Title of Invention

METHOD OF HEAT TREATING A NICKEL-BASE ALLOY AND THE ALLOY SO PRODUCED

Abstract The Invention discloses a method of heat treating a 718-type nickel-base alloy comprising: pre-solution treating the nickel-base alloy wherein an amount of at least one grain boundary precipitate selected from the group consisting of δ-phase precipitates and η-phase precipitates is formed within the nickel-base alloy, the at least one grain boundary precipitate having a short, generally rod-shaped morphology; solution treating the nickel-base alloy wherein substantially all γ'-phase precipitates and γ"-phase precipitates in the nickel-base alloy are dissolved while at least a portion of the amount of the at least one grain boundary precipitate is retained; cooling the nickel-base alloy after solution treating the nickel-base alloy at a first cooling rate sufficient to suppress formation of γ'-phase and γ"-phase precipitates in the nickel-base alloy; aging the nickel-base alloy in a first aging treatment wherein primary precipitates of γ'-phase and γ"-phase are formed in the nickel-base alloy; and aging the nickel-base alloy in a second aging treatment wherein secondary precipitates of γ'-phase and γ"-phase are formed in the nickel- base alloy, the secondary precipitates being finer than the primary precipitates; wherein after heat treating the nickel-base alloy, the nickel-base alloy has a matrix comprising γ'-phase precipitates and γ"-phase precipitates, wherein the γ'-phase precipitates are predominant strengthening precipitates in the nickel-base alloy, and an amount of grain boundary precipitates sufficient to pin the majority of the grain boundaries in the matrix, the grain boundary precipitates being selected from the group consisting of δ-phase precipitates, η-phase precipitates, and mixtures thereof, and having short, generally rod-shaped morphologies.
Full Text TITLE OF THE INVENTION
METHOD OF HEAT TREATING A NICKEL-BASE ALLOY
AND THE ALLOY SO PRODUCED
BACKGROUND OF THE INVENTION
FIELD OF THE INVENTION
Embodiments of the present invention generally relate to nickel-base alloys
and methods of heat treating nickel-base alloys. More specifically, certain
embodiments of the present invention relate to nickel-base alloys having a desired
microstructure and having thermally stable mechanical properties (such as one or
more of tensile strength, yield strength, elongation, stress-rupture life, and low notch
sensitivity). Other embodiments of the present invention relate to methods of heat
treating nickel-base alloys to develop a desired microstructure that can impart
thermally stable mechanical properties at elevated temperatures, especially tensile
strength, stress-rupture life, and low notch-sensitivily, to the alloys
DESCRIPTION OF RELATED ART
Alloy 718 is one of the most widely used nickel-base alloys, and is described
generally in U.S. Patent No. 3,046,108, the specification of which is specifically
incorporated by reference herein,
The extensive use of Alloy 718 stems from several unique features of the alloy.
For example, Alloy 718 has high strength and stress-rupture properties up to about
1200°F, Additionally, Alloy 718 has good processing characteristics, such as castability
and hot-workability, as well as good weldability. These characteristics permit
components made from Alloy 718 to be easily fabricated and, when necessary,
repaired. As discussed below, Alloy 718's unique features stem from a precipitation-
hardened microstructure that is predominanily strengthened by ?"-phase precipitates.
In precipitation-hardened, nickel-base alloys, there are two pnncipal
strengthening phases: ?'-phase (or "gamma prime") precipitates and ?"-phase (or
"qamma double prime") precipitates. Both the ?-phase and the ?"phase are
stoichiometric, nickel-rich intermetaliic compounds. However, the ?'-phase typically
comprises aluminum and titanium as the major alloying elements, i.e., Ni3(Al, Ti); while
the ?"phase contains primary-nibioum, i.e., Ni3Nb. While both the ?'-phase and the ?"-
phase form coherent precipitates in the face centered cubic austenite matrix, because
there is a larger misfit strain energy associated with the ?"-phase precipitates (which
have a body centered tetragonal crystal structure) than with the ?'-phase precipitates
(which have a face centered cubic crystal structure), ?"-phase precipitates tend to be
more efficient strengtheners than ?'-phase precipitates. That is, for the same
precipitate volume fraction and particle size, nickel-base alloys strengthened by ?'-
phase precipitates are generally stronger than nickel alloys that are strengthened
primarily by ?'-phase precipitates.
However, one disadvantage to such a ?"-phase precipitate strengthened
microstructure is that at temperatures higher than 1200°F, the ?"-phase is unstable and
will transform into the more stable d-phase (or "delta-phase"). While d-phase
precipitates have the same composition as ?'-phase precipitates (i.e., Ni3Nb), d-phase
precipitates have an orthorhombic crystal structure and are incoherent with the
austenite matrix. Accordingly, the strengthening effect of d-phase precipitates on the
matrix is generally considered to be negligible. Therefore, as a result of this
transformation, the mechanical properties of Alloy 718, such as stress-rupture life,
deteriorate rapidly at temperatures above 1200°F. Therefore, the use of Alloy 718
typically is limited to applications below this temperature.
In order to form the desired precipitation-hardened microstructure, the nickel-
base alloys must be subjected to a heat treatment or precipitation hardening
process. The precipitation hardening process for a nickel-base alloy generally
involves solution treating the alloy by heating the alloy at a temperature sufficient to
dissolve substantially all of the ?'-phase and ?"-phase precipitates that exist in the
alloy (i.e., a temperature near, at or above the solvus temperature of the
precipitates), cooling the alloy from the solution treating temperature, and
subsequently aging the alloy in one or more aging steps. Aging is conducted at
temperatures below the solvus temperature of the gamma precipitates in order to
permit the desired precipitates to develop in a controlled manner.
The development of the desired microstructure in the nickel-base alloy
depends upon both the alloy composition and precipitation hardening process (i.e.,
the solution treating and aging processes) employed. For example, a typical
precipitation hardening procedure for Alloy 718 for high temperature service involves
solution treating the alloy at a temperature of 1750°F for 1 to 2 hours, air cooling the
alloy followed by aging the alloyin a two-step aging process. The first aging step
involves heating the alloy at a first aging temperature of 1325°F for 8 hours, cooling
the alloy at about 50 to 100°F per hour to a second aging temperature of 1150°F,
and aging the alloy at the second aging temperature for 8 hours. Thereafter, the
alloy is air cooled to room temperature. The precipitation-hardened microstructure
that results after the above-described heat treatment is comprised of discrete ?' and
?"-phase precipitates, but is predominantly strengthened by the ?"-phase precipitates
with minor amounts of the ?'-phase precipitates playing a secondary strengthening
role.
Due to the foregoing limitations, many attempts have been made to improve
upon Alloy 718. For example, modified Alloy 718 compositions that have controlled
aluminum, titanium, and niobium alloying additions have been developed in order to
improve the high temperature stability of the mechanical properties of the alloy. In
particular, these alloys were developed in order to promote the development of a
"compact morphology" microstructure during the precipitation hardening process. The
compact morphology microstructure consists of large, cubic ?'-phase precipitates with
?"-phase precipitates being formed on the faces of the cubic ?'-phase precipitates. In
other words, the ?"-phase forms a shell around the ?'-phase precipitates.
In addition to modified chemistry, a specialized heat treatment or precipitation
hardening process is necessary to achieve the compact morphology microstructure,
instead of the discrete ?'-phase and ?"-phase precipitate hardened microstructure
previously discussed. One example of a specialized heat treatment that is useful in
developing the compact morphology microstructure involves solution treating the
alloy at a temperature around 1800°F, air cooling the alloy, and subsequently aging
the alloy at a first aging temperature of approximately 1562°F for about a half an
hour, in order to precipitate coarse ?'-phase precipitates. After aging at the first aging
temperature, the alloy is rapidly cooled to a second aging temperature by air cooling,
and held at the second aging temperature, which is arourrd 1200°F, for about 16
hours in order to form the ?"-phase shell. Thereafter, the alloy is air cooled to room
temperature. As previously discussed, after this precipitation hardening process, the
alloy will have the compact morphology microstructure described above and will
have improved high temperature stability. However, the tensile strength of alloys
having the compact morphology microstructure is generally significantly lower than
for standard Alloy 718.
Many -?-phase strengthened nickel-base alloys exist, for example, Waspaloy®
nickel alloy, which is commercially available from AHvac of Monroe, North Carolina.
However, because Waspaloy® nickel alloy contains increased levels of alloying
additions as compared to Alloy 718, such as nickel, cobalt, and molybdenum, this
alloy tends to be more expensive than Alloy 718. Further, because of the relatively
fast precipitation kinetics of the ?'-phase precipitates as compared to the ?'-phase
precipitates, the hot workability and weldability of this alloy is generally considered to
be inferior to Alloy 718.
