A method for welding a stack of sheets having a plurality of sheets of different materials is provided. In an aspect, the stack of sheets includes an aluminum sheet and a galvanneal steel sheet. In an aspect, the method includes resistively spot welding the galvanneal sheet to a hot-stamped steel sheet placed between the aluminum sheet and the galvanneal sheet, the sheet of hot-stamped steel including stress relief sections. The method further includes placing a metal foil on the aluminum sheet and vaporizing the metal foil to project portions of the aluminum sheet through the stress relief sections of the hot-stamped steel sheet to weld the portions of the aluminum sheet to the galvanized steel sheet. In another aspect, the method includes placing the metal foil on a raised portion of the aluminum sheet and projecting the raised portion of the aluminum onto the galvanneal steel sheet.

Seam welding is performed by clamping a coupling portion of an upper sash with a first roller electrode and a second roller electrode, and applying electricity while rotating first roller electrode and the second roller electrode. The first roller electrode includes a plurality of first projecting portions and second projecting portions that are at intervals in a circumferential direction around a first rotational center. The second roller electrode may include a plurality of first opposing projecting portions and second opposing projecting portions that are at intervals in a circumferential direction around a second rotational center, by clamping a coupling portion of an upper sash and applying electricity while rotating.

This disclosure relates to weldability of steel alloys that provide weld joints which retain hardness values in a heat affected zone adjacent to a fusion zone and which also have improved resistance to liquid metal embrittlement due to the presence of zinc coatings.

An automotive framework member 1 includes a first steel sheet 10, a second steel sheet 20, and a first weld metal part 40 joining an interface between the first steel sheet 10 and the second steel sheet 20, in which tensile strength of the first steel sheet 10 is 1.0 GPa or more and 1.6 GPa or less, tensile strength of the second steel sheet 20 is 1.8 GPa or more and 2.5 GPa or less, the first steel sheet 10 includes a groove part 18, the second steel sheet 20 is overlapped with the groove part 18, and a minimum Vickers hardness of a region within 4 mm of a periphery of the first weld metal part 40 of the second steel sheet 20 is 80% or more of a hardness of an outside of the region of the second steel sheet 20.

An automotive framework member 1 includes a first steel sheet 10, a second steel sheet 20, and a first weld metal part 40 joining an interface between the first steel sheet 10 and the second steel sheet 20, in which tensile strength of the first steel sheet 10 is 1.0 GPa or more and 1.6 GPa or less, tensile strength of the second steel sheet 20 is 1.8 GPa or more and 2.5 GPa or less, the first steel sheet 10 includes a groove part 18, the second steel sheet 20 is overlapped with the groove part 18, and a minimum Vickers hardness of a region within 4 mm of a periphery of the first weld metal part 40 of the second steel sheet 20 is 80% or more of a hardness of an outside of the region of the second steel sheet 20.

A spot welded joint in which a high CTS is obtained even if including one or more high strength steel sheets and a method of welding of the same, that is, a spot welded joint 1 including a plurality of steel sheets, wherein one or more steel sheets is a tensile strength 750 to 2500 MPa high strength steel sheet and, at a cross-section in the sheet thickness direction of the steel sheets, when defining superposed surfaces of a high strength steel sheet S1 arranged at an outermost side and another steel sheet 1B as the “plane A” and defining a plane passing through a point of one-half of a distance between a nugget end position E of a high strength steel sheet S1 side on the line L1 in the sheet thickness direction and a crossing point O of the plane A and the line L1 and parallel to the plane A as the “plane B”, at a square area SA of sides of 30 μm centered about a crossing point X of a line L2, which is separated by 250 μm to the heat affected zone side from a tangent at any position on a nugget end line NEL sandwiched between the plane A and plane B and parallel to that tangent, and a line L3 vertical to L2 included in a heat affected zone 4 having a high strength steel sheet S1 as a base material, an average value of widths of the blocks formed from lath martensite is 0.5 to 7.0 μm.

A method for producing a welded metal blank (16) includes cutting a first initial metal sheet (1) and a second initial metal sheet (3) from a first and second metal strip (4); joining the first and second initial metal sheets (1,3) by welding so as to obtain an initial welded metal blank (9), the initial welded metal blank (9) comprising a weld joint (10) joining the first and the second initial metal sheets (1,3); and cutting said initial welded metal blank (9) by a process involving metal melting so as to obtain at least one final welded metal blank (16) comprising a first metal blank portion (17) and a second metal blank portion (18) joined by a weld joint portion (19) consisting of a portion of the weld joint (10) obtained during the joining step.

Provided is an automotive member, or particularly, a steel sheet having a tensile strength exceeding 900 MPa. The automotive member has a resistance weld for fixing two or more steel sheets containing a predetermined composition, in which a maximum hardness (HV.sub.BM) in a heat-affected zone of the resistance weld is at least 1.1 times hardness (HV.sub.W) of a nugget in the resistance weld formed in a softest steel sheet of a sheet set during resistance welding, and furthermore, an average grain size of a steel sheet structure of the heat-affected zone within 2 mm in a direction at a right angle to a sheet thickness from an end part of the nugget of the high-strength steel sheet is 3 m or less, and a minimum hardness (HV.sub.min) in the heat-affected zone is at least 90% of hardness (HV.sub.) of the high-strength steel sheet before the resistance welding.

A vehicle composite member to be joined at a perimeter section to a ferrous vehicle body member is provided. The vehicle composite member includes a lightweight panel that is formed of a lightweight material having a lighter specific weight than iron, and a ferrous perimeter member that has been integrated with the lightweight panel. The perimeter section is configured by the ferrous perimeter member.

A method of producing an endless metal ring by butting and welding ends of a steel plate includes a welding process in which, while the ends of the steel plate are heated at a temperature lower than a melting temperature, the ends are pressed against each other and welded by butt welding; and a heat treatment process in which heating is performed at an austenite transformation temperature or lower after the welding process.