Beta titanium alloy

Abstract

A beta titanium alloy comprises 25 wt % vanadium, 15 wt % chromium, 2 wt % aluminium, up to 0.15 wt % oxygen, 0.1 to 0.3 wt % carbon and the balance titanium plus incidental impurities. The carbon is present in the form of titanium carbide precipitates distributed throughout the beta titanium alloy matrix, the titanium carbide precipitates refine the grain size of the beta titanium alloy matrix and remove oxygen from the beta titanium alloy matrix to reduce precipitation of alpha titanium in the beta titanium alloy matrix to increase the ductility of the beta titanium alloy. The alloy is useful for gas turbine engine compressor blades ( 10 ), compressor vanes, compressor casings etc.

We claim:  
     
         1 . A beta titanium alloy comprising 20 to 30 wt % vanadium, 13 to 17 wt % chromium, 1.0 to 3.0 wt % aluminium, 0.1 to 0.4 wt % carbon, up to 0.2 wt % oxygen and the balance titanium plus incidental impurities, wherein the carbon is present in the form of titanium carbide precipitates distributed throughout the beta titanium alloy matrix, the titanium carbide precipitates refine the grain size of the beta titanium alloy matrix and remove oxygen from the beta titanium alloy matrix to reduce precipitation of alpha titanium in the beta titanium alloy matrix to increase the ductility of the beta titanium alloy.  
     
     
         2 . A beta titanium alloy as claimed in  claim 1  wherein the beta titanium alloy comprises 1.5 to 2.5 wt % aluminium.  
     
     
         3 . A beta titanium alloy as claimed in  claim 1  wherein the beta titanium alloy comprises 0.15 to 0.3 wt % carbon.  
     
     
         4 . A beta titanium alloy as claimed in  claim 1  wherein the beta titanium alloy comprises less than 0.15 wt % oxygen.  
     
     
         5 . A beta titanium alloy as claimed in  claim 1  wherein the beta titanium alloy comprises 23-27 wt % vanadium, 13-17 wt % chromium, 1-3 wt % aluminium, up to 0.15 wt % oxygen, 0.1 to 0.3 wt % carbon and the balance titanium plus incidental impurities.  
     
     
         6 . A beta titanium alloy as claimed in  claim 1  wherein the beta titanium alloy comprises 25 wt % vanadium, 15 wt % chromium, 2 wt % aluminium, up to 0.15 wt % oxygen, 0.1 to 0.3 wt % carbon and he balance titanium plus incidental impurities.  
     
     
         7 . An article comprising a beta titanium alloy, the beta titanium alloy comprising 20 to 30 wt % vanadium, 13 to 17 wt % chromium, 1.0 to 3.0 wt % aluminium, 0.1 to 0.4 wt % carbon, up to 0.2 wt % oxygen and the balance titanium plus incidental impurities, wherein the carbon is present in the form of titanium carbide precipitates distributed throughout the beta titanium alloy matrix, the titanium carbide precipitates refine the grain size of the beta titanium alloy matrix and remove oxygen from the beta titanium alloy matrix to reduce precipitation of alpha titanium in the beta titanium alloy matrix to increase the ductility of the beta titanium alloy.  
     
     
         8 . An article as claimed in  claim 7  wherein the beta titanium alloy comprises 23-27 wt % vanadium, 13-17 wt % chromium, 1-3 wt % aluminium, up to 0.15 wt % oxygen, 0.1 to 0.3 wt % carbon and the balance titanium plus incidental impurities.  
     
     
         9 . An article as claimed in  claim 8  wherein the beta titanium alloy comprises 25 wt % vanadium, 15 wt % chromium, 2 wt % aluminium, up to 0.15 wt % oxygen, 0.1 to 0.3 wt % carbon and the balance titanium plus incidental impurities.  
     
     
         10 . An article as claimed in  claim 7  wherein the article comprises a component for a gas turbine engine.  
     
     
         11 . An article as claimed in  claim 10  wherein the component comprises a compressor blade or a compressor vane.  
     
     
         12 . An article as claimed in  claim 10  wherein the component comprises a tip portion for a compressor blade.  
     
     
         13 . A beta titanium alloy comprising at least 10 wt % of one or more beta stabilising elements, aluminium, 0.1 to 0.4 wt % carbon up to 0.2 wt % oxygen and the balance titanium and incidental impurities, wherein the carbon is present in the form of titanium carbide precipitates distributed throughout the beta titanium alloy matrix, the titanium carbide precipitates refine the grain size of the beta titanium alloy matrix and remove oxygen from the beta titanium alloy matrix so reduce precipitation of alpha titanium in the beta titanium alloy matrix to increase the ductility of the beta titanium alloy.  
     
     
         14 . A beta titanium alloy as claimed in  claim 13  wherein the beta stabilising element is selected from the group comprising vanadium, molybdenum, tantalum, niobium, chromium, tungsten, manganese and iron.  
     
     
         15 . A beta titanium alloy as claimed in  claim 13  wherein the beta titanium alloy comprises 1.5 to 2.5 wt % aluminium.  
     
     
         16 . A beta titanium alloy as claimed in  claim 13  wherein the beta titanium alloy comprises 0.15 to 0.3 wt % carbon.  
     
     
         17 . A beta titanium alloy as claimed in  claim 13  wherein the beta titanium alloy comprises less than 0.15 wt % oxygen.