Friction welding

Abstract

A method of bonding two materials by friction welding method. A first material may be made from a titanium aluminide intermetallic alloy and a second material may be made from a titanium alloy. The first material may be heated to a temperature between about 300° C. and about 800° C. The second material may be rotated relative to the first material. The first material and the second material may be pressed against each other while one of the first material, and the second material is rotated. The rotation of one of the first material and the second material may be stopped, and the first material and the second material may be pressed against each other after the rotation of one of the first material and the second material is stopped.

1 . A method of bonding two materials comprising:
 providing a first material made from a titanium aluminide intermetallic alloy and a second material made from a titanium alloy;   heating the first material to a temperature between about 300° C. and about 800° C.;   rotating the second material relative to the first material;   pressing the first material and the second material against each other while rotating one of the first material and the second material;   stopping the rotation of one of the first material and the second material; and   pressing the first material and the second material against each other after stopping the rotation of one of the first material and the second material.   
     
     
         2 . The method of  claim 1 , wherein the temperature is between about 400° C. and 650° C. 
     
     
         3 . The method of  claim 1 , wherein pressing the first material and the second material against each other while rotating one of the first material and the second material includes pressing the first material and the second material against each other at a pressure of about 10 MPa to 200 MPa for about 5 to 60 seconds. 
     
     
         4 . The method of  claim 1 , wherein pressing the first material and the second material against each other while rotating one of the first material and the second material includes:
 pressing the first material and the second material against each other at a first pressure for a first time period; and   pressing the first material and the second material against each other at a second pressure for a second time period, the second pressure being different from the first pressure.   
     
     
         5 . The method of  claim 4 , wherein the first pressure is about 20 MPa to 60 MPa, and the first time period is about 5 to 30 seconds, and the second pressure is about 50 MPa to 200 MPa, and the second time period is about 0.5 to 5 seconds. 
     
     
         6 . The method of  claim 1 , wherein pressing the first material and the second material against each other after stopping the rotation of one of the first material and the second material includes pressing the first material and the second material against each other at a pressure of about 200 MPa or greater for about 5 to 60 seconds after stopping the rotation of one of the first material and the second material. 
     
     
         7 . The method of  claim 1 , wherein providing a second material made from a titanium alloy includes providing a second material having a cavity at an end of the second material. 
     
     
         8 . The method of  claim 1 , wherein providing a first material made from a titanium aluminide intermetallic alloy includes providing a turbine rotor wheel made from the titanium aluminide intermetallic alloy, and wherein providing a second material made from a titanium alloy includes providing a rotor shaft made from the titanium alloy. 
     
     
         9 . The method of  claim 1 , wherein providing a first material made from a titanium aluminide intermetallic alloy includes providing a turbine rotor wheel made from the titanium aluminide intermetallic alloy, and wherein providing a second material made from a titanium alloy includes providing a section of a turbine rotor shaft, and wherein the section is made from the titanium alloy. 
     
     
         10 . The method of  claim 1 , wherein providing a first material made from a titanium aluminide intermetallic alloy includes providing a valve head having a diameter of about four inches (10.16 cm) or greater. 
     
     
         11 . A method of producing a turbine rotor assembly comprising:
 heating a turbine rotor wheel to a temperature between about 300° C. and about 800° C., wherein the turbine rotor wheel is made from a titanium aluminide intermetallic alloy;   rotating a turbine rotor shaft relative to the turbine rotor wheel;   pressing the turbine rotor shaft against the turbine rotor wheel while rotating the turbine rotor shaft;   stopping the rotation of the turbine rotor shaft; and   pressing the turbine rotor shaft against the turbine rotor wheel after stopping the rotation of the turbine rotor shaft.   
     
     
         12 . The method of  claim 11 , wherein the turbine rotor shaft is made from a titanium alloy. 
     
     
         13 . The method of  claim 12 , wherein the turbine rotor shaft includes a cavity at an end to be bonded to the turbine rotor wheel. 
     
     
         14 . The method of  claim 11 , wherein the turbine rotor shaft includes a section to be bonded to the turbine rotor wheel, the section being made from a titanium alloy. 
     
     
         15 . The method of  claim 14 , wherein the section of the turbine rotor shaft includes a cavity at an end to be bonded to the turbine rotor wheel. 
     
     
         16 . The method of  claim 11 , wherein the temperature is between about 400° C. and 650° C. 
     
     
         17 . The method of  claim 11 , wherein pressing the turbine rotor shaft against the turbine rotor wheel while rotating the turbine rotor shaft includes pressing the turbine rotor shaft and the turbine rotor wheel against each other at a pressure of about 10 MPa to 200 MPa for about 5 to 60 seconds. 
     
     
         18 . An assembly made by a friction welding process comprising:
 a first material; and   a second material,   wherein at least one of the first material and the second material includes a cavity at an end of the at least one of the first material and the second material to be coupled to the other material, the cavity being at least partially filled with at least one of the first material and the second material as a result of the friction welding process.   
     
     
         19 . The assembly of  claim 18 , wherein the first material includes a turbine rotor wheel made from a titanium aluminide intermetallic alloy. 
     
     
         20 . The assembly of  claim 18 , wherein the second material includes a turbine rotor shaft having at least a section made from a titanium alloy.