Abstract: In a heat exchanger plate freedom of design of the flow channel is improved. A flat main body on a surface of which is formed at least one first groove having a rectangular cross-sectional shape, and a second groove having a rectangular cross-sectional shape that is narrower than the first groove, and that is formed following along opposite side faces of the first groove at a center of a bottom face of the first groove; and a flat cover which covers an entire surface of the main body, and on a rear face of which is formed a protrusion whose top face contacts a bottom face of the first groove and whose opposite side faces contact opposite side faces of the first groove, when the cover is superposed on the surface of the main body, and which forms a flow channel by means of a top face thereof and the second groove, are joined by friction stir welding.

Abstract: In a heat exchanger plate, machine time required for processing can be shortened, production costs can be reduced, and a penetration bead of a weld can be prevented from intruding into a flow channel, thereby preventing the weld from deforming a cover section. The heat exchanger plate comprises: a flat main body on a surface of which is formed at least one first groove having a rectangular cross-sectional shape; and a cover which has substantially the same shape as the first groove in plan view and which is formed such that when embedded in the first groove, a rear face thereof contacts a bottom of the first groove and opposite side faces thereof contact opposite side faces of the first groove, and a surface thereof is substantially flush with that of the main body, wherein there is provided a second groove formed extending along the opposite side faces at a center of the rear face, and the cover is joined to the main body by friction stir welding.

Abstract: A friction stir welding (FSW) method and apparatus are provided by which power needed for FSW is reduced and a compact FSW tool can be used. In the FSW method, metal members are lapped one on another and a rotating probe of an FSW tool is inserted into a contact portion of the metal members. The contact portion is softened by frictional heat and stirred by the probe so that the metal members are welded together. A portion of the metal members surrounding the probe is heated by a heater.

Abstract: Friction stir welding (FSW) method and apparatus are provided by which power needed for the FSW is reduced and a compact FSW tool can be used. In the FSW method comprising the steps of lapping metal members one on another and inserting a rotating probe of a FSW tool into a contact portion of the metal members making contact with the probe so that the contact portion is softened by frictional heat and stirred by the probe and the metal members are welded together, a portion of the metal members surrounding the probe is heated by a heating means.