Abstract: Provided is a robot control device that can suppress the stoppage of operations due to the detection of a contact error. The robot control device controls a robot that implements welding in association with contact with a to-be-welded object, said device comprising: an action stoppage unit that stops the action of the robot if detected that the robot has been subjected to an external force equal to or greater than a threshold; an instructing unit that instructs a welding power supply device to start welding; and a detection sensitivity adjustment unit that lowers the sensitivity at which as external force is detected at the action stoppage unit during a period of time from the point in time at which the instructing unit instructs the welding power supply device to start welding until a prescribed wait time has elapsed.

Abstract: A sealing method that uses an electrostatic energy storage welding machine which includes an energy storage section including a plurality of energy storage parts is provided. A method of sealing a liquid inlet port of a power storage device includes burring in advance a through-hole of the liquid sealing port to raise a hole edge of the through-hole into a form of a projection, wherein the liquid sealing port of the power storage device to be sealed with electrolyte contained therein corresponds to an object to be welded; placing a spherical body that is a lid body on the projection; and performing resistance welding between the projection and the spherical body to seal the liquid inlet port.

Abstract: The present disclose provides a method of resistance spot welding that can inhibit Liquid Metal Embrittlement-induced cracking in zinc-coated steel plates irrespective of the plate thicknesses. One aspect of the present disclosure provides a method of resistance spot welding that includes welding a workpiece with a resistance spot welding apparatus. The workpiece includes two or more steel plates in an overlapping state. The two or more steel plates include at least one steel plate coated with zinc. The welding includes causing a cooling rate of a high-tensile steel plate among the two or more steel plates to be higher than a cooling rate of an other steel plate among the two or more steel plates. The high-tensile steel plate has a tensile strength higher than a tensile strength of the other steel plate.

Abstract: A method for the manufacture of an assembly of at least two metallic substrates spot welded together through at least one spot welded joint, such method including two steps, the assembly obtainable according to this method and the use of this assembly for the manufacture of automotive vehicle.

Abstract: A welded assembly includes a first component including an aluminum material, a second component including a stainless steel, and a third component including a steel material. An ultrasonic weld is formed between the first and second components to join them and form a stack. A sealant and/or adhesive may be applied to the stack. A resistance spot weld is used to join the third component to the stack to form the welded assembly. The resistance spot weld encompasses a portion of the first, second, and third components, and a portion of the ultrasonic weld. The resistance spot weld is completely encompassed in the welded assembly, and thus is sealed from electrolyte in a surrounding environment.

Abstract: Discussed is a battery module, and more particularly, to a battery module in which an inner space between a battery cell and a metal plate is filled with a heat transfer member so that conduction of heat generated in the battery cell is improved.

Abstract: The present invention is directed to a system and method of remotely controlling a welding machine with command signals transmitted to the welding power source across a weld cable connecting the power source to a remote device, such a wire feeder. A transmitter transmits the control commands containing desired welding operational parameters to a receiver disposed in the power source across a weld cable also designed to carry welding power from the power source to the wire feeder.

Abstract: Provided is a resistance spot welding method. The resistance spot welding method for joining a sheet set including a plurality of lapped steel sheets includes: holding the sheet set between a pair of electrodes; and energizing the sheet set under application of electrode force to thereby join the steel sheets together. At least one of the plurality of lapped steel sheets is a surface-treated steel sheet including a metal coating layer on a surface thereof. The energizing includes: a primary energizing step of performing energization to form a nugget portion; a non-energizing step in which, after the primary energizing step, the energization is suspended for an energization suspension time Tc (cycles); and a secondary energizing step of, after the non-energizing step, performing energization for reheating while the nugget portion is prevented from growing. During the energizing, the relations of a particular formula are satisfied.

Abstract: A highly corrosion-resistant spot weldment can be produced at low cost without occurrence of prominent protrusions and the like on the surface. The spot weldment is joined by a nugget formed inside stacked sheet materials through bringing a pair of electrodes arranged opposite to each other into pressure contact with the stacked sheet materials from outside and energizing the stacked sheet materials from the electrodes. The nugget has a diameter that is ?4?t (t: thickness of sheet material) and a flattening level of 3.5 to 8, which is a ratio of diameter to thickness. Both outer surface parts of the sheet materials are free from protrusions formed due to bulging of molten metal. Even when the electrodes are made of a copper alloy, the increased amount of Cu in the outer surface parts is 0.2 mass % or less with respect to the component composition before spot welding.

