Abstract: By obtaining a spot-welded joint being a spot-welded joint formed by overlapping a plurality of pieces of steel plates (1A, 1B) and performing spot welding on the steel plates, including a high-strength steel plate whose tensile strength is 750 (MPa) to 2500 (MPa), being at least one piece of steel plate out of the plurality of pieces of steel plates, in which a carbon equivalent Ceq of the high-strength steel plate is 0.20 mass % to 0.55 mass %, and ten or more of iron-based carbides in each of which a length of a longest portion is 0.1 (?m) or more exist in a square region 103 within a heat-affected zone 4 of a cross section that passes through a center of a welding mark, and is cut along a plate thickness direction of the steel plates (1A, 1B), a cross tensile strength of the spot-welded joint to be formed is improved.

Abstract: A spot welding method is a method of performing spot welding to obtain a spot welded joint, the method including a spot welding with two-stage welding, setting a ratio (I2/I1) of a current I2 of a second welding process to a current I1 of a first welding process to from 0.5 to 0.8, setting a time tc of a cooling process within a range of from 0.8×tmin to 2.5×tmin wherein tmin is calculated using the equation (0.2×H2) according to a sheet thickness H of the steel sheets, setting an welding time t2 of a second welding process within a range of from 0.7×tmin to 2.5×tmin, and setting a pressure from the cooling process onward to greater than a pressure until the first welding process.

Abstract: When two high-strength steel sheets (1A, 1B) whose sheet thickness ratio={the sum of sheet thicknesses of the steel sheets}/{the sheet thickness of the thinner steel sheet (when they have the same thickness, the sheet thickness per one sheet)} is within a range of not less than 2 nor more than 5 and which both have tensile strength of not less than 780 MPa nor more than 1850 MPa are stacked to be subjected to resistance spot welding, a first welding step being pre-welding with a pressurizing force P1 kN and a welding current I1 kA and a second welding step being main welding with a pressurizing force P2 kN and a welding current I2 kA are performed, the pressurizing forces P1, P2 are set to a fixed pressurizing force P=P1=P2 all through the first welding step and the second welding step and are set within a range expressed by {0.5?P?3.

Abstract: In a spot welded joint according to an aspect of the present invention, with respect to a rectangular planar region of 100 ?m×100 ?m which is perpendicular to a sheet surface of the plurality of the steel sheets and which centers around an inner point spaced away by 100 ?m in a direction parallel with the sheet surface from an edge of a nugget, in a case of measuring a P concentration at a pitch of 1 ?m to obtain measured values of the P concentration at 100×100 of measurement points, and in a case of repetitively calculating an average value of the measured values of the P concentration at 20 of the measurement points which are adjacent to each other and which are arranged in a row in the direction parallel with the sheet surface among the 100×100 of the measurement points while shifting each one point to obtain 81×100 of the average values, the number of the average values which are more than two times an average P concentration is 0 to 100.

Abstract: A structure (10) for a front section of a vehicle body in a vehicle body (1) comprising a front chamber (3) disposed on the forward side of a vehicle interior (2) is provided with the following: a pair of front side members (11), located within the front chamber, that extend in the longitudinal direction of the vehicle body; a pair of strut towers (16) disposed on either side in the width direction of the front chamber and within which front wheel suspensions are disposed; and reinforcement members (20) that link the top of each strut tower with the front side members that face the strut towers, and that extend between the strut towers and the front side members. This configuration allows a structure for a front section of a vehicle body to be provided that can efficiently improve the rigidity of the vehicle body of an automobile against torsion and against lateral bending, and that can efficiently reduce the weight of the vehicle body by means of thickness reduction using a high-strength steel plate.

Abstract: A tailored blank for hot stamping includes a welded portion formed by butt-welding a first aluminum-plated steel sheet and a second aluminum-plated steel sheet, an Average Al concentration of a weld metal in the welded portion is in a range of 0.3 mass % to 1.5 mass %, an Ac3 point of the weld metal is 1250° C. or lower, and furthermore, an aluminum layer formed during the butt-welding is present on a surface of the welded portion.

Abstract: A structure (10) for a front section of a vehicle body in a vehicle body (1) comprising a front chamber (3) disposed on the forward side of a vehicle interior (2) is provided with the following: a pair of front side members (11), located within the front chamber, that extend in the longitudinal direction of the vehicle body; a pair of strut towers (16) disposed on either side in the width direction of the front chamber and within which front wheel suspensions are disposed; and reinforcement members (20) that link the top of each strut tower with the front side members that face the strut towers, and that extend between the strut towers and the front side members. This configuration allows a structure for a front section of a vehicle body to be provided that can efficiently improve the rigidity of the vehicle body of an automobile against torsion and against lateral bending, and that can efficiently reduce the weight of the vehicle body by means of thickness reduction using a high-strength steel plate.

Abstract: At a plurality of welding positions in an overlap portion of a plurality of members including a high-tensile steel sheet whose carbon content is 0.07 weight % or more, first beads (31 to 36) in a closed loop shape or a closed loop-like shape and second beads (41 to 46) in a closed loop shape or a closed loop-like shape on inner sides of the first bead (31 to 36) are formed by remote laser welding for joining. At this time, there are a procedure for successively forming the plural first beads (31 to 36) and a procedure for successively forming the plural second beads (41 to 46) for the plural formed first beads (31 to 36), and in both of the cases, the beads are each formed at a position except the closest welding position among the plural welding positions. Consequently, it is possible to enhance strength of a weld zone and to suppress welding deformation.

Abstract: There is provided a tailored blank article for press forming, the article having an excellent formability and comprising multiple different plates of different thickness, which can evade a break of a low strength plate (or low-thickness plate) due to strength rate-determining is provided in press forming. The tailored blank article for press forming, having an excellent formability and comprising two or more kinds of raw plates, continuously welded together, each having a different tensile strength, is characterized in that a ratio (n1/n2) of a work hardening property value (n1) of a higher tensile strength plate and a work hardening property value (n2) of a lower tensile strength plate is set to be 0.75 or more and 3.8 or less.

Abstract: In order to safely transport a building material to its mounting area of a building body and to temporarily hold the same until it is firmly mounted on the mounting area on the building site, according to the present invention, there is provided, an apparatus for transporting/mounting a building material including a self-propelled vehicle body provided with a steering/driving device, the vehicle body assuming a substantially L-shaped form constructed of an upright main body and a pair of lower frames which are parallelly spaced apart from each other and horizontally extend from opposite sides of a lower portion of the main body; an elevator unit movably mounted on a vertical side portion of the main body so as to be vertically movable along the vertical side portion of the main body; a first frame horizontally extending forward from a vertical side of the elevator unit, the first frame having its base end mounted on the elevator unit so as to be horizontally movable in a horizontal plane; a second frame slida

Abstract: Method and apparatus for high-power-density beam welding in combination with upset welding. The method comprises forming, along abutting edges of metal materials to be welded, a continuous upset weld line, and subsequently beam welding the metal materials by irradiation by a high-power-density beam along the weld line. The output of the high-power-density beam is determined on the basis of an input heat produced by resistance heating in the metal materials during the upset welding, as well as a welding pressure given to the metal materials during the upset welding.