite electrodes and the base are respectively installed on the beam through fastening bolts. The other side of the beam The first bracket and the second bracket are respectively installed through bolts, and the first bracket and the second bracket are made of insulating material, and the ends of the first bracket and the second bracket away from the beam are installed with an upper mounting ring through bolts, and the The mounting ring mounts the mounting arm coaxially away from the beam. The invention can effectively refine the grains of the heat-affected zone, increase the dislocation density and reduce the residual stress after welding, improve the uniformity of the structure of the heat-affected zone, thereby improving the reliability of the LSAW tube in the actual service process.

Description

technical field [0001] The invention relates to a pulse current assisted welding process device and method for LSAW pipes, belonging to the technical field of straight seam double-sided submerged arc welded pipes. Background technique [0002] In the past ten years, the production and consumption of natural gas in my country have maintained a continuous growth trend, but the natural gas production area is far away from the place of demand and needs to be transported by pipeline. At present, spiral submerged arc welded pipes are used in the natural gas transmission network in my country's first-class areas, while longitudinal submerged arc welded pipes or high-frequency straight seam welded pipes are used in the second, third, and fourth types of areas; There are fewer spiral submerged arc welded pipes. For a long time, the advantages of LSAW pipe have become more and more prominent due to the characteristics of high conveying pressure, large pipe diameter and thick wall. ...

AI Technical Summary

Problems solved by technology

However, even the double-sided submerged arc welded pipe with good test performance sometimes leaks in actual service, mainly because the measured test performance is actually a comprehensive reflection of the performance of the base metal, weld and heat-affected zone, It does not reflect the toughness of the weakest part of the welded joint, and the distance from the fusion line to each part of the heat-affected zone is different, and the thermal cycles experienced are different, which makes the structure distribution of the heat-affected zone extremely uneven, and the heat-affected zone is a straight seam Weakest area of ​​welded joints of double-sided submerged arc welded pipes

[0004] Therefore, how to solve the problem of extremely uneven tissue distribution in the heat-affected zone of straight seam double-sided submerged arc welded pipe has important engineering practical significance

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