METHOD FOR FABRICATING A THICK Ti64 ALLOY ARTICLE TO HAVE A HIGHER SURFACE YIELD AND TENSILE STRENGTHS AND A LOWER CENTERLINE YIELD AND TENSILE STRENGTHS

Abstract

A Ti-6Al-4V-0.2O (Ti64) forged article is fabricated by forging a workpiece to make a forged gas turbine engine component having a thick portion thereof with a section thickness greater than 2¼ inches. The forged article is heat treated by solution heat treating at a temperature of from about 50° F. to about 85° F. below the beta-transus temperature of the alloy, thereafter water quenching the gas turbine engine component to room temperature, and thereafter aging the gas turbine engine component at a temperature of from about 900° F. to about 1350° F.

1 . A method for fabricating a forged titanium-alloy article, comprising the steps of
 providing a workpiece made of an alpha-beta titanium alloy having a nominal composition in weight percent of 6 percent aluminum, 4 percent vanadium, 0.2 percent oxygen, balance titanium and impurities, wherein the titanium alloy has a beta-transus temperature; thereafter   forging the workpiece at a temperature below the beta-transus temperature to make an alpha-beta forged gas turbine engine component, wherein the forged gas turbine engine component has a thick portion thereof with a section thickness greater than 2¼ inches; thereafter   rough machining the forged gas turbine engine component; thereafter   heat treating the machined forged gas turbine engine component by the steps consisting essentially of
 solution heat treating the machined forged gas turbine engine component at a temperature of from about 50° F. to about 85° F. below the beta-transus temperature, thereafter 
 water quenching the gas turbine engine component to room temperature, and thereafter 
 aging the gas turbine engine component at a temperature of from about 900° F. to about 1350° F.; and thereafter 
   final machining the forged gas turbine engine component.   
   
   
       2 . The method of  claim 1 , wherein the step of providing the workpiece includes the steps of
 preparing a melt of the titanium alloy, thereafter   casting the melt of the titanium alloy to form an ingot, thereafter   converting the ingot to a billet by hot working, and thereafter   cutting the billet transversely to form a mult that serves as the workpiece.   
   
   
       3 . The method of  claim 1 , wherein the step of forging the workpiece includes the step of forging the workpiece to make the forged gas turbine engine component selected from the group consisting of a compressor disk, a fan disk, and a gas turbine engine mount. 
   
   
       4 . The method of  claim 1 , wherein the step of forging the workpiece includes the step of forging the workpiece to make a forged compressor disk or a forged fan disk. 
   
   
       5 . The method of  claim 1 , wherein the step of aging comprises aging the gas turbine engine component at a temperature of about 1300° F. 
   
   
       6 . The method of  claim 1 , wherein the step of solution heat treating includes the step of solution heat treating the machined forged gas turbine engine component at a temperature of from about 55° F. to about 85° F. below the beta-transus temperature 
   
   
       7 . The method of  claim 1 , wherein the step of forging includes the step of forging at a temperature within about 60° F. of the beta transus temperature. 
   
   
       8 . The method of  claim 1 , wherein the step of solution heat treating includes the step of solution heat treating the forged gas turbine engine component for a time of from about 45 minutes to about 75 minutes. 
   
   
       9 . The method of  claim 1 , wherein the step of water quenching is initiated within about 20 seconds of completing the step of solution heat treating. 
   
   
       10 . The method of  claim 1 , wherein the step of aging includes the step of aging the forged gas turbine engine component for a time of at least about 4 hours. 
   
   
       11 . The method of  claim 1 , including an additional step, after the step of forging the workpiece and before the step of heat treating, of ultrasonically inspecting the forged gas turbine engine component. 
   
   
       12 . The method of  claim 1 , including an additional step, after the step of forging the workpiece and before the step of final machining, of ultrasonically inspecting the forged gas turbine engine component. 
   
   
       13 . A method for fabricating a forged titanium-alloy article comprising the steps of
 providing a workpiece made of an alpha-beta titanium alloy having a nominal composition in weight percent of 6 percent aluminum, 4 percent vanadium, 0.2 percent oxygen, balance titanium and impurities, wherein the titanium alloy has a beta-transus temperature; thereafter   forging the workpiece at a temperature within about 60° F. of the beta transus temperature to make an alpha-beta forged gas turbine engine component, wherein the forged gas turbine engine component has a thick portion thereof with a section thickness greater than 2¼ inches; thereafter   rough machining the forged gas turbine engine component; thereafter   heat treating the machined forged gas turbine engine component by the steps consisting essentially of
 solution heat treating the machined forged gas turbine engine component at a temperature of from about 55° F. to about 85° F. below the beta-transus temperature, thereafter 
 water quenching the gas turbine engine component to room temperature, and thereafter 
 aging the gas turbine engine component at a temperature of about 1300° F.; and thereafter 
   final machining the gas turbine engine component.   
   
   
       14 . The method of  claim 13 , wherein the step of providing the workpiece includes the steps of
 preparing a melt of the titanium alloy, thereafter   casting the melt of the titanium alloy to form an ingot, thereafter   converting the ingot to a billet by hot working, and thereafter   cutting the billet transversely to form a mult that serves as the workpiece.   
   
   
       15 . The method of  claim 13 , wherein the step of forging the workpiece includes the step of forging the workpiece to make the forged gas turbine engine component selected from the group consisting of a compressor disk, a fan disk, and a gas turbine engine mount. 
   
   
       16 . The method of  claim 13 , wherein the step of forging the workpiece includes the step of forging the workpiece to make a forged compressor disk or a forged fan disk. 
   
   
       17 . The method of  claim 13 , wherein the step of solution heat treating includes the step of solution heat treating the forged gas turbine engine component for a time of from about 45 minutes to about 75 minutes. 
   
   
       18 . The method of  claim 13 , wherein the step of water quenching is initiated within about 20 seconds of completing the step of solution heat treating. 
   
   
       19 . The method of  claim 13 , wherein the step of aging includes the step of aging the forged gas turbine engine component for a time of at least about 4 hours. 
   
   
       20 . The method of  claim 13 , wherein the step of final machining includes the step of removing alpha-case at a surface of the gas turbine engine component.