Device for assisting in welding process of LSAW pipe through pulse current and using method

Abstract

The invention relates to a device for assisting in the welding process of an LSAW pipe through pulse current and a using method. The device comprises two nuts, two graphite electrodes, two bases, beams, a first bracket, a second bracket, a servo motor, a gear, a mounting ring and a mounting arm, wherein the nuts and the graphite electrodes are coaxially mounted on the bases, a spring is mounted between each graphite electrode and the corresponding base, and the nuts, the graphite electrodes and the bases are arranged on the beams respectively through fastening bolts; and the other sides of thebeams are provided with the first bracket and the second bracket through bolts respectively, the first bracket and the second bracket are made from an insulation material, the mounting ring is mounted at the ends, away from the beams, of the first bracket and the second bracket through a bolt, and the mounting arm is coaxial to the mounting ring and is mounted in the direction away from the beams. The device can effectively refine grains in a heat-affected zone, increase the dislocation density, and reduce the residual stress after welding, the homogeneity of the structure in the heat-affected zone is improved, and thus the reliability of the LSAW pipe in the actual using process is improved.

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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