Method of soldering a compressor nozzle ring of a gas turbine

Abstract

Titanium-based metal parts ( 1, 3 ) are soldered by using as a filler metal ( 7 ) an aluminium alloy containing magnesium and virtually no silicon. Application to the bonding of blades ( 3 ) to the inner shroud ( 1 ) of an aeronautical gas turbine engine compressor nozzle ring.

1 . Method of bonding titanium-based metal parts ( 1 ,  3 ), characterised in that it comprises soldering under a gas pressure of less than 1.10 −2  Pa using as a filler metal an aluminium alloy containing magnesium and virtually no silicon.  
   
   
       2 . Method according to  claim 1 , wherein the aluminium alloy contains 0.5 to 8% magnesium by mass.  
   
   
       3 . Method according to  claim 2 , wherein the aluminium alloy contains about 5% magnesium by mass.  
   
   
       4 . Method according to one of the preceding claims, wherein the aluminium alloy contains no more than 0.3% silicon by mass.  
   
   
       5 . Method according to one of the preceding claims, wherein the metal parts ( 1 ,  3 ) consist of a titanium-based alloy containing 5.5 to 6.75% aluminium and 3.5 to 4.5% vanadium by mass.  
   
   
       6 . Method according to one of the preceding claims, wherein the maximum temperature reached by the parts to be soldered ( 1 ,  3 ) during soldering is between about 660 and 670° C.  
   
   
       7 . Method according to  claim 6 , wherein the duration of exposure of the parts to be soldered ( 1 ,  3 ) to temperatures of between about 660 and 670° C. is about 10 min.  
   
   
       8 . Method according to one of the preceding claims, wherein the filler metal penetrates into an assembly gap or clearance ( 9 ) between the parts to be soldered ( 1 ,  3 ), the gap having a width of less than 0.8 mm.  
   
   
       9 . Method according to one of the preceding claims, wherein the filler metal penetrates into a gap ( 9 ) between the parts to be soldered ( 1 ,  3 ), the gap having a width at least equal to 0.05 mm.  
   
   
       10 . Method according to either of claims  8  or  9 , wherein the quantity of filler metal used is between 1.5 and 2 times the volume of the gap.  
   
   
       11 . Method according to one of the preceding claims, wherein the aluminium alloy is applied in the form of a wire ( 8 ).  
   
   
       12 . Method according to  claim 11 , wherein the wire ( 8 ) has a diameter of about 0.5 to 2.5 mm.  
   
   
       13 . Method according to one of the preceding claims, wherein the metal parts are an inner shroud ( 1 ) and a plurality of blades ( 3 ) of a gas turbine compressor nozzle ring, the blades being distributed in the circumferential direction and extending radially from the inner shroud to an outer shroud ( 2 ), each blade passing through a corresponding aperture ( 4 ) formed in the inner shroud ( 1 ).  
   
   
       14 . Method according to  claim 13 , wherein end regions ( 5 ) of the blades ( 3 ) project radially inwards beyond the inner shroud ( 1 ).  
   
   
       15 . Method according to either of claims  13  or  14 , in combination with  claim 11 , wherein the wire ( 8 ) is placed in contact with the inner face ( 6 ) of the inner shroud ( 1 ) and along the profile of the blades ( 3 ).  
   
   
       16 . Gas turbine compressor nozzle ring comprising a titanium-based inner shroud ( 1 ), an outer shroud ( 2 ) and a plurality of titanium-based blades ( 3 ) distributed in the circumferential direction and extending radially from the inner shroud to the outer shroud, each blade passing through a corresponding aperture ( 4 ) formed in the inner shroud, characterised in that the blades are fixed to the inner shroud by an aluminium-based solder ( 7 ) containing magnesium and virtually no silicon, formed by the method according to one of  claims 1  to  15 .