Abstract: A metal material processing method includes arranging two metal materials to face each other in a processing portion and inserting a distal end of a rod-shaped rotary tool into the processing portion while rotating the rotary tool, the two metal materials are processed. The distal end of the rotary tool has a probe protruding in a central portion and a shoulder in a peripheral portion, and the probe and the shoulder are constituted by different materials in at least surface portions that are in contact with the metal materials.

Abstract: In a metal material processing method, two metal materials are arranged to face each other in a processing portion, and a distal end of a rod-shaped rotary tool is inserted into the processing portion while rotating the rotary tool, thereby the two metal materials are processed. The distal end of the rotary tool has a probe protruding in a central portion and a shoulder in a peripheral portion. The probe and the shoulder are constituted by different materials in at least surface portions that are in contact with the metal materials.

Abstract: A method of connecting metal materials to each other, wherein a pin fitted to the tip of a metal bar-like rotating tool (10) is inserted between the end pan of a metal member (I) and the end part of a metal member (1?), and moved, while rotating, along the longitudinal direction of these end parts. By this frictional heat is generated between the metal members (1) and (1?) and the rotating tool (10), and the metal member (1) is connected to the metal member (1?). The rotating tool (10) is formed of a wide shoulder (12) and a thin pin (11) formed at the tip thereof and inserted between the end parts of the metal members. The pin (11) is a right circular cylindrical pin. The side face of the pin (11) is formed in a smooth curved surface, and a thread groove is not formed therein.

Abstract: A pin formed at front end of a rotary tool 10 made of a metal in a rod shape is inserted between an edge of a metallic member 1 and an edge of a metallic member 1?, which inserted pin is moved along the longitudinal direction of the edges while rotating the pin, thereby generating friction heat between each of the metallic members 1 and 1? and the rotary tool 10 to weld the metallic member 1 with the metallic member 1? together. The rotary tool 10 is structured by a wide shoulder 12 and a thin pin 11 formed at the front end of the shoulder 12 and being inserted between the edges of the metallic members. Here, the pin 11 is in a right-cylindrical shape, being formed into smooth curved surface on the side thereof, and having no thread groove thereon.