Abstract: In a method of friction stir welding two pieces of material of greatly differing melting temperatures, provision is made that the first piece of material is overlapped by the second piece of material. The rotating pin of the friction stir welding tool provides for a butt joint welding and an overlap welding at the same time in that the pin is moved along the face side and contacts it either not at all or at most to a minimum extent. The same also applies to the planar side of the first piece of material, which is overlapped by the less stable piece of material.

Abstract: An additive manufacturing method includes: providing a metal substrate; pressing a plurality of first metal parts to weld the same on the metal substrate one by one using a welding unit through friction welding so as to form a first stacked layer laminated on the metal substrate; pressing a plurality of second metal parts to weld the same on the first stacked layer one by one using the welding unit through friction welding so as to form a second stacked layer laminated on the first stacked layer; and repeating formation of the second stacked layer until a required amount of the second stacked layers are additively laminated on the first stacked layer to obtain a final three-dimensional (3D) article.

Abstract: A method for producing a connection between a sandwich element and a metal element is disclosed herein. In this method, the sandwich element has an interlayer arranged between two cover elements. The method includes providing the sandwich element and the metal element; placing the sandwich element and the metal element in face-to-face contact at least partially overlapping; adding a fastener from the sandwich-element side while a base of the fastener extends within the sandwich element; and friction welding, from the metal-element side, to form a hybrid connection having a mechanical connection between the fastener and the sandwich element and a welding connection between the fastener and the metal element.

Abstract: A method of manufacturing a liquid-cooled jacket, includes a preparation step which includes placing a sealing body on a stepped portion to allow a step side surface and a sealing-body side surface of the sealing body to butt each other, and a primary joining step which includes allowing a primary joining rotary tool to move once around the sealing body, while moving the rotary tool along a butted portion formed in the preparation step, to carry out friction stir welding. The primary joining step includes employing the primary joining rotary tool provided with a stirring pin having a length dimension greater than a thickness dimension of the sealing body, and carrying out friction stirring with only the stirring pin being brought into contact with a jacket body and the sealing body.

Abstract: A friction stir welding apparatus that includes a rotary tool and a heating device. The heating device is placed in front of the rotary tool to heat steel sheets that are used as a workpiece. The rotary tool is moved in the welding direction so that steel sheet is softened by frictional heat. Additionally, the surface temperature, the area, and the position of the heated region during the heating process are strictly controlled. The heating of the steel sheets by the welding apparatus provides sufficient strength and good welding workability by advantageously eliminating plastic flow defects generated due to insufficient heating of workpieces.

Abstract: Some examples include welding a first workpiece to a second workpiece. For instance, the first workpiece may be secured adjacent to the second workpiece. At least one of the first workpiece or the second workpiece includes a channel or a portion of a channel in a respective surface such that a complete channel is presented when the first workpiece and the second workpiece are secured adjacent to each other. A rotating tip of a welding tool is inserted into the complete channel for welding the first workpiece to the second workpiece. A surface burr resulting from the welding is located within the complete channel.

Abstract: A method for fabricating an article that includes: providing a first workpiece component formed of a first steel material; joining a second workpiece component to the first workpiece component to form a workpiece, the second workpiece component being formed of a second steel material that is different from the first steel material; and forming a plurality of teeth on the workpiece, the teeth being wholly formed of the first steel material.

Abstract: A separator for sealing a cavity in a motor vehicle includes a first separator part for sealing a portion of the cavity that includes a first expandable layer located around an outer edge and a second separator part for sealing a second portion of the cavity that includes a second expandable layer. The first separator part abuts the second separator part when installed in the cavity of the motor vehicle. The first expandable layer and second expandable layer expand to provide a seal around the first separator part and second separator part when heated. The separator further includes a third separator part for sealing a third portion of the cavity that includes an expandable tape that adheres to a surface of the third portion of the cavity. The expandable tape expands to seal the third portion of the cavity when heated.

Abstract: A method for joining a plurality of workpieces includes providing a rotating drive tool. A fastener is secured to the drive tool. The drive tool is then rotatably driven such that a distal end of the fastener rotates against a surface of the plurality of workpieces. A heated material zone is then generated on the plurality of workpieces as caused by friction from the rotation of the fastener against the surface of the plurality of workpieces. The distal end of the fastener is rotatably and axially driven through the heated material zone. Finally, the drive tool is removed from the fastener, such that when the heated material zone cools, a portion of the heated material zone is fused to the fastener.

