Titanium alloy microstructural refinement method and high temperature-high strain rate superplastic forming of titanium alloys

Abstract

A method for refining the microstructure of titanium alloys in a single thermomechanical processing step, wherein the titanium alloy comprises boron. In some embodiments, the method comprises the steps of first adding boron to the titanium alloy then subjecting the boron-containing titanium alloy to a thermomechanical processing step. Also provided is a method for achieving superplasticity in titanium alloys comprising the steps of selecting a boron-containing titanium alloy, determining the temperature and strain rate necessary to achieve beta superplasticity, and applying sufficient temperature and strain rate to the boron-containing titanium alloy to deform the alloy to the desired shape. Also provided methods of forming titanium alloy parts and the parts prepared by these methods.

1 . A method for refining the microstructure in titanium alloys in a single thermo-mechanical processing (TMP) step, comprising the step of subjecting a boron-containing titanium alloy to a TMP step to provide a titanium alloy having a fine-grained, equiaxed microstructure after a single TMP step. 
     
     
         2 . The method of  claim 1  wherein the boron-containing titanium alloy comprises an alloy selected from the group consisting of Ti-5Al-2.5Sn, Ti-6Al-4V, Ti-5.5Al-1 Fe, Ti-6Al-2Sn-4Zr-2Mo, Ti-6Al-2Sn-4Zr-6Mo, Ti-8Al-Mo-1V, Ti-10V-2Fe—Mo, Ti-4.5Fe-6.8Mo-1.5Al, Ti-5Al-1Fe, Ti-8Mn, and CP Ti. 
     
     
         3 . The method of  claim 2  wherein the boron-containing titanium alloy comprises Ti-6Al-4V. 
     
     
         4 . The method of  claim 1  wherein the titanium alloy comprises from 0.01% to 18.4% boron by weight. 
     
     
         5 . The method of  claim 5  wherein the titanium alloy comprises from 0.5% to 1.6% boron by weight. 
     
     
         6 . The method of  claim 1  comprising the additional step of subjecting the titanium alloy having a fine-grained, equiaxed microstructure to one or more additional IMP steps to produce a desired shape. 
     
     
         7 . A method for refining the microstructure in titanium alloys in a single TMP step comprising the steps of:
 a) adding boron to a titanium alloy to form a boron-containing titanium alloy; and   b) subjecting the boron-containing titanium alloy to a TMP step; wherein a fine-grained, equiaxed microstructure in the titanium alloy is achieved after a single thermo-mechanical processing step.   
     
     
         8 . The method of  claim 7  wherein the boron is added to the titanium alloy in a liquid state, wherein the boron is dissolved in the liquid titanium alloy. 
     
     
         9 . The method of  claim 7  wherein the boron is added to the titanium alloy through intermixing of a boron-containing powder and a titanium-containing powder. 
     
     
         10 . The method of  claim 7  wherein the boron is selected from the group consisting of elemental boron, TiB 2 , or a boron-containing alloy. 
     
     
         11 . The method of  claim 7  wherein the boron is added to the titanium alloy in the range from 0.01% to 18.4% by weight. 
     
     
         12 . The method of  claim 11  wherein the boron is added to the titanium alloy in the range from 0.5% to 1.6% by weight. 
     
     
         13 . The method of  claim 7  wherein the boron-containing titanium alloy comprises an alloy selected from the group consisting of Ti-5Al-2.5Sn, Ti-6Al-4V, Ti-5.5Al-1 Fe, Ti-6Al-2Sn-4Zr-2Mo, Ti-6Al-2Sn-4Zr-6Mo, Ti-8Al-Mo-1V, Ti-10V-2Fe—Mo, Ti-4.5Fe-6.8Mo-1.5Al, Ti-5Al-1 Fe, Ti-8Mn, and CP Ti. 
     
     
         14 . The method of  claim 13  wherein the boron-containing titanium alloy comprises Ti-6Al-4V. 
     
     
         15 - 26 . (canceled)