U.S. patent application number 10/933638 was filed with the patent office on 2006-03-02 for high strength low cost titanium and method for making same.
This patent application is currently assigned to Coastcast Corporation. Invention is credited to Antonio F. Del Rosario, Jose Monterrosa, Rahbar Nasserrafi, Michael Wyte.
Application Number | 20060045789 10/933638 |
Document ID | / |
Family ID | 35241019 |
Filed Date | 2006-03-02 |
United States Patent
Application |
20060045789 |
Kind Code |
A1 |
Nasserrafi; Rahbar ; et
al. |
March 2, 2006 |
High strength low cost titanium and method for making same
Abstract
A titanium alloy and method of making the same are provided. The
alloy comprises one or more elements selected from the group
consisting of chromium, iron, and manganese. In an as-cast
condition, the alloy has a yield strength of at least about 135,000
psi, a tensile strength of at least about 155,000 psi and a percent
elongation of at least about 5.0 percent.
Inventors: |
Nasserrafi; Rahbar; (Chula
Vista, CA) ; Wyte; Michael; (Culver City, CA)
; Del Rosario; Antonio F.; (Whittier, CA) ;
Monterrosa; Jose; (Southgate, CA) |
Correspondence
Address: |
CHRISTIE, PARKER & HALE, LLP
PO BOX 7068
PASADENA
CA
91109-7068
US
|
Assignee: |
Coastcast Corporation
Rancho Dominguez
CA
|
Family ID: |
35241019 |
Appl. No.: |
10/933638 |
Filed: |
September 2, 2004 |
Current U.S.
Class: |
420/420 |
Current CPC
Class: |
C22C 14/00 20130101;
C22F 1/183 20130101 |
Class at
Publication: |
420/420 |
International
Class: |
C22C 14/00 20060101
C22C014/00 |
Claims
1. A titanium alloy, comprising: aluminum, in a range of about 3.5
to about 6.25 percent by weight of the alloy; vanadium, in a range
of about 3.0 to about 4.5 percent by weight of the alloy; one or
more elements selected from the group consisting of chromium, iron,
and manganese, wherein said one or more elements are present in a
range of about 1.0 to about 5.0 percent by weight of the alloy;
titanium being present in a remaining amount; wherein in an as-cast
condition, the alloy has a yield strength of at least about 135,000
psi.
2. The alloy of claim 1, wherein in an as-cast condition, the alloy
has a tensile strength of at least about 155,000 psi.
3. The alloy of claim 1, wherein in an as-cast condition, the alloy
has a percent elongation of at least about 5 percent.
4. The alloy of claim 1, wherein the amount of chromium is in a
range of about 1.0 to about 2.5 percent by weight of the alloy.
5. The alloy of claim 1, wherein the amount of chromium is in a
range of about 1.2 to about 2.0 percent by weight of the alloy.
6. The alloy of claim 1, wherein the amount of manganese is in a
range of up to about 2.0 percent by weight of the alloy.
7. The titanium alloy of claim 1, wherein the amount of manganese
is in a range of about 0.75 to about 1.25 percent by weight of the
alloy.
8. The titanium alloy of claim 1, wherein the amount of iron is in
a range of up to about 1.0 percent by weight of the alloy.
9. The titanium alloy of claim 1, wherein the amount of aluminum is
in a range of about 5.0 to about 6.0 percent by weight of the
alloy.
10. The titanium alloy of claim 1, wherein the amount of vanadium
is in a range of about 3.3 to about 4.5 percent by weight of the
alloy.
11. The titanium alloy of claim 1, wherein the combined amount of
chromium, manganese, and iron is in a range of about 2.0 percent to
about 3.5 percent by weight of the alloy.
12. The titanium alloy of claim 1, further comprising oxygen in a
range of up to about 0.3 percent by weight of the alloy.
13. A titanium alloy, comprising: titanium; and one or more
elements selected from the group consisting of chromium, manganese,
and iron, wherein in an as-cast condition, the alloy has a yield
strength of at least about 135,000 psi.
14. The titanium alloy of claim 13, further comprising
aluminum.
15. The titanium alloy of claim 14, wherein the amount of aluminum
is in a range of about 3.5 to about 6.25 percent by weight of the
alloy.
16. The titanium alloy of claim 13, further comprising
vanadium.
17. The titanium alloy of claim 16, wherein the amount of vanadium
is in a range of about 3.0 to about 4.5 percent by weight of the
alloy.
18. The titanium alloy of claim 13, wherein the amount of chromium
is in a range of up to about 3.8 percent by weight of the
alloy.
19. The titanium alloy of claim 13, further comprising oxygen.
20. The titanium alloy of claim 19, wherein the amount of oxygen is
in a range of up to about 0.3 percent by weight of the alloy.
21. The titanium alloy of claim 13, wherein the amount of manganese
is in a range of up to about 2.0 percent by weight of the
alloy.
22. The titanium alloy of claim 13, wherein the amount of manganese
is in a range of about 0.75 to about 1.25 percent by weight of the
alloy.
23. The titanium alloy of claim 13, wherein the amount of chromium
is in a range of about 1.0 to about 2.5 percent by weight of the
alloy.
24. The titanium alloy of claim 13, wherein the amount of iron is
in a range of up to about 1.0 percent by weight of the alloy.
