Friction stir extrusion of nonweldable materials for downhole tools

1. A downhole tool comprising:

a body having an outer surface; and

a friction stir welded assembly including:

a non-weldable workpiece having a wear surface and a connection surface on opposing sides of the non-weldable workpiece,

recesses located in the connection surface extending into the non-weldable workpiece, the recesses each having a first width proximate the connection surface and a second width within the non-weldable workpiece, wherein the first width is smaller than the second width,

a weldable workpiece having a welding surface and an extrusion surface on opposing sides of the weldable workpiece, wherein at least a portion of the extrusion surface is extruded at least partially into at least one of the recesses to connect the weldable workpiece to the non-weldable workpiece,

a friction stir weld between at least a portion of the welding surface of the weldable workpiece and the outer surface of the body that fixes the weldable workpiece and non-weldable workpiece connected thereto to the outer surface of the body,

wherein the recesses include a pair of elongate recesses each having a length; and

wherein the elongate recesses intersect and the lengths of the elongate recesses extend at a recess angle relative to one another.

2. The downhole tool of claim 1 , wherein the non-weldable workpiece comprises a carbide.

3. The downhole tool of claim 1 , wherein the recesses include a closed recess.

4. The downhole tool of claim 3 , wherein the closed recess is a rotationally symmetrical closed recess.

5. The downhole tool of claim 1 , wherein the outer surface of the body is curved.

6. The downhole tool of claim 1 , wherein the body is cylindrical and has a body longitudinal axis, the friction stir welded assembly having an assembly centerline transverse to the body longitudinal axis.

7. The downhole tool of claim 1 , further comprising a plurality of friction stir welded assemblies.

8. The downhole tool of claim 1 , wherein the friction stir welded assembly further comprises a plurality of non-weldable workpieces.

9. The downhole tool of claim 1 , wherein the body is configured to connect to a downhole tool or tubular.

10. The downhole tool of claim 1 , wherein the body is a tubular.

11. The downhole tool of claim 1 , wherein the body includes a material selected from the group consisting of steel, titanium alloy, or nickel superalloy.

12. The downhole tool of claim 1 wherein the non-weldable workpiece has a hardness greater than 40 gigapascals when measured by the Vickers hardness test.

13. A method of affixing a non-weldable workpiece to a weldable workpiece and to an exterior of a downhole tool, the method comprising:

positioning a weldable workpiece adjacent a non-weldable workpiece, the non-weldable workpiece having recesses therein, the recesses each having a first width adjacent a surface of the non-weldable workpiece and a second width within the non-weldable workpiece, the first width being smaller than the second width;

applying a force to the weldable workpiece by friction stirring the weldable workpiece;

extruding at least a portion of the weldable workpiece into at least one of the recesses to connect the weldable workpiece and the non-weldable workpiece;

positioning the weldable workpiece adjacent an outer surface of a body of the downhole tool; and

friction stir welding a portion of the weldable workpiece and a portion of the outer surface of the downhole tool body to affix the weldable workpiece to the exterior of the downhole tool;

wherein the recesses include a pair of elongate recesses each having a length; and

wherein the elongate recesses intersect and the lengths of the elongate recesses extend at a recess angle relative to one another.

14. The method of claim 13 , wherein the at least one of the recesses is a dovetail.

15. The method of claim 13 , wherein the is recesses include a rotationally symmetrical dovetail.

16. The method of claim 13 , wherein the non-weldable workpiece has a curved surface.

17. The method of claim 13 , wherein the outer surface includes a material selected from the group consisting of steel, titanium alloy, or nickel superalloy.

18. The method of claim 13 , wherein the non-weldable workpiece is a carbide.

19. The method of claim 13 , wherein positioning the weldable workpiece further comprises orienting an assembly centerline at an angle with a body longitudinal axis.

20. A downhole tool apparatus comprising:

a downhole tool body having an outer surface;

a non-weldable workpiece having a wear surface and a connection surface on opposing sides of the non-weldable workpiece;

recesses located in the connection surface extending into the non-weldable workpiece, the recesses each having a first width proximate the connection surface and a second width within the non-weldable workpiece, the first width being smaller than the second width;

a weldable workpiece having a welding surface and an extrusion surface on opposing sides of the weldable workpiece, wherein at least a portion of the extrusion surface is extruded at least partially into at least one of the recesses to connect the weldable workpiece to the non-weldable workpiece; and

a friction stir weld between at least a portion of the welding surface of the weldable workpiece and the outer surface of the downhole tool body that fixes the weldable workpiece and the non-weldable workpiece connected thereto to the outer surface of the downhole tool body;

wherein the recesses include a pair of elongate recesses each having a length; and

wherein the elongate recesses intersect and the lengths of the elongate recesses extend at a recess angle relative to one another.