Process for manufacture of fasteners from titanium or a titanium alloy

Abstract

A process for making parts from titanium or a titanium alloy is disclosed. The process includes the step of preparing an intermediate form of titanium or a titanium alloy. The intermediate form is then solution heat treated under conditions of temperature and time that are selected to produce a desired level of strength when the titanium or titanium alloy part is subsequently age hardened. The solution treated intermediate form is then thermomechanically formed into a desired part or a preform for a desired part. The part or preform is then age-hardened under conditions of temperature and time that are selected to produced the desired level of strength in the finished part.

1 . A process for making parts from titanium or a titanium alloy comprising the steps of: 
 preparing an intermediate form of titanium or of a titanium alloy selected from the group consisting of an alpha alloy, a near-alpha alloy, and an alpha-beta alloy; then    solution heat treating the intermediate form under conditions of temperature and time that are selected to produce a desired level of strength when the titanium or titanium alloy are subsequently age hardened; then    thermomechanically forming the solution treated intermediate form into a desired part or a preform for a desired part; and then    age hardening the as-formed part or preform under conditions of temperature and time that are selected to produced the desired level of strength.    
     
     
         2 . The process as set forth in  claim 1  wherein the intermediate form is prepared from an alpha-beta titanium alloy.  
     
     
         3 . The process as set forth in  claim 1  wherein the intermediate form is prepared from a titanium alloy comprising about 6% aluminum, about 4% vanadium, and the balance titanium and usual impurities.  
     
     
         4 . The process as set forth in  claim 1  wherein the step of preparing the intermediate form comprises the step of forming the titanium alloy into an elongated form selected from the group consisting of wire, rod, and bar.  
     
     
         5 . The process as set forth in  claim 1  wherein the step of thermomechanically forming the solution treated intermediate form comprises the steps of cutting the elongated form into pieces having a substantially uniform length, heating the pieces to an elevated temperature, and then forming the desired part or preform by a forming operation selected from the group consisting of forging, heading, extruding, and a combination thereof.  
     
     
         6 . The process as set forth in  claim 5  wherein the step of thermomechanically forming the solution treated intermediate form comprises the step of rapidly cooling the part from the elevated temperature after said forming step.  
     
     
         7 . The process as set forth in  claim 1  wherein the step of preparing the intermediate form of titanium or the titanium alloy comprises the step of preparing the titanium or titanium alloy such that it contains not more than about 0.10% carbon, not more than about 0.05% nitrogen, not more than about 0.0125% hydrogen, and not more than about 0.20% oxygen.  
     
     
         8 . The process as set forth in  claim 7  wherein the step of preparing the titanium or titanium alloy comprises the step of controlling the melting of the titanium or titanium alloy such that it contains not more than about 0.17% oxygen.  
     
     
         9 . The process as set forth in  claim 1 , wherein the step of solution treating the intermediate form comprises the step of heating the intermediate form at a temperature of about 1650-1775° F. (899-968° C.) for at least about 1 minute up to about 2 hours, and then quenching the intermediate form in water.  
     
     
         10 . The process as set forth in  claim 1  wherein the step of thermomechanically forming the solution treated intermediate form comprises the step of mechanically working the intermediate form at a temperature of about 1600-800° F. (871-427° C.).