Accordingly, it would be desirable to develop an affordable, precipitation-
hardened 718-type nickel-base alloy having a microstructure that is predominantly
strengthened by the more thermally stable ?'-phase precipitates, that possesses
thermally stable mechanical properties at temperatures greater than 1200°F, and
that has comparable hot-workability and weldability to ?'-phase strengthened alloys.
Further, it is desirable to develop methods of heat treating nickel-base alloys to
develop a microstructure that is predominanty strengthened by thermally stable ?'-
phase precipitates and that can provide nickel-base alloys with thermally stable
mechanical properties and comparable hot-workability and weldability to ?"-phase
strengthened alloys.
BRIEF SUMMARY OF THE INVENTION
Certain embodiments of the present invention are directed toward methods of
heat treating nickel-base alloys. For example, according to one non-limiting
embodiment there is provided a method of heat treating a nickel-base alloy
comprising pre-solution treating the nickel-base alloy wherein an amount of at least
one grain boundary precipitate selected from the group consisting of d-phase
precipitates and ?-phase precipitates is formed within the nickel-base alloy, the at
least one grain boundary precipitate having a short, generally rod-shaped
morphology; solution treating the nickel-base alloy wherein substantially all ?'-phase
precipitates and ?"-phase precipitates in the nickel-base alloy are dissolved while at
least a portion of the amount of the at least one grain boundary precipitate is
retained; cooling the nickel-base alloy after solution treating the nickel-base alloy at a
first cooling rate sufficient to suppress formation of ?'-phase and ?"-phase
precipitates in the nickel-base alloy; aging the nickel-base alloy in a first aging
treatment where in primaryprecipitates of ?'-phase and ?'-phase are formed in the
nickel-base alloy; and aging the nickel-base alloy in a second aging treatment
wherein secondary precipitates of ?'-phase and ?"-phase are formed in the nickel-
base alloy, the secondary precipitates being finer than the primary precipitates; and
wherein after heat treating the ?'-phase precipitates are predominant strengthening
precipitates in the nickel-base alloy .
According to another non-limiting embodiment there is provided a method of
heat treating a 718-type nickel-base alloy, the nickel-base alloy including up to 14
weight percent iron, the method comprising pre-solution treating the nickel-base alloy
at a temperature ranging from 1500°F to 1650°F for a time ranging from 2 to 16
hours, solution treating the nickel-base alloy for no greater than 4 hours at a solution
temperature ranging from 1725°F to 1850°F; cooling the nickel-base alloy at a first
cooling rate of at least 800°F per hour after solution treating the nickel-base alloy;
aging the nickel-base alloy in a first aging treatment for no greater than 8 hours at a
temperature ranging from 1325°F to 1450°F; and aging the nickel-base alloy in a
second aging treatment at least 8 hours at a second aging temperature, the second
aging temperature ranging from 1150°F to 1300°F.
Still another non-limiting embodiment provides a method of heat treating a
nickel-base alloy, the nickel-base alloy comprising, in weight percent, up to 0.1
carbon, from 12 to 20 chromium, up to 4 molybdenum, up to 6 tungsten, from 5 to 12
cobalt, up to 14 iron, from 4 to 8 niobium, from 0.6 to 2.6 aluminum, from 0.4 to 1.4
titanium, from 0.003 to 0.03 phosphorus, from 0.003 to 0.015 boron, and nickel;
wherein a sum of the weight percent of molybdenum and the weight percent of
tungsten is at least 2 and not more than 8, and wherein a sum of atomic percent
aluminum and atomic percent titanium is from 2 to 6, a ratio of atomic percent
aluminum to atomic percent titanium is at least 1.5, and the sum of atomic percent
aluminum and atomic percent titanium divided by atomic percent niobium is from 0.8
to 1.3. The method comprises solution treating the nickel-base alloy for no reater
than 4 hours at a solution temperature ranging from 1725°F to 1850°F; cooling the
nickel-base alloy at a first cooling rate after solution treating the nickel-base alloy;
aging the solution treated nickel-base alloy in a first aging treatment for no greater
than 8 hours at a temperature ranging from 1365°F to 1450°F; and aging the nickel-
base alloy in a second aging treatment for at least 8 hours at a second aging
temperature, the second aging temperature ranging from 1150°F to 1300°F.
Other embodiments' of the present invention contemplate nickel-base alloys
having a desired microstructure. For example, in one non-limiting embodiment there
is provided a nickel-base alloy comprising a matrix comprising ?'-phase precipitates
and ?"-phase precipitates, wherein the ?'-phase precipitates are predominant
strengthening precipitates in the nickel-base alloy, and an amount of a at least one
grain boundary precipitate selected from the group consisting of d-phase precipitates
and Ti-phase precipitates, wherein the at least one grain boundary precipitate has a
short, generally rod-shaped morphology; and wherein the nickel-base alloy has a
yield strength at 1300°F of at least 120 ksi, a percent elongation at 1300°F of at least
12 percent, a notched stress-rupture life of at least 300 hours as measured at
1300°F and 80 ksi, and a low notch-sensitivity.
Another non-limiting embodiment provides a 718-type nickel-base alloy
including up to 14 weight percent iron and comprising ?'-phase precipitates and ?"-
phase precipitates, wherein the ?'-phase precipitates are the predominant
strengthening precipitates in the nickel-base alloy, and an amount of at least one
grain boundary precipitate selected from the group consisting of d-phase precipitates
and ?-phase precipitates, wherein the at least one grain boundary precipitate has a
short, generally rod-shaped morphology; wherein the nickel-base alloy is heat
treated by pre-solution treating the nickel-base alloy at a temperature ranging from
1500°F to 1650°F for a time ranging from 2 to 16 hours; solution treating the nickel-
base alloy by heating the nickel-base alloy for no greater than 4 hours at a solution
temperature ranging from 1725°F to 1850°F; cooling the nickel-base alloy at a first
cooling rate of at least 800°F per hour after solution treating the nickel-base alloy;
aging the nickel-base alloy in a first aging treatment from 2 hours to 8 hours at a
temperature ranging from 1325°F to 1450°F; and aging the nickel-base alloy in a
second aging treatment for at least 8 hours at a second aging temperature, the
second aging temperature ranging from 1150°F to 1300°F.
Articles of manufacture and methods of forming article of manufacture are
also contemplated by various embodiments of the present invention. For example,
there is provided in one non-limiting embodiment of the present invention, an article
of manufacture comprising a nickel-base alloy, the nickel-base alloy comprising a
matrix comprising ?'-phase precipitates and ?"-phase precipitates, wherein the ?'-
phase precipitates are predominant strengthening precipitates in the nickel-base
alloy, and an amount of at least one grain boundary precipitate selected from the
group consisting of d-phase precipitates and ?-phase precipitates, wherein the at
least one grain boundary precipitates has a short, generally rod-shaped morphology;
and wherein the nickel-base alloy has a yield strength at 1300°F of at least 120 ksi, a
percent elongation at 1300°F of at least 12 percent, a notched stress-rupture life of
at least 300 hours as measured at 1300°F and 80 ksi, and a low notch-sensitivity.
Another non-limiting embodiment provides a method of forming an article of
manufacture comprising a 718-type nickel-base alloy including up to 14 weight
percent iron, the method comprising forming the nickel-base alloy into a desired
configuration, and heat treating the nickel-base alloy, wherein heat treating the
nickel-base alloy comprises pre-solution treating the nickel-base alloy at a
temperature ranging from 1500°F to 1650°F for a time ranging from 2 to 16 hours,
solution treating the nickel-base alloy for no greater than 4 hours at a solution
temperature ranging from 1725°F to 1850°F, cooling the nickel-base alloy at a first
cooling rate of at least 800°F per hour after solution treating the nickel-base alloy,
aging the nickel-base alloy in a first aging treatment from 2 hours to 8 hours at a
temperature ranging from 1325°F to 1450°F, and aging the nickel-base alloy in a
second aging treatment for at least 8 hours at a second aging temperature, the
second aging temperature ranging from 1150°F to 1300°F.
BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE ACCOMPANYING DRAWING(S)
Embodiments of the present invention will be better understood if read in
conjunction with the figures, in which:
Fig. 1 is an SEM micrograph of a nickel-base alloy according to embodiments of the
present invention;
Fig. 2 is an optical micrograph of a nickel-base alloy according to embodiments of
the present invention;
Fig. 3 is an SEM micrograph of a nickel-base alloy having excessive grain boundary
phase development;and
Fig. 4 is an optical micrograph of a nickel-base alloy having excessive grain
boundary phase development.