25. The titanium alloy of claim 13, wherein the combined amount of
chromium, manganese, and iron is in a range of about 1.0 to about
5.0 percent by weight of the alloy.
26. The titanium alloy of claim 13, wherein the combined amount of
chromium, manganese, and iron is in a range of about 2.0 to about
3.5 percent by weight of the alloy.
27. The titanium alloy of claim 13, wherein in an as-cast
condition, the alloy has a tensile strength of at least about
155,000 psi.
28. The titanium alloy of claim 13, wherein in an as-cast
condition, the alloy has a percent elongation of at least about 5.0
percent.
29. A method of making a titanium alloy, comprising: combining a
titanium material with one or more elements selected from the group
consisting of chromium, manganese, and iron, wherein in an as-cast
condition, the titanium alloy has a yield strength of at least
about 135,000 psi.
30. The method of claim 29, wherein the combined amount of
chromium, manganese, and iron in the alloy is in a range of about
1.0 to about 5.0 percent by weight of the alloy.
31. The method of claim 29, wherein the combined amount of
chromium, manganese, and iron in the alloy is in a range of about
2.0 to about 3.5 percent by weight of the alloy.
32. The method of claim 29, wherein the alloy comprises oxygen in a
range of up to about 0.3 percent by weight of the alloy.
33. The method of claim 32, wherein the amount of oxygen in the
alloy is greater than about 0.2 percent by weight of the alloy.
34. The method of claim 29, wherein the amount of manganese in the
alloy is in a range of up to about 2 percent by weight of the
alloy.
35. The method of claim 29, wherein the amount of manganese in the
alloy is in a range of about 0.75 to about 1.25 percent by weight
of the alloy.
36. The method of claim 29, wherein the amount of chromium in the
alloy is in a range of up to about 3.8 percent by weight of the
alloy.
37. The method of claim 29, wherein the amount of chromium in the
alloy is in a range of about 1.0 to about 2.5 percent by weight of
the alloy.
38. The method of claim 29, wherein the amount of iron in the alloy
is in a range of up to about 1.0 percent by weight of the
alloy.
39. The method of claim 29, wherein the titanium material is a
recycled titanium material.
40. The method of claim 29, wherein the titanium material is a
Ti-6Al-4V material.
41. The method of claim 29, wherein the titanium material is a
commercially pure titanium material.
42. The method of claim 41, further comprising the step of
combining aluminum with the titanium material, wherein the amount
of aluminum in the alloy is in a range of about 3.5 to about 6.25
percent by weight of the alloy.
43. The method of claim 41, further comprising the step of
combining vanadium with the titanium material, wherein the amount
of vanadium in the alloy is in a range of about 3.0 to about 4.5
percent by weight of the alloy.
44. The method of claim 29, wherein the titanium material is a
Ti-3Al-2,5V material.
45. The method of claim 44, further comprising the step of
combining aluminum with the titanium material, wherein the amount
of aluminum in the alloy is in a range of about 3.5 to about 6.25
percent by weight of the alloy.
46. The method of claim 44, further comprising the step of
combining vanadium with the titanium material, wherein the amount
of vanadium in the alloy is in a range of about 3.0 to about 4.5
percent by weight of the alloy.
47. The method of claim 29, wherein the titanium material is scrap
titanium material.
48. The method of claim 29, wherein the titanium material comprises
aluminum in a range of about 3.5 to about 6.25 percent by weight of
the alloy.
49. The method of claim 29, wherein the titanium material comprises
vanadium in a range of about 3.0 to about 4.5 percent by weight of
the alloy.
50. The method of claim 29, wherein in an as-cast condition, the
alloy has a tensile strength of at least about 155,000 psi.
51. The method of claim 29, wherein in an as-cast condition, the
alloy has a percent elongation of at least about 5.0 percent.
52. A method of making a titanium alloy, comprising: providing a
titanium material comprising aluminum in a range of about 3.5 to
about 6.25 percent by weight of the alloy, oxygen in a range of up
to about 0.3 percent by weight and vanadium in a range of about 3.0
to about 4.5 percent by weight of the alloy; combining the titanium
material with manganese, such that the amount of manganese in the
alloy is in a range of about 0.75 to about 2.0 percent by weight of
the alloy, chromium, such that the amount of chromium in the alloy
is in a range of up to about 3.8 percent by weight of the alloy,
and iron, such that the amount of iron in the alloy is in a range
of up to about 1.0 percent by weight of the alloy, wherein the
combined amount of manganese, chromium, and iron in the alloy is in
a range of about 1.0 to about 5.0 percent by weight of the
alloy.
53. The method of claim 52, wherein the combined amount of
manganese, chromium, and iron in the alloy is in a range of about
2.0 to about 3.5 percent by weight of the alloy.
54. The method of claim 52, wherein the amount of chromium in the
alloy is in a range of about 1.0 to about 2.5 percent by weight of
the alloy.
55. The method of claim 52, wherein in an as-cast condition, the
alloy has a yield strength of at least about 135,000 psi.
56. The method of claim 52, wherein in an as-cast condition, the
alloy has a tensile strength of at least about 155,000 psi.
57. The method of claim 52, wherein in an as-cast condition, the
alloy has a percent elongation of at least about 5.0 percent.
