Friction stir welding tool

A friction stir welding tool comprising a probe having a front end surface and an outer circumferential surface, the outer circumferential surface including, formed therein, an outer circumferential recess extending to the front end surface, the friction stir welding tool being configured to rotate the probe about a rotation axis and embed the probe inside a workpiece during rotation of the probe to thereby weld the workpiece,

• wherein a front end recess is formed in the front end surface, and the front end recess extends to the outer circumferential surface in a manner that the front end recess does not communicate with the outer circumferential recess,
• wherein the front end recess comprises:
• a central recess provided at a center of the front end surface;
• a front end groove extending in a radially outward direction of the probe from the central recess to the outer circumferential surface, and
• the front end recess is edged.

A friction stir welding tool comprising a probe having a front end surface and an outer circumferential surface, the outer circumferential surface including, formed therein, an outer circumferential recess extending to the front end surface, the friction stir welding tool being configured to rotate the probe about a rotation axis and embed the probe inside a workpiece during rotation of the probe to thereby weld the workpiece,

• wherein a front end recess is formed in the front end surface, and the front end recess extends to the outer circumferential surface in a manner that the front end recess does not communicate with the outer circumferential recess,
• wherein the front end recess comprises a plurality of front end grooves formed in the front end surface in a manner to intersect with each other;
• the front end grooves extend straight in a manner that, as viewed from a front end of the probe, a central line of each of the front end grooves passes through a position shifted from a center of the front end surface of the probe;
• the front end surface includes a claw formed between the front end grooves that are adjacent to each other in a circumferential direction of the probe, and
• the front end recess is edged.