Method of hardening a beta titanium member

Abstract

A method of hardening the surface of a beta titanium member comprises the step of heating the beta titanium member in a gas mixture consisting essentially of an inert gas and oxygen.

1 . A method of hardening the surface of a beta titanium member comprising the step of process heating the beta titanium member in a gas mixture consisting essentially of an inert gas and oxygen.  
     
     
         2 . The method according to  claim 1  wherein the gas mixture has an oxygen concentration in a range of from approximately 0.05 vol % to approximately 20 vol %.  
     
     
         3 . The method according to  claim 2  wherein the gas mixture has an oxygen concentration in a range of from approximately 1.0 vol % to approximately 10 vol %.  
     
     
         4 . The method according to  claim 1  wherein the inert gas comprises argon.  
     
     
         5 . The method according to  claim 4  wherein the inert gas consists of argon.  
     
     
         6 . The method according to  claim 1  wherein the process heating step comprises the step of heating the beta titanium member at a temperature from approximately 700° C. to approximately 1000° C.  
     
     
         7 . The method according to  claim 6  wherein the process heating step comprises the step of heating the beta titanium member at a temperature from approximately 700° C. to approximately 1000° C. for a time period of from approximately 10 minutes to approximately 30 minutes.  
     
     
         8 . The method according to  claim 7  wherein the time period is from approximately 15 minutes to approximately 25 minutes.  
     
     
         9 . The method according to  claim 6  wherein the process heating step comprises the step of heating the beta titanium member at a temperature from approximately 850° C. to approximately 950° C.  
     
     
         10 . The method according to  claim 9  wherein the process heating step comprises the step of heating the beta titanium member at a temperature from approximately 850° C. to approximately 950° C. for a time period of from approximately 10 minutes to approximately 30 minutes.  
     
     
         11 . The method according to  claim 10  wherein the time period is from approximately 15 minutes to approximately 25 minutes.  
     
     
         12 . The method according to  claim 1  further comprising the step of subsequently heating the beta titanium member in a temperature range of from approximately 400° C. to approximately 550° C. after the process heating step.  
     
     
         13 . The method according to  claim 12  wherein the subsequent heating step comprises the step of heating the beta titanium member in a temperature range of from approximately 400° C. to approximately 550° C. for a time period of from approximately 6 hours to approximately 16 hours.  
     
     
         14 . The method according to  claim 13  wherein the time period is from approximately 10 hours to approximately 14 hours.  
     
     
         15 . The method according to  claim 12  wherein the subsequent heating step comprises the step of heating the beta titanium member in a temperature range of from approximately 450° C. to approximately 500° C.  
     
     
         16 . The method according to  claim 15  wherein the subsequent heating step comprises the step of heating the beta titanium member in a temperature range of from approximately 450° C. to approximately 500° C. for a time period of from approximately 6 hours to approximately 16 hours after the process heating step.  
     
     
         17 . The method according to  claim 16  wherein time period is from approximately 10 hours to approximately 14 hours.  
     
     
         18 . A method of hardening the surface of a beta titanium member comprising the steps of: 
 process heating the beta titanium member in a gas mixture consisting essentially of an inert gas and oxygen at a temperature from approximately 700° C. to approximately 1000° C. for a time period of from approximately 10 minutes to approximately 30 minutes to form an oxygen diffusion layer; and    subsequently heating the beta titanium member in a temperature range of from approximately 400° C. to approximately 550° C. for a time period of from approximately 6 hours to approximately 16 hours.    
     
     
         19 . The method according to  claim 18  wherein the time period for the process heating step is from approximately 15 minutes to approximately 25 minutes, and wherein the time period for the subsequent heating step is from approximately 10 hours to approximately 14 hours.  
     
     
         20 . The method according to  claim 19  wherein the gas mixture has an oxygen concentration in a range of from approximately 1.0 vol % to approximately 10 vol %.  
     
     
         21 . A method of hardening the surface of a beta titanium member comprising the step of heating the beta titanium member in a gas mixture consisting essentially of an inert gas and oxygen to form a hardened layer and an oxidized layer above the hardened layer, wherein the oxidized layer has a thickness less than or equal to approximately 0.5 μm after the heating has completed.  
     
     
         22 . The method according to  claim 20  wherein the hardened layer has a thickness in a range of from approximately 70 μm to approximately 100 μm.