Abstract: A joining method includes abutting an end face of a first metal member in a plate shape having a projecting part on the end face on a rear face of a second metal member in a plate shape having a hole that is bored through the second metal member in a plate thickness direction and simultaneously inserting the projecting part into the hole. The method includes inserting a stirring pin of a rotary tool into an abutment portion of a wall of the hole and an outer peripheral surface of the projecting part from a front face side opposite to the rear face of the second metal member. The rotary tool is moved along the abutment portion to join the abutment portion by friction stirring. The abutment portion is joined together with only the stirring pin of the rotary tool being in contact with the first and second metal members.

Abstract: The invention relates to a method for manufacturing a housing of a turbomachine, in particular a gas turbine. The method comprises at least the steps: providing a housing blank, manufacturing a housing element, producing an assembly opening corresponding to the housing element in the housing blank, arranging the housing element in the assembly opening, and joining the housing element to the housing blank by means of a welding method. In addition, the invention relates to a turbomachine housing.

Abstract: The present disclosure relates to methods for forming a golf club head assembly using a combination of different, but separate heat treatments for the golf club head body and high strength faceplate, and vibrational waves to relive stress in the weld heat affected zones of the golf club body and face.

Abstract: Described are enclosures that include a friction stir weld, including electronic device enclosures, and precursors thereof, that contain a base and a cover that in an assembled condition form a joint at which a friction stir weld can be produced, as well as methods for producing a friction stir weld at a joint of such an assembly.

Abstract: A friction stir welding tool and method for forming a friction stir weld joint includes a rotatable body having a rotatable shoulder for maintaining surface contact and maintaining plunge depth and a rotatable pin extending from the rotatable shoulder. The rotatable pin is integrally formed with the rotatable shoulder. The tool further includes a stationary body annularly disposed around the rotatable body. The stationary body has a stationary shoulder annularly disposed around the rotatable shoulder for further maintaining surface contact and managing plunge depth.

Abstract: Disclosed herein are systems, methods, and devices for repairing holes in weld seams created by bobbin friction stir welding tools. A hole may be created when a welding tool or, more specifically, a pin of the tool is removed or otherwise extracted from a weld seam created by the tool. The method may involve inserting a plug (e.g., a rivet) into the hole, reshaping the plug in the hole (e.g., riveting) thereby securing the plug in the component, and creating another weld seam through the plug thereby consuming the plug. In some embodiments, the hole may be reshaped prior to inserting the plug. For example, the hole may be drilled out and/or a countersink may be created on one or both ends of the hole. Furthermore, the plug may extend outside of the hole prior to its reshaping and, in some embodiments, even after reshaping.

Abstract: A friction welding method includes: applying axial force to first and second metallic components so as to force the components against each other at an interface therebetween, while oscillating the two components relative to each other in a cyclic motion, so as to generate friction and heat at the interface; rapidly stopping the cyclic motion; and applying a spike in the axial force to complete a weld between the first and second components.

Abstract: An objective of the present invention is to provide a friction stir welding device with which the temperature in the proximity of a weld part on a member to be welded can be intermittently measured by enabling the temperature of a plurality of sites in a rotary tool (4) used for friction stir welding to be ascertained in real-time when welding. This rotary tool (4) for a friction stir welding device comprises: a hollow channel (26a) that extends from the upper end of a shoulder part (4c) to the proximity of the lower end of a probe (4d), and that is on substantially the same axis as the axis of rotation of the shoulder part (4c); and a hollow, outer periphery channel (26b) that is apart from the axis of rotation of the shoulder part (4c) in the radial direction and in proximity of the outer periphery of the shoulder part (4c), and that extends from the upper end of the shoulder part to the proximity of the lower end thereof.

Abstract: Certain embodiments relate to a heat exchanger plate capable of performing friction stir welding at a deep position of the heat exchanger plate, and improving air-tightness and water-tightness. A method may include a lid groove closing process to insert a lid plate into a lid groove formed at a periphery of a concave groove opening to a surface of a base member. The method may also include a primary joining process to perform friction stirring while relatively moving a primary joining rotary tool equipped with a stirring pin along a butting portion of a side wall of the lid groove and a side surface of the lid plate. In the primary joining process, the rotating stirring pin may be inserted into the butting portion, and the friction stirring may be performed in a state of only the stirring pin being in contact with the base member and the lid plate.