Abstract: A resistance spot welding method may involve spot welding a workpiece stack-up that includes a steel workpiece and an aluminum alloy workpiece. A pair of opposed welding electrodes are pressed against opposite sides of the workpiece stack-up with one welding electrode contacting the aluminum alloy workpiece and the other welding electrode contacting the steel workpiece. The welding electrodes are constructed so that, when an electrical current is passed between the electrodes and through the workpiece stack-up, the electrical current has a greater current density in the steel workpiece than in the aluminum alloy workpiece to thereby concentrate heat within a smaller zone in the steel workpiece. Concentrating heat within a smaller zone in the steel workpiece is believed to modify the solidification behavior of the resultant molten aluminum alloy weld pool in a desirable way.

Abstract: An arrangement for connecting different parts includes two vehicle components. The vehicle body components include a first vehicle body component taking the form of a sheet metal component with a joining flange and being connected at this joining flange to the second vehicle body component via a welded connection. The joining flange on the first vehicle body component has a turned-over rim and is thereby formed with a doubled sheet metal thickness.

Abstract: A spacer grid welding fixture comprises a frame sized to receive an assembled spacer grid comprising a first set of parallel straps and a second set of parallel straps oriented orthogonally to the first set of parallel straps, the first and second sets of parallel straps interlocked together by slots cut into the straps. A first set of grid engagement bars is placed on a first side of the spacer grid with each grid engagement bar arranged parallel with the straps of the first set of parallel straps and engaging the straps of the second set of parallel straps. A second set of grid engagement bars is placed on an opposite second side of the spacer grid with each grid engagement bar arranged parallel with the straps of the second set of parallel straps and engaging the straps of the first set of parallel straps.

Abstract: Disclosed is a vehicle wheel having a wheel rim and a wheel disc connected to an inner side of the wheel rim. The wheel disc is connected to the wheel rim by a connecting element which is guided through a through-hole of the rim base and inserted in the wheel disc. The through-hole is arranged in the tire seat of the rim base and the connecting element is joined substantially in the direction of the radial extension of the wheel disc which is associated to the tire seat on the inner side of the rim. In the method for producing the wheel the connection between wheel rim and wheel disc is produced in the region of the tire seat of the rim base, and, after the insertion of the connecting element into the wheel disc, a portion of the connecting element protruding the contour of the outer side of the rim of the tire seat is shaped so that the connecting element conforms to the contour of the outer side of the rim of the tire seat.

Abstract: A weld joint is disclosed that weld bonds together an aluminum workpiece and a steel workpiece. The weld joint includes an aluminum weld nugget, an intermetallic layer, and an annular ring of aluminide particles that is selected from the group consisting of nickel aluminide particles, iron aluminide particles, and a combination thereof. The annular ring of aluminide particles extends upwards from a weld bond surface of the weld joint such that the annular ring of aluminide particles extends radially inwardly into the aluminum weld nugget and protects the weld bond surface of the weld joint against crack propagation that may originate from a notch root of the weld joint.

Abstract: In the present invention, while a welding current is applied with respect to a laminate body comprising thick metal plates and thin metal plates, a first welding pressure (F1) with respect to the laminate body from an upper tip contacting the metal plate and a second welding pressure (F2) with respect to the laminate body from a lower tip contacting the metal plate are changed relative to each other. Specifically, F1<F2 in a first step which is an initial period of welding, F1=F2 in a second step which is an intermediate period of welding, and F1>F2 in a third step which is a final period of welding.

Abstract: A heat sealing apparatus including a first sealing bar having a first sealing bar contact surface with a first resistance heating element extending along the upper sealing bar contact surface; a second sealing bar having a second sealing bar contact surface; a sealing bar moving mechanism for moving the first sealing bar and the second sealing bar away from and toward each other into compression contact; a power pulsing mechanism including a microprocessor running a computer program for delivering electric power pulses to the first resistance heating element in selected pulse durations separated by at least one selected interval duration and at a frequency between 0.001 and 5000 Hertz; an electric power source and an apparatus circuit including the first resistance heating element and the sealing bar moving mechanism.

Abstract: An oval nugget can reliably be obtained with this indirect spot welding method. In this indirect spot welding method, an electrode end portion of a welding electrode includes a tip of the welding electrode, and as viewed from the tip, the electrode end portion has a two-step dome shape formed by a first curved surface with a curvature radius r1 (mm) located within a range of a circle of radius R (mm) centering on the tip and a second curved surface with a curvature radius r2 (mm). 2?t?R?6?t (1), 30?r1 (2), and 6?r2?12 (3), where t is the sheet thickness (mm) of a thinner metal sheet.