58. A titanium alloy, comprising: chromium, in a range of up to
about 3.8 percent by weight of the alloy; iron, in a range of up to
about 1.0 percent by weight of the alloy; manganese, in a range of
about 0.75 to about 1.25 percent by weight of the alloy; titanium,
being present in a remaining amount; wherein the combined amount of
chromium, iron and manganese is in a range of about 1.0 to about
5.0 percent by weight of the alloy.
59. The titanium alloy of claim 58, further comprising oxygen in a
range of up to about 0.3 percent by weight of the alloy.
60. The titanium alloy of claim 58, further comprising aluminum in
a range of about 3.5 to about 6.25 percent by weight of the
alloy.
61. The titanium alloy of claim 58, further comprising vanadium in
a range of about 3.0 to about 4.5 percent by weight of the
alloy.
62. The titanium alloy of claim 58, wherein the combined amount of
chromium, manganese, and iron is in a range of about 2.0 to about
3.5 percent by weight of the alloy.
63. The titanium alloy of claim 58, wherein in an as-cast
condition, the alloy has a yield strength of at least about 135,000
psi.
64. The titanium alloy of claim 58, wherein in an as-cast
condition, the alloy has a tensile strength of at least about
155,000 psi.
65. The titanium alloy of claim 58, wherein in an as-cast
condition, the alloy has a percent elongation of at least about 5.0
percent.
66. An titanium alloy, comprising: aluminum, in a range of about
3.5 to about 6.25 percent by weight of the alloy; vanadium, in a
range of about 3.0 to about 4.5 percent by weight of the alloy;
iron, in a range of up to about 1.0 percent by weight; chromium, in
a range of up to about 3.8 percent by weight of the alloy;
manganese, in a range of about 0.75 to about 2.0 percent by weight
of the alloy; and oxygen, in an range of up to about 0.3 percent by
weight of the alloy; and titanium, being present in a remaining
amount; wherein the combined amount of manganese, chromium and iron
is in a range of about 1.0 to about 5.0 percent by weight of the
alloy.
67. The titanium alloy of claim 66, wherein the amount of chromium
is in a range of about 1.0 to about 2.5 percent by weight of the
alloy.
68. The titanium alloy of claim 66 further comprising a
pre-existing titanium material.
69. The titanium alloy of claim 68, wherein the pre-existing
titanium material is a recycled titanium material.
70. The titanium alloy of claim 66, wherein the combined amount of
manganese, chromium and iron is in a range of about 2.0 to about
3.5 percent by weight of the alloy.
71. The titanium alloy of claim 66, wherein in an as-cast
condition, the alloy has a yield strength of at least about 135,000
psi.
72. The titanium alloy of claim 66, wherein in an as-cast
condition, the alloy has a tensile strength of at least about
155,000 psi.
73. The titanium alloy of claim 66, wherein in an as-cast
condition, the alloy has a percent elongation of at least about 5.0
percent.
74. A titanium alloy, comprising: aluminum, in a range of about 3.5
to about 6.25 percent by weight of the alloy; vanadium, in a range
of about 3.0 to about 4.5 percent by weight of the alloy; chromium,
in a range of up to about 3.8 percent by weight of the alloy;
manganese, in a range of up to about 2.0 percent by weight of the
alloy; iron, in a range of up to about 1.0 percent by weight of the
alloy; oxygen, in a range of more than about 0.2 percent to about
0.3 percent by weight of the alloy; and titanium present in a
remaining amount; wherein, the combined amount of chromium,
manganese and iron is in a range of about 2.0 to about 3.5 percent
by weight of the alloy.
75. The alloy of claim 74, wherein the amount of aluminum is in a
range of about 5.0 to about 6.0 percent by weight of the alloy.
76. The alloy of claim 74, wherein the amount of vanadium is in a
range of about 3.3 to about 4.5 percent by weight of the alloy.
77. The alloy of claim 74, wherein the amount of manganese is in a
range of up to about 1.5 percent by weight of the alloy.
78. The alloy of claim 74, wherein the amount of manganese is in a
range of about 0.75 to about 1.25 percent by weight of the
alloy.
79. The alloy of claim 74, wherein the amount of chromium is in a
range of about 1.0 to about 2.5 percent by weight of the alloy.
80. The alloy of claim 74, wherein in an as-cast condition, the
alloy has a yield strength of at least about 135,000 psi.
81. The alloy of claim 74, wherein in an as-cast condition, the
alloy has a percent elongation of at least about 5.0 percent by
weight.
82. The alloy of claim 74, wherein in an as-cast condition, the
alloy has a tensile strength of at least about 155,000 psi.
83. The alloy of claim 74, further comprising nitrogen in a range
of up to about 0.05 percent by weight of the alloy.
84. The alloy of claim 83, further comprising carbon in a range of
up to about 0.1 percent by weight.
85. The alloy of claim 84, further comprising other elements,
wherein each said other element is present in a range of up to
about 0.1 percent by weight of the alloy and the combined amount of
said other elements is in a range of up to about 0.4 percent by
weight of the alloy.
86. A method of making a titanium alloy, comprising: providing a
titanium material; combining the titanium material with manganese,
such that the amount of manganese in the alloy is in a range of
about 0.75 to about 1.25 percent by weight of the alloy, chromium,
such that the amount of chromium in the alloy is in a range of up
to about 3.8 percent by weight of the alloy, and iron, such that
the amount of iron in the alloy is in a range of up to about 1.0
percent by weight of the alloy; wherein the combined amount of
chromium, manganese, and iron in the alloy is in a range of about
1.0 to about 5.0 percent by weight of the alloy.
