U.S. patent application number 12/069496 was filed with the patent office on 2008-08-21 for metastable beta-titanium alloy.
Invention is credited to Igor Vasilievich Levin, Denis Valeryervich Sosnovsky, Vladislav Valentinovich Tetyukhin.
Application Number | 20080199350 12/069496 |
Document ID | / |
Family ID | 20254397 |
Filed Date | 2008-08-21 |
United States Patent
Application |
20080199350 |
Kind Code |
A1 |
Tetyukhin; Vladislav Valentinovich
; et al. |
August 21, 2008 |
Metastable beta-titanium alloy
Abstract
Metastable .beta.-titanium alloy contains, in mass %: from 1.5
to 3.5 aluminum; from 4.5 to 8.0 molybdenum; from 1.0 to 3.5
vanadium; from 1.5 to 3.8 iron; titanium balance. This alloy
combines high strength and ductility. This allows to use it for
production of a wide range of critical parts including fastener
components and different coil springs (e.g. in automobile
industry).
Inventors: |
Tetyukhin; Vladislav
Valentinovich; (Moscow, RU) ; Levin; Igor
Vasilievich; (Sverdlovskaya Obl, RU) ; Sosnovsky;
Denis Valeryervich; (Sverdlovskaya Obl, RU) |
Correspondence
Address: |
David M. Ostfeld;Adams and Reese, LLP
4400 One Houston Center, 1221 McKinney Street
Houston
TX
77010
US
|
Family ID: |
20254397 |
Appl. No.: |
12/069496 |
Filed: |
February 11, 2008 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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10496493 |
Jul 21, 2005 |
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PCT/RU02/00502 |
Nov 18, 2002 |
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12069496 |
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Current U.S.
Class: |
420/590 |
Current CPC
Class: |
C22C 14/00 20130101 |
Class at
Publication: |
420/590 |
International
Class: |
C22C 1/00 20060101
C22C001/00 |
Foreign Application Data
Date |
Code |
Application Number |
Nov 22, 2001 |
RU |
2001131383 |
Claims
1: Process for preparation of a metastable .beta.-titanium alloy
containing aluminum, molybdenum, and iron, and vanadium, consisting
essentially of (mass %): TABLE-US-00004 Aluminum 1.5-3.5 Molybdenum
4.5-8.0 Vanadium 1.0-3.5 Iron 1.6-3.8 Titanium balance,
wherein the molybdenum is added as ferromolybdenum with 55-75% of
molybdenum and a balance of iron.
2: The process of claim 1 wherein the vanadium is added as
ferrovanadium with 65-80% of vanadium and a balance of iron.
3: The process of claim 1 wherein the vanadium is added as a
Ti--Al--V system scrap.
4: A process for preparation of a metastable .beta.-titanium-base
alloy consisting of (mass %): TABLE-US-00005 Aluminum 1.5-3.5
Molybdenum 4.5-8.0 Vanadium 1.0-3.5 Iron 1.5-3.8
Incidental impurities; and Titanium balance, wherein the molybdenum
is added as ferromolybdenum with 55-75% of molybdenum and a balance
of iron.
5: The process of claim 4 wherein the vanadium is added as
ferrovanadium with 65-80% of vanadium and a balance of iron.
6: The process of claim 4 wherein the vanadium is added as a
Ti--Al--V system scrap. Metastable .beta.-titanium alloy containing
aluminum, molybdenum and iron, wherein it additionally contains
vanadium, at the following content of components (mass %):
TABLE-US-00006 Aluminum 1.5-3.5 Molybdenum 4.5-8.0 Vanadium 1.0-3.5
Iron 1.6-3.8 Titanium balance
Description
CROSS-REFERENCE TO RELATED APPLICATION
[0001] This application is a divisional application based on U.S.
Ser. No. 10/496,493 filed on Jul. 21, 2005 entitled "Metastable
.beta.-Titanium Alloy" which is a .sctn. 371 filing of a
PCT/RU02/00502 filed Nov. 18, 2002, which claims priority to
Russian Federation Application No. 2001131383 filed Nov. 22,
2001.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] This invention relates to the non-ferrous metallurgy, and
more particularly to the development of new titanium-base alloys
combining high strength and ductility properties using relatively
low-cost alloying elements. The alloys of this invention can be
applied in a wide range of products especially fasteners and
different coil springs.
[0004] 2. Background Art
[0005] Pure titanium is normally of a hexagonal (alpha--.alpha.)
structure that transforms to a body-centered cubic (beta--.beta.)
when heated above 882.degree. C. The addition of alloying elements
to titanium influences this transition temperature. In many alloys,
this results in beta being retained at room temperature. A material
may thus be produced which contains both alpha and beta phases or,
in some circumstances, a material which is wholly beta. The
relative amounts of alpha and beta phases in any particular alloy
affect tensile strength, ductility, creep properties, weldability
and formability.
[0006] A metastable-beta titanium alloy retains an all-beta
structure upon air-cooling of thin sections. A beta titanium alloy
is termed "metastable" because the resultant beta phase is not
truly stable--it can be aged to precipitate alpha for strengthening
purposes. As used herein, the "metastable" terminology embraces a
near-beta alloy which may also decompose to alpha plus beta upon
aging.
[0007] One of the known titanium alloys is the alloy containing
(mass %): 2-6 Al; 6-9 Mo; 1-3 V; 0.5-2 Cr; 0-1.5 Fe; Ti balance.
