Methods and articles relating to high strength erosion resistant titanium alloy

Abstract

A method of treating an article including a titanium alloy having 5-6.5% aluminum by weight; 1.5-2.5% tin by weight; 1.5-2.5% chromium by weight; 1.5-2.5% molybdenum by weight; 1.5-2.5% zirconium by weight; and titanium. The method includes heat treating the titanium alloy without exposing the titanium alloy to a beta anneal process. There is also an article that has been subjected to a heat treatment process that does not include a beta anneal.

1 . A method of treating an article comprising a titanium alloy, said method comprising the steps of:
 exposing the titanium alloy to a forging start temperature ranging from 1500° F. to 1800° F.;   exposing the titanium alloy to an alpha-beta anneal process having a temperature ranging from 1550° F. to 1850° F.;   exposing the titanium alloy to an aging process having a temperature ranging from 800° F. to 1000° F. for a length of time ranging from 1 hour to 24 hours;   wherein the method does not include a method step comprising exposing the titanium alloy to a beta anneal process; and   wherein the titanium alloy comprises:   5-6.5% aluminum by weight;   1.5-2.5% tin by weight;   1.5-2.5% chromium by weight;   1.5-2.5% molybdenum by weight;   1.5-2.5% zirconium by weight; and   titanium.   
     
     
         2 . The method according to  claim 1 , wherein the titanium alloy comprises
 5.25-6.25% aluminum by weight;   1.75-2.25% tin by weight;   1.75-2.25% chromium by weight;   1.75-2.25% molybdenum by weight;   1.75-2.25% zirconium by weight; and   titanium.   
     
     
         3 . The method according to  claim 2 , wherein the titanium alloy further comprises:
 0.05-0.25% silicon by weight;   0-0.25% iron by weight;   0-0.15% carbon by weight;   0-0.25% oxygen by weight;   0-0.1% nitrogen by weight; and   0-0.025% hydrogen by weight.   
     
     
         4 . The method according to  claim 3 , wherein the titanium alloy further comprises:
 0.1-0.2% silicon by weight;   0-0.15% iron by weight;   0-0.08% carbon by weight;   0-0.15% oxygen by weight;   0-0.05% nitrogen by weight; and   0-0.015% hydrogen by weight.   
     
     
         5 . The method according to  claim 2  comprising the steps of:
 exposing the titanium alloy to a forging start temperature ranging from 1600° F. to 1700° F.;   exposing the titanium alloy to an alpha-beta anneal process having a temperature ranging from 1650° F. to 1750° F.; and   exposing the titanium alloy to an aging process having a temperature ranging from 900° F. to 1100° F. for a length of time ranging from 6 hours to 10 hours.   
     
     
         6 . The method according to  claim 5  comprising the steps of:
 exposing the titanium alloy to a forging start temperature at 1650° F.;   exposing the titanium alloy to an alpha-beta anneal process having a temperature at 1700° F.; and   exposing the titanium alloy to an aging process having a temperature at 1000° F. for a length of time of 8 hours.   
     
     
         7 . The method according to  claim 5  further comprising the step of forming the titanium alloy into a shape of a turbine blade having a length longer than 45 inches. 
     
     
         8 . The method according to  claim 7  further comprising the step of forming the turbine blade into a steam turbine blade. 
     
     
         9 . The method according to  claim 7  further comprising the step of forming the turbine blade such that the turbine blade has a percent elongation of greater than 9% at room temperature. 
     
     
         10 . The method according to  claim 7  further comprising the step of forming the turbine blade such that the turbine blade has a percent reduction-in-area of greater than 15% at room temperature. 
     
     
         11 . The method according to  claim 7  further comprising the step of forming the turbine blade such that the turbine blade has a high cycle fatigue of greater than 190,000 cycles at room temperature. 
     
     
         12 . The method according to  claim 7  further comprising the step of forming the turbine blade such that the turbine blade has a low cycle fatigue with a high strain range of 1% of greater than 12,000 cycles at room temperature. 
     
     
         13 . An article comprising:
 5.25-6.25% aluminum by weight;   1.75-2.25% tin by weight;   1.75-2.25% chromium by weight;   1.75-2.25% molybdenum by weight;   1.75-2.25% zirconium by weight;   0.1-0.2% silicon by weight;   0-0.15% iron by weight;   0-0.08% carbon by weight;   0-0.15% oxygen by weight;   0-0.05% nitrogen by weight;   0-0.015% hydrogen by weight; and   titanium;   wherein the article has been subjected to a heat treatment process that does not include a beta anneal.   
     
     
         14 . The article of  claim 13 , wherein the article is a turbine blade 
     
     
         15 . The article of  claim 14 , wherein the turbine blade has a length longer than 45 inches. 
     
     
         16 . The article of  claim 15 , wherein the turbine blade is a steam turbine blade. 
     
     
         17 . The article of  claim 14 , wherein the turbine blade has a percent elongation of greater than 9% at room temperature. 
     
     
         18 . The article of  claim 14 , wherein the turbine blade has a percent reduction-in-area of greater than 15% at room temperature. 
     
     
         19 . The article of  claim 14 , wherein the turbine blade has a high cycle fatigue of greater than 190,000 cycles at room temperature. 
     
     
         20 . The article of  claim 14 , wherein the turbine blade has a low cycle fatigue with a high strain range of 1% of greater than 12,000 cycles at room temperature.