DETAILED DESCRIPTION OF THE INVENTION
Certain non-limiting embodiments of the present invention can be
advantageous in providing nickel-base alloys having a desired microstructure and
thermally stable mechanical properties at elevated temperatures. As used herein.
the phrase themally stable mechanical properties" means that the mechanical
properties of the alloy (such as tensile strength, yield strength, elongation, and
stress-rupture life) are not substantially decreased after exposure at 1400°F for 100
hours as compared to the same mechanical properties before exposure. As used
herein the term "low notch-sensitivit?" means that samples of the alloy, when tested
according to ASTM E292, do not fail at the notch. Further, the non-limiting
embodiments of the present invention may be advantageous in providing
predominantly ?'-phase strengthened nickel-base alloys comprising at least one grain
boundary phase precipitate and having comparable hot-workability and weldability to
?'-phase strengthened alloys.
Methods of heat treating nickel-base alloys according to various non-limiting
embodiments of the present Invention will now be described. Although not limiting
herein-, the methods of heat treating nickel-base alloys discussed herein can be used
in conjunction with a variety of nickel-base alloy compositions, and are particularly
suited for use with 718-type nickel-base alloys and derivatives thereof. As used
herein the term "nickel-base alloy(s)" means alloys of nickel and one or more alloying
elements. As used herein the term "718-type nickel-base alloy(s)" means nickel-
base alloys comprising chromium and iron that are strengthened by one or more of
niobium, aluminum, and titanium alloying additions.
One specific, non-limiting example of a 718-type nickel-base alloy for which
the heat treating methods of the various non-limiting embodiments of the present
invention are particularly well suited is a 718-type nickel-base alloy including up to 14
weight percent iron. Although not meant to be limiting herein, 718-type nickel-base
alloys including up to 14 weight percent iron are believed to be advantageous in
producing alloys having good stress-rupture life. While not intending to be bound by
any particular theory, it is believed by the inventors that when the iron content of the
alloy is high, for example 18 weight percent, the effectiveness of cobalt in lowering
stacking fault energy rnay be reduced. Since low stacking fault energies are
associated with improved stress-rupture life. In certain embodiments of the present
invention, the iron content of the nickel-base alloy is desirably maintained at or below
14 weight percent.
Another specific, non-limiting example of a 718-type nickel-base alloy for
which the heat treating methods according to the various non-limiting embodiments
of the present invention are particularly well suited is a nickel-base alloy comprising,
In percent by weight up to 0.1carbon, from 12 to 20 chromium, up to 4
molybdenum, up to 6 tungsten, from 5 to 12 cobalt, up to 14 iron, from 4 to 8
niobium, from 0.6 to 2.6 aluminum, from 0.4 to 1.4 titanium, from 0.003 to 0.03
phosphorus, from 0.003 to 0.015 boron, and nickel; wherein a sum of the weight
percent of molybdenum and the weight percent of tungsten is at least 2 and not more
than 6, and wherein a sum of atomic percent aluminum and atomic percent titanium
is from 2 to 6, a ratio of atomic percent aluminum to atomic percent titanium is at
least 1.5, and the sum of atomic percent aluminum and atomic percent titanium
divided by atomic percent niobium is from 0.8 to 1.3. Such alloys are described in
detail in co-pending U.S. Application Serial Number 10/144,369, the specification of
which is specifically incorporated by reference herein.
A method of heat treating a nickel-base alloy according to a first, non-limiting
embodiment of the present invention comprises pre-solution treating the nickel-base
alloy, solution treating the nickel-base alloy, and aging the nickel-base alloy to form a
nickel-base alloy having a microstructure wherein ?'-phase precipitates are the
predominant strengthening precipitates and d-phase and/or ?-phase precipitates
having a desired morphology are present in one or more of the grain boundaries of
the alloy.
More specifically, the method of heat treating a nickel-base alloy according to
the first non-limiting embodiment comprises pre-solution treating the nickel-base
alloy wherein an amount of at least one grain boundary precipitate is formed within
the nickel-base alloy. As used herein the term "pre-solution treating" means heating
the nickel-base alloy, prior to solution treating the nickel-base alloy, at a temperature
such that an amount of at least one grain boundary precipitate is formed within the
nickel-base alloy. As used herein, the term "form" with respect to any phase means
nucleation and/or growth of the phase. For example, although not limiting herein,
pre-solution treating the nickel-base alloy can comprise heating the nickel-base alloy
in a furnace at a temperature ranging from about 1 SOOT to about 1 1650°F for about 2
hours to about 16 hours. In one specific, non-limiting example of a pre-solution
treatment that can be particularly useful in processing wrought nickel-base alloys,
the pre-solution treatment can comprise heating the alloy at a temperature ranging
from about 1550°F to 1600°F for about 4 to 16 hours.
As discussed above, during the pre-solution treatment, an amount of at least
one grain boundary precipitate is formed in the nickel-base alloy. According to the
First non-limting embodiment,-tne at least one grain boundary precipitate formed
during the pre-solution treatment is selected from the group consisting of d-phase
("delta-phase") precipitates and ?-phase ("eta-phase") precipitates. Delta-phase
precipitates are known in the art to consist of the ordered Intermetaliic phase Ni3Nb
and have an orthorhombic crystal structure. Eta-phase precipitates are known in the
art to consist of the ordered intermetaliic phase Ni3Ti and have a hexagonal crystal
structure. Further, according to this embodiment, during pre-solution treatment both
d-phase and ?-phase grain boundary precipitates can be formed.
While generally the formation of d-phase and/or ?-phase precipitates
(hereinafter "d/?-phase" precipitates) in nickel-base alioys due to the overaging of ?"-
phase precipitates is undesirable because these precipitates are incoherent and do
not contribute to the strengthening of the austenite matrix, the Inventors have
observed that the precipitation of a controlled amount of d/?-phase precipitates
having a desired morphology and location in grain boundaries of the nickel-base
alloy (as discussed in more detail below) can strengthen the grain boundaries and
contribute to reduced notch-sensitivity, and improved stress-rupture life and ductility
in the alloy at elevated temperatures. Further, as discussed below in more detail,
when the controlled amount of at least one grain boundary precipitate is combined
with ?'-phase and ?"-phase precipitates having the desired size distribution, nickel-
base alloys having low notch-sensitivity, good tensile strength, stress-rupture life,
and thermally stable mechanical properties to at least 1300°F can be achieved.
Referring now to the figures, in Fig. 1, there is shown an SEM micrograph of a
nickel-base alloy according to embodiments of the present invention taken at 3000X
magnification. In Fig. 2 there is shown an optical micrograph of the same nickel-
base alloy taken at 500X magnification. The nickel-base alloy shown in Figs. 1 and
2 comprises an amount of at least one grain boundary precipitate having the desired
morphology and location according to certain non-limiting embodiments of the
present invention. As shown in Fig. 1the nickel-base alloy comprisesd/?-phase
precipitates 110, the majority of which have a short, generally rod-shaped
morphology and are located within the grain boundaries of the alloy. As used herein
the phrase "short, generally rod-shaped" with reference to the precipitates means the
precipitates having a length to thickness aspect ratio no greater than about 20, for
example as shown in Figs. 1 and 2. In certain non-limiting embodiments of the
present invention, the aspect ratio of the short, generally rod-shaped precipitates
ranges from 1to 20. While"d/?-phase precipitates at twin boundaries in the nickel-
base alloy can occasionally be present (for example, as shown in Fig. 1, d/?-phase
precipitates 111 can be observed at twin boundary 121), no significant formation of
intragranular, needle-shaped d/?-phase precipitates should be present in the nickel-
base alloys processed in accordance with the various non-limiting embodiments of
the present invention.
Although not meaning to be bound by any particular theory, it is believed by
the inventors that both the morphology of the precipitates and location of precipitates
at the grain boundaries, shown in Figs. 1 and 2, are desirable in providing a nickel-
base alloy having low notch-sensitivity and improved tensile ductility and stress-
rupture life because these grain boundary precipitates can restrict grain boundary
sliding in the alloy at elevated temperatures. In other words, because of their
morphology and location, the grain boundary precipitates according to embodiments
of the present invention effectively strengthen the grain boundaries by resisting
movement of the grain boundaries by "locking" or "pinning" the grain boundaries in
place. Since grain boundary sliding contributes substantially to creep deformation
and the formation of inter-granular cracks, which can decrease stress-rupture life
and increase notch-sensitivity of the alloy, by restricting grain boundary sliding in the
nickel-base alloys according to embodiments of the present invention, the grain
boundary precipitates can increase the tensile ductility and stress-rupture life of the
alloy and decrease the notch-sensitivity of the alloy. In contrast, when no grain
boundary phase is present, or when excessive precipitation occurs (as shown in
Figs. 3 and 4, which are discussed below), the grain boundaries will not be
strengthened and the stress-rupture life of the alloy will not be improved.
