Efficient laser-electric arc composite heat source high-strength steel pipeline straight seam welding process

Abstract

The invention provides an efficient laser-electric arc composite heat source high-strength steel pipeline straight seam welding process which comprises the following steps that a groove is machined according to the plate thickness of a to-be-welded workpiece, greasy dirt at a welded part is removed, and the surface of the to-be-welded workpiece is kept dry; spot welding fixing is conducted on the to-be-welded workpiece before formal welding according to the size of the to-be-welded workpiece; a laser-MAG electric arc composite main mode is selected for welding, mixed gas of 82% of Ar and 18% of CO2 is selected as protective gas, and a high-strength steel welding wire with the diameter ranging from 1.0 mm to 1.6 mm is selected as a welding wire; the to-be-welded workpiece is subjected to multi-layer and multi-pass welding with different welding modes and parameter matching on each layer, and high-quality forming of a straight welding seam of a pipeline is achieved; and polishing and cleaning are conducted on the periphery of the welding seam after welding. According to the efficient laser-electric arc composite heat source high-strength steel pipeline straight seam welding process, the welding steps are simplified, the welding mode is simple, material selection is accurate and standard, and the titanium pipe welding quality can be guaranteed.

Description

technical field [0001] The invention relates to the technical field of material engineering welding, in particular to a high-efficiency laser-arc composite heat source straight seam welding process for high-strength steel pipes. Background technique [0002] In the process of oil and gas transportation, in order to increase the transportation volume per unit time, you can choose to expand the diameter of the transportation pipeline and increase the transportation speed by increasing the pipeline pressure during the transportation. Enlarging the diameter of the pipeline will greatly increase the cost of pipeline production and laying. Therefore, the current method mostly chooses to pressurize the section of pipeline transportation to increase the transportation speed, which puts forward higher requirements for the quality of pipeline materials and weld seams. Among them, roll The straight seam welding technology after the plate is formed into a tube is the key technology. ...

AI Technical Summary

Problems solved by technology

The commonly used welding methods now include the use of electrode arc welding, which requires a large-angle V-shaped groove to implement multi-layer and multi-pass welding, which requires a large amount of metal filling, low production efficiency, and unstable production quality.

When MAG welding is used, the lack of single arc penetration requires a large heat input and basically V-shaped grooves are used. Although the groove angle is reduced compared with electrode arc welding, the welding wire needs to go deep due to the limitation of the pipe wall thickness. Inside the groove, if the angle of the groove is small, the phenomenon of arcing on the side wall will occur, and the arc energy will be dispersed, and a stable molten pool cannot be formed, and defects such as penetration and undercut will easily form on the back of the weld

In addition, MAG welding for medium and thick plates has the problem of large welding heat input, which not only increases the size of the molten pool, reduces the stability of the molten pool, poorly formed the back of the weld, expands the heat-affected zone, and reduces the mechanical properties. During the welding process of pipeline straight weld seam, the unwelded weld seam part will be affected by the phenomenon of increased gap or wrong edge due to excessive stress, which will affect the welding quality

The high-energy beam welding method has the characteristics of very concentrated energy density, no need for metal filling, fast welding speed and small thermal influence zone, etc., but this method requires high-precision cooperation between the particle beam and the weld seam, and is not suitable for welding Longitudinal seam welding of pipes with large seam length and workpiece volume

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