Abstract: In the indirect spot welding apparatus, a lower limit in a stable pressing force region where the pressing force of the spot welding electrode against the metal sheets can be controlled within a tolerance of ±10% ranges from 70 N to 200 N and an upper limit in the stable pressing force region ranges from 800 N to 2000 N, and an overshoot OS(%)=(PL?AL)/AL×100 of the pressing force occurring when the spot welding electrode is pressed against the metal sheets is controlled to be 10% or less.

Abstract: The invention relates to a cylinder for storing coolant, with which a heat exchanger of an air-conditioning circuit is to be provided, said cylinder defining a first cavity (2) accommodating a desiccator, and a second cavity (3) capable of enabling fluid communication with said circuit. Said cylinder is configured such that said first (2) and second (3) cavities remain isolated from each other up to a first inner pressure threshold, and are placed in fluid communication once said second cavity (3) is subjected to a second inner pressure threshold that is greater than the first threshold. The invention also relates to a condenser provided with such a cylinder.

Abstract: A resistance welding device is provided with a lower tip and an upper tip that serve as welding tips, and pressing rods that serve as pressing members. The upper tip and the pressing rods press a stacked body, which is to be welded, from the metallic plate side, which is the outermost member of the stacked body. The lower tip presses the stacked body from the lowermost metallic plate side. In this state, and electric current is conducted from the upper tip to the lower tip.

Abstract: To bond bonding target members stacked on top of each other without generating dust or spatter into an electrically bonded article with improved mechanical strength against strong vibration etc. A first bonding target member or second bonding target member includes a relative displacement amount setting portion for setting the distance by which the bonding target portion of the first member and the bonding target portion of the second member are relatively displaced during bonding, and a current conduction suppressing layer is formed on the relative displacement amount setting portion. The second or first member includes a setting face that is placed opposed to the current conduction suppressing layer of the first or second member. In a state where the first and second members have been positioned, the distance between the current conduction suppressing layer and the setting face is equal to the width H of the bonded portion.

Abstract: A method of single-sided resistance welding includes providing a first workpiece and a second workpiece. The first workpiece is positioned so that at least a portion of the first workpiece is in contact with at least a portion of the second workpiece. A weld electrode is positioned in contact with the first workpiece, and a ground electrode is positioned in contact with the second workpiece. A determination is made as to whether a gap or other high resistance condition is present between the first workpiece and the second workpiece. If a gap or other high resistance condition is determined to be present between the first workpiece and the second workpiece, the gap or other high resistance condition is reduced, and the first workpiece and the second workpiece are joined through welding.

Abstract: A method is provided for producing a body part of a vehicle. The method includes, but is not limited to providing a first profile part with at least one first welding flange and with a first opening as well as a second profile part with at least one third welding flange. The welding flange is at least partially arranged on the third welding flange subject to the formation of an at least partially closed form of the body part. The first welding flange and the third welding flange are arranged within the at least partially closed form. A first laser beam is guided through the first opening onto the first welding flange subject to the formation of at least one first laser weld seam between the first welding flange and the third welding flange.

Abstract: Embodiments include a modular flex plate assembly with a plurality of modular segments connectable with at least another modular segment by joining a first end of one modular segment to a second end of another modular segment to form a ring gear. The ring gear can be mounted to a substrate and mounted or fastened to a component of an engine or a transmission system. A plurality of securing devices can cooperatively engage the ring gear to a substrate, such that the gear teeth of the ring gear align with the perimeter edge of the substrate.

Abstract: A compression device for being wrapped around a body portion of a wearer includes an inner layer and an outer cover. First and second bladder layers are secured together to define an inflatable bladder having an outer perimeter. The inner layer, outer cover and first and second bladder layers are joined together at a plurality of discrete spot welds within the outer perimeter of the inflatable bladder.

Abstract: A secondary battery has an electrode laminated body and a collector member. The laminated body is formed of a laminated electrode sheet. The collector member is bonded to a collector foil laminated portion of the electrode sheet not formed with an active material layer. The collector foil laminated portion and the collector member are bonded at overlapped portions by resistance welding using electrodes. When a pressure welding direction is a projection direction, an area ratio (Yd)/(Xd) is 1.2-4, in which Xd is a projection area of a surface of the electrode made contact with the collector foil laminated portion and Yd is a projection area of a surface of the electrode made contact with the collector member.