87. The method of claim 86, wherein the titanium material comprises
aluminum in a range of about 3.5 to about 6.25 percent by weight of
the alloy.
88. The method of claim 86, wherein the titanium material comprises
vanadium in a range of about 3.0 to about 4.5 percent by weight of
the alloy.
89. The method of claim 86, wherein the titanium material comprises
commercially pure titanium.
90. The method of claim 89, further comprising the step of
combining aluminum with the titanium material, wherein the amount
of aluminum in the alloy is in a range of about 3.5 to about 6.25
percent by weight of the alloy.
91. The method of claim 89, further comprising the step of
combining vanadium with the titanium material, wherein the amount
of vanadium in the alloy is in a range of about 3.0 to about 4.5
percent by weight of the alloy.
Description
FIELD OF THE INVENTION
[0001] The present invention relates generally to titanium alloys,
and more particularly, to a new titanium alloy and method for
making the same which can be manufactured from recycled
titanium.
BACKGROUND OF THE INVENTION
[0002] Titanium alloys offer attractive combinations of physical
and mechanical properties which make them ideal for applications
requiring high strength, low weight, and good corrosion properties.
However, titanium alloys are expensive to manufacture, which
severely limits their application. A number of processing steps are
required to refine titanium from its raw form to a usable form. In
addition, because of its highly reactive nature, the refining
process must be carefully controlled, further increasing
manufacturing costs. As a result, the use of titanium is typically
limited to military vehicles, airplane engine and air-frame
components, chemical processing, and sports hardware.
[0003] It is desirable to use recycled titanium to reduce
manufacturing costs. However, the ability to use recycled materials
is limited. To obtain the desired strength and ductility, the
oxygen content of most conventional medium and high strength
titanium alloys is typically limited to 0.2 percent by weight of
the alloy. This relatively low oxygen limit makes it difficult to
use recycled titanium materials. During the recycling process, the
titanium materials are exposed to air while being melted and
subsequently cooled. As a result they tend to absorb oxygen and
other interstitial elements each time they are recycled.
[0004] As a result, a need has arisen for a new titanium alloy and
a method of making the same.
SUMMARY OF THE PREFERRED EMBODIMENTS
[0005] In accordance with one aspect of the present invention, a
titanium alloy is provided. The alloy comprises titanium and one or
more elements selected from the group consisting of chromium,
manganese, and iron, wherein in an as-cast condition, the alloy has
a yield strength of at least about 135,000 psi.
[0006] The alloy preferably comprises aluminum in a range of about
3.5 to about 6.25 percent by weight of the alloy, with ranges of
about 4.5 to about 6.0 percent and about 5.0 to about 6.0 percent
being more preferred and especially preferred, respectively. In a
preferred embodiment, the alloy comprises vanadium in a range of
about 3.0 to about 4.5 percent by weight of the alloy, with ranges
of about 3.3 to about 4.5 percent and about 3.5 to about 4.5
percent being more preferred and especially preferred,
respectively. In accordance with another preferred embodiment, the
amount of chromium is in a range of up to about 3.8 percent by
weight of the alloy, with ranges of about 1.0 to about 2.5 percent
and about 1.2 to about 2.0 percent being more preferred and
especially preferred, respectively. In other preferred embodiments,
the amount of manganese is in a range of up to about 2.0 percent by
weight of the alloy, with ranges of up to about 1.5 percent and
about 0.75 to about 1.25 percent being more preferred and
especially preferred, respectively.
[0007] In yet other preferred embodiments, the alloy comprises
oxygen in a range of up to about 0.3 percent by weight, with ranges
of up to about 0.29 percent and up to about 0.27 percent being more
preferred and especially preferred, respectively. It is further
preferred that the combined amount of chromium, manganese, and iron
is in a range of about 1.0 to about 5.0 percent by weight of the
alloy, with ranges of about 1.0 to about 4.5 percent and about 2.0
to about 3.5 percent being more preferred and especially preferred,
respectively.
[0008] In accordance with another aspect of the present invention,
a titanium alloy is provided. The alloy comprises aluminum, in a
range of about 3.5 to about 6.25 percent by weight of the alloy;
vanadium, in a range of about 3.0 to about 4.5 percent by weight of
the alloy; and one or more elements selected from the group
consisting of chromium, iron, and manganese, wherein the one or
more elements are present in a range of about 1.0 to about 5.0
percent by weight of the alloy. Titanium is present in a remaining
amount, and in an as-cast condition, the alloy preferably has a
yield strength of at least about 135,000 psi.
[0009] The amount of aluminum is more preferably in a range of
about 4.5 to about 6.0 percent by weight of the alloy, with a range
of about 5.0 to about 6.0 percent being especially preferred. The
amount of vanadium is more preferably in a range of about 3.3 to
about 4.5 percent by weight of the alloy, with a range of about 3.5
to about 4.5 percent being especially preferred. The amount of
chromium in the alloy is preferably in a range of up to about 3.8
percent by weight of the alloy, with ranges of about 1.0 to about
2.5 percent and about 1.2 to about 2.0 percent being more preferred
and especially preferred, respectively. The amount of manganese is
preferably in a range of up to about 2.0 percent by weight of the
alloy, with ranges of up to about 1.5 percent and about 0.75 to
about 1.25 percent being more preferred and especially preferred,
respectively. The amount of iron is preferably in a range of up to
about 1.0 percent by weight of the alloy. The amount of oxygen is
preferably in a range of up to about 0.3 percent by weight of the
alloy, with ranges of up to about 0.29 percent and up to about 0.27
percent being more preferred and especially preferred,
respectively. The alloy preferably has a tensile strength of at
least about 155,000 psi and a percent elongation of at least about
5.0 percent.
