US4631092A
Expired / Lapsed
US
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Method for heat treating cast titanium articles to improve their mechanical properties
Assignee: Garrett Corp
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Filing: 1984-10-18
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Granted: 1986-12-23
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Expires: 2004-10-18
Abstract
Abstract Cast titanium alloys and a method of heat treating the alloys in order to obtain fatigue and mechanical properties comparable to wrought titanium is disclosed. The heat treatment is practiced by solution heat treating a cast titanium article above its beta transus, rapidly cooling, stabilizing at a temperature within the alloy's alpha/beta phase range, and finally aging the article to achieve the desired properties.
Inventors
- 👤 Duane L. Ruckle
- 👤 Ponciano P. Millan, Jr.
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-25 03:59
CPC Classifications
C; C22; C22F; C22F1/00; C22F1/16; C22F1/18; C22F1/183; Y; Y10; Y10T; Y10T29/00; Y10T29/49; Y10T29/49316; Y10T29/49336
Claims Analysis
Total Claims: 28
Claim 1
Independent Claim
68 words
A method of heat treating a cast titanium alloy article comprising the steps of: heating the article to a temperature above its beta transus temperature; rapidly cooling the article to produce an acicular martensitic microstructure; thermally decomposing the martensitic microstructure by stabilizing the article at a temperature between 1500°-825° F.; and aging the article at a temperature of 1000°-1300° F. for a time of 1 to 8 hours.
Claim 2
Independent Claim
68 words
A method of heat treating a cast titanium alloy article comprising the steps of: heating the article to a temperature above its beta transus temperature; rapidly cooling the article to produce an acicular martensitic microstructure; thermally decomposing the martensitic microstructure by stabilizing the article at a temperature between 1500°-825° F.; and aging the article at a temperature of 1000°-1300° F. for a time of 1 to 8 hours.
Claim 3
Dependent Claim
13 words
The method according to claim 1 wherein the alloy is a Ti-6%Al-4%V alloy.
Claim 4
Dependent Claim
16 words
The method according to claim 1 wherein said cooling step comprises quenching the article in liquid.
Claim 5
Dependent Claim
26 words
The method according to claim 3 wherein said cooling step comprises quenching the article in a liquid selected from the group consisting of water and oil.
Claim 6
Dependent Claim
17 words
The method according to claim 1 wherein said cooling step comprises quenching the article in a gas.
Claim 7
Dependent Claim
31 words
The method according to claim 5 wherein the step of rapid cooling is comprised of the step of quenching in a gas selected from the group consisting of argon and helium.
Claim 8
Dependent Claim
17 words
The method according to claim 1 further including the initial step of hot isostatically pressing the article.
Claim 9
Dependent Claim
11 words
A gas turbine airfoil produced by the method of claim 1.
Claim 10
Dependent Claim
78 words
An airfoil for use in a gas turbine engine or the like comprising a cast titanium alloy having a tensile strength of about 145 to 161 KSI produced by a method comprising the steps of: heat treating the airfoil to a temperature above its beta transus temperature; rapidly cooling the airfoil; stabilizing the airfoil at a temperature between 1500°-1825° F.; and aging the airfoil at a temperature of 1000°-1300° F. for a time of 1 to 8 hours.
Claim 11
Dependent Claim
78 words
An airfoil for use in a gas turbine engine or the like comprising a cast titanium alloy having a tensile strength of about 145 to 161 KSI produced by a method comprising the steps of: heat treating the airfoil to a temperature above its beta transus temperature; rapidly cooling the airfoil; stabilizing the airfoil at a temperature between 1500°-1825° F.; and aging the airfoil at a temperature of 1000°-1300° F. for a time of 1 to 8 hours.
Claim 12
Dependent Claim
12 words
The airfoil according to claim 9 wherein the titanium alloy is Ti-6%Al-4%V.
Claim 13
Dependent Claim
18 words
The airfoil according to claim 9 wherein the titanium alloy has a Charpy impact strength of 12-24 ft-lbs.
Claim 14
Dependent Claim
17 words
An airfoil comprising: a cast titanium alloy having a tensile strength of about 145 to 161 KSI.
Claim 15
Dependent Claim
17 words
An airfoil comprising: a cast titanium alloy having a tensile strength of about 145 to 161 KSI.
Claim 16
Dependent Claim
11 words
The airfoil according to claim 12 wherein the alloy is Ti-6%Al-4%V.
