Deposition friction stir welding process and assembly

1. A friction stir weld process of joining work pieces using a rotary friction stir welding apparatus comprising a die having an aperture adapted to receive a cylindrical, shouldered rotary tool, said die further comprising a recessed portion defining an inlet zone adapted to accommodate a filler material, the process comprising the steps of:

placing a filler material on and about a joint line formed by butting a first work piece surface against a second work piece surface by inserting the filler material into the inlet zone of the die; and

frictionally heating the filler material by placing the die over the joint line to soften the filler material and portions of the first and second work piece surfaces in thermal contact with the filler material and form a weld between the first and second work pieces, wherein frictionally heating is at a temperature below a melting point of the filler material and the first and second workpiece surfaces.

2. The process of claim 1 , wherein the filler material comprises a bar, a pellet, or a powder.

3. The process of claim 1 , further comprising containing the softened filler material and portions of the first and second work piece surfaces.

4. The process of claim 1 , wherein frictionally heating the filler material spot welds the work pieces.

5. The process of claim 1 , wherein frictionally heating the filler material is carried out in a direction that traverses along the joint line.

6. The process of claim 1 , further comprising multiple passes of frictionally heating the filler material on and about the joint line to increase a cross sectional thickness of the weld.

7. The process of claim 1 , further comprising butting at least one additional work piece surface against the first and second workpiece surfaces to form the joint line.

8. A process for depositing material and contouring a surface of a work piece using a rotary friction stir welding apparatus comprising a die having an aperture adapted to receive a cylindrical, shouldered rotary tool, said die further comprising a recessed portion defining an inlet zone and an extrusion zone, the process comprising the steps of:

inserting a filler material into the inlet zone of the die;

frictionally heating the filler material and a selected surface of the work piece at a temperature below a melting point of the work piece, wherein the filler material and the selected surface softens to form a plasticized region; and

containing the filler material and the selected surface of the work piece with the extrusion zone of the die to contour the plasticized region and prevent flash material from being discharged during the frictional heating.

9. The process of claim 8 , wherein the process is robotically controlled.

10. The process of claim 8 , wherein frictionally heating the filler material and the selected surface of the work piece comprises adjusting for varying thicknesses of the work piece.

11. The process of claim 8 , wherein frictionally heating the filler material softens all of the filler material and the selected surface of the work piece.

12. The process of claim 8 , wherein frictionally heating the filler material and the selected surface repairs the selected surface of the work piece.

13. A spot friction weld process using a rotary friction stir welding apparatus comprising a die having an aperture adapted to receive a cylindrical, shouldered rotary tool, said die further comprising a recessed portion defining an inlet zone and an extrusion zone, the process comprising the steps of:

inserting a filler material into the inlet zone of the die;

frictionally heating a spot and the filler material on a work piece surface to a temperature effective to soften the filler material and a region at and about the spot, wherein the temperature is below a melting point of the work piece surface; and

containing the spot with the extrusion zone of the die to prevent discharge of a flash material from the work piece surface.

14. The spot friction weld process of claim 13 , wherein frictionally heating the spot comprises plunging the rotary tool onto the spot.

15. The spot friction weld process of claim 13 , wherein the spot subsequent to frictionally heating the spot and the filler material is free of a keyhole effect.