In certain non-limiting embodiments of the present invention, after heat
treating the nickel-base alloy a majority of grain boundaries of the nickel-base alloy
are pinned by at least one short, generally rod-shaped grain boundary precipitate,
such as precipitate 210 shown in Fig, 2. In other embodiments of the present
invention, at least two-thirds (2/3) of the grain boundaries are pinned by at least one
short, generally rod-shaped grain boundary phase precipitate. Thus, according to
these non-limiting embodiments, although pinning of all of the grain boundaries by at
least one grain boundary precipitate is contemplated, it is not necessary that all of
the grain boundaries be pinned.
In contrast; Figs.3 and 4 are micrographs of a nickel-base alloy having
excessive formation of d/?-phase precipitates. As shown in Fig. 3, the majority of the
precipitates 310 have a sharp, needle-like morphology with a much larger aspect
ratio than those shown in Figs. 1 and 2, and extend a significant distance into the
grains, and in some cases, extend across an individual grain. Although not meant to
be bound by any particular theory, It is believed by the Inventors that the d/?-phase
precipitate morphology and the location of the precipitates in the grains shown in
Figs. 3 and 4 is undesirable because the d/?-phase precipitates (310 and 410,
shown in Figs. 3 and 4 respectively) do not strengthen the grain boundaries as
discussed above. Instead, the interface between the precipitate and the grain matrix
becomes the easiest path for crack propagation. Further, the excessive formation of
d/?-phase precipitates reduces the amount of strengthening precipitates (i.e., ?' and
?") in the alloy, thereby reducing the strength of the alloy (as previously discussed).
Accordingly, although the precipitates such as those shown in Figs. 3 and 4 can
contribute to an increase in elevated temperature ductility, such precipitation will
significantly reduce alloy tensile strength and stress-rupture life.
While not intending to be bound by any particular theory, the inventors have
also observed that the morphology of d/?-phase grain boundary precipitates is
related to precipitation temperature and the grain size of the alloy. Thus, for
example, although not limiting herein, for certain wrought alloys when the
precipitation temperature is greater than about 1600°F, and for certain cast alloys
when the precipitation temperature is greater than about 1650°F, generally the d/?-
phase precipitates will form both on grain boundaries and intragranularly as high
aspect ratio needles. As discussed above, this typically decreases the tensile
strength and stress-rupture life of the alloy. However, when precipitation of the d/?-
phase occurs in these alloys at temperatures below about 1600°F and 1650°F,
respectively, d/?-phase precipitates having a relatively short, generally rod-shaped
morphology form at the grain boundaries with little intragranular precipitation. As
previously discussed, the formation of these grain boundary precipitates in the
nickel-base alloy is desirable because these grain boundary precipitates can lock or
pin the grain boundaries, thereby improving the tensile strength and ductility, and
stress-rupture life, while decreasing notch-sensitivity of the alloy.
After pre-solution treating, according to the first non-limiting embodiment of
the present invention, the nickel-base alloy can be cooled to 1000°F or less prior to
solution treating.For example, although not limiting herein, the alloy can be cooled
to room temperature prior to solution treating. As used herein, the term "solution
treating" means heating the nickel-base alloy at a solution temperature near (i.e., a
temperature no less than about 100°F below), at or above the solvus temperature of
the ?' and ?'-phase precipitates, but below the solvus temperature for the grain
boundary precipitates. Thus, as discussed above, during solution treatment of the
nickel-base alloy, substantially all the ?'- and ?"-phase precipitates that exist in the
nickel-base alloy are dissolved. As used herein, the term "substantially all" with
respect to the dissolution of the ?' and ?'-phase precipitates during solution treating
means at least a majority of the ?' and ?"-phase precipitates are dissolved.
Accordingly, dissolving substantially all of the ?'- and ?"-phase precipitates during
solution treating includes, but is not limited to, dissolving all of the ?'- and ?"-phase
precipitates. However, since the solution temperature is below the solvus
temperature for the grain boundary precipitates (i.e., the S/ri-phase precipitates
formed during pre-solution treatment), at least a portion of the amount of the at least
one grain boundary precipitate is retained in the nickel-base alloy during solution
treatment.
Although not limiting herein, according to this non-limiting embodiment,
solution treating the nickel-base alloy can comprise heating the nickel-base alloy at a
solution temperature no greater than 1850°F for no more'than 4 hours. More
particularly, solution treating the nickel-base alloy can comprise heating the nickel-
base alloy at a solution temperature ranging from 1725T to 1850°F, and more
preferably comprises heating the nickel-base alloy from 1750°F to 1800°F for a time
ranging from 1 to 4 hours, and more preferably from 1 to 2 hours. However, it will be
appreciated by those skilled in the art that the exact solution treatment time required
to dissolve substantially all of the ?'- and ?"-phase precipitates will depend on several
factors, including but not limited to, the size of the nickel-base alloy being solution
treated, thus, the bigger the nickel-base alloy (or work piece comprising the nickel-
base alloy) being treated, generally the longer the solution time required to achieve
the desired result will be.
Although not meaning to be bound by any particular theory, it has been
observed by the inventors that if the solution temperature is above about 1850°F, a
less than desired amount of grain boundary precipitates may be retained in the
nickel-base alloy after solution treating. Accordingly, the notch-sensitivity, elevated
temperature stress-rupture fire and ductility of the alloy can be detrimentally affected.
However, for applications in which these properties are not critical, solution
temperatures greater than 1850°F can be utilized in accordance with this non-limiting
embodiment of the present invention. Further, it has been observed by the inventors
that if the solution temperature is below about 1725°F, substantially all of the ?'-
phase and ?"-pha.se precipitates will not dissolve during solution treatment.
Accordingly, undesirable growth and coarsening of the undissolved ?'-phase and ?"-
phase precipitates can occur, leading to lower tensile strength and stress-rupture life.
After solution treating the nickel-base alloy, the nickel-base alloy is cooled at a
first cooling rate sufficient to suppress formation of ?'-phase and ?"-phase
precipitates in the nickel-base alloy during cooling. Although not meant to be limiting
herein, the inventors have observed that if the nickel-base alloy is cooled too slowly
after solution treatment, in addition to the undesired precipitation and coarsening of
?'-phase and ?"-phase precipitates, the formation of excessive grain boundary
precipitates can occur. As discussed above, the formation of excessive grain
boundary precipitates can detrimentally impact the tensile strength and stress-
rupture life of the alloy. Thus, according to the first non-limiting embodiment of the
present invention, the first cooling rate is at least 800°F per hour, and can be at least
1000°F per hour or greater. Cooling rates in excess of 800°F or 1000°F can be
achieved, for example by air cooling the alloys from the solution temperature.
After solution treating and cooling the nickel-base alloy according to the first
non-limiting embodiment of the present invention, the nickel-base alloy is aged in a
first aging treatment. As used herein the term "aging" means heating the nickel-base
alloy at a temperature below the solvus temperatures for the ?'-phase and the ?"-
phase to form ?'-phase and ?"-phase precipitates. During the first aging treatment,
primary precipitates of ?'-phase and ?"-phase are formed in the nickel-base alloy.
Although not limiting herein, according to this non-limiting embodiment, the first
aging treatment can comprise heating the nickel-base alloy at temperatures ranging
from 1325°F to 1450°F for a time period ranging from 2 to 8 hours. More particularly,
the first aging treatment can comprise heating the nickel-base alloy at a temperature
ranging from 1365°F to 1450°F for 2 to 8 hours. Although not meant to be limiting
herein, aging at a first aging temperature greater than about 1450°F or less than
about 1325° can result in overaging or underaging of the alloy, respectively, with an
accompanying loss of strength.
After the first aging treatment, the nickel-base alloy is cooled to a second
aging temperature and aged in a second aging treatment. Although not required,
according to this embodiment of the present Invention the second cooling rate can
be 50°F per hour or greater. For example, a cooling rate ranging from about 50°F
per hour to about 100°F per hour can be achieved by allowing the nickel-base alloy
to cool in the furnace while the furnace cools to a desired temperature or after the
power to the furnace is turned off (i.e., furnace cooling the alloy). Alternatively,
although not limiting herein, the nickel-base alloy can be more rapidly cooled, for
example by air cooling to room temperature, and then subsequently heated to the
second aging temperature. However, if a more rapid cooling rate is employed,
longer aging times may be required in order to develop the desired microstructure.
The nickel-base alloy is aged at the second aging temperature to form
secondary precipitates of ?'-phase and ?"-phase in the nickel-base alloy. The
secondary precipitates of ?'-phase and ?"-phase formed during the second aging
treatment are generally finer than the primary precipitates formed during the first
aging treatment. That is, the size of the precipitates formed during the second aging
treatment will generally be smaller than the size of the primary precipitates formed
during the first aging treatment. Although not meaning to be bound by any particular
theory, the formation of ?'-phase precipitates and ?"-phase precipitates having a
distribution of sizes, as opposed to a uniform precipitate size, is believed to improve
the mechanical properties of the nickel-base alloy.