Abstract: A process of producing shell and tube heat exchangers where the ends of the tubes are secured to a tube sheet while reacting applied FSW forces without introducing a crevice or local deformation near the ends of the tubes. In particular, an interference fit is used to lock the ends of the tubes into the tube sheet without flaring or expanding the tube ends. A FSW process is then used to weld the ends of the tubes to the tube sheet.

Abstract: A mounting apparatus includes a Y-axis movable base 36 movable in a Y-axis direction, a Z-axis movable base 40 attached to the Y-axis movable base 36 and movable in a Z-axis direction, a mounting head 12 attached to the Z-axis movable base 40 and including a mounting tool 16 for sucking and holding a semiconductor chip, a pressurizing mechanism 20 attached to the Y-axis movable base 36 and arranged to apply a force in the Z-axis direction to the mounting head 12, and a pressure receiving member 22 provided independently of the Y-axis and Z-axis movable bases 36 and 40 and installed in proximity to the pressurizing mechanism 20 to receive a reaction force in the Z-axis direction from the pressurizing mechanism 20, the pressurizing mechanism 20 slidable on the pressure receiving member 22. This prevents the mounting apparatus from being increased in the total size while maintaining the mounting accuracy high.

Abstract: A panel member for an automobile has: a first plate member; a second plate member joined to the first plate member via a first joining portion in a state of being adjacent to the first plate member, a tensile strength of the second plate member is lower than a tensile strength of the first plate member; one or more third plate members joined to the first plate member and the second plate member via a second joining portion that intersects the first joining portion in a state of being adjacent to the first plate member and the second plate member; and a high strength portion that is provided at the second plate member, and that includes a peak portion including the first joining portion and the second joining portion, a tensile strength of the high strength portion being higher than the tensile strength of the second plate member.

Abstract: Described are tools useful to produce a friction stir weld, methods of forming a friction stir weld, and assemblies such as electronic devices that include a friction stir weld.

Abstract: System for friction stir welding of two parts which includes a welding unit which includes at least one welding head fitted with a rotating pin and a counter-bearing unit which has a support surface to support the parts against a pressure exerted by the welding head, and wherein each welding head can be moved relative to the support surface in a first direction parallel to an axis of rotation of the rotating pin and in a second direction orthogonal to the axis of rotation, and wherein the support surface can be moved in the second direction and is formed of two coaxial clamp rollers which are set apart from each other.

Abstract: A method for producing a plate heat exchanger and the plate heat exchanger, particularly a soldered aluminium plate heat exchanger. In the method, a heat exchanger block is provided having a plurality of partition plates and edge strips arranged between the partition plates. A connection device is provided to be mounted on the heat exchanger block. A planar region for securing the connection device to the heat exchanger block is provided with at least one welded weld bead by means of a first weld. The connection device is welded onto the weld bead by means of a second weld. The welding method used for the first weld is a friction stir welding method.

Abstract: A method for solid state joining of dissimilar materials using a friction stir welding device wherein a pin is inserted through an aperture defined in a first material and a second material to hold the materials together and then held in place by friction stir welding a portion of the pin to a material adjacent said pin, or by friction stir welding a cap or plug that holds the pin in place to the adjacent material. The result is a connection or join wherein the central portion of the pin is not friction stir welded but the portions holding the pin in place (the ends or caps) generally are.

Abstract: A method of mechanically processing a metallic material component is provided whereby alloying, carburizing, nitriding and boriding can be performed using a friction stir processing tool. This method for mechanically processing metallic material surfaces is cost effective, efficient and does not require specialized equipment.

Abstract: A friction stir welding device includes: a control device which causes a pin part to be inserted into members to be joined while causing a joining tool to rotate and which causes a joining head to move along a joint line via a robot main body; and an image pickup device which detects a junction deviation that is a deviation between the joining head and a direction along the joint line. Also, when a junction deviation is generated, this control device causes the joining head to move in a direction toward the joint line and thus resolves the junction deviation.

