High integrity welding and repair of metal components

Abstract

A method for welding and repairing cracks in metal parts is provided by subjecting the metal parts to be welded to friction stir welding and the cracks to be repaired to friction stir processing under conditions sufficient to provide a weld joint or crack repair having a preselected property or set of properties based upon the intended use of the weldment.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic illustration of the method of joining two tubular work pieces by FSW.

FIG. 2 is a diagram showing the use of a metallic shim in joining two pipes according to an embodiment of the present invention.

FIG. 3 is cross section micrograph (a) of FSW butt welded L80 steel plates (Run 1, Table 1) and diamond pyramid microhardness (DPH, 100 gram load) profile across this weldment (b).

Claims

1. A method for welding metal parts and repairing cracks in metal parts by subjecting the faying surfaces of the metal parts to be welded to FSW and the cracks to be repaired to FSP under conditions sufficient to provide a weld joint or crack repair having a preselected property or set of properties based on the intended use of the weldment.

2. The method of claim 1 wherein the preselected property or set of properties is selected from toughness, hardness, strength, fatigue, grain size, and residual stress.

3. The method of claim 2 wherein the conditions sufficient to provide the weld joint or crack repair are selected from at least one of the rotational speed, load and travel speed of the FSW tool used to affect the weld or repair.

4. The method of claim 3 wherein the condition sufficient to provide a weld joint having a preselected property or set of properties includes interposing a metal shim of preselected chemistry between the faying surfaces of the metal parts to be welded before subjecting them to FSW.

5. The method of claim 3 wherein the metal parts are ferrous metal parts of the same composition.

6. The method of claim 4 wherein the shim and metal parts are ferrous metal parts of the same composition.

7. The method of claim 3 wherein the ferrous metal has a CE equal to or greater than 0.48.

8. The method of claim 7 wherein the ferrous metal has a CE of about 0.94.

9. A method for welding two pieces of metal to produce a weld joint having a specific property or set of properties chosen for an intended application, the method comprising: obtaining a data base of weld properties for weld joints formed by FSW under a plurality of conditions and from various metal compositions;correlating the weld conditions and metal compositions to the weld properties;selecting weld conditions from the data base that will produce a weld joint having the property or set of properties best suited to the intended application;subjecting the work pieces to FSW under the conditions selected.

10. The method of claim 9 wherein the metal pieces are ferrous metals having a CE equal to or greater than 0.48.

11. The method of claim 10 wherein the FSW conditions include rotational speed, load and travel speed of the FSW tool used to effect the weld.