Repair of gas turbine blade tip without recoating the repaired blade tip

Abstract

A damaged gas turbine blade which has previously been in service, and which is made of a base metal, is furnished. Any damaged material is removed from the damaged blade tip. The damaged blade tip is weld repaired with a nickel-base superalloy that is more resistant to oxidation resistance than is the base metal in the operating environment of the tip-repaired gas turbine blade. The method does not include any step of coating a lateral surface of the repaired blade tip with a non-ceramic coating after the step of weld repairing.

1 . A repaired gas turbine blade comprising:
 a blade tip comprising a nickel-base superalloy repair alloy, the nickel-base superalloy repair alloy having a nominal composition, in weight percent, of from about 7.4 to about 7.8 percent chromium, from about 5.3 to about 5.6 percent tantalum, from about 2.9 to about 3.3 percent cobalt, from about 7.6 to about 8.0 percent aluminum, from about 0.12 to about 0.18 percent hafnium, from about 0.5 to about 0.6 percent silicon, from about 3.7 to about 4.0 percent tungsten, from about 1.5 to about 1.8 percent rhenium, from about 0.01 to about 0.03 percent carbon, from about 0.01 to about 0.02 percent boron, balance nickel.   
   
   
       2 . The repaired gas turbine blade of  claim 1 , further comprising a blade body, wherein the blade body does not comprise the nickel-base superalloy repair alloy. 
   
   
       3 . The repaired gas turbine blade of  claim 2 , wherein there is no non-ceramic coating on a lateral surface of the blade tip. 
   
   
       4 . The repaired gas turbine blade of  claim 3 , wherein the blade body comprises a base-metal superalloy, and wherein the nickel-base superalloy repair alloy is more resistant to oxidation than the base-metal superalloy. 
   
   
       5 . The repaired gas turbine blade of  claim 4 , wherein the blade body comprises a second lateral surface, the second lateral surface comprising a non-ceramic coating. 
   
   
       6 . The repaired gas turbine blade of  claim 1 , wherein the nickel-base superalloy repair alloy comprises manganese, and the nominal composition, in weight percent, of the nickel-base superalloy repair alloy comprises a maximum of 0.1 percent manganese. 
   
   
       7 . The repaired gas turbine blade of  claim 1 , wherein the nickel-base superalloy repair alloy comprises phosphorus, and the nominal composition, in weight percent, of the nickel-base superalloy repair alloy comprises a maximum of 0.01 percent phosphorus. 
   
   
       8 . The repaired gas turbine blade of  claim 1 , wherein the nickel-base superalloy repair alloy comprises sulfur, and the nominal composition, in weight percent, of the nickel-base superalloy repair alloy comprises a maximum of 0.004 percent sulfur. 
   
   
       9 . The repaired gas turbine blade of  claim 1 , wherein the nickel-base superalloy repair alloy comprises molybdenum, and the nominal composition, in weight percent, of the nickel-base superalloy repair alloy comprises a maximum of 0.10 percent molybdenum. 
   
   
       10 . The repaired gas turbine blade of  claim 1 , wherein the nickel-base superalloy repair alloy comprises titanium, and the nominal composition, in weight percent, of the nickel-base superalloy repair alloy comprises a maximum of 0.02 percent titanium. 
   
   
       11 . The repaired gas turbine blade of  claim 1 , wherein the nickel-base superalloy repair alloy comprises selenium, and the nominal composition, in weight percent, of the nickel-base superalloy repair alloy comprises a maximum of 0.005 percent selenium. 
   
   
       12 . The repaired gas turbine blade of  claim 1 , wherein the nickel-base superalloy repair alloy comprises platinum, and the nominal composition, in weight percent, of the nickel-base superalloy repair alloy comprises a maximum of 0.3 percent platinum. 
   
   
       13 . The repaired gas turbine blade of  claim 1 , wherein the nickel-base superalloy repair alloy comprises zirconium, and the nominal composition, in weight percent, of the nickel-base superalloy repair alloy comprises a maximum of 0.03 percent zirconium. 
   
   
       14 . The repaired gas turbine blade of  claim 1 , wherein the nickel-base superalloy repair alloy comprises niobium, and the nominal composition, in weight percent, of the nickel-base superalloy repair alloy comprises a maximum of 0.1 percent niobium. 
   
   
       15 . The repaired gas turbine blade of  claim 1 , wherein the nickel-base superalloy repair alloy comprises vanadium, and the nominal composition, in weight percent, of the nickel-base superalloy repair alloy comprises a maximum of 0.1 percent vanadium. 
   
   
       16 . The repaired gas turbine blade of  claim 1 , wherein the nickel-base superalloy repair alloy comprises copper, and the nominal composition, in weight percent, of the nickel-base superalloy repair alloy comprises a maximum of 0.1 percent copper. 
   
   
       17 . The repaired gas turbine blade of  claim 1 , wherein the nickel-base superalloy repair alloy comprises iron, and the nominal composition, in weight percent, of the nickel-base superalloy repair alloy comprises a maximum of 0.2 percent iron. 
   
   
       18 . The repaired gas turbine blade of  claim 1 , wherein the nickel-base superalloy repair alloy comprises magnesium, and the nominal composition, in weight percent, of the nickel-base superalloy repair alloy comprises a maximum of 0.0035 percent magnesium. 
   
   
       19 . The repaired gas turbine blade of  claim 1 , wherein the nickel-base superalloy repair alloy comprises oxygen and nitrogen, and the nominal composition, in weight percent, of the nickel-base superalloy repair alloy comprises a maximum of 0.01 percent oxygen and a maximum of 0.01 percent nitrogen. 
   
   
       20 . A repaired gas turbine blade comprising:
 a blade tip comprising a nickel-base superalloy repair alloy, the nickel-base superalloy repair alloy having a nominal composition, in weight percent, of 0.01-0.03 percent carbon, 0.1 percent maximum manganese, 0.5-0.6 percent silicon, 0.01 percent maximum phosphorus, 0.004 percent maximum sulfur, 7.4-7.8 percent chromium, 2.9-3.3 percent cobalt, 0.10 percent maximum molybdenum, 3.7-4.0 percent tungsten, 5.3-5.6 percent tantalum, 0.02 percent maximum titanium, 7.6-8.0 percent aluminum, 1.5-1.8 percent rhenium, 0.005 percent maximum selenium, 0.3 percent maximum platinum, 0.01-0.02 percent boron, 0.03 percent maximum zirconium, 0.12-0.18 percent hafnium, 0.1 percent maximum niobium, 0.1 percent maximum vanadium, 0.1 percent maximum copper, 0.2 percent maximum iron, 0.0035 percent maximum magnesium, 0.01 percent maximum oxygen, 0.01 percent maximum nitrogen, balance nickel, with other elements totaling 0.5 percent maximum.