Abstract:
Applying material along parallel welding lines per welding layer, and by changing direction of extension of the welding tracks by 90° for the next welding layer, provided.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims priority to PCT Application No. PCT/EP2015/072697, having a filing date of Oct. 1, 2015, based off of European application No. DE 102014220483.6 having a filing date of Oct. 9, 2014, the entire contents of which are hereby incorporated by reference. 
     
    
     FIELD OF TECHNOLOGY 
       [0002]    The following relates to a build-up strategy during deposition welding of a crown base of a turbine blade and to the thereby produced turbine blade with a feathered edge on the crown base. 
       BACKGROUND 
       [0003]    In particular, the tips of a turbine blade suffer more severe wear and are repaired for re-use, wherein material has to be deposited again in order to restore the original geometry, the so-called feathered edge which constitutes an encompassing wall along the outer contour of the blade airfoil. 
         [0004]    Deposition welding methods such as laser deposition welding methods are the prior art. 
         [0005]    The restored turbine blade in the region of the crown base has to be free of defects and pores, is to have small macrograins, the welding material is to be applied to the blade airfoil with an allowance, and is also to be produced inexpensively. 
         [0006]    In this case, in addition to the laser parameters such as heating, laser power, powder mass flow and feed speed, the corresponding travel strategy of the welding head also plays a role. 
       SUMMARY 
       [0007]    An aspect relates to proposing a build-up strategy by means of which the above-mentioned requirements can be fulfilled. 
         [0008]    T 
     
    
     
       BRIEF DESCRIPTION 
         [0009]    Some of the embodiments will be described in detail, with reference to the following figures, wherein like designations denote like members, wherein: 
           [0010]      FIG. 1  shows a top view of a surface of a turbine blade on which material is deposited, in accordance with embodiments of the present invention; 
           [0011]      FIG. 2  shows a cross section through an intended geometry of a blade tip, in accordance with embodiments of the present invention; 
           [0012]      FIG. 3  shows a procedure of the build-up strategy, in accordance with embodiments of the present invention; 
           [0013]      FIG. 4  shows a turbine blade, in accordance with embodiments of the present invention; and 
           [0014]      FIG. 5  shows a list of superalloys, in accordance with embodiments of the present invention. 
       
    
    