Claim 17
Dependent Claim
59 words
The airfoil according to claim 12 produced by a method comprising the steps of: heat treating the airfoil to a temperature above its beta transus temperature; rapidly cooling the airfoil; stabilizing the airfoil at a temperature within its alpha/beta phase field; and aging the airfoil at a temperature of 1000°-1300° F. for a time of 1 to 8 hours.
Claim 18
Independent Claim
86 words
A method of heat treating a cast alpha/beta titanium alloy article comprising the steps of: transforming the alpha/beta microstructure of the article to a substantially beta microstructure by heating the article to a temperature above its beta transus temperature; converting the beta microstructure to a martensitic microstructure by rapidly quenching the article; stabilizing the martensite into alpha and beta platelets by heating the article to a temperature between 1500°-1825° F.; and decomposing a portion of the beta microstructure into an alpha/beta microstructure by aging the article.
Claim 19
Independent Claim
86 words
A method of heat treating a cast alpha/beta titanium alloy article comprising the steps of: transforming the alpha/beta microstructure of the article to a substantially beta microstructure by heating the article to a temperature above its beta transus temperature; converting the beta microstructure to a martensitic microstructure by rapidly quenching the article; stabilizing the martensite into alpha and beta platelets by heating the article to a temperature between 1500°-1825° F.; and decomposing a portion of the beta microstructure into an alpha/beta microstructure by aging the article.
Claim 20
Dependent Claim
36 words
The method according to claim 15, wherein the step of transforming the alpha/beta microstructure into substantially beta microstructure takes place at a temperature between the beta transus temperature and the beta transus temperature plus 150° F.
Claim 21
Dependent Claim
26 words
The method according to claim 15 wherein the step of decomposing the beta microstructure is performed by aging at approximately 1300° F. for approximately 2 hours.
Claim 22
Independent Claim
115 words
A method of providing a hollow cast titanium alloy article comprising the steps of: casting a slightly oversized article around a leachable core within a mold by vacuum skull melting; removing the article from the mold; placing the article into a leaching agent to disintegrate the core; milling an oxygen enriched layer off the article; hot isostatically pressing the article; heat treating the article to a temperature above its beta transus temperature; rapidly cooling the article to produce an acicular martensitic microstructure; thermally decomposing the martensitic microstructure by stabilizing the article at a temperature between 1500°-1825° F.; and aging the article at a temperature of 1000°-1300° F. for a time of 1 to 8 hours.
Claim 23
Independent Claim
115 words
A method of providing a hollow cast titanium alloy article comprising the steps of: casting a slightly oversized article around a leachable core within a mold by vacuum skull melting; removing the article from the mold; placing the article into a leaching agent to disintegrate the core; milling an oxygen enriched layer off the article; hot isostatically pressing the article; heat treating the article to a temperature above its beta transus temperature; rapidly cooling the article to produce an acicular martensitic microstructure; thermally decomposing the martensitic microstructure by stabilizing the article at a temperature between 1500°-1825° F.; and aging the article at a temperature of 1000°-1300° F. for a time of 1 to 8 hours.
Claim 24
Independent Claim
80 words
A method of heat treating a cast titanium alloy article to relatively inexpensively provide the article with mechanical properties similar to those of a wrought titanium alloy article, said method comprising the steps of: heating the cast article; cooling the heated article to produce therein a acicular martensitic microstructure; stabilizing the cooled article at a first temperature in a manner casuing decomposition of the martensitic microstructure; and aging the stabilized article at a second temperature less than said first temperature.
Claim 25
Independent Claim
80 words
A method of heat treating a cast titanium alloy article to relatively inexpensively provide the article with mechanical properties similar to those of a wrought titanium alloy article, said method comprising the steps of: heating the cast article; cooling the heated article to produce therein a acicular martensitic microstructure; stabilizing the cooled article at a first temperature in a manner casuing decomposition of the martensitic microstructure; and aging the stabilized article at a second temperature less than said first temperature.
Claim 26
Dependent Claim
22 words
The method according to claim 19 wherein said heating step comprises heating the article to a temperature above its beta transus temperature.
Claim 27
Dependent Claim
28 words
The method according to claim 19 wherein said stabilizing step comprises stabilizing the cooled article within a temperature range of from about 1500° F. to about 1825° F.
Claim 28
Dependent Claim
29 words
The method according to claim 21 wherein said aging step comprises aging the stabilized article within a temperature range having an upper temperature limit less than about 1500° F.
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