U.S. patent application number 10/535791 was filed with the patent office on 2006-06-01 for titanium-based alloy.
Invention is credited to Igor Vasilievich Levin, Vladisal Valentinovich Tetyukhin, Jury Ivanovich Zakharov.
Application Number | 20060115374 10/535791 |
Document ID | / |
Family ID | 32390762 |
Filed Date | 2006-06-01 |
United States Patent
Application |
20060115374 |
Kind Code |
A1 |
Tetyukhin; Vladisal Valentinovich ;
et al. |
June 1, 2006 |
Titanium-based alloy
Abstract
The inventive titanium-based alloy contains 2.2-3.8 mass %
aluminium, 4.5-5.9 mass % vanadium, 4.4-5.9 mass % molybdenum,
2.0-3.6 mass % chromium, 0.1-0.4 mass % zirconium, 0.01-0.18 mass %
iron and 0.03-0.25 mass % oxygen, the rest being titanium. Said
alloy exhibits a high processing plasticity in hardened condition
thereof associated with a high strength. The alloy has a high
temperature range, thereby making it possible to use it not only
for screw heads and helical springs but also for producing
large-sized semi-products whose cross section ranges up to 60 mm
and which are used in high temperature conditions.
Inventors: |
Tetyukhin; Vladisal
Valentinovich; (Moscow, RU) ; Zakharov; Jury
Ivanovich; (Moscow, RU) ; Levin; Igor
Vasilievich; (Sverdlovskaya obl., RU) |
Correspondence
Address: |
Adams and Reese
4400 One Houston Center
1221 McKinney
Houston
TX
77010
US
|
Family ID: |
32390762 |
Appl. No.: |
10/535791 |
Filed: |
August 21, 2003 |
PCT Filed: |
August 21, 2003 |
PCT NO: |
PCT/RU03/00378 |
371 Date: |
May 23, 2005 |
Current U.S.
Class: |
420/420 |
Current CPC
Class: |
C22C 14/00 20130101 |
Class at
Publication: |
420/420 |
International
Class: |
C22C 14/00 20060101
C22C014/00 |
Foreign Application Data
Date |
Code |
Application Number |
Nov 25, 2002 |
RU |
2002131 |
Claims
1. Alloy with the base of titanium, containing aluminum, vanadium,
molibdenum, chromium, iron, zirconium, carbon, oxygen, differing in
the fact that the alloy components are taken in the following ratio
of the % by weight. TABLE-US-00004 Aluminum 2.2-3.8 Vanadium
4.5-5.9 Molibdenum 4.5-5.9 Chromium 2.0-3.6 Zirconium 0.1-0.4 Iron
0.01-0.18 Carbon 0.01-0.25 Oxygen 0.03-0.25 Titanium balance
Description
FIELD OF THE INVENTION
[0001] The invention relates to the metallurgical one, and more
particularly to creation of the modern titanium alloys used for
making high-strength and high-tech items, including the large-sized
ones, i.e. alloys having the high generecity.
PRIOR STATE OF ART
[0002] One of the known titanium alloys is the alloy containing, in
% by weight: aluminum 2-6, molybdenum 6-9, vanadium 1-3, chromium
0.5-2.0, iron 0-1.5, titanium--balance (Inventor's Certificate USSR
No. 180351, Class C22C 14/00, published 1966).
[0003] This alloy was proposed for making die-forgings and forgings
for the highly loaded structural parts. The significant drawback is
its tendency to forming the high density inclusions when melting
ingots due to the high content of the refractory element molybdenum
(>6%). The presence of such inclusions in the high-loaded parts
leads to destruction of such parts when being in service.
[0004] The other known titanium alloy, containing % by weight:
4.0-6.3 Al; 4.0-5.0 V; 1.5-2.5 Mo; 0.8-1.4 Cr; 0.4-0.8 Fe;
0.01-0.08 Zr; 0.01-0.25 C; 0.03-0.25 O; balance--titanium
(Inventor's Certificate USSR No. 555161, Class C22C 14/00,
published 1977).
[0005] This alloy has the high strength properties, fine ductility,
not disposed to forming the high density inclusions.
[0006] The drawback of this alloy is the impossibility of cold
die-forging, caused by insufficient level of the index of the
process plasticity as age, such as the degree of cold upsetting
(less than 60%).
[0007] The closest to the claimed invention from the technical
point is the alloy with the base of titanium, containing % by
weight: 2.2-3.8 Al; 4.5-5.9 V; 4.5-5.9 Mo; 2.0-3.6 Cr; 0.2-0.8 Fe;
0.01-0.08 Zr; 0.01-0.25 C; 0.03-0.25 O; Ti--balance (RF Patent No.
2150528, Class C22C 14/00, published 2000)--prototype.
[0008] Alloy has the high level of plasticity as quenched, in this
case they achieve the degree of cold upsetting >75%.
[0009] However, the known alloy has the insufficiently high level
of the working temperatures, this limits the scope of its
application as a structural material for making parts, used at
increased temperatures.
DISCLOSURE OF THE INVENTION
[0010] This invention aims at creation of the titanium alloy with
the increased heat-resistance, which ensures the possibility of
making the heavy large-sized parts with the high level of the
strength and plastic properties, used at increased
temperatures.
[0011] The technical result achieved when patent pending is in
regulating the optimum combination of .alpha.- and
.beta.-stabilizing alloying elements in the finished
semiproduct.
