Methods for finishing extruded titanium products

Abstract

The present disclosure relates to methods of finishing extruded titanium alloy workpieces by generating an extruded near net shape workpiece, cooling the extruded near net shape workpiece to a cooled temperature below the beta transus temperature, and then rolling the extruded near net shape workpiece one or more times at a rolling temperature to yield a final shape workpiece with desired properties.

What is claimed is: 
     
         1 . A method of creating a titanium alloy workpiece comprising:
 a. heating a cast ingot or wrought billet of a titanium alloy to a temperature above its beta transus temperature to yield a heated workpiece;   b. initiating extrusion of the heated workpiece while the heated workpiece is above the beta transus temperature, thereby generating an extruded near net shape workpiece;   c. cooling the extruded near net shape workpiece to a cooled temperature below the beta transus temperature; and   d. rolling the extruded near net shape workpiece one or more times at one or more rolling temperatures to yield a final shape workpiece, wherein the rolling temperature is below an incipient melting temperature of the alloy and within 600° F. (333° C.) of the beta transus temperature.   
     
     
         2 . The method of  claim 1 , wherein the titanium alloy is an alpha-beta titanium alloy. 
     
     
         3 . The method of  claim 1 , further comprising after the heating step (a), protecting a surface of the heated workpiece with a protectant. 
     
     
         4 . The method of  claim 3 , wherein the protectant is a lubricant or parting agent. 
     
     
         5 . The method of  claim 3 , wherein the method further comprises, after the cooling step (c), cleaning the near net shape workpiece prior to the rolling step (d) to remove any protectant. 
     
     
         6 . The method of  claim 1 , wherein the cooled temperature is within 500° F. (278° C.) of the beta transus temperature. 
     
     
         7 . The method of  claim 1 , wherein the cooled temperature is within 100° F. (55.6° C.) of the beta transus temperature. 
     
     
         8 . The method of  claim 1 , wherein the cooled temperature is room temperature. 
     
     
         9 . The method of  claim 1 , wherein the rolling temperature is above the beta transus temperature and below the incipient melting temperature. 
     
     
         10 . The method of  claim 1 , wherein the rolling temperature is above the beta transus temperature and within 50° F. (27.8° C.) of the beta transus temperature. 
     
     
         11 . The method of  claim 1 , wherein the rolling temperature is below the beta transus temperature and within 600° F. (333° C.) of the beta transus temperature. 
     
     
         12 . The method of  claim 1 , wherein the rolling temperature is below the beta transus temperature and within 50° F. (27.8° C.) of the beta transus temperature. 
     
     
         13 . The method of  claim 1 , wherein the rolling step (d) further comprises rolling at a strain rate of from 0.1 s −1  to 100 s −1 . 
     
     
         14 . The method of  claim 1 , wherein the rolling step comprises uniformly reducing the near net shape workpiece by a relative reduction of from 1% to 95%, thereby achieving the final shape workpiece. 
     
     
         15 . The method of  claim 14 , wherein the relative reduction is from 40 to 75%. 
     
     
         16 . The method of  claim 1 , wherein the rolling step comprises reducing a first section of the near net shape workpiece by a first relative reduction of from 1% to 95%, thereby achieving a final shape workpiece with the first section being reduced. 
     
     
         17 . The method of  claim 16 , wherein the rolling step further comprises reducing at least a second section of the near net shape workpiece by a second relative reduction of from 1% to 95% thereby achieving the final shape workpiece with at least the first and second sections being reduced, wherein the first relative reduction is different than the second relative reduction. 
     
     
         18 . The method of  claim 1 , wherein the final shape workpiece realizes at least 3% higher tensile yield strength (L) over a referenced titanium alloy body; wherein the referenced titanium alloy body has the same composition as the final shape workpiece, and is in the same temper as the final shape workpiece. 
     
     
         19 . The method of  claim 18 , wherein the final shape workpiece comprises isotropic strength properties, wherein the tensile yield strength in the LT direction is within 10 ksi of the tensile yield strength in the L direction. 
     
     
         20 . The method of  claim 19 , wherein the final shape workpiece realizes an elongation (L) of at least 6% and an elongation (LT) of at least 6%.