Spot welding device, method of controlling spot welding device, spot welded joint, and method of producing spot welded joint

A method of controlling a spot welding device for performing spot welding on a plurality of steel sheets overlapping with each other by clamping the plurality of steel sheets between a pair of electrodes facing each other, and energizing the plurality of steel sheets while pressurizing the plurality of steel sheets, the method comprising:

• limiting a speed at which the pair of electrodes approach each other to at least 12.0 mm/s or slower during a period from start of the energization to end of the energization.

A spot welded joint produced by overlapping a plurality of steel sheets having a tensile strength of 980 MPa or more and performing spot welding on the plurality of steel sheets,

• wherein, when a minimum thickness of the plurality of steel sheets having a tensile strength of 980 MPa or more is denoted by t, a nugget diameter formed by the spot welding is 5.0 √t or more,
• a minimum thickness of the spot welded joint is 0.70 times or more a sum of thicknesses of the plurality of steel sheets, and
• an area of a splash portion measured in an X-ray transmission image of a welded portion is 30% to 160% of an area of a pressure-welded portion.