Single-wire submerged arc welding and multi-wire submerged arc welding of SSAW Steel Pipe

Submerged arc welding is also a welding method using an arc as a heat source in the welding process of the SSAW steel pipe. It is covered by a layer of granular meltable flux... Submerged arc welding power supply should generally have steep drop characteristics, available AC (arc welding transformer), DC (arc welding generator or arc welding rectifier) Or AC, DC and use.

After the welding wire is determined (usually depends on the type of steel being welded), the supporting flux is a key material. It directly affects the mechanical properties (especially plasticity and low temperature toughness), crack resistance, and welding defect occurrence of the weld metal. And welding productivity. The weight ratio of that to flux is: welding wire: flux = 1.1-1.6, depending on the type of welding joint, the type of flux used, and welding specification parameters. Compared with smelting flux, the amount of sintered flux is saved, and about 20% can be used less.

SSAW steel tube monofilament submerged arc welding in the welding tube welding due to the small size of the weld pool, the quality is small, there is a short time, crystal cooling speed, under a certain welding specification, their speed is limited, generally 300 ~ 600mm/min, Too fast welding speed can easily cause the molten pool to cool and crystallize faster and produce welding defects. The too slow speed leads to excessive heat input and widened heat affected zone, which leads to decrease of joint performance and low production efficiency. The multi-wire submerged arc welding is mostly multi-wire longitudinal tandem, forming a common molten pool in the welding process. When the three-wire welding, the molten pool length can reach 80~100mm, the molten pool has a long time, and the metallurgical reaction is sufficient. Ample time for gas and impurities to float. The welding quality is good, as long as the process and specifications are well controlled, there are few welding defects. Their speed can reach 1.0~2m/min and the production efficiency is high. It is 3 to 5 times higher than single wire submerged arc welding.

This is a method in which an arc is combusted under a flux layer for welding. Its inherent stability in welding quality, high welding productivity, no arc, and little smoke and other advantages, making it the main welding method for the production of pressure vessels, pipe section manufacturing, box beam and other important steel structures. In recent years, although there have been many new high-efficiency and high-quality welding methods, the application of this has not been affected.

Multi-wire submerged arc welding of spiral welded steel pipes refers to the use of two or more wires to complete the submerged arc welding of the same weld. Multi-wire submerged arc welding unit welding equipment for them: The internal welding device consists of five parts: mechanical system, electrical control system, welding system, flux supply and recovery system, and camera monitoring system. Among them, mechanical systems mainly include: welding heads, cantilever beams, cantilever beam support mechanisms, weld seam tracking adjustment systems, machine bases, and ground wire lifters.

Spiral tube welding wire is tilted forward and backward. The direction and size of the dip are different, and the force and heat effect of the arc on the molten pool are also different, thus affecting the weld formation. When the welding wire is tilted backwards, the weldment in front of the weld pool is preheated due to the arc pointing in the welding direction, and the discharge of the liquid metal from the arc to the molten pool is weakened, resulting in a wide weld and a shallow depth of penetration. On the contrary, the weld width is smaller and the weld depth is larger, but it is easy to cause unwelded and undercut edges of the weld seam and poor weld formation.

A worker from a steel pipe company, which is located in China.