Further, according to the first non-limiting embodiment, the second aging
treatment can comprise heating the nickel-base alloy at a second aging temperature
ranging from 1150°F to 1300°F, and more specifically can comprise heating the
nickel-base alloy at a second aging temperature ranging from 1150°F to 1200°F for
at least 8 hours.
As previously discussed, after heat treating the nickel-base alloy according to
the first non-limiting-embodiment of the present invention, the ?'-phase precipitates
are predominant strengthening precipitates in the nickel-base alloy. As used herein,
the phrase "predominant strengthening precipitates" with respect to the ?'-phase
precipitates means the nickel-base alloy comprises at least about 20 volume percent
?'-phase and no more than about 5 volume percent ?"-phase. Further, after heat
treating, the nickel-base alloy according to this non-limiting embodiment comprises
an amount of at least one grain boundary precipitate selected from the group
consisting of d-phase precipitates and ?-phase precipitates and having a short,
generally rod-shaped morphology.
In a second non-limiting embodiment of the present invention, the nickel-base
alloy is heated to a pre-solution temperature ranging from about 1500°F to 1600°F
for a period of time in order to precipitate a controlled amount of at least one grain
boundary precipitate selected from the group consisting of d-phase precipitates and
?-phase precipitates. As discussed above with respect to the first non-limiting
embodiment, desirably, the at least one precipitate has a short, generally rod-shaped
morphology and is located at the grain boundaries of the alloy.
Thereafter, the temperature is increased to a solution temperature ranging
from 1725°F to about 1850°F, without cooling, and the nickel-base alloy is solution
treated (i.e., the alloy is directly heated to the solution temperature). The nickel-base
alloy is held at the solution temperature for a time period sufficient to dissolve
substantially all of the ?'-phase and ?"-phase precipitates as discussed above. For
example, although not limiting herein, the nickel-base alloy can be held at the
solution temperature for no greater than 4 hours. In one specific, non-limiting
example according to the second non-limiting embodiment, the solution temperature
ranges from 1750°F to about 1800°F and the alloy is held at the solution temperature
for no greater than 2 hours. Thereafter, the nickel-base alloy can be cooled to room
temperature and aged as discussed above with respect to the first non-limiting
embodiment of the present invention.
A third non-limiting embodiment of the present invention provides a method of
heat treating a 718-type nickel-base alloy including up to 14 weight percent iron, the
method comprising pre-solution treating the nickel-base alloy at a temperature
ranging from 1500°F to 1650°F for a time ranging from 2 to 16 hours. After pre-
solution treatment, the nickel-base alloy is solution treated for no greater than 4
hours at a solution temperature ranging from 1725°F to 1850°F, and preferably for
no greater than 2 hours at a solution temperature ranging from 1750°F to 1800°F.
Thereafter, the nickel-base alloy can be cooled to room temperature and aged as
discussed above with respect to the first non-limiting embodiment of the present
invention. After heat treating the nickel-base alloy according to this non-limiting
embodiment of the present invention, the nickel-base alloy desirably has a
microstructure comprising ?'-phase precipitates and ?"-pha'se precipitates, wherein
the ?'-phase precipitates are predominant strengthening precipitates in the nickel-
base alloy, and an amount of at least one grain boundary precipitate selected from
the group consisting of d-phase precipitates and ?-phase precipitates, the at least
one grain boundary precipitate having a short, generally rod-shaped morphology.
A fourth non-limiting embodiment according to the present invention provides
a method of heat treating a nickel-base alloy, the nickel-base alloy comprising, in
weight percent, up to 0.1 carbon, from 12 to 20 chromium, up to 4 molybdenum, up
to 6 tungsten, from 5 to 12 cobalt, up to 14 iron, from 4 to 8 niobium, from 0.6 to 2.6
aluminum, from 0.4 to 1.4 titanium, from 0.003 to 0.03 phosphorus, from 0.003 to
0,015 boron, and nickel; wherein a sum of the weight percent of molybdenum and
the weight percent of tungsten is at least 2 and not more than 8, and wherein a sum
of atomic percent aluminum and atomic percent titanium is from 2 to 6, a ratio of
atomic percent aluminum to atomic percent titanium is at least 1.5, and the sum of
atomic percent aluminum and atomic percent titanium divided by atomic percent
niobium is from 0.8 to 1.3. The method comprises solution treating the nickel-base
alloy by heating the nickel-base alloy for no greater than 4 hours at a solution
temperature ranging from 1725°F to 1850°F, and more particularly comprises
solution treating the nickel-base alloy by heating the nickel-base alloy for not greater
than 2 hours at a solution temperature ranging from 1750°F to 1800°F. The method
further comprises cooling the nickel-base alloy after solution treating at a first cooling
rate, and aging the nickel-base alloy as discussed above with respect to the first
non-limiting embodiment of the present invention. After heat treating the nickel-
base alloy according to the fourth non-limiting embodiment of the present invention,
the nickel-base alloy desirably has a microstructure that is predominantly
strengthened by ?'-phase precipitates and may comprise an amount of at least one
grain boundary precipitate selected from the group consisting of d-phase precipitates
and r|-phase precipitates, the at least one grain boundary precipitate having a short,
generally rod-shaped morphology.
Although not required, the method according to the fourth non-limiting
embodiment of the present invention can further comprise pre-solution treating the
nickel-base alloy at a temperature ranging from 1500°F to 1650° for a time period
ranging from 2 to 16 hours prior to solution treating the nickel-base alloy. As
previously discussed, by pre-solution treating the nickel-base alloy, a controlled
amount of at least one grain boundary precipitate can be formed in the alloy.
Accordingly, after heat treating the nickel-base alloy, the nickel-base alloy desirably
has a microstructure that is primarily strengthened by ?'-phase precipitates and
comprises an amount of at least one grain boundary precipitate selected from the
group consisting of d-phase precipitates and ?-phase precipitates, wherein the at
least one grain boundary precipitate has a short, generally rod-shaped morphology.
Although not limiting herein, after heat treating the nickel-base alloy according
to the various non-limiting embodiments of the present invention discussed above,
the nickel-base alloy can have a yield strength at 1300°F of at least 120 ksi, a
percent elongation at 1300°F of at least 12 percent, a notched stress-rupture life of
at least 300 hours as measured at 1300°F and 80 ksi, and a low notch- sensitivity.
Although not required, after heat treating the alloy can have a grain size of ASTM 5-
8.
Nickel-base alloys having a desired microstructure according to certain non-
limiting embodiments of the present invention will now be discussed. In one non-
limiting embodiment of the present Invention, there is provided a nickel-base alloy
comprising a matrix comprising ?'-phase precipitates and ?'-phase precipitates,
wherein the ?'-phase precipitates are predominant strengthening precipitates in the
nickel-base alloy, and a controlled amount of at least one grain boundary precipitate,
the at least one grain boundary precipitate being selected from the group consisting
of d-phase precipitates and ?-phase precipitates; and wherein the nickel-base alloy
has a yield strength at 1300°F of at least 120 ksi, a percent elongation at 1300°F of
at least 12 percent, a notched stress-rupture life of at least 300 hours as measured
at 1300°F and 80 ksi, and a low notch-sensitivity.
According to this non-limiting embodiment, the nickel-base alloy can be a 718-
type nickel-base alloy. For example, the 718-type nickel-base alloy can be a 718-
type nickel-base alloy comprising up to 14 weight percent iron. Further, the 718-type
nickel-base alloy can be a nickel-base alloy comprising, in weight percent, up to 0.1
carbon, from 12 to 20 chromium, up to 4 molybdenum, up to 6 tungsten, from 5 to 12
cobalt,up to 14 iron, from 4 to 8 niobium, from 0.6 to 2.6 aluminum, from 0.4 to 1.4
titanium, from 0.003 to 0.03 phosphorus, from 0.003 to 0.015 boron, and nickel;
wherein a sum of the weight percent of molybdenum and the weight percent of
tungsten is at least 2 and not more than 8, and wherein a sum of atomic percent
aluminum and atomic percent titanium is from 2 to 6, a ratio of atomic percent
aluminum to atomic percent titanium is at least 1.5, and the sum of atomic percent
aruminum and atomic percent utanium divided by atomic percent niobium is from 0.8
to 1.3.
The nickel-base alloy according to this non-limiting embodiment can be a cast
or wrought nickel-base alloy. For example, although not limiting herein, the nickel-
base alloy can be manufactured by melting raw materials having the desired
composition in a vacuum induction melting ("VIM") operation, and subsequently
casting the molten material into an ingot. Thereafter, the cast material can be further
refined by remelting the ingot. For example, the cast material can be remelted via
vacuum arc remelting ("VAR"), electro-slag remelting ("ESR"), or a combination of
ESR and VAR, all of which are known in the art. Alternatively, other methods known
in the art for melting and remelting can be utilized.
