Welded joints for welded structures and their manufacturing method

The horizontal whipping welding method addresses the low strength and penetration issues in conventional welding by creating a periodically concavo-convex HAZ shape, enhancing the tensile and yield strength of welded joints in large structures.

JP7884874B1Active Publication Date: 2026-07-06YONEMORI CO LTD
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Patent Information

Authority / Receiving Office
JP · JP
Patent Type
Patents
Current Assignee / Owner
YONEMORI CO LTD
Filing Date
2025-03-27
Publication Date
2026-07-06

AI Technical Summary

Technical Problem

Conventional welding methods for large structures like bridges and buildings result in low tensile strength and yield strength of welded joints due to low hardness in the heat-affected zone (HAZ), leading to potential fractures, and issues with penetration and slag inclusion.

Method used

A new rod handling method, known as the horizontal whipping welding method, involves stopping the welding wire just before it contacts the groove surface, allowing deep penetration and rapid heating/cooling, resulting in a periodically concavo-convex shape of the HAZ, which enhances tensile and yield strength.

Benefits of technology

The method produces welded joints with improved tensile and yield strength, preventing fractures in the weld metal and HAZ, even with low-strength materials, by narrowing the HAZ width and maintaining hardness.

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Abstract

The present invention provides a welded joint in a welded structure that has excellent tensile strength and yield strength, preventing fracture in the weld metal or heat-affected zone (HAZ), and also provides a welding method for obtaining such a welded joint. [Solution] A welded joint for a welded structure, wherein the cross-sectional shape of the welded joint parallel to the surface of the base material is such that the width of the HAZ (Hammer Zone) periodically repeats irregularities, and this shape is the shape at a position 2 mm below the surface of the base material. Furthermore, it is preferable that the difference between the maximum and minimum values ​​of the HAZ width at a position 2 mm below the surface of the base material is 3 mm or more. The welding method is a gas shielded arc welding method in which the tip of the wire is stopped just before it touches one groove surface, the tip of the wire is brought into contact with the groove surface at the moment the groove surface melts, then quickly moved away from that groove surface and moved to the other groove surface or the same groove surface, and the same operation is repeated periodically to weld while moving the groove surface in the direction of progression.
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Citation Information

Patent Citations

  • JP1987146513U

  • JP2014085322A

  • JP2021501692A

  • WO2016194322A1

  • WO2023243728A1