[0010] In accordance with yet another aspect of the present
invention, a titanium alloy is provided which comprises chromium,
in an range of up to about 3.8 percent by weight of the alloy;
iron, in a range of up to about 1.0 percent by weight of the alloy;
and manganese, in a range of about 0.75 to about 1.25 percent by
weight of the alloy, wherein the combined amount of chromium, iron,
and manganese is in a range of about 1.0 to about 5.0 percent by
weight of the alloy. Titanium is present in a remaining amount.
[0011] In accordance with still another aspect of the present
invention, a titanium alloy is provided which comprises aluminum in
a range of about 3.5 to about 6.25 percent by weight of the alloy;
vanadium, in a range of about 3.0 to about 4.5 percent by weight of
the alloy; chromium, in range of up to about 3.8 percent by weight
of the alloy; manganese, in a range of up to about 2.0 percent by
weight of the alloy; iron, in a range of up to about 1.0 percent by
weight of the alloy; oxygen, in a range of more than about 0.2 to
about 0.3 percent by weight of the alloy; and titanium in a
remaining amount, wherein the combined amount of chromium,
manganese, and iron is in a range of about 2.0 to about 3.5 percent
by weight of the alloy.
[0012] In accordance with another aspect of the present invention,
a method of making a titanium alloy is provided. The method
comprises combining a titanium material with one or more elements
selected from the group consisting of chromium, manganese, and
iron, wherein in an as-cast condition, the titanium alloy has a
yield strength of at least about 135,000 psi. In a preferred
embodiment, the combined amount of chromium, manganese, and iron in
the alloy is in a range of about 1.0 to about 5.0 percent by weight
of the alloy. In still other preferred embodiments, the combined
amount of chromium, manganese, and iron in the alloy is in a range
of about 2.0 to about 3.5 percent by weight of the alloy.
[0013] Preferably, the alloy comprises oxygen in range of up to
about 0.3 percent by weight of the alloy. Even more preferably, the
amount of oxygen in the alloy is greater than about 0.2 percent by
weight of the alloy. In another preferred embodiment, the amount of
manganese in the alloy is in a range of about 0.75 to about 1.25
percent of the alloy. In additional preferred embodiments, the
amount of chromium in the alloy is in a range of up to about 3.8
percent by weight of the alloy, with a range of about 1.0 to about
2.5 percent being more preferred. In other preferred embodiments,
the amount of iron in the alloy is in a range of up to about 1.0
percent by weight of the alloy.
[0014] In a preferred embodiment, the titanium material is a
recycled titanium material. In other preferred embodiments, the
titanium material is a Ti-6Al-4V material. In yet other preferred
embodiments, the titanium material is a commercially pure titanium
material. In still other preferred embodiments, the titanium
material is a Ti-3Al-2,5Al material.
[0015] In accordance with an additional aspect of the present
invention, a method of making a titanium alloy is provided which
comprises providing a titanium material and combining it with
manganese, such that the amount of manganese in the alloy is in a
range of about 0.75 to about 1.25 percent by weight of the alloy;
chromium, such that the amount of chromium in the alloy is in an
range of up to about 3.8 percent by weight of the alloy; and iron,
such that the amount of iron in the alloy is in an range of up to
about 1.0 percent by weight of the alloy, wherein the combined
amount of chromium, manganese, and iron in the alloy is in a range
of about 1.0 to about 5.0 percent by weight of the alloy.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0016] The present invention is directed to titanium alloys that
can be produced from recycled commercial titanium alloys. As
indicated in Table 1, in order to maintain desirable strength and
ductility, commercial titanium alloys are typically limited to an
oxygen content of no more than 0.2 percent by weight of the alloy.
TABLE-US-00001 TABLE 1 Conventional Titanium alloys Alloy Al V Mo
Sn Zr Cr Fe Mn O Ti--6Al--4V 5.5-6.75 3.5-4.5 0.3 max 0.2 max
Ti--6Al--2Sn-- 5.25-6.25 1.75-2.25 1.75-2.25 1.75-2.25 1.75-2.25
0.13 max 2Mo--2Zr--2Cr Ti--6Al--2Sn-- 5.5-6.5 5.5-6.5 1.75-2.25
3.5-4.5 0.15 max 0.15 max 4Zr--6Mo Ti--15V--3Cr-- 2.5-3.5
14.0-1about 6.0 2.5-3.5 2.5-3.5 0.25 max 0.13 max 3Al--3Sn
Ti--10V--2Fe--3Al 2.6-3.4 9.0-11.0 1.6-2.2 0.13 max
[0017] As is known to those skilled in the art, at temperatures
below approximately 880.degree. C., titanium assumes a close-packed
hexagonal structure referred to as the "alpha" phase. At
temperatures of 880.degree. C. and above, titanium assumes a body
centered cubic structure known as the "beta" phase. It has been
found that by adding at least one beta-eutectoid stabilizing
element, preferably one selected from the group consisting of
chromium, iron and manganese, titanium alloys of the present
invention can tolerate higher levels of oxygen, and therefore, can
be manufactured from increased amounts of recycled materials.