[0012] The technical result is achieved due to the fact that in the
alloy with the base of titanium, containing aluminum, vanadium,
molibdenum, chromium, iron, zirconium, carbon, oxygen, according to
the invention, the components are taken in the following ratio,
weight %: TABLE-US-00001 Aluminum 2.2-3.8 Vanadium 4.5-5.9
Molibdenum 4.5-5.9 Chromium 2.0-3.6 Zirconium 0.1-0.4 Iron
0.01-0.18 Carbon 0.01-0.25 Oxygen 0.03-0.25 Titanium balance
[0013] The combination of high strength and plasticity of the
proposed alloy is achieved as a result of the task-oriented choice
and experimental evaluation of the alloying ranges. Content of the
.alpha.-stabilizing elements (aluminum, oxygen, carbon) and
.beta.-stabilizers (molibdenum, vanadium, chromium, iron) is chosen
as required and sufficient for achievement of the set target.
Besides, the proposed alloy ensures the possibility to effectively
regulate the strength level of the alloy as aged within the wide
ranges.
[0014] Balancing aluminum and chromium content in the claimed alloy
ensures high alloy ability for cold die forging (fine rolling to
bar) and possibility of alloy strengthening by the thermal
techniques obtaining the high level of the strength and plastic
properties.
[0015] With aluminum and chromium content below the minimum values
the alloy strength is lowered after thermostrengthening
(.sigma..sub.B<1400 MPa), i.e. the problem put is not
achieved.
[0016] When aluminum and chromium content exceeds the declared
limit the alloy plasticity lowers (.delta.<8%, .psi.<40%)
with the high strength level (.sigma..sub.B >1400 MPa).
[0017] To ensure the required strength (>1150 MPa) as quenched
and aged, as well as to perform quenching in the air, not in water,
the content of V and Mo is set as >4.5%.
[0018] V and Mo content is accepted 5.9% max due to the hazard of
significant growth of segregation non-uniformity and occurrence of
defects when using the hard master alloys.
[0019] As the increase of V and Mo content, as already said, is not
recommended to be above 5.9%, then for the subsequent (above 1150
MPa) increase of the strength properties (as quenched and aged)
they introduce the moderate additions of Cr (2.0-3.6%) and Fe (to
0.18%) within the limits, which do not bring to the occurrence of
the visible dentritic or zonal segregation.
[0020] In the proposed alloy, as compared to the prototype, the
iron content with the value of the distribution number is
decreased. ( K = Csolid .times. .times. phase .times. .times. %
Cliquid .times. .times. phase .times. .times. % ) ##EQU1## is
significantly below one, and this predetermines the iron tendency
to segregation, which is aggravated with the increase of the ingot
and item size.
[0021] Amount of zirconium in the alloy from 0.1 to 0.4% ensures
increase of the tensile strength without lowering of the metal
processibility during hot (not increases the flow stress) and cold
(not decreases the plasticity resource) deformation. In this case
stabilizing the .alpha.-phase, zirconium increases creep resistance
and high-temperature strength.
[0022] Introduction of zirconium exceeding 0.4% significantly
lowers the alloy processing plasticity during cold strain.
[0023] Ranges of alloying with zirconium and iron are selected on
the base of experimental evaluation of the alloy mechanical
properties in the proposed composition range. Content of zirconium
from 0.1 to 0.4% and iron to 0.18% ensures the increase of the
ultimate strength of the alloy in the as quenched and aged
condition.
[0024] The proposed combination of the components of the alloy and
their % ratio in complex ensures the possibility of the alloy
deformation in the greater temperature range and obtaining parts by
cold die forging.
EMBODIMENTS OF THE INVENTION
[0025] For the evaluation of the alloy properties the double-melt
ingots were vaccum arc remelting melted with the following alloy
compositions (Table 1). TABLE-US-00002 TABLE 1 Alloy chemistry, %
by weight Alloy Al V Mo Cr Fe Zr C O.sub.2 Ti 1 2.2 4.5 4.5 2.0 0.1
0.1 0.01 0.03 balance 2 3.0 5.2 4.8 2.8 0.15 0.2 0.2 0.2 balance 3
3.8 5.9 5.9 3.6 0.18 0.4 0.25 0.25 balance
[0026] The bars were made of each ingot with the diameter of 50 mm.
The bars were heat-treated to obtain the high strength. The
mechanical properties of bars at room temperature are show in Table
2. TABLE-US-00003 TABLE 2 Rate of Mechanical properties deformation
Resistance when cold Ultimate Yield Elonga- Reduction to shear
upsetting Strength Strength tion of Area .tau..sub.cp. Alloy
.epsilon., % .sigma..sub.B(MPa) .sigma..sub.0,2(MPa) .delta.(%)
.psi.(%) (MPa) 1 77 1425 1370 11 48 915 2 75 1470 1385 10 43 945 3
72 1515 1455 9 41 975 Required level 70 1400 1300 8 40 900 of
properties
[0027] Test results show that the declared items (bars with dia 50
mm) from titanium-base alloy have the high processing plasticity
level as quenched, in this case they achieve the degree of cold
upsetting >75% in combination with high strength obtained as a
result of the subsequent ageing (.sigma..sub.B>1500 Mpa).
COMMERCIAL PRACTICABILITY
[0028] The claimed alloy has the higher range of the working
temperatures (10-15.degree. C. higher than the alloy-prototype
has), this gives the possibility to use it not only when making the
bolt heads through cold heading, in cold threading, in production
of coil springs, and for making large semis up to 60 mm in section,
with the high level of strength and plastic properties, used at
increased temperatures.
* * * * *