Submerged arc welding method for steel sheets

Abstract

Provided is a submerged arc welding method enables welds with high toughness to be provided with low input heat, deep penetration, and a wide bead width to be sufficiently obtained in the welding of thick materials such that the welding speed is not more than 3 m / minute. The wire diameter of a first electrode at the head in the welding direction is established at 3.9 to 4.1 mm. Two electrodes are positioned on both sides of a weld line at the tail end in the welding direction. Wire tip positions of the two electrodes on the surface of a steel sheet are positioned on the same line, which is perpendicular to the weld line, and the distance (W) (mm) between the wire tip positions and the weld line is established at 5 to 20 mm.

Description

technical field [0001] The invention relates to submerged arc welding of steel plates, in particular to submerged arc welding suitable for seam welding of large-diameter steel pipes such as UOE steel pipes and spiral steel pipes. Background technique [0002] Submerged arc welding (for example, refer to Patent Documents 1 and 2) using two or more electrodes for seam welding of large-diameter steel pipes such as UOE steel pipes and spiral steel pipes has become popular, and is widely used from the viewpoint of improving the productivity of large-diameter steel pipes. It is an efficient double-sided single-layer surfacing welding with one bead on the inner surface side and one bead on the outer surface side. [0003] In double-sided single-layer surfacing welding, it is necessary to ensure the depth of penetration so that the weld metal on the inner surface side and the weld metal on the outer surface side are fully fused without producing unmelted parts. Therefore, a large cu...

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Problems solved by technology

[0004] On the other hand, in the seam welding of large-diameter steel pipes, there are problems such as deterioration of the toughness of the welded part, especially the heat-affected zone. In order to improve the toughness of the welded part, it is necessary to reduce the welding heat input as much as possible.

However, if the welding heat input is reduced, there is a problem that the risk of insufficient penetration increases, unmelted parts are likely to occur, and surface defects such as undercuts are likely to occur

[0009] However, in the technology disclosed in Patent Document 4, although the effect of increasing the width of the bead is obtained, it is necessary to introduce a device for applying a magnetic field, so the structure of the device becomes complicated. Increased load required for maintenance

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