Method of repairing a metallic artifact
A method of repairing a metallic artefact ( 40 ) with an open defect in or on a metallic surface or substrate of the metallic artefact includes cold forging the open defect to close the open defect and thereafter laser cladding the cold forged defect with a plurality of laser clad beads ( 44 ) applied to the metallic surface or substrate to cover the cold forged defect with a cladded metal layer. Advantageously, in-situ repair of fluid-filled vessels, pipes or the like is made possible by the repair method, in some instances eliminates the need to shut equipment down thereby reducing downtime and the cost associated with lost production.
1. A method of repairing a metallic artifact with an open defect in or on a metallic surface or substrate of the metallic artifact, the method including
cold forging the open defect to close the open defect; and
laser cladding the cold forged defect with a plurality of laser clad beads applied to the metallic surface or substrate to cover the cold forged defect with a cladded metal layer.
2. The method as claimed in claim 1 , in which the metallic artifact is a steel or stainless steel artifact, and in which the metallic artifact is stationary and is repaired in situ without removing the metallic artifact from where it is located in use or without removing the metallic artifact from service.
3. The method as claimed in claim 1 , in which the metallic artifact is a 304L stainless steel water-filled vessel or a component of such a vessel with the open defect being a stress corrosion induced crack in a wall of the vessel or in said component of the vessel.
4. The method as claimed in claim 1 , in which the metallic artifact holds or carries a fluid behind the open defect during performance of the method, the fluid being at a pressure of more than 0.1 bar(g).
5. The method as claimed in claim 4 , in which the fluid is at a pressure of between 1 bar(g) and 3 bar(g).
6. The method as claimed in claim 4 , in which the laser cladding generates a melt pool, and in which the viscosity of the melt pool is made sufficiently high by limiting the size of the melt pool and by ensuring a sufficiently high solidification rate, to contain the fluid under pressure.
7. The method as claimed in claim 1 , in which cold forging of the open defect is in the form of, or includes hammer peening of the open defect.
8. The method as claimed in claim 7 , in which an air hammer with a rounded steel tip is used for the hammer peening.
9. The method as claimed in claim 1 , in which the laser clad beads are parallel and overlapping thereby to form the cladded metal layer.
10. The method as claimed in claim 1 , in which the chemical composition of the cladded metal is different from that of the metallic surface or substrate of the metallic artifact.
11. The method as claimed in claim 1 , in which the defect is elongate, and in which the clad beads are applied transverse to a longitudinal axis or direction of the elongate defect.
12. The method as claimed in claim 1 , in which the cladded metal layer covers the entire defect and extends beyond the limits of the defect, so that on all sides of the defect there is a zone where the cladded metal layer is between the defect and uncladded substrate.
13. The method as claimed in claim 1 , in which the cladded metal layer still shows an open defect after laser cladding, the method including cold forging the open defect in the cladded metal layer which is a first cladded metal layer, and applying a further cladded metal layer by means of laser cladding over at least part of the first cladded metal layer.
14. The method as claimed in claim 1 , in which laser clad beads are deposited at speeds that range between 0.3 m and 3 m per minute, with a bead overlay of 50% to 70%, to ensure that a continuous cladded metal layer is formed.