Ref: USSR Inventor's Certificate No. 180351, Class C22C 14/00,
1966.
[0008] However, this alloy has insufficient ductility due to the
high content of Al and the presence of Cr. Besides this alloy is
rather expensive.
[0009] The other known titanium alloy contains (mass %): 4-6.3 Al;
4.5-5.9 V; 4.5-5.9 Mo; 2.0-3.6 Cr; 0.2-0.5 Fe; Ti balance. Ref: RF
Patent No. 2169204, Class C22C 14/00, published 2001.
[0010] The said alloy as-heat treated has high strength properties
in heavy section forgings, but its ductility is insufficient and so
the alloy cannot be used for production of such parts as coil
springs.
[0011] The most close to the claimed invention is the metastable
.beta.-titanium alloy containing (mass %): 4-5 Fe; 4-7 Mo; 1-2 Al;
02 up to 0.25; Ti balance. Ref: U.S. Pat. No. 5,294,267, Class C22C
14/00, published 1994. This alloy will be the prototype.
[0012] This alloy has high machinability, demands relatively low
costs and is widely used for production of coil cylindrical springs
in automotive industry.
[0013] However, the said alloy has low ductility properties,
especially elongation, which reduces the application of this alloy
and is of importance during manufacture of some types of coil
springs and fastener components.
[0014] It is known that the beta phase in pure titanium is stable
from approximately 882.degree. C. (1620.degree. F.) to the melting
point of about 1688.degree. C. (3040.degree. F.). Where beta is the
predominant phase in the microstructure of a titanium alloy,
certain properties may be obtained depending upon the processing
methodologies followed.
SUMMARY OF THE INVENTION
[0015] The object of this invention is to provide a titanium alloy
with combination of high ductility and strength properties in
as-heat treated condition, which can be produced using low cost
alloying elements.
[0016] In accordance with the invention this is achieved by
addition of vanadium to the metastable .beta.-titanium alloy
containing aluminum, molybdenum and iron at the following content
of components (mass %):
TABLE-US-00001 Aluminum 1.5-3.5 Molybdenum 4.5-8.0 Vanadium 1.0-3.5
Iron 1.6-3.8 Titanium balance
[0017] The addition of 1.0-3.5% vanadium increases the alloy
ductility as required.
[0018] To achieve high strength properties this alloy has higher
content of aluminum than the prototype. The content of aluminum of
less than 3.5% does not significantly influence on the alloy
ductility. The contents of aluminum greater than 3.5% and iron
greater than 3.8% increases the .alpha.-phase quantity, causes
hardening and reduces ductility lower than desired. The lower
content of iron (<4%) than in the prototype ensures greater
phase stability during thermal cycles (deformation and heat
treatment). The desired strength properties cannot be achieved with
aluminum below 1.5%. The content of molybdenum below 4.5% and iron
below 1.6% reduces .beta.-phase quantity and does not lead to high
strength of the as-heat treated alloy.
[0019] The increase in the content of such P-stabilizers as
molybdenum and vanadium exceeding the specified limits reduces the
alloy stability in hardened and aged conditions and increases the
grain size during heat treatment, which significantly reduces the
alloy ductility (.beta.<4%; .PSI.<7%).
[0020] Molybdenum is added as ferromolybdenum with 55-75% of
molybdenum and iron balance.
[0021] Vanadium is added as ferrovanadium with 65-85% of vanadium
and iron balance or Ti--Al--V system scrap.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0022] To study the properties of the alloy, ingots with the
composition shown in Table 1 were melted in a vacuum arc furnace
and 20 mm diameter bars were made from these ingots. The bars were
heat treated under the following conditions: heating to temperature
of 30.degree. C. below beta transus temperature, water cooling,
heating to 480.degree. C. for 8 hours, air cooling. Then tensile
specimens were tested according to ASTM E 8.
[0023] As used herein, the "beta transus temperature" refers to the
temperature at which the titanium alloy will be transformed
completely to the beta phase. ASTM E 8 ("Standard Test Method for
Tension Testing of Metallic Materials"). This method covers the
tension testing of metallic materials in any form at room
temperature-specifically the methods of determination of yield
strength, yield point, tensile strength, elongation, and reduction
of area. The tension tests determine the strength and ductility of
materials under uniaxial tensile stress.
[0024] Mechanical properties of the produced bars from the
evaluated alloys are shown in Table 2.
TABLE-US-00002 TABLE 1 Element Content (wt %) Example Al Mo V Fe Ti
1 1.5 4.5 1.0 1.5 balance 2 2.5 5.5 2.0 2.5 balance 3 3.0 6.5 3.0
3.5 balance 4 3.5 8.0 3.5 3.8 balance
TABLE-US-00003 TABLE 2 Mechanical Properties Yield Ultimate
Strength Elongation Reduction Example Strength .sigma..sub.B, MPa
.sigma..sub.0.2, MPa .delta., % of Area, .PSI. % 1 1100 1020 25.1
58.7 2 1250 1190 20.2 46.4 3 1440 1390 6.1 10.2 4 1520 1480 4.9
7.3
Commercial Practicability
[0025] The claimed metastable .beta.-titanium alloy as compared to
the known alloys has the specified optimal combination of beta and
alpha stabilizing alloying elements, which ensure high strength and
ductility of the as-heat treated ally. It is low cost and can be
used for production of a wide range of critical parts, especially
fastener components and different coil springs.
* * * * *