After melting, the nickel-base alloy can be heat treated to form the desired
microstructure. For example, although not limiting herein, the nickel-base alloy can
be heat treated according to the methods of heat treating discussed in the various
non-limiting embodiments of the present invention discussed above to form the
desired microstructure. Alternatively, the alloy can be first forged or hot or cold
worked prior to heat treating.
One specific, non-limiting embodiment of a nickel-base alloy according to the
present invention provides a 718-type nickel-base alloy including up to 14 weight
percent iron and comprising ?'-phase precipitates and ?"-phase precipitates, wherein
the ?'-phase precipitates are predominant strengthening precipitates in the nickel-
base alloy, and an amount of at least one grain boundary precipitate selected from
the group consisting of 6-phase precipitates and ?-phase precipitates, the at least
one grain boundary precipitate having a short, generally rod-shaped morphology.
According to this non-limiting embodiment, the nickel-base alloy can be formed, for
example, by pre-solution treating the nickel-base alloy by heating the nickel-base
alloy at a temperature ranging from 1500°F to 1650°F for a time ranging from 4 to 16
hours,solution treating the nickel-base alloy by heating the nickel-base alloy for no
greater than 4 hours at a solution temperature ranging from 1725°F to 1850°F,
cooling the nickel-base alloy at a first cooling rate of at least 800°F per hour after
solution treating the nickel-base alloy, aging the nickel-base alloy in a first aging
treatment by heating the nickel-base alloy for 2 to 8 hours at a temperature ranging
from 1325°F to 1450°F, and aging the nickel-base alloy in a second aging treatment
by heating the nicker-base alloy for at least 8 hours at the second aging temperature,
the second aging temperature ranging from 1150°F to 1300°F.
Embodiments of the present invention further contemplate articles of
manufacture made using the nickel-base alloys and methods of heat treating nickel-
base alloys of the present invention. Non-limiting examples of articles of
manufacture that can be made using the nickel-base alloys and methods of heat
treating nickel-base alloys according to the various embodiments of the present
invention include, but are not limited to, turbine or compressor disks, blades, cases,
shafts, and fasteners.
For example, although not limiting herein, one embodiment of the present
invention provides an article of manufacture comprising a nickel-base alloy, the
nickel-base alloy comprising a matrix comprising ?'-phase precipitates and ?"-phase
precipitates, wherein the ?'-phase precipitates are predominant strengthening
precipitates in the nickel-base alloy, and an amount of at least one grain boundary
precipitate selected from the group consisting of d-phase precipitates and ?-phase
precipitates; and wherein the nickel-base alloy has a yield strength at 1300°F of at
least 120 ksi, a percent elongation at 1300°F of at least 12 percent, a notched
stress-rupture life of at least 300 hours as measured at 1300°F and 80 ksi, and a low
notch-sensitivity. Although not required, the nickel-base alloy can have a grain size
of ASTM 5-8.
Although not limiting herein, the articles of manufacture according to this non-
limiting embodiment of the present invention can be formed, for example, by fonning
a cast or wrought nickel-base alloy having the desired composition into the desired
configuration, and then subsequently heat treating the nickel-base alloy to form the
desired microstructure discussed above. More particularly, although not limiting
herein, according to certain embodiments of the present invention the articles of
manufacture can be formed from cast or wrought 718-type nickel-base alloys, and
more particuJarly 718-type nickel-base alloys that include up to 14 weight percent
iron. In one specific non-limiting embodiment of the present invention, the article of
manufacture is formed from a nickel-base alloy comprising, in percent by weight, up
to 0.1 carbon, from 12 to 20 chromium, up to 4 molybdenum, up to 6 tungsten, from
5 to 12 cobalt, up to 14 iron, from 4 to 8 niobium, from 0.6 to 2.6 aluminum, from 0.4
to 1.4 titanium, from 0.003 to 0.03 phosphorus, from 0.003 to 0.015 boron, and
nickel; wherein a sum of the weight percent of molybdenum and the weight percent
of tungsten is at least 2 and not more than 8, and wherein a sum of atomic percent
aluminum and atomic percent titanium is from 2 to 6, a ratio of atomic percent
aluminum to atomic percent titanium is at least 1.5, and the sum of atomic percent
aluminum and atomic percent titanium divided by atomic percent niobium is from 0.8
to 1.3.
Various non-iimiting embodiments of the present invention will now be
Illustrated in the following non-limiting examples.
EXAMPLES
Example 1
A 718-type nickel-base alloy was melted prepared using in a VIM operation
and subsequently cast into an ingot. Thereafter, the cast material was remelted
using VAR. The cast material was then forged into an 8" diameter, round billet and
test samples were cut the billet. The alloy had a grain size ranging from ASTM 6 to
ASTM 8, with an average grain size of ASTM 7, as determined according to ASTM E
112, as determined according to ASTM E 112. The composition of alloy is given
below.
The test samples were then divided into sample groups and the sample
groups were subjected the pre-solution treatment indicated below in Table 1.
Table 1
After pre-solution treatment, each of the sample groups were solution treated
at 1750°F for 1 hour, air cooled, aged for 2 hours at 1450°F, furnace cooled, aged for
8 hours at 1200°F, and air cooled to room temperature. After heat treating the
following tests were performed. At least 2 samples from each sample group were
subjected to tensile testing at 1300°F according to ASTM E21 and the tensile
strength, yield strength, percent elongation, and percent reduction in area for each
sample were determined. At least 2 samples from each sample group were
subjected to' stress-rupture life testing at 1300°F and 80 ksi according to ASTM 292
and the stress-rupture life and percent elongation at rupture for each sample were
determined. At least 2 samples from each group were subjected to Charpy testing
at room temperature according to ASTM E262 and the impact strength and lateral
expansion ("LE") of each sample were determined.
The results of the aforementioned tests are indicated below in Table 2,
wherein the tabled value is the average value of the samples tested from each
sample group.
Table 2
As can be seen from Table 2, the samples that were pre-solution treated at
1550°F for 8 hours (i.e., Sample Group 2) had better tensile strength, yield strength,
elongation, and reduction in area, significantly better stress-rupture life and impact
strength than the samples that were not pre-solution treated (i.e. Sample Group 1),
as well as those that were pre-solution treated at 1600°F and 1650°F for 8 hours (i.e.
Sample Groups 3 and 4). Further, the properties of the Sample Group 4 samples
were slightly lower than for the samples that were not pre-solution treated, but were
still considered to be acceptable.
As previously discussed, pre-solution treating wrought nickel-base alloys at a
temperature ranging from 1550°F to 1600°F can result in the advantageous
precipitation of the at least one grain boundary phase. Further, as previously
discussed, the grain boundary phase, when present in the desired amount and form,
is believed to strengthen the grain boundaries of the nickel-base alloy and thereby
cause an improvement in the elevated temperature properties of the alloys.
Example 2
Test samples were prepared as discussed above in Example 1. The test
samples were then divided into sample groups and the sample groups were
subjected to the solution and aging treatments indicated below in Table 3.
Table 3
Between solution treating and the first aging treatment, the samples were air
cooled, while a cooling rate of about 100°F per hour (i.e., furnace cooling) was
employed between the first and second aging treatments. After the second aging
treatment, the samples were cooled to room temperature by air cooling.
After heat treating, the samples from each group were tested as described
above in Example 1, except that instead of the room temperature Charpy tests
conducted above in Example 1, the samples of Sample Groups 5-8 were subjected
to additional tensile testing at room temperature ('Trm"). The results of these tests
are given below in Table 4, wherein the tabled values are average values for the
samples tested.
Table 4
*Notch Break Observed
As can be seen from the results in Table 4, the test samples of Sample
Groups 5, 6 and 8 had yield strengths of at least about 120 ksi at 1300°F, and
percent elongations of at least about 12 percent at 1300°F. Further, Sample Groups
5-7 also had stress-rupture lives at 1300°F and 80 ksi of at least about 300 hours
and low notch sensitivity.
Between the two sample groups that were solution treated at 1750°F (i.e.,
Sample Group 5 and Sample Group 6), the tensile and yield strength, both at room
temperature and at 1300°F, the elevated temperature ductility, and the stress-rupture
life of the Sample Group 6 test samples were generally improved as compared to the
Sample Group 5 samples. Although not meant to be limiting herein, this is believed
to be attributable to the higher aging temperatures used in aging the Sample Group
6 samples.