Alloys of the present invention preferably have yield strengths of
at least about 135,000 psi, tensile strengths of at least about
155,000 psi and percent elongation values of at least about 5
percent.
[0018] The base titanium material used to form alloys of the
present invention is preferably a Ti-3Al-2,5V alloy, a Ti-6Al-4V
alloy or commercially pure titanium. As used herein, the term
"commercially pure titanium" refers to a titanium material in which
the amount of titanium is at least about 98 percent by weight of
the material. Ti-6Al-4V alloys and commercially pure titanium are
abundantly available in various forms, including electrodes, scrap
and plate material and are readily available for recycling.
[0019] A first preferred embodiment of the present invention will
now be described. According to this embodiment, the alloy
preferably comprises aluminum in a range of about 3.5 to about 6.25
percent by weight of the alloy. A range of about 4.5 to about 6.0
percent is more preferred, and a range of about 5.0 to about 6.0
percent is especially preferred. Aluminum is an alpha-phase
stabilizer which helps increase alloy strength. As is known to
those skilled in the art, Rosenberg's empirical formula describes a
relationship between titanium alloying elements which can be used
to prepare alloys having good ductility, strength and metallurgical
stability. In particular, it is used to develop high temperature
titanium alloys having maximum aluminum equivalents. Rosenberg's
formula is as follows: Al+1/3Sn+1/6Zr+10 Oxygen.ltoreq.9
[0020] In accordance with this embodiment, the alloy preferably
contains no tin or zirconium. It is especially preferred that the
aluminum content not exceed about 6.0 percent aluminum, because in
the absence of tin and zirconium, such an alloy will satisfy
Rosenberg's formula at oxygen levels of up to 0.3 percent by weight
of the alloy.
[0021] In accordance with this embodiment, the alloy preferably
contains vanadium in a range of about 3.0 to about 4.5 percent by
weight of the alloy. Vanadium is a beta-isomorphous stabilizer
which is used to increase the strength of the alloy. The ratio of
vanadium to aluminum may impact the alloy's phase balance and is
preferably maintained at a level which allows for optimization of
mechanical properties by precipitation hardening alpha-beta and
metastable beta titanium alloys.
[0022] The alloy also preferably contains at least one
beta-eutectoid stabilizing element selected from the group
consisting of chromium, iron and manganese. The combined amount of
chromium, iron, and manganese is preferably in a range of about 1.0
to about 5.0 percent by weight of the alloy. A range of about 1.0
to about 4.5 percent is more preferred, and a range of about 2.0 to
about 3.5 percent is especially preferred.
[0023] Chromium is preferably present in a range of up to about 3.8
percent by weight of the alloy. A chromium range of about 1.0 to
about 2.5 percent is more preferred, and a range of about 1.2 to
about 2.0 percent is especially preferred.
[0024] In accordance with this embodiment, iron is preferably
present in a range of up to about 1.0 percent by weight. Manganese
is preferably present in a range of up to about 2.0 percent by
weight of the alloy. A manganese range of up to about 1.5 percent
is more preferred, and a range of about 0.75 to about 1.25 percent
by weight is especially preferred. It has been found that adding
Manganese in the foregoing levels improves alloy strength.
[0025] Chromium, iron, and manganese are effective beta-eutectoid
stabilizers. They are used to increase strength and control
ductility and the alloy's response to thermal treatment. They are
easy to melt and can be added in their elemental forms. As a
result, they are relatively inexpensive to process. Although all
three elements are beta-eutectoid stabilizers, it has been found
that combining them is especially preferred for obtaining alloys
with excellent strength and ductility from recycled titanium
materials.
[0026] As explained previously, it has been found that the addition
of the foregoing beta-eutectoid stabilizing elements allows the
alloys of the present invention to tolerate increased oxygen levels
while still maintaining excellent ductility. In accordance with
this embodiment, oxygen is present in a range of up to about 0.3
percent by weight of the alloy. Oxygen ranges of up to 0.29 percent
are more preferred, and an oxygen range of up to about 0.27 percent
is especially preferred. The ability of alloys of this embodiment
to tolerate such levels of oxygen allows them to be manufactured
from increased amounts of recycled titanium materials. In addition,
the increased levels of oxygen improve alloy ductility.
[0027] In accordance with this embodiment, other elements may also
be present. Preferably, nitrogen levels are not more than about
0.05 percent by weight of the alloy. Nitrogen levels of not more
than about 0.04 percent are more preferred, and nitrogen levels of
not more than about 0.035 percent are especially preferred. The
alloy preferably contains carbon levels of not more than about 0.1
percent by weight of the alloy. Carbon levels of not more than
about 0.05 percent are more preferred, and carbon levels of not
more than about 0.03 are especially preferred.
