Abstract: This arc spot welding method for dissimilar materials joins a steel upper plate and a non-ferrous metal lower plate. The upper plate has a flat plate-like base part and an upright wall part erected on the base part. The base part has a through-hole. The arc spot welding method for dissimilar materials includes superposing the base part on the lower plate so that the lower plate faces the base part via the through-hole; and arc-welding the base part and the lower plate by filling the through-hole with a molten weld metal at a position, which is a target position, offset in the direction opposite the upright wall part from the center of the through-hole.

Abstract: A resistance spot welding machine contains a pair of electrodes each having an electrode tip to sandwich a plurality of steel sheets; and an angle correction mechanism that is provided in at least one of the pair of electrodes and that is capable of correcting the angle of the electrode tip to the steel sheets. The resistance spot welding machine spot welds the plurality of steel sheets by sandwiching the plurality of steel sheets with the pair of electrode tips and applying current while a welding force is applied to the pair of electrode tips, and the angle correction mechanism has a pair of universal joints each having an engaging portion having an end with a convex spherical shape and an engaged portion having a concave spherical shape to which the engaging portion fits slidably.

Abstract: The arc spot welding method for joining dissimilar materials, in which a first sheet (10) made of an Al-based material or an Mg-based material and a second sheet (20) made of ultra-high tensile steel having a tensile strength of 1180 MPa or more are joined, includes a step of forming a hole in the first sheet (10), a step of overlapping the first sheet (10) and the second sheet (20), a step of inserting a joining auxiliary member (30) made of steel, in which a hollow portion is formed, into the hole of the first sheet (10), and a step of joining the first sheet (10) and the second sheet (20) via the joining auxiliary member (30) using a welding material containing 13 mass % or more of Ni.

Abstract: A resistance spot welding method for spot welding plural steel sheets including at least one galvanized steel sheet containing 0.08 mass % or more of C and 0.50 mass % or more of Si and having a tensile strength of 980 MPa or more, the resistance spot welding method includes, using a pair of electrodes including a pair of electrode tips configured to sandwich and pressurize the plural steel sheets and a pressurizing force absorbing mechanism provided in at least one of the pair of electrode tips and capable of absorbing a pressurizing force in an axial direction of the electrode tips, welding by sandwiching the plural steel sheets between the pair of electrode tips and energizing the pair of electrode tips with a pressurizing force applied, while absorbing a fluctuation load of the pressurizing force generated during the energization by the pressurizing force absorbing mechanism.