Abstract: A joining method includes a butting process configured to butt a first metal member and a second metal member each having a front surface with various heights to form therebetween a butt portion with various heights; and a welding process configured to apply a friction stirring to the butt portion by a stirring pin of a rotation tool while only the stirring pin of the rotation tool contacts with the first metal member and the second metal member of the butt portion. The welding process may be configured to insert the stirring pin of the rotation tool into the butt portion from front surfaces of the first metal member and the second metal member and apply the friction stirring to the butt portion while an insertion depth of only the stirring pin is kept approximately constant.

Abstract: A process for producing a multilayer pipe by expansion is disclosed, with or without heating, in which a multilayer pipe (1) comprises at least one outer pipe of metallic material (10) and an inner pipe of metallic material (20), the inner pipe of metallic material (20) having a yield strength lower than the yield strength of the outer pipe (23) and an external diameter smaller than the internal diameter of the outer pipe. The process for producing the multilayer pipe comprises a mounting step (34) between the pipes (10, 20), wherein the inner pipe is inserted inside the outer pipe, and at least one mechanical expansion step (36), comprising moving a mandrel (2) longitudinally and internally in the inner pipe (20) while the outer pipe and the inner pipe are held at a fixed position, wherein at least part of the mandrel (2) has a greater external diameter than the internal diameter of the inner pipe.

Abstract: A method for forming a metal matrix composite (MMC) structure includes forming an assembly including at least two blocks of a primary phase material sharing an interface at which a secondary phase material is disposed. The assembly has a length, a width, and a thickness. The method also includes clamping the assembly to at least one of urge the at least two blocks toward each other or maintain the at least two blocks at a predetermined position. Also, the method includes passing a rotating friction-stir pin along the interface from the front edge to the rear edge. The friction-stir pin has a mixing length extending at least the width of the assembly, and passing the friction-stir pin along the length of the assembly disperses the secondary phase material into the primary phase material and welds the at least two blocks together.

Abstract: A friction stir welding method includes a first friction stir welding process of forming a first stirring region in a beveled part, by moving a first rotary tool disposed on an upper side in a thickness direction across the beveled part, while rotating the first rotary tool; and a second friction stir welding process of forming a second stirring region in the beveled part, by moving a second rotary tool disposed on a lower side in the thickness direction across the beveled part, while rotating the second rotary tool, simultaneously with the first friction stir welding process or after performing the first friction stir welding process.

Abstract: A battery cell assembly includes a pouch-type battery cell having a battery member, an external housing, and first and second electrical terminals. The external housing has a central housing portion and a peripheral lip member extending around a periphery of the central housing portion. The central housing portion encloses the battery member therein. The first and second electrical terminals are electrically coupled to the battery member and extend outwardly from the peripheral lip member. The assembly further includes a first tube disposed against the peripheral lip member of the external housing. The peripheral lip member extends around the first tube such that the first tube is at least partially disposed within a first interior region defined by the peripheral lip member.

Abstract: A different materials joint structure includes: a thinned-plate shaped iron member and a thinned-plate shaped aluminum member integrally joined together. The iron member comprises two or more steel thinned plates stacked on each other and an electrodeposition coating is applied to the thinned plates so as to form electrodeposition coating films on surfaces of the thinned plates. The iron member and the aluminum member are then stacked on each other with stacked surfaces, and are joined together by friction stir welding tool inserted from an aluminum member side toward an iron member side in a direction perpendicular to the stacked surfaces.

Abstract: A fuel cell according to one mode includes a plurality of stacked cell units, each cell unit including at least an electrically conductive interconnector having a front surface and a back surface; a pair of connection members which are electrically connected to the interconnector; a single cell which includes an anode, a cathode, and an electrolyte therebetween and which is electrically connected to the connection members; and a separator having an opening which is connected to an outer peripheral portion of the single cell, the cell units being clamped together in a stacking direction, wherein the connection member on an anode side or a cathode side of the single cell of at least one cell unit of the cell units has a thickness different from that of the connection member on the anode side or the cathode side of the single cell of another cell unit.

Abstract: A secondary battery according to an embodiment includes a container having a pouring hole through which an electrolyte is poured, and housing the electrolyte, poured through the pouring hole, together with an electrode body; and a sealing lid which is fixed to the container and is closing the pouring hole. The sealing lid has a welding mark existing in a ring shape with a depth through the sealing lid to a lid body of the container, and an inner circumferential side molten mark existing in a ring shape overlapping with the welding mark, on the inner circumferential side of the welding mark in the sealing lid, with a depth corresponding to the thickness of the sealing lid.