[0028] Hydrogen levels are preferably maintained at not more than
about 150 ppm of the alloy weight. Hydrogen levels of not more than
about 125 ppm are especially preferred. If present, it is preferred
that any elements other than the foregoing are present in amounts
of not more than about 0.1 percent by weight each, with their
combined amounts not exceeding 0.4 percent by weight. For ease of
reference, set forth below in Table 2 are the preferred, most
preferred, and especially preferred ranges of ingredients used in
this embodiment of the present invention: TABLE-US-00002 TABLE 2
Ranges of elements as weight percent of alloy Preferred More
Preferred Especially Element Range Range Preferred Range aluminum
about 3.5-about about 4.5-about about 5.0-about 6.25 6.0 6.0
vanadium about 3.0-about about 3.3-about about 3.5-about 4.5 4.5
4.5 chromium up to about 3.8 about 1.0 to about 1.2 to about 2.5
about 2.0 manganese up to about 2.0 up to about 1.5 about 0.75-
about 1.25 iron up to about 1.0 up to about 1.0 up to about 1.0
oxygen up to about 0.3 up to about up to about 0.29 0.27 nitrogen
not more than not more than not more than about 0.05 about 0.04
about 0.035 hydrogen not more than not more than not more than
about 150 ppm about 125 ppm about 125 ppm carbon not more than not
more than not more than about 0.1 about 0.05 about 0.03 others,
each not more than not more than not more than about 0.1 about 0.1
about 0.1 others, total not more than not more than not more than
about 0.4 about 0.4 about 0.4 Cr + Mn + Fe about 1.0 to about 1.0
to about 2.0 to about 5.0 about 4.5 about 3.5.
[0029] In their as-cast condition, alloys prepared in accordance
with this embodiment will preferably have a tensile strength of at
least about 135,000 psi. They will also preferably have a yield
strength of at least about 155,000 psi and a percent elongation of
at least about 5.0 percent. As used herein, the term "as-cast"
refers to the condition of the alloy following casting but prior to
any heat treatment, annealing, forming, or any other
thermo-mechanical treatment. It is expected that wrought products
which have undergone such processes will have even higher yield
strengths, tensile strengths and percent elongation values.
[0030] An embodiment of a method of making a titanium alloy in
accordance with the present invention will now be described.
According to this embodiment, a pre-existing commercially pure
titanium material, which is preferably recycled or scrap titanium,
is provided. In this embodiment, Grade 1 commercially pure titanium
designated as UNS (Unified Numbering System) R50250 is used. In
addition to titanium, R50250 comprises 0.20 weight percent iron and
0.18 weight percent oxygen. Because it is recycled, however, the
oxygen level will be higher than that of virgin R50250
material.
[0031] According to this embodiment, the R50250 material is melted
and combined with an aluminum/vanadium master alloy. Preferably,
the amount of aluminum in the Al/V master alloy is such that the
aluminum composition in the titanium alloy is in a range of about
3.5 to about 6.25 percent by weight of the alloy. The amount of
vanadium in the Al/V master alloy is preferably such that the
vanadium composition of the titanium alloy is in a range of about
3.0 to about 4.5 percent by weight of the alloy. At least one
beta-eutectoid stabilizer selected from the group consisting of
chromium, iron and manganese is added such that their combined
amount in the alloy is in a range of about 1.0 to about 5.0 percent
by weight of the alloy. The amount of chromium in the alloy is
preferably in a range of up to about 3.8 percent by weight of the
alloy, and the amount of manganese in the alloy is preferably in a
range of up to about 2.0 percent by weight of the alloy. The amount
of iron in the alloy is preferably in a range of up to about 1.0
percent by weight of the alloy. The amount of oxygen in the alloy
is preferably in a range of up to about 0.3 percent by weight of
the alloy. Oxygen levels are preferably controlled by selecting
scrap titanium or sponge with suitably low oxygen content. If
present, carbon, hydrogen, nitrogen and additional impurities are
preferably kept within the ranges specified in the "preferred
range" in Table 1. Levels of these elements in the alloy are also
preferably controlled by selecting recycled titanium materials with
suitably low levels of them.
[0032] It is more preferable to add amounts of aluminum, vanadium,
chromium, manganese and iron which yield the weight percentages
specified in the "more preferred range" column of Table 2 and to
control the levels of oxygen, nitrogen, hydrogen, carbon and other
impurities in the alloy to the levels specified in the more
preferred range column. It is especially preferred that alloys
prepared in accordance with this embodiment contain the amounts of
the foregoing elements listed in the "especially preferred range"
column of Table 2. Alloys prepared according to the method of this
embodiment will preferably have a yield strength of at least about
135,000 psi, a tensile strength of at least about 155,000 psi, and
a percent elongation of at least about 5.0 percent.
[0033] In accordance with another embodiment of the present
invention, a method of preparing a titanium alloy from a
pre-existing Ti-6Al-4V material is provided. The Ti-6Al-4V material
is preferably a recycled or scrap material. Commercially produced
Ti-6Al-4V contains 5.5 to 6.75 percent by weight aluminum, 3.5
percent to 4.5 percent by weight vanadium, up to 0.3 percent by
weight iron, and up to 0.2 percent by weight oxygen. However, due
to the use of recycled material, the oxygen content will typically
exceed 0.2 percent. In accordance with this embodiment, the
aluminum content in the Ti-6Al-4V will preferably not exceed about
6.0 percent by weight of the alloy.
[0034] At least one beta-eutectoid stabilizer selected from the
group consisting of chromium, manganese, and iron is combined with
the Ti-6Al-4V material such that the combined amount of chromium,
manganese, and iron is within the preferred range specified in
Table 2. It is more preferred to use the range specified in the
more preferred column of Table 2 and especially preferred to use
the range specified in the especially preferred column of Table 2.
