Method to restore an airfoil leading edge

Abstract

The present invention provides methods and apparatus to restore a blade leading edge on a gas turbine engine component such as an airfoil of a turbine blisk. The method utilizes welding image technology and power control systems in order to provide effective welding with superalloy materials such as Inconel 713 and Inconel 625. The method includes machining away a damaged leading edge and providing a repaired region through successive depositions of superalloy powder filler through laser fusion welding. Deposition material is added until the repaired region exceeds the original dimensions of the airfoil. The airfoil is then machined and finished to return it to original airfoil dimensions.

1 . A method for resurfacing a leading edge of an airfoil comprising the steps of: 
 removing material from the leading edge of an airfoil;    preparing at least the airfoil leading edge for welding;    selecting a weld path using an image system;    determining welding parameters in order to avoid cracking; and    laser cladding filler material at least onto the airfoil leading edge, and along a selected weld path, using powder fusion welding of superalloy powder and the determined welding parameters.    
   
   
       2 . The method according to  claim 1  wherein the step of laser cladding filler material further comprises laser cladding filler material in a high stress region of the airfoil.  
   
   
       3 . The method according to  claim 1  wherein the substrate comprises Inconel 713.  
   
   
       4 . The method according to  claim 1  wherein the filler material comprises Inconel 625.  
   
   
       5 . The method according to  claim 1  wherein the laser cladding comprises laser cladding with a CO 2  laser.  
   
   
       6 . The method according to  claim 1  wherein the laser cladding step further comprises laser cladding with an energy between about 50 and about 2500 watts.  
   
   
       7 . The method according to  claim 1  wherein the laser cladding step further comprises laser cladding wherein the laser directs a beam on the workpiece with an area of between about 0.02 and about 0.100 square inches.  
   
   
       8 . The method according to  claim 1  wherein the laser cladding step further comprises laser cladding wherein the laser traverses the workpiece surface at a rate of between about 3 and about 22 inches per minute.  
   
   
       9 . The method according to  claim 1  wherein the laser cladding step deposits filler material in a series of deposition steps.  
   
   
       10 . The method according to  claim 1  wherein the laser cladding step follows a single pass.  
   
   
       11 . The method according to  claim 1  wherein the laser cladding step follows a stitching pattern.  
   
   
       12 . A method for resurfacing a damaged leading edge of a turbine blisk airfoil comprising the steps of: 
 machining material away from the damaged leading edge to a selected height and depth whereby a machined area is formed;    inspecting the machined area by fluorescent penetrating inspection;    preparing at least the machined area for welding;    determining a weld path with a laser image system on the machined area;    performing a laser fusion welding of at least the machined area with a superalloy powder filler and a CO 2  laser; and    automatically controlling material deposition, energy, and laser travel velocities during the laser fusion welding to minimize heat cracking in the airfoil.    
   
   
       13 . The method according to  claim 12  wherein the step of performing a laser fusion welding further comprises performing a laser fusion welding across a high stress region of an airfoil.  
   
   
       14 . The method according to  claim 12  further comprising measuring the depth of the deposition and repeating a laser fusion welding until a desired thickness is achieved.  
   
   
       15 . The method according to  claim 12  wherein the superalloy powder filler comprises Inconel  625  superalloy powder.  
   
   
       16 . The method according to  claim 12  wherein the step of machining material further comprises machining material to a selected height and depth so as to remove damaged portions of the leading edge.  
   
   
       17 . The method according to  claim 12  wherein the step of inspecting the airfoil further comprises inspecting in order to confirm the absence of cracks that would disqualify the airfoil from repair.  
   
   
       18 . The method according to  claim 12  further comprising the step of machining a repaired airfoil to a desired contour.  
   
   
       19 . The method according to  claim 18  further comprising a rough machining.  
   
   
       20 . The method according to  claim 18  further comprising a final machining by hand blending.  
   
   
       21 . The method according to  claim 12  wherein the step of performing a laser fusion welding further comprises laser fusion welding with a co-axial powder feeder.  
   
   
       22 . A resurfaced airfoil comprising: 
 an airfoil integrally connected to a blisk, the airfoil including at least a leading edge, a trailing edge, a top edge, a substrate region, and a repaired region; 
 wherein the repaired region: 
 is welded by powder fusion repair to the substrate region, and extends from a welding surface to the airfoil leading edge and from the welding surface to the airfoil top edge.  
 
   
   
   
       23 . The resurfaced airfoil according to  claim 22  wherein the repaired region is formed by overlapping laser cladding depositions of powdered alloy.  
   
   
       24 . The resurfaced airfoil according to  claim 22  wherein the repaired region crosses a high stress region of the airfoil.  
   
   
       25 . The resurfaced airfoil according to  claim 22  wherein said repaired region further comprises a superalloy.  
   
   
       26 . The resurfaced airfoil according to  claim 25  wherein said repaired region further comprises Inconel 625.  
   
   
       27 . The resurfaced airfoil according to  claim 22  wherein said substrate region further comprises a superalloy.  
   
   
       28 . The resurfaced airfoil according to  claim 27  wherein said substrate region further comprises Inconel 713.  
   
   
       29 . The resurfaced airfoil according to  claim 22  wherein the substrate region further comprises a weld surface at which the repaired region is welded to the substrate region.  
   
   
       30 . The resurfaced airfoil according to  claim 29  wherein the weld surface is arcuate in shape.  
   
   
       31 . The resurfaced airfoil according to  claim 22  wherein the repaired region extends beyond the leading edge.  
   
   
       32 . The resurfaced airfoil according to  claim 22  wherein said repaired region and said substrate region further comprise a turbine blisk airfoil.