Method for manufacturing a titanium alloy bar

Abstract

A method for manufacturing an α+β titanium alloy bar comprising hot rolling an α+β titanium alloy consisting essentially of 4 to 5% Al, 2.5 to 3.5% V, 1.5 to 2.5% Fe, 1.5 to 2.5% Mo, by mass, and a balance of Ti, while keeping the surface temperature thereof to a temperature of β transus or below.

1 . A method for manufacturing an α+β titanium alloy bar comprising hot rolling an α+β titanium alloy consisting essentially of 4 to 5 mass % Al, 2.5 to 3.5 mass % V, 1.5 to 2.5 mass % Fe, 1.5 to 2.5 mass % Mo and a balance of Ti, while keeping the surface temperature thereof to a temperature of f transus or below.  
     
     
         2 . The method for manufacturing an α+β titanium alloy bar of  claim 1 , wherein the α+β titanium alloy is hot rolled at a reduction rate of 40% or less per rolling pass.  
     
     
         3 . The method for manufacturing an α+β titanium alloy bar of  claim 1 , wherein the hot rolling is carried out at a rolling speed of 6 m/sec or less with a reverse rolling mill.  
     
     
         4 . The method for manufacturing an α+β titanium alloy bar of  claim 1 , wherein the hot rolling is carried out at a rolling speed of 1.5 m/sec or less with tandem rolling mills.  
     
     
         5 . The method for manufacturing an α+β titanium alloy bar of  claim 1 , wherein a waiting time before starting a succeeding rolling is 0.167×S 1/2  or more seconds when the α+β titanium alloy has a cross sectional area of 3500 mm 2  or more in a direction normal to the rolling direction is hot rolled to a cross sectional area of S mm 2 .  
     
     
         6 . The method for manufacturing an α+β titanium alloy bar of  claim 1 , wherein the α+β titanium alloy is reheated during the hot rolling.  
     
     
         7 . The method for manufacturing an α+β titanium alloy bar of  claim 2 , wherein the hot rolling is carried out at a rolling speed of 6 m/sec or less with a reverse rolling mill.  
     
     
         8 . The method for manufacturing an α+β titanium alloy bar of  claim 2 , wherein the hot rolling is carried out at a rolling speed of 1.5 m/sec or less with tandem rolling mills.  
     
     
         9 . The method for manufacturing an α+β titanium alloy bar of  claim 2 , wherein the α+β titanium alloy is reheated during hot rolling.  
     
     
         10 . A method for manufacturing an α+β titanium alloy bar comprising heating an α+β titanium alloy having a β transus temperature of Tβ° C. and consisting essentially of 4 to 5 mass % Al, 2.5 to 3.5 mass % V, 1.5 to 2.5 mass % Fe, 1.5 to 2.5 mass % Mo and a balance of Ti, so that the surface temperature thereof is between (Tβ-150) and Tβ° C. to provide a heated α+β titanium alloy; and 
 hot rolling the heated α+β titanium alloy while keeping the surface temperature thereof during the hot rolling between (Tβ-300) and (Tβ-50)° C. and keeping a finish surface temperature thereof, as a surface temperature immediately after a final rolling pass, between (Tβ-300) and (Tβ-100)° C.    
     
     
         11 . The method for manufacturing an α+β titanium alloy bar of  claim 10 , wherein the α+β titanium alloy is hot rolled at a reduction rate of 40% or less per rolling pass.  
     
     
         12 . The method for manufacturing an α+β titanium alloy bar of  claim 10 , wherein the hot rolling is carried out at a rolling speed of 6 m/sec or less with a reverse rolling mill.  
     
     
         13 . The method for manufacturing an α+β titanium alloy bar of  claim 10 , wherein the hot rolling is carried out at a rolling speed of 1.5 m/sec or less with tandem rolling mills.  
     
     
         14 . The method for manufacturing an α+β titanium alloy bar of  claim 10 , wherein a waiting time before starting a succeeding rolling is 0.167×S 1/2  or more seconds when a cross sectional area of 3500 mm 2  or more in a direction normal to the rolling direction is hot rolled to a cross sectional area of S mm 2 .  
     
     
         15 . The method for manufacturing an α+β titanium alloy bar of  claim 10 , wherein the α+β titanium alloy is reheated during the hot rolling.  
     
     
         16 . The method for manufacturing an α+β titanium alloy bar of  claim 11 , wherein the hot rolling is carried out at a rolling speed of 6 m/sec or less with a reverse rolling mill.  
     
     
         17 . The method for manufacturing an α+β titanium alloy bar of  claim 11 , wherein the hot rolling is carried out at a rolling speed of 1.5 m/sec or less with tandem rolling mills.  
     
     
         18 . The method for manufacturing an α+β titanium alloy bar of  claim 11 , wherein the α+β titanium alloy is reheated during hot rolling.  
     
     
         19 . The method for manufacturing an α+β titanium alloy bar of  claim 16 , wherein the α+β titanium alloy is reheated during hot rolling.  
     
     
         20 . The method for manufacturing an α+β titanium alloy bar of  claim 17 , wherein the α+β titanium alloy is reheated during hot rolling.