Abstract: A resistance spot welding method may involve spot welding a workpiece stack-up that includes a steel workpiece and an aluminum alloy workpiece that overlap one another to provide a faying interface. A pair of opposed welding electrodes are pressed against opposite sides of the workpiece stack-up with one welding electrode contacting the aluminum alloy workpiece and the other welding electrode contacting the steel workpiece. The welding electrodes are constructed so that, when an electrical current is passed between the electrodes and through the workpiece stack-up, the electrical current has a greater current density in the steel workpiece than in the aluminum alloy workpiece to thereby concentrate heat within a smaller zone in the steel workpiece. Concentrating heat within a smaller zone in the steel workpiece is believed to modify the solidification behavior of the resultant molten aluminum alloy weld pool in a desirable way.

Abstract: A method of resistance spot welding a steel workpiece and an aluminum or aluminum alloy workpiece together includes several steps. One step involves inserting a cover between the aluminum or aluminum alloy workpiece and an adjacent welding electrode. In another step, the adjacent welding electrode is pressed against cover, and another opposed welding electrode is pressed against the steel workpiece at a weld site. In yet another step, electrical current is passed between the welding electrodes, passed through the cover, and passed through the workpieces in order to initiate and grow a molten weld pool within the aluminum or aluminum alloy workpiece.

Abstract: A welding device for welding a thicker sheet and a thinner sheet arranged congruently together. A first welding electrode having a first heat reflector or welding mirror contacts the thicker sheet with a first contact surface. A second welding electrode having a heat reflector or second welding mirror contacts the thinner sheet with a second contact surface. The first and second contact surfaces 8, 10 are at least partially congruent, and the first contact surface is larger than the second contact surface by at least a factor of two.

Abstract: Weld faces of electrodes for resistance spot welding are formed with a suitable area of protrusions and/or intrusions. The size, shape, and elevation or depths of the protrusions or intrusions are determined for the formation of suitable spot welds in and between metal workpieces such as aluminum or steel panels for vehicle bodies. The protrusions or intrusions are also conceived and used to form an image on at least a visible surface of the welded article to produce an attractive appearance on the surface of the welded sheet.

Abstract: An apparatus is provided including: at least one first sheet comprising a first material; at least one second sheet comprising a second material, wherein the first material comprises at least one of: a thermal conductivity and an electrical conductivity that is at least 10% lower than that of the second material; and a joint comprising at least one resistance spot weld (RSW), wherein the first sheet is at least about 1.5 times the thickness of the second sheet. Methods are also provided.

Abstract: An annular core plate for a multiplate clutch assembly includes a main annular portion and an engagement annular portion extending from the main annular portion. The engagement annular portion has teeth extending therefrom. The teeth are thicker than the main annular portion. A multiplate clutch assembly is provided that includes at least one annular core plate or friction plate and at least one annular separator plate. A method of constructing at least one plate for a multiplate clutch assembly is also provided. The method includes forming an annular separator plate from sheet metal by removing a circular section from a separator plate main body portion of the sheet metal, removing a portion of the circular section to form teeth in the circular section, and attaching the circular section to an annular plate.

Abstract: Resistance spot welding of a thin-gauge steel workpiece to another steel workpiece is achieved by through the combined use of specific spot welding electrodes and a pulsating welding current. Each of the spot welding electrodes has a weld face that is smaller in diameter than a typical steel spot welding electrode. And the pulsating welding current that is used in conjunction with the smaller-sized spot welding electrodes includes at least two stages of electrical current pulses.

Abstract: Resistance spot welding of a steel workpiece to an aluminum or an aluminum alloy workpiece can be facilitated by replacing the refractory aluminum oxide-based layer(s) on at least the faying surface of the aluminum or aluminum alloy workpiece with a protective coating that is more conducive to the spot welding process. The protective coating may be a metallic coating or a metal oxide conversion coating. In a preferred embodiment, the protective coating is a coating of zinc, tin, or an oxide of titanium, zirconium, chromium, or silicon.

Abstract: A cold-formed electrode tip for use in spot welding is provided. The cold-formed electrode tip includes a base, a rounded face, and an annular wall extending along a longitudinal axis of the electrode tip, the annular wall having a thickness such that the annular wall is configured to be readily deformed by a handheld tool.

