Welded joint

A welded joint, comprising:

• a first steel sheet and a second steel sheet that are connected to a welding bead part with an extension direction set as a longitudinal direction in plan view, wherein
• the first steel sheet and the second steel sheet each have a heat-affected zone located around the welding bead part and a non-heat-affected zone that is not affected by heat from welding,
• the second steel sheet includes a base iron and a first plating layer on the base iron at the non-heat-affected zone,
• the first plating layer is a plating layer having a chemical composition containing, in mass %,
• Al:
• 10.00 to 70.00%,
• Mg:
• 3.00 to 20.00%, and
• Fe:
• 0.01 to 15.00%, and
• selectively containing one or two or more elements selected from the group consisting of an element group A, an element group B, an element group C, an element group D, an element group E, an element group F, and an element group G described below, with the balance consisting of 5.0000 mass % or more of Zn and impurities,
• the direction normal to the surface of the second steel sheet at the non-heat-affected zone is defined as a Z-axis direction, the extension direction is defined as a Y-axis direction, and the direction perpendicular to the Z-axis direction and the Y-axis direction is defined as an X-axis direction,
• when, in a cross section obtained by cutting the first steel sheet and the second steel sheet along the Z-axis direction,
• the surface on the positive direction side in the Z-axis direction is set as a first surface and the surface on the negative direction side in the Z-axis direction is set as a second surface, and when at a surface on the side where out of a toe-to-toe-distance of the welding bead part in the X-axis direction on the first surface side and a toe-to-toe-distance of the welding bead part in the X-axis direction on the second surface side, the toe-to-toe-distance is smaller, or at one of the first surface side and the second surface side, the toes are not present, the surface on the side where the toes are not present is set as a rear surface of the welded joint, and
• at this time, at the rear surface of the cross section, the middle of a line segment connecting out of ends of the heat-affected zone, the end closest to one end of the first plating layer and the end farthest from the one end of the first plating layer in the X-axis direction is defined as the center of the heat-affected zone at the rear surface,
• at the rear surface of the cross section, a second plating layer containing a Zn—Mg structure is present on the welding bead part or on the heat-affected zone within a range starting from the center up to 1 mm on both sides in the X-axis direction,
• when at the rear surface of the cross section, the length of a field of view in the X-axis direction when observing the range starting from the center with an electron microscope is set to 100 μm, and the sum of lengths of the Zn—Mg structures each having a circle-equivalent diameter of 0.5 μm or more within the field of view projected perpendicularly onto a plane parallel to the X-axis direction is represented as ΣLi, a ratio of the ΣLi to the length of 100 μm of the field of view is 0.05 or more, and
• further, at the rear surface of the cross section, an average thickness of a ZnO layer present within a range starting from the center up to 5 mm on both sides in the X-axis direction is 1.0 μm or less,
• [Element group A]:
• One or two selected from the group consisting of Si:
• greater than 0% and 10.00% or less, and Ca:
• greater than 0% and 4.00% or less
• [Element group B]:
• One or two or more selected from the group consisting of Sb:
• greater than 0% and 0.5000% or less, Pb:
• greater than 0% and 0.5000% or less, and Sr:
• greater than 0% and 0.5000% or less
• [Element group C]:
• One or two or more selected from the group consisting of Cu:
• greater than 0% and 1.0000% or less, Ti:
• greater than 0% and 1.0000% or less, Cr:
• greater than 0% and 1.0000% or less, Nb:
• greater than 0% and 1.0000% or less, Ni:
• greater than 0% and 1.0000% or less, Mn:
• greater than 0% and 1.0000% or less, Mo:
• greater than 0% and 1.0000% or less, Co:
• greater than 0% and 1.0000% or less, and V:
• greater than 0% and 1.0000% or less
• [Element group D]:
• One or two or more selected from the group consisting of Sn:
• greater than 0% and 1.0000% or less, In:
• greater than 0% and 1.0000% or less, and Bi:
• greater than 0% and 1.0000% or less
• [Element group E]:
• One or two or more selected from the group consisting of Zr:
• greater than 0% and 1.0000% or less, Ag:
• greater than 0% and 1.0000% or less, and Li:
• greater than 0% and 1.0000% or less
• [Element group F]:
• One or two or more selected from the group consisting of La:
• greater than 0% and 0.5000% or less, Ce:
• greater than 0% and 0.5000% or less, and Y:
• greater than 0% and 0.5000% or less
• [Element group G]:
• B:
• greater than 0% and 0.5000% or less.