Oxygen, carbon, hydrogen, nitrogen, and other impurities are also
preferably kept within the ranges specified in Table 2. Alloys
prepared according to the method of this embodiment will preferably
have a yield strength of at least about 135,000 psi, a tensile
strength of at least about 155,000 psi, and a percent elongation of
at least about 5.0 percent.
[0035] According to another embodiment of the present invention, a
method of making a titanium alloy from a pre-existing Ti-3Al-2,5V
alloy is provided. The alloy is preferably recycled. According to
this embodiment, aluminum and vanadium are combined with the
recycled Ti-3Al-2,5V material such that the resulting alloy
contains aluminum in a range of about 3.5 to about 6.25 percent by
weight of the alloy and vanadium in a range of about 3.0 to about
4.5 percent by weight of the alloy. At least one beta eutectoid
stabilizer selected from the group consisting of chromium,
manganese, and iron is added such that their combined amounts in
the alloy are in a range of about 1.0 to about 5.0 percent by
weight of the alloy. Preferably, the alloy has an oxygen content in
a range of up to about 0.3 percent by weight of the alloy. The
remaining preferred, more preferred, and especially preferred
values for the various elements in Table 2 are applicable to this
method as well.
[0036] The invention may be better understood by referring to the
following examples of titanium alloys prepared in accordance with
the present invention. All samples were heat treated by hipping
(hot isostatically pressing) at 1650.degree. F. and 15,000.+-.500
psi for 2 hours followed by aging in a range of from 900.degree. F.
to 1100.degree. F. for periods of from 4 to 12 hours.
TABLE-US-00003 TABLE 3 Examples Sample Sample Sample Sample Sample
Sample Sample Sample Element 1 2 3 4 5 6 7 8 Al 5.81 5.76 5.5 5.8
5.89 5.7 5.44 5.62 V 3.77 3.73 3.69 3.8 3.71 3.7 3.64 3.83 Cr 1.37
2.22 1.8 1.16 1.15 1.93 1.28 -- Mn -- -- 1.03 -- 1.15 1.58 0.98
1.84 Fe 0.19 0.15 0.17 0.12 0.17 0.014 0.96 0.17 O 0.27 0.26 0.27
0.24 0.27 0.29 0.28 0.29 N 0.022 0.02 0.023 0.018 0.024 0.03 0.038
0.03 H 0.0029 0.007 0.0075 0.0037 0.0049 0.0014 0.0034 0.0015 C
0.02 0.02 0.02 0.02 0.02 0.01 0.02 0.01 Ti bal. bal. bal. bal. bal.
bal. bal. bal. Condition as as as as as as as as cast cast cast
cast cast cast cast cast YS, ksi 138 143 143 136 145 149 UTS, ksi
161 164 164 159 166 169 % elong. 8.5 8.5 7.5 9.5 6.5 7 % RA 19 23
18 17 17 14 Condition heat heat heat heat heat heat heat heat treat
treat treat treat treat treat treat treat YS, ksi 144 146 150 145
150 152 153 149 UTS, ksi 160 162 165 165 171 167 165 164 % elong.
9.5 11 10 9 7 9 8 7.5 % RA 23 22 22 15 14 17 21 16.5 Key: bal. =
balance, YS = yield strength, Ksi = 1000 lb/(.in).sup.2, UTS =
Ultimate Tensile Strength, % elong. = percent elongation, % RA =
percent reduction in area. The term "heat treat" refers to the
material following heat treating.
[0037] As the data indicates, the alloys in Table 3 all had oxygen
levels well above the conventional limit of 0.2 weight percent, yet
attained as-cast yield strengths of greater than 135,000 psi,
tensile strengths of greater than 155,000 psi, and percent
elongation values of greater than 5%. In addition, strength and
ductility were further improved with heat treating.
[0038] Table 4 provides a comparison of the yield strength, tensile
strength, and percent elongation of certain of the alloys in Table
3 with several commercial alloys: TABLE-US-00004 TABLE 4 Comparison
of Commercial Alloys to Embodiments of the Present Invention YS UTS
% Alloy and condition ksi ksi elongation Ti--6Al--4V (cast and heat
treated) 120 134 8 Ti--6Al--4V (wrought mill annealed) 137 151 14
Ti--6Al--2Sn--2Mo--2Zr--2Cr 131 155 5 (cast and heat treated) BT-22
(cast and heat treated) 151 151 1.5 Sample 1 (cast and heat
treated) 144 160 9.5 Sample 3 (cast and heat treated) 150 165 10
Sample 7 (cast and heat treated) 153 165 8 Sample 8 (cast and heat
treated) 149 164 7.5
[0039] As indicated in Table 4, the samples prepared in accordance
with the foregoing embodiments of the present invention achieved
yield and tensile strengths comparable or superior to those found
in virgin Ti-6Al-4V and Ti-6Al-2Sn-2Mo-2Zr-2Cr, while tolerating
significantly higher oxygen levels (See Tables 1 and 3). As a
result of their increased oxygen tolerance, alloys of the present
invention can be manufactured from greater amounts of recycled
materials than alloys with lower oxygen tolerances.
[0040] The embodiments described above are exemplary embodiments of
a the present invention. Those skilled in the art may now make
numerous uses of, and departures from, the above-described
embodiments without departing from the inventive concepts disclosed
herein. Accordingly, the present invention is to be defined solely
by the scope of the following claims.
* * * * *