The present invention provides a friction stir welding apparatus operable for welding one or more metals, metal alloys, or other materials, and a method for friction stir welding. The friction stir welding apparatus includes a pin tool holder, a shoulder having a surface coupled to the pin tool holder, and a pin tool coupled to the pin tool holder, the pin tool at least partially protruding from the surface of the shoulder, wherein the pin tool is made of a consumable pin tool material. The method includes introducing the pin tool into a workpiece; traversing the pin tool along a joint to be welded on the workpiece; and substantially continuously feeding the pin tool into the weld joint as it is traversed along the joint, thereby incorporating at least a portion of the consumable pin tool material into the volume of the joint to be welded.