Abstract: A friction stir spot welding device includes a pin member, a shoulder member, a rotation driving unit, a tool driving unit, a position detector, and a controller, wherein the controller sets as reference position of the tip end surface of the pin member or shoulder member at a time point when the pin member tip end surface or shoulder member contacts an obverse surface of an object and controls the tool driving unit reducing a pressing force to the object by the pin member and pressing force to the object by the shoulder member in a next welding process, and/ or controls the rotation driving unit reducing the pin member rotational speed and shoulder member rotational speed in the next welding process, in case where a first position is the position of the tip end surface of the pin member or the shoulder member is within a first region.

Abstract: Apparatus and method for increasing the quality of the weld seam in friction stir welding, with the following features: a) a receiving plate (1) with a drive head (2), the latter having a receiving flange (19) for receiving a holding bell (3) connected by means of a union nut (7) to a welding shoe (4) with a welding pin tip (5), b) the welding shoe (4) has a circular basic shape, on which there is a transverse web running over the cross section and rising at a right angle to said basic shape, said transverse web having a width of approximately ¼ to ? of the diameter of the basic shape and having an arc-shaped shoe sliding surface and shoe smoothing surface (9), c) the welding pin tip (5) has substantially a surface structure in the form of a tapering thread, this thread-like structure not being arranged in a purely circular manner.

Abstract: A mechanically conformable micro-heat exchanger for use in managing temperature of a subject component. The exchanger includes a flexible fluid tube. In various embodiments, the tube is connected to a flexible substrate, such as by a flexible polymer. The exchanger can be changed manually from an initial shape to a first shape to conform to a shape of the subject component. The flexible fluid tube is configured to channel heat-transfer fluid through a heat-transfer tube section of the tube. The heat-transfer fluid is configured to cool or heat the subject component when, in operation of the mechanically conformable micro-heat exchanger, the heat-transfer fluid is channeled through the heat-transfer tube section.

Abstract: Method and device for quick and reliable tool changing in the process of friction stir welding, comprising the following features: a) a robot (1) with a robot pivoting head (2) and a friction welding head (3) with a welding shoe (13), wherein the robot (1) can select a friction welding head (2) from a tool magazine (4), b) a device for sensing the mechanical forces at the welding pin tip (14) of each welding shoe (13) of a friction welding head (2), wherein a sensor (16) is attached to the frustoconical part of the tool (11), wherein a sensor (21) is provided, and wherein furthermore a sensor (25) is provided in the flared pin receptacle (26) and a piezoelectric force-measuring sensor (24) is provided in the longitudinal axis of the pin shaft (27) for measuring the axial force acting on the welding pin tip, c) an RFDI code provided on the pin shaft (27) of each welding shoe (13) for identification, d) a changing skid (28) provided on each welding shoe (13).

Abstract: A welding method for connecting at least two workpieces at a connection region by means of friction stir welding using a welding tool having a probe and a shoulder. The method includes rotating the probe around a rotation axis, wherein the connection region is softened by friction heat provided by the probe during said friction stir welding to form a welded seam at the connection region. The method also includes molding, simultaneously with forming the welded seam, at least one of a bevel, a rounding and a chamfer on an edge of the connection region using the shoulder, wherein the shoulder is configured to separate the connection region from the surroundings.

Abstract: In a friction stir welding method, a pair of plate materials is arranged opposing one another such that the ends thereof are butted together, after which friction stir welding is performed. A first shoulder is arranged at one surface of the pair of plate materials and a second shoulder is arranged at the other surface of the plate materials to sandwich therebetween a joint to be formed by friction stirring of the end parts of the plate materials, and the first shoulder and the second shoulder are rotated, thereby friction stirring the joint of the pair of plate materials. As the joint is friction stirred, the first shoulder and the second shoulder are moved from the other surface toward the one surface of the plate materials, thereby forming at the joint a protruding part protruding from the one surface of the plate materials as the friction stir welding is performed.

Abstract: A hollow profile connection to connect at least two hollow profiles via a gusset plate which makes contact with the end regions of the hollow profiles to be connected, in the outer region thereof. At least the end regions of the hollow profiles in cross-section have a profile formed by webs or ribs. The gusset plate is connected to the at least two hollow profiles via a friction-stir weld which run along the ribs or webs of the at least two hollow profiles.