As further indicated in Table 4, notch breaks were observed in Sample Group
8. However, as indicated in Table 5, when stress-rupture testing was repeated on 4"
round forged billet samples that were heat treated in a manner similar to the Sample
Group 8 samples, notch breaks were not observed. Although the repeat testing was
performed on 4" round forged billet samples as opposed to 8" round forged billet
samples, the absence of notch breaking is not believed to be attributable to the
different size of the sample. Accordingly, heat treatments such as the one used to
heat treat Sample Group 8 are believed to be suitable in developing nickel-base
alloys having desirable stress-rupture properties.
Table 5
*Between solution treating and the first aging treatment, the samples were air cooled.
**Between the first and second aging treatments, the samples were furnace cooled at a rate of about
100°F per hour
***After the second aging treatment, the samples were cooled to room temperature by air cooling.
Example 3
Test samples were prepared as discussed above in Example 1. The test
samples were then divided into sample groups and the sample groups were then
solution treated at 1750°F for the times indicated below for each sample group in
Table 6. After solution treatment, each of the test samples was air cooled to room
temperature, and subsequently aged at 1450°F for 2 hours, furnace cooled to
1200°F, and aged for 8 hours before being air cooled to room temperature.
After heat treating, the samples from each sample group were tested as
described above in Example 1, except that Charpy impact testing was not conducted
on the test samples. The results of these tests are given below in Table 7, wherein
the tabled values are average values for the samples tested.
As can be seen from the data in Table 7, while only Sample Group 9 had a
stress-rupture life of at least 300 hours at 1300°F and 80 ksi, all of the samples had
yield strengths at 1300°F of at least 120 ksi and percent elongations at 1300°F of at
least 12 percent. Although the stress-rupture properties of Sample Groups 10 and
11 are lower than those of Sample Group 9, It Is believed that solution treatment
times greater than 2 hours may, nevertheless, be useful In certain applications.
Further, as previously discussed, when larger sized samples or work-pieces are heat
treated, solution times greater than 2 hours may be required in order to dissolve
substantially all of the ?' and ?"-phase precipitates.
Example 4
Test samples were prepared from a 4" diameter, round-cornered, square
reforged billet having a grain size ranging from ASTM 4.5 to ASTM 5.5, with an
average grain size of ASTM 5, as determined according to ASTM E 112. The test
samples were then divided into sample groups and the sample groups were solution
treated at 1750°F for 1 hour and cooled to room temperature at the cooling rates
indicated below for each sample group in Table 8. After cooling to room
temperature, the samples were aged at 1450°F for 2 hours, furnace cooled to
1200°F, and aged for 8 hours before being air cooling to room temperature.
After heat treating, the samples from each sample group were tested as
described above in Example 3. The results of these tests are given below in Table
9, wherein the tabled values are average values for the samples tested.
As can be seen from the data in Table 9, when the cooling rate after solution
treatment was low (e.g., 400°F per hour for Sample Group 14), yield strengths less
than 120 ksi at 1300°F were achieved. At higher cooling rates (e.g., 1000°F per hour
for Sample Group 13 and 22,500°F per hour for sample group 14), yield strengths of
at least 120 ksi at 1300°F were observed. However, percent elongations at 1300°F
of at least 12 percent and stress-rupture lives of at least 300 hours at 1 SOOT and 80
ksi were observed for all samples.
Example 5
Test samples were prepared as discussed above in Example 1. Thereafter,
the test samples were divided into Sample Groups 15-21. The samples were
solution treated at 1750°F for 1 hour. After solution treatment, the samples were
cooled to room temperature at a rate of about 22,500°F per hour (air cool) prior to
aging as indicated in Table 10.
After the first aging treatment, all of the samples were furnace cooled to the
second aging temperature, resulting in an average cooling rate of about 50°F to
about 100°F per hour. Further, after the second aging treatment was completed, the
samples were air cooled to room temperature.
After heat treating, at least 2 samples from each sample group were tested as
described above in Example 3. The results of these tests are given below in Table
11, wherein the tabled values are average values for the samples tested.
Table 11
The thermal stability of the mechanical properties at elevated temperatures of
the test samples was also tested by exposing at least 2 samples from each sample
group to 1400°F for 100 hours prior to testing as indicated above. The results of
these tests are given in Table 12 below.
As can be seen from the data of Tables 11 and 12, samples aged at a first
aging temperature of about 1450°F for 2 hours and a second aging temperature of
about 1200°F for 8 hours (i.e., Sample Group 21) had the highest combination of
1300°F ultimate tensile and yield strengths and the highest stress-rupture life. After
thermal exposure at 1400°F (Table 12), the samples of Sample Group 21 had the
highest 1300°F yield strength and stress-rupture life. These results were followed
closely by samples from Groups 15,16, and 20.
Further, it can be seen that the ductility of the alloys was improved after long-
term thermal exposure. Although not meant to be bound by any particular theory, it
is believed that because the samples were not pre-solution treated and the cooling
rate employed in cooling the samples from the solution temperature was high (about
22,500°F/hour), formation of desirable grain boundary d/?-phase precipitates, as
previously discussed in detail, was not achieved until after thermal exposure.
It is to be understood that the present description illustrates aspects of the
invention relevant to a clear understanding of the invention. Certain aspects of the
invention that would be apparent to those of ordinary skill in the art and that,
therefore, would not facilitate a better understanding of the invention have not been
presented in order to simplify the present description. Although the present invention
has been described in connection with certain embodiments, the present invention is
not limited to the particular embodiments disclosed, but is intended to cover
modifications that are within the spirit and scope of the invention, as defined by the
appended claims.
1. A method of heat treating a 718-type nickel-base alloy comprising:
pre-solution treating the nickel-base alloy wherein an amount of at least one
grain boundary precipitate selected from the group consisting of d-phase
precipitates and ?-phase precipitates is formed within the nickel-base
alloy, the at least one grain boundary precipitate having a short, generally
rod-shaped morphology;
solution treating the nickel-base alloy wherein substantially all ?'-phase
precipitates and ?"-phase precipitates in the nickel-base alloy are
dissolved while at least a portion of the amount of the at least one grain
boundary precipitate is retained;
cooling the nickel-base alloy after solution treating the nickel-base alloy at a
first cooling rate sufficient to suppress formation of ?'-phase and ?"-phase
precipitates in the nickel-base alloy;
aging the nickel-base alloy in a first aging treatment wherein primary
precipitates of ?'-phase and ?"-phase are formed in the nickel-base alloy;
and
aging the nickel-base alloy in a second aging treatment wherein secondary
precipitates of ?'-phase and ?"-phase are formed in the nickel-base alloy,
the secondary precipitates being finer than the primary precipitates;
wherein after heat treating the nickel-base alloy, the nickel-base alloy has a matrix
comprising ?'-phase precipitates and ?"-phase precipitates, wherein the ?'-phase
precipitates are predominant strengthening precipitates in the nickel-base alloy, and
an amount of grain boundary precipitates sufficient to pin the majority of the grain
boundaries in the matrix, the grain boundary precipitates being selected from the
group consisting of d-phase precipitates, T|-phase precipitates, and mixtures thereof,
and having short, generally rod-shaped morphologies.
2. The method as claimed in claim 1 wherein the nickel-base alloy comprises, in
percent by weight, up to 0.1 carbon, from 12 to 20 chromium, up to 4 molybdenum,
up to 6 tungsten, from 5 to 12 cobalt, up to 14 iron, from 4 to 8 niobium, from 0.6 to
2.6 aluminum, from 0.4 to 1.4 titanium, from 0.003 to 0.03 phosphorus, from 0.003 to
0.015 boron, and nickel; wherein a sum of the weight percent of molybdenum and
We claim :
the weight percent of tungsten is at least 2 and not more than 8, and wherein a sum
of atomic percent aluminum and atomic percent titanium is from 2 to 6, a ratio of
atomic percent aluminum to atomic percent titanium is at least 1.5, and the sum of
atomic percent aluminum and atomic percent titanium divided by atomic percent
niobium is from 0.8 to 1.3.
3. The method as claimed in claim 1 wherein pre-solution treating the nickel-base
alloy comprises heating the nickel-base alloy at a temperature ranging from 1500°F
to 1650°F for a time ranging from 2 hours to 16 hours
4. The method as claimed in claim 1 wherein pre-solution treating the nickel-base
alloy comprises heating the nickel-base alloy at a temperature ranging from 1550°F
to 1600°F for a time ranging from 2 hours to 16 hours.
5. The method as claimed in claim 1 wherein solution treating the nickel-base alloy
comprises heating the nickel-base alloy at a temperature ranging from 1725°F to
1850°F for no greater than 4 hours.
6. The method as claimed in claim 1 wherein solution treating the nickel-base alloy
comprises heating the nickel-base alloy at a temperature ranging from 1750°F to
1800°F for no greater than 2 hours.
7. The method as claimed in claim 1 wherein the first cooling rate is at least 800°F
per hour.