       [0015]    The description and figures represent only exemplary embodiments of the invention. 
       DETAILED DESCRIPTION 
       [0016]    Shown in  FIG. 1  is a top view of a surface  4 , especially of a blade tip  415  ( FIG. 4 ) of a turbine blade  120 ,  130 , or generally as a component  1 . 
         [0017]    The surface  4 ,  415  is preferably planar. 
         [0018]    The longitudinal, curved shape or the typical geometry of a blade airfoil  406  ( FIG. 4 ) is to be seen in cross section. In order to achieve an intended geometry in cross section as in  FIG. 2 , material is to be deposited upon the surface  4 ,  415  which in particular represents a correspondingly reconditioned surface of an already used turbine blade  120 ,  130 . 
         [0019]    The blade airfoil of the turbine blade  120 ,  130  has an outer contour  7 . 
         [0020]    In the first step, an outer encompassing welding track  10  is preferably laid along the contour  7  before first welding tracks for weld layers are applied. 
         [0021]    If the encompassing wall  13  is deposition welded, an inner encompassing welding track  11  is preferably similarly laid along an inner contour  8 , which is to be generated, before first welding tracks are applied for weld layers between the contours  7  and  8 . 
         [0022]    Shown in  FIG. 2  is a cross section through an intended geometry of a crown base  4  with an encompassing wall  13 , especially a feathered edge of a turbine blade, and a cavity  6 . Material has been deposited onto the surface  4 ,  415  so that a wall  13  has been formed along the contour  7  so that a top-open cavity  6  is created with the inner contour  8 . 
         [0023]    It may be preferably necessary to also completely coat or to generate the surface  4 ,  415  in first steps in a multiplicity of weld layers before an encompassing wall  13  is welded. An inner encompassing welding track  11  is preferably not then first of all implemented. 
         [0024]    The wall  13  is at least two welding track widths wide. 
         [0025]    In the middle of the surface  4 ,  415 , a top-open cavity  6  is formed with the inner surface  5 . 
         [0026]      FIG. 3  shows first steps for large-area build-up of material, especially for an encompassing wall  13 . 
         [0027]    The welding tracks  26  ( 26 ′,  26 ″, . . . ),  29  ( 29 ′,  29 ″ . . . ) are laid parallel to a longitudinal line  20 . 
         [0028]    The longitudinal line  20  is preferably oriented toward the longitudinal direction of the surface  4 ,  415 . The longitudinal line  20  can especially extend through an end  40  of the surface  4 ,  415  and constitutes there the almost longest, rectilinear progression on the surface  4 ,  415 . 
         [0029]    The weld beads  26 ,  29  start preferably at one end, especially  26 ′ of the surface  4 ,  415 , and extend in a straight line. If the welding track leaves the outer contour  7 , then the deposition process is shifted to the next welding track which is displaced by a defined distance. 
         [0030]    In the regions in which the cavity  6  exists no material is deposited so that the longitudinal line  20  or parallels to it only represent the progression of the relative movement between substrate  120  and welding head (not shown). 
         [0031]    In the first weld layer, the surface  4 ,  415 , which is to be coated with material, is created completely with parallel extending welding tracks  26 ,  29 . The welding tracks are shifted, preferably continuously, from one side, in this case  26 ′, to the other side, in this case  29 ′. 
         [0032]    In a second step, a second weld layer of welding tracks, which are laid parallel to a transverse line  23  ( 33 ′,  33 ″. . . ), is created. The transverse line  23  extends transversely to the longitudinal line  20 , especially at an angle of 70° to 110°, rather especially 80° to 110°, to a longitudinal line  20 . 
         [0033]    The transverse line  23  preferably extends perpendicularly to the longitudinal line  20 . 
         [0034]    The second weld layer covers the first weld layer. 
         [0035]    In this case also, the lines  33 ′,  33 ″, . . . only represent the relative movement between the blade tip and the welding head, i.e. when the inner surface  5  is created, no material is deposited there by the material feed in the region being stopped. 
         [0036]    The second weld layer preferably begins at one end  40  of the surface  4 ,  415  and is then subsequently coated by means of welding tracks which are directly adjacent to each other or preferably overlap. 
         [0037]    The sequence can also be reversed: 
         [0038]    The welding tracks  33  ( 33 ′,  33 ″, . . . ) are laid parallel to a transverse line  23 . The transverse line  23  is preferably oriented transversely to the longitudinal direction  20  of the surface  4 ,  415 . 
         [0039]    The weld beads  33 ′,  33 ″ preferably start at one end, e.g.  40 , of the surface  4 ,  415  and extend in a straight line. If the welding track leaves the outer contour  7 , then the deposition process is shifted to the next welding track which is displaced by a defined distance. 
         [0040]    In the regions in which the cavity  6  exists, no material is deposited so that the transverse line  23  or parallels to it only represent(s) the progress of the relative movement between substrate  120  and welding head (not shown). 
         [0041]    In the first weld layer, the surface  4 ,  415  which is to be coated with material is created completely with parallel extending welding tracks  33 . The welding tracks are shifted, preferably continuously, from one side, in this case  40 ,  412 , to the other side, in this case  409  ( FIG. 4 ). 
         [0042]    In a second step, a second weld layer of welding tracks, which are laid parallel to a longitudinal line  20  ( 26 ,  29 ), is created, wherein the longitudinal line  20  extends transversely to the transverse line  23 , especially at an angle of 70° to 110°, rather especially 80° to 110°, to the transverse line  23 . 
         [0043]    The longitudinal line  20  preferably extends perpendicularly to the transverse line  23 . 
         [0044]    The second weld layer covers the first weld layer. 
         [0045]    In this case also, the lines  26 ,  29 , . . . only represent the relative movement between the blade tip and the welding head, i.e. when the inner surface  5  is created, no material is deposited there by the material feed in the region being stopped. 
         [0046]    The second weld layer preferably begins on one side of the surface  4 ,  415  and is then subsequently coated by means of welding tracks which are directly adjacent to each other or preferably overlap. 
         [0047]    The desired height of the wall  13  is achieved by the procedure according to  FIG. 3  being repeated until the desired height of the wall  13  is achieved. 
         [0048]    The turbine blade  120 ,  130  features a nickel-based or cobalt-base superalloy, especially an alloy according to  FIG. 5 . 
         [0049]    The welding material also constitutes a nickel-based or cobalt-based alloy and preferably differs from the material of the component  1 ,  120 ,  130 . The difference means that at least one alloy element has a 10% higher or lower proportion of this alloy element. 
         [0050]    Although the present invention has been disclosed in the form of preferred embodiments and variations thereon, it will be understood that numerous additional modifications and variations could be made thereto without departing from the scope of the invention. 
         [0051]    For the sake of clarity, it is to be understood that the use of “a” or “an” throughout this application does not exclude a plurality, and “comprising” does not exclude other steps or elements.