Abstract: Additive friction stir methods for joining materials are provided. The methods comprise providing first and second substrates to be joined; providing a forming plate comprising one or more forming cavities; placing the first and second substrates in communication with the forming plate; placing the first and second substrates in communication with each other; rotating and translating an additive friction-stir tool relative to the substrates; feeding a filler material through the additive friction-stir tool; deforming the filler material and the first and second substrates; and extruding one or more of the filler material and the first and second substrates into one or more of the forming cavities of the forming plate. Interaction of the additive friction-stir tool with the substrates generates heat and plastic deformation at the joint to weld the substrates at the joint. The methods include introduction of reinforcing material at the joint through addition of the filler material.

Abstract: A method of joining heat-treatable aluminum alloy members by friction stir welding, including the steps of: a T4-treatment-performing step of performing a T4 treatment on heat-treatable aluminum alloy members so as to impart T4 temper to the heat-treatable aluminum alloy members; a joining step of joining the heat-treatable aluminum alloy members with T4 temper by friction stir welding to provide a joined product; and a reversion-treatment-performing step of performing a reversion treatment, the reversion-treatment-performing step being carried out prior to or after the joining step.

Abstract: A method of fabrication by friction stir welding (FSW) at an interface between adjoining components such as pipe lengths of a pipeline has layers of different metals on each side. FSW is performed from one side of the adjoining components by effecting relative movement of a first FSW tool along the interface. FSW is performed from an opposite side of the adjoining components by effecting relative movement of a second FSW tool along the interface. Advantageously, FSW is performed simultaneously from both sides of the adjoining components with the FSW tools applying loads in mutual opposition about the adjoining components.

Abstract: A method of manufacturing a liquid-cooled jacket, includes a preparation step which includes placing a sealing body on a stepped portion to allow a step side surface and a sealing-body side surface of the sealing body to butt each other, and a primary joining step which includes allowing a primary joining rotary tool to move once around the sealing body, while moving the rotary tool along a butted portion formed in the preparation step, to carry out friction stir welding. The primary joining step includes employing the primary joining rotary tool provided with a stirring pin having a length dimension greater than a thickness dimension of the sealing body, and carrying out friction stirring with only the stirring pin being brought into contact with a jacket body and the sealing body.

Abstract: Process for linear transparency friction stir welding of a flange of a stiffener onto at least one panel for an aircraft, wherein a weld bead is made along the flange of the stiffener and wherein the weld bead extends in cross-section from a first lateral edge to an opposite second lateral edge of the stiffener flange. System for the implementation of the above welding process, which includes three welding heads arranged as a triangle, each of which includes a rotating pin as well as a shoulder extending at the base of said rotating pin.

Abstract: This invention discloses a 3D printing apparatus and method utilizing friction stir welding (FSW). The apparatus includes a material feeding mechanism, a control mechanism, a friction stir welding (FSW) mechanism, and a friction stir welding (FSW) rotation drive mechanism. The control mechanism controls the material feeding mechanism, the FSW mechanism and the FSW rotation drive mechanism. In addition to the control mechanism, the FSW mechanism also connects to the FSW rotation drive mechanism. The method comprises the steps of: 1, start the control mechanism; step 2, the control mechanism controls the material feeding mechanism to feed filling material; step 3, print 3D product with FSW mechanism. The invention achieves additive manufacturing and 3D printing with a new friction stir welding technology.

Abstract: A friction stir welding apparatus includes: a rotating shaft, on which a thread for friction stirring is formed; and a drive unit rotatably supporting the rotating shaft. A rotating shoulder configured to rotate together with the rotating shaft to generate frictional heat between the rotating shoulder and back surfaces of workpieces is fixed to a distal end of the rotating shaft. The rotating shoulder is pushed against the back surfaces of the workpieces by a pushing mechanism. A stationary shoulder penetrated by the rotating shaft and configured to hold the workpieces in a sandwiching manner together with the rotating shoulder is non-rotatably mounted to the drive unit or a member connected to the drive unit.

Abstract: The friction stir welding apparatus includes a pin (20) on which a soft nitrided layer (50) is formed. The soft nitrided layer (50) is formed of an iron lithium oxide layer (51) and a nitrided diffusion layer (52). The atom of the iron lithium oxide layer (51) penetrates into a space between atoms at the surface of the pin (20) to form the nitrided diffusion layer (52).