Turbine components formed of titanium alloys

Abstract

A turbine component comprised of a titanium alloy that has been modified from Ti-64 is provided. The modification preserves the desired properties of Ti-64 (e.g., relatively isotropic properties, a relatively low density, tolerance to FOD, repairability, and low cost) while improving the thick section strength, HCF capability, creep strength, and low deformation following FOD to approach those beneficial aspects of Ti-17 and Ti-6246. Methods of forming such turbine components are also provided.

We claim: 
     
         1 . A turbine component comprising a titanium alloy, wherein the titanium alloy comprises:
 5.50 wt % to 6.90 wt % aluminum;   3.50 wt % to 4.50 wt % vanadium;   0.01 wt % to 0.03 wt % carbon;   0.20 wt % to 0.70 wt % iron;   1.00 wt % to 1.50 wt % molybdenum;   0.10 wt % to 0.30 wt % silicon;   up to 0.21 wt % oxygen;   up to 0.016 wt % nitrogen; and   a balance of titanium,   wherein the Al, O, Fe, Si, Mo are present in amounts that result in a predicted °C 0.2% yield strength≥1000 MPa according to the formula: 469.3+48.8*Al (wt %)+748*O (wt %)+96.1*Fe (wt %)+188*Si (wt %)+57.7*Mo (wt %), or wherein the Fe, Si, Mo are present in amounts that result in a predicted 23°C. % plastic elongation≥15.0% according to the formula: 10{circumflex over ( )}1.149+0.211*Fe (wt %) - 0.514*Si (wt %)+0.076*Mo (wt %)).   
     
     
         2 . The turbine component as in  claim 1 , wherein the titanium alloy is substantially free from copper. 
     
     
         3 . The turbine component as in  claim 1 , wherein the titanium alloy has a 0.2% yield strength of 1000 MPa to 1380 MPa, and wherein the titanium alloy has a plastic elongation of 15.0% to 30.0%. 
     
     
         4 . The turbine component as in  claim 1 , wherein the titanium alloy has an ultimate tensile strength of 1060 MPa or greater. 
     
     
         5 . The turbine component as in  claim 1 , wherein the titanium alloy has an ultimate tensile strength of 1060 MPa to 1450 MPa. 
     
     
         6 . The turbine component as in  claim 1 , wherein the titanium alloy has a ballistic impact resistance measured by a crack length of 3.048 mm or less. 
     
     
         7 . The turbine component as in  claim 1 , wherein the turbine component has a reduction in area that is 45% RA or greater. 
     
     
         8 . The turbine component as in  claim 1 , wherein the turbine component has a reduction in area that is 45% RA to 75% RA. 
     
     
         9 . The turbine component as in  claim 1 , wherein the titanium alloy has a 0.2% yield strength of 1000 MPa to 1380 MPa, an ultimate tensile strength of 1060 MPa to 1450 MPa, a ductility of 15.0% to 30.0%, and a reduction in area that is 45 % RA to 75% RA. 
     
     
         10 . The turbine component as in  claim 1 , wherein the titanium alloy is substantially free from chromium, tin, nickel, zirconium, and tungsten. 
     
     
         11 . The turbine component as in  claim 1 , wherein the titanium alloy is substantially free from any other elements. 
     
     
         12 . The turbine component as in  claim 1 , wherein the Al, O, Fe, Si, Mo are present in amounts that result in a predicted 23°C. 0.2% yield strength≥1000 MPa according to the formula: 469.3+48.8*Al (wt %)+748*O (wt %)+96.1*Fe (wt %)+188*Si (wt %)+57.7*Mo (wt %), and wherein the Fe, Si, Mo are present in amounts that result in a predicted 23°C. % plastic elongation≥15.0% according to the formula: 10{circumflex over ( )}1.149+0.211*Fe (wt %)−0.514*Si (wt %)+0.076*Mo (wt %)). 
     
     
         13 . The turbine component as in  claim 1 , wherein the titanium alloy comprises 3.80 wt % to 4.43 wt % vanadium. 
     
     
         14 . The turbine component as in  claim 1 , wherein the titanium alloy comprises 0.45 wt % to 0.57 wt % iron. 
     
     
         15 . The turbine component as in  claim 1 , wherein the titanium alloy comprises 0.14 wt % to 0.28 wt % silicon. 
     
     
         16 . The turbine component as in  claim 1 , wherein the titanium alloy consists of:
 5.50 wt % to 6.90 wt % aluminum;   3.50 wt % to 4.50 wt % vanadium;   0.01 wt % to 0.03 wt % carbon;   0.20 wt % to 0.70 wt % iron;   1.00 wt % to 1.50 wt % molybdenum;   0.10 wt % to 0.30 wt % silicon;   up to 0.21 wt % oxygen;   up to 0.016 wt % nitrogen; and   a balance of titanium.   
     
     
         17 . A method of forming a turbine component, the method comprising:
 forging the titanium alloy of  claim 1  into the turbine component.   
     
     
         18 . The method as in  claim 17 , wherein forging the titanium alloy into the turbine component comprises:
 forging the titanium alloy at a forging temperature that is below a beta transus temperature of the titanium alloy.   
     
     
         19 . The method as in  claim 18 , wherein the method comprises:
 heat treating the titanium alloy.   
     
     
         20 . The method as in  claim 18 , wherein the method comprises:
 solution heat treating the titanium alloy at a heat treatment temperature that is below a beta transus temperature of the titanium alloy.