Welded Joint

Abstract: This welded joint comprises a first steel plate and a second steel plate connected by a weld bead part having an elongation direction oriented in a longitudinal direction in a plan view. The first steel plate and the second steel plate have a heat-affected portion positioned surrounding the weld bead part and a non-heat-affected portion that is not affected by heat due to welding. The first steel plate and/or the second steel plate has ferrite and a first plating layer on the ferrite in the non-heat-affected portion. The first plating layer is a plating layer having a chemical composition comprising, in terms of mass%, 0.50-5.00% of Al, 0.50% to less than 3.00% of Mg, and 0.01-15.00% of Fe, selectively comprising one or more types of elements selected from the group consisting of element group A, element group B, element group C, element group D, element group E, element group F, and element group G, with the remaining being 5.0000 mass% or more of Zn, and impurities. A second plating layer containing an Mg-Zn structure is present on the weld bead part or on the heat-affected portion. When an end part position of a weld toe side of the second plating layer is used as a starting point, and a cross section of an region of a range up to 100 µm from the starting point in a direction orthogonal to the elongation direction of the weld bead part and separating from the weld toe stipulated by JIS Z3001 (2018) is observed using an electron microscope with the cross section being cut in a direction orthogonal to the elongation direction, an average thickness of an Fe-Zn layer formed by an Fe-Zn based intermetallic compound phase in the second plating layer is 2.0 µm or greater, and the total length in the separating direction of the Mg-Zn structure included in a range of 0.5 µm from an interface between the second plating layer and the ferrite or a substrate steel plate that is the heat-affected portion is 10 µm or less.

Patent Information

Applicants

Inventors

Specification

Documents

Application Documents