Abstract: A method and apparatus inspect a quality of an adhesive material used for joining a pair of work surfaces during a weld-bonding process. A pair of work pieces are at least partially bonded by a layer of the adhesive material, and the dynamic displacement of one or both electrodes is measured through a duration of the resistance welding process to determine relative moisture content of the adhesive. A control action is executed when the dynamic displacement exceeds a stored threshold value. The apparatus includes a welding device having a pair of electrodes for providing a clamping force and an electrical current necessary for forming the welded joint, a sensor for measuring a dynamic displacement of at least one of the pair of electrodes and/or another portion of the welding device during formation of the welded joint. A controller has an algorithm for determining a relative moisture using the dynamic displacement.

Abstract: A welding electrode includes an electrode holder and an electrode cap removably attached to the holder and having a central longitudinal axis. The cap includes a body having an end, and a welding surface that is substantially smooth and free from any grooves defined therein, and has a first diameter of from about 7 to 10 mm, a first radius of curvature, and a second radius of curvature that is different from the first radius. The cap includes a skirt portion extending away from the body and configured to bear against the holder. The skirt portion has a first face that is substantially parallel to the axis and spaced apart from the surface. The body has a second face interconnecting the first face and the surface, and the body tapers from the first face to the surface. A method of forming a resistance spot weld joint is also disclosed.

Abstract: A programmable polarity module that permits rapid on-demand control of the polarities assigned to the welding electrodes retained on a welding gun is disclosed. The programmable polarity module is electrically connectable to the welding gun and a direct current power supply unit to provide direct current to the welding electrodes for exchange during spot welding. A first interchangeable polarity output lug and a second interchangeable polarity output lug of the programmable polarity module permit the polarities of the welding electrodes to be switched without having to electrically disconnect the module from the welding gun.

Abstract: A method for improving a resistance spot weld includes stacking two or more metal sheets and positioning first and second opposed electrodes on opposite sides of the metal stack. At least one of the metal sheets is chilled in the region where the weld is to be made. Weld current is applied to the electrodes and passes through the metal sheets to create the electric resistance spot weld only after the chilling of the at least one metal sheet reduces the temperature at the faying interface at least 5° C., thereby improving the formation of the weld nugget and quality of the weld joint. The chilling can be obtained by flowing chilled gas onto the surface of one or both of the outermost metal sheets, or by contacting the outermost metal sheets with the chilled electrode for a period of time prior to applying the weld current.

Abstract: There is illustrated and described a method for joining a composite sheet metal member to an additional component, the composite sheet metal member having at least two outer covering metal sheets and at least one non-metal layer which is arranged between the covering metal sheets and the additional component having at least one outer metal layer, wherein the composite sheet metal member and the additional component are moved so as to overlap each other between two electrodes of a resistance welding unit. In order to be able to join composite sheet metal members in an operationally reliable manner by means of resistance welding, there is provision for an electrically conductive dummy element to be moved into abutment with an outer covering metal sheet and for at least one current path between the two electrodes to be closed by means of an electrically conductive dummy element.

Abstract: A pressure sensor (1) is specified, comprising a housing (2), a membrane (3), which forms with the housing (2) a chamber (4) closed off toward the outside, and a filling opening (6) for filling the chamber (4) with a fluid medium (5). The filling opening (6) is closed by means of a soldering or welding closure (7, 8). Furthermore, a method for producing a pressure sensor (1) is specified, wherein a housing (2), which together with a membrane (3) forms a chamber (4), is provided, the chamber (4) is filled with a fluid medium (5) through a filling opening (6), and the filling opening (6) is subsequently closed by means of soldering or welding.

Abstract: The invention is directed at a method for welding a composite material and to welded structures thus prepared. The method includes a step of contacting a substrate material with a composite material, wherein the composite material includes a pair of spaced apart steel sheets and a core layer between the sheets; the volume of the core layer is about 25 volume % or more, based on the total volume of the composite material; the core layer includes a plurality of steel fibers arranged in one or more masses of fibers that extend the thickness of the core layer so that the core layer is in electrical communication with the steel sheets; and the steel fibers have a cross sectional area perpendicular to the length of the fibers from about 1×10?5 mm2 to about 2.5×10?2 mm2.

Abstract: Disclosed herein are bonded structures and methods of forming the same. One embodiment of a bonded structure comprises first and second metallic layers and a bonding interface between the first and second metallic layers formed by diffusion and comprising a layer of at least one intermetallic compound. The intermetallic compound layer is formed in an area 52% or greater of an area of the bonding interface and has a thickness of 0.5 to 3.2 ?m.

