Spot Welded Joint Method For Manufacturing Spot Welded Joint And Automobile Component

Abstract: A spot welded joint according to one aspect of the present invention comprises: a plurality of high strength steel sheets one or more of which has a tensile strength of 980 MPa or higher; a weld part; and a zinc based plating layer that is positioned at least on a surface where the steel sheets overlap and is in contact with one or more of the high strength steel sheets. The nugget diameter is 4.0 ???Tave or greater Tave being a value obtained by halving the total thickness of the plurality of steel sheets in units of millimeters. Outside of the weld part the concentration of B atoms at a prior austenite grain boundary of the high strength steel sheet in contact with the zinc based plating layer is 2.0 atm% or greater. Additionally outside of the weld part the average effective crystal grain diameter of the high strength steel sheet in contact with the zinc based plating layer is 7.0 ??m or less. In an outer side end portion of a corona bond formed at the overlap surface where the zinc based plating layer is positioned and in a peripheral edge portion of an indentation formed in the surface where the zinc based plating layer is positioned the average effective crystal grain diameter of a heat affected portion of the high strength steel sheets is 15.0 ??m or less.

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