Abstract: A method of resistance spot welding aluminum alloy workpieces together includes several steps. In one step a welding electrode is provided. The welding electrode has a weld face. In another step, the weld face of the welding electrode is shaped to have a desired radius of curvature. The shaped weld face is then textured to a desired surface roughness, and resistance spot welding using the welding electrode is performed to the aluminum alloy workpieces. In yet another step, the weld face is dressed to an extent sufficient to remove contamination build-up that may have accumulated on the weld face from the aluminum alloy workpieces.

Abstract: A weld cylinder having a single piston arrangement is provided. The cylinder has a movable retract piston assembly with the piston arranged within the retract piston assembly. The piston supports a rod that is movable between home, intermediate, work, and advanced work positions. The rod moves rapidly from the home position to the intermediate position however, the rod moves more slowly from the intermediate position to the work position to reduce the impact force. A cushion chamber slowly exhausts through a pre-orifice and a hole in the cushion valve while an isolator is in an open position. Once the cushion valve opens in response to a retract-forward pressure on the cushion valve, the cushion chamber exhausts rapidly so that weld force increases rapidly to minimize increases in cycle time. Advance of a retract piston assembly is also cushioned. A weld-forward port is no longer provided on a cylinder barrel.

Abstract: Spot welding electrodes with generally dome shaped welding faces are provided with surface features for welding both aluminum alloy sheet assemblies and steel sheet assemblies. A raised circular plateau is formed on the central axis of the dome and, in one embodiment, a suitable number of round bumps are formed in concentric spacing from adjacent the circumference of the plateau toward the circular edge of the welding face. For welding steel workpieces the plateau mainly serves as the engaging feature of the electrode. Both the plateau and concentric bumps are used in penetrating light metal surfaces for suitable current passage. In another embodiment, the domed surface is shaped with concentric terraces for engagement with the workpieces.

Abstract: Disclosed is a bonding method for dissimilar materials made from metals and its resulting structures. The materials to be bonded are formed by layering three or more sheets such that a dissimilar material interface and a same material interface are formed. A first current is conducted between a three-sheet layered plate material wherein an aluminum alloy plate, a zinc plated steel plate and a bare steel plate, for example, are layered in order. A nugget is formed in an interface between the zinc plated steel plate and the bare steel plate, which are the same materials. Then, a second current greater than the first current is conducted, and a nugget is formed in an interface between the aluminum alloy plate and the zinc plated steel plate.

Abstract: The first embodiment of the invention is a spot welding method using a welding gun including a pair of electrodes holding and welding a welding point of a workpiece. The method including: transmitting an ultrasonic from one of the electrode pair to the workpiece with the electrode pair holding the workpiece; receiving the ultrasonic at the other electrode passed through the electrode pair and the workpiece; and detecting a holding state of the workpiece on the basis of an amplitude of the received ultrasonic. According to the embodiments of the invention, the welding gun can hold the workpiece at the proper position and with the correct angle, thereby reducing the welding flaws.

Abstract: Provided is a joint product of a steel product and an aluminum material, the joint product being formed by joining the steel product having a sheet thickness t1 of 0.3 to 3.0 mm with the aluminum material having a sheet thickness t2 of 0.5 to 4.0 mm by spot welding, wherein a nugget area in a joint part is from 20×t20.5 to 100×t20.5 mm2, an area of a portion where a thickness of an interface reaction layer is from 0.5 to 3 ?m is 10×t20.5 mm2 or more, and a difference between the thickness of the interface reaction layer at a joint part center and the thickness of the interface reaction layer at a point distant from the joint part center by a distance of one-fourth of a joint diameter is 5 ?m or less, and wherein the aluminum material is pure aluminum or an aluminum alloy material.

Abstract: In the present invention, when spot welding a cold rolled steel sheet and an aluminum alloy sheet, pre-electrification is performed ahead of time in conditions wherein the sheet thickness (ta) of the aluminum alloy sheet and the sheet thickness (ts) of the cold rolled steel sheet that are to be joined are in specific ranges, dust is not generated between the steel sheet and an electrode, and the aluminum alloy sheet side is not caused to melt, and afterwards, main spot welding is performed. The welding conditions of the main spot welding and the pre-electrification further satisfy a relational expression that is determined by each electrification condition and each sheet thickness.