8. The method as claimed in claim 1 wherein cooling the nickel-base alloy after
solution treating comprises cooling the nickel-base alloy to 1000°F or less.
9. The method as claimed in claim 1 wherein the first aging treatment comprises
heating the nickel-base alloy at a temperature ranging from 1325°F to 1450°F for a
time ranging from 2 hours to 8 hours.
10. The method as claimed in claim 1 wherein the first aging treatment comprises
heating the nickel-base alloy at a temperature ranging from 1365°F to 1450°F for a
time ranging from 2 hours to 8 hours.
11. The method as claimed in claim 1 wherein the second aging treatment
comprises heating the nickel-base alloy at a temperature ranging from 1150°F to
1300°F for at least 8 hours.
12. The method as claimed in claim 1 wherein the second aging treatment
comprises heating the nickel-base alloy at a temperature ranging from 1150°F to
1200°F for at least 8 hours.
13. The method as claimed in claim 1 wherein after heat treating the nickel-base
alloy, the nickel-base alloy has a yield strength at 1300°F of at least 120 ksi, a
percent elongation at 1300°F of at least 12 percent, a notched stress-rupture life of
at least 300 hours as measured at 1300°F and 80 ksi, and a low notch-sensitivity.
14. The method as claimed in claim 1 further comprising cooling the nickel-base
alloy to 1000°F or less after pre-solution treating and prior to solution treating the
nickel-base alloy.
15. The method as claimed in claim 1 further comprising cooling the nickel-base
alloy after the first aging treatment to a second aging temperature at a cooling rate
ranging from 50°F per hour to 100°F per hour.
16. A method of heat treating a 718-type nickel-base alloy, the nickel-base alloy
including up to 14 weight percent iron, the method comprising:
pre-solution treating the nickel-base alloy at a temperature ranging from
1500°F to 1650°F for a time ranging from 2 to 16 hours;
solution treating the nickel-base alloy for no greater than 4 hours at a solution
temperature ranging from 1725°F to 1850°F;
cooling the nickel-base alloy at a first cooling rate of at least 800°F per hour
after solution treating the nickel-base alloy;
aging the nickel-base alloy in a first aging treatment for no greater than 8
hours at a temperature ranging from 1325°F to 1450°F; and
aging the nickel-base alloy in a second aging treatment for at least 8 hours at
a second aging temperature, the second aging temperature ranging from
1150°F to 1300°F.
17. The method as claimed in claim 16 wherein the nickel-base alloy further
includes up to 0.1 carbon, from 12 to 20 chromium, up to 4 molybdenum, up to 6
tungsten, from 5 to 12 cobalt, from 4 to 8 niobium, from 0.6 to 2.6 aluminum, from
0.4 to 1.4 titanium, from 0.003 to 0.03 phosphorus, from 0.003 to 0.015 boron, and
nickel; wherein a sum of the weight percent of molybdenum and the weight percent
of tungsten is at least 2 and not more than 8, and wherein a sum of atomic percent
aluminum and atomic percent titanium is from 2 to 6, a ratio of atomic percent
aluminum to atomic percent titanium is at least 1.5, and the sum of atomic percent
aluminum and atomic percent titanium divided by atomic percent niobium is from 0.8
to 1.3
18. The method as claimed in claim 16 wherein after pre-solution treating the nickel-
base alloy, the nickel-base alloy is cooled to 1000°F or less prior to solution treating
the nickel-base alloy.
19. The method as claimed in claim 16 wherein after pre-solution treating the nickel-
base alloy the nickel-base alloy is directly heated to the solution temperature.
20. The method as claimed in claim 16 wherein solution treating the nickel-base
alloy comprises heating the nickel-base alloy for no greater than 2 hours at a solution
temperature ranging from 1750°F to 1800°F.
21. The method as claimed in claim 16 wherein the first aging treatment comprises
heating the nickel-base alloy for 2 to 8 hours a temperature ranging from 1365°F to
1450°F.
22. The method as claimed in claim 16 wherein after heat treating, the nickel-base
alloy has a yield strength at 1300°F of at least 120 ksi, a percent elongation at
1300°F of at least 12 percent, a notched stress-rupture life of at least 300 hours as
measured at 1300°F and 80 ksi, and a low notch-sensitivity.
23. The method as claimed in claim 16 wherein after heat treating the nickel-base
alloy, the nickel-base alloy comprises:
?'-phase precipitates and ?'-phase precipitates, wherein the ?'-phase
precipitates are predominant strengthening precipitates in the nickel-base
alloy; and
an amount of grain boundary precipitates sufficient to pin the majority of the
grain boundaries in the matrix, the grain boundary precipitates being
selected from the group consisting of d-phase precipitates, ?-phase
precipitates, and mixtures thereof, and having short, generally rod-shaped
morphologies.
24. A method of heat treating a nickel-base alloy, the nickel-base alloy comprising,
in weight percent, up to 0.1 carbon, from 12 to 20 chromium, up to 4 molybdenum,
up to 6 tungsten, from 5 to 12 cobalt, up to 14 iron, from 4 to 8 niobium, from 0.6 to
2.6 aluminum, from 0.4 to 1.4 titanium, from 0.003 to 0.03 phosphorus, from 0.003 to
0.015 boron, and nickel; wherein a sum of the weight percent of molybdenum and
the weight percent of tungsten is at least 2 and not more than 8, and wherein a sum
of atomic percent aluminum and atomic percent titanium is from 2 to 6, a ratio of
atomic percent aluminum to atomic percent titanium is at least 1.5, and the sum of
atomic percent aluminum and atomic percent titanium divided by atomic percent
niobium is from 0.8 to 1.3, the method comprising:
solution treating the nickel-base alloy for no greater than 4 hours at a solution
temperature ranging from 1725°F to 1850°F;
cooling the nickel-base alloy at a first cooling rate after solution treating the
nickel-base alloy;
aging the solution treated nickel-base in a first aging treatment for no greater
than 8 hours at a temperature ranging from 1365°F to 1450°F; and
aging the nickel-base alloy in a second aging treatment for at least 8 hours at
a second aging temperature, the second aging temperature ranging from
1150°F to1300°F.
25. The method as claimed in claim 24 wherein solution treating the nickel-base
alloy comprises heating the nickel-base alloy for no greater than 2 hours at a solution
temperature ranging from 1750°F to 1800°F.
26. The method as claimed in claim 24 wherein the first cooling rate is at least
SOOT per hour.
27. The method as claimed in claim 24 wherein aging the nickel-base alloy in a
second aging treatment comprises heating the nickel-base alloy at a second aging
temperature ranging from 1150°F to 1200°F.
28. The method as claimed in claim 24 wherein after heat treating, the nickel-base
alloy has a yield strength at 1300°F of at least 120 ksi, a percent elongation at
1300°F of at least 12 percent, a notched stress-rupture life of at least 300 hours as
measured at 1300°F and 80 ksi, and a low notch-sensitivity.
29. The method as claimed in claim 24 further comprising pre-solution treating the
nickel-base alloy at a temperature ranging from 1500°F to 1650°F for a time period
ranging from 2 to 16 hours prior to solution treating the nickel-base alloy.
30. The method as claimed in claim 29 wherein after heat treating the nickel-base
alloy, the nickel-base alloy comprises:
?'-phase precipitates and ?"-phase precipitates, wherein the ?'-phase
precipitates are predominant strengthening precipitates in the nickel-base
alloy; and
an amount of grain boundary precipitates sufficient to pin the majority of the
grain boundaries in the matrix, the grain boundary precipitates being
selected from the group consisting of d-phase precipitates, ?-phase
precipitates, and mixtures thereof, and having short, generally rod-shaped
morphologies.
31. A 718-type nickel-base alloy comprising:
a matrix comprising ?'-phase precipitates and ?"-phase precipitates, wherein
the ?'-phase precipitates are predominant strengthening precipitates in the
nickel-base alloy; and
an amount of grain boundary precipitates sufficient to pin the majority of the
grain boundaries in the matrix, the grain boundary precipitates being
selected from the group consisting of 6-phase precipitates, ?-phase
precipitates, and mixtures thereof, and having short, generally rod-shaped
morphologies; and
wherein the nickel-base alloy includes, in percent by weight, up to 0.1 carbon, from
12 to 20 chromium, up to 4 molybdenum, up to 6 tungsten, from 5 to 12 cobalt, up to
14 iron, from 4 to 8 niobium, from 0.6 to 2.6 aluminum, from 0.4 to 1.4 titanium, from
0.003 to 0.03 phosphorus, from 0.003 to 0.015 boron, and nickel; wherein a sum of
the weight percent of molybdenum and the weight percent of tungsten is at least 2
and not more than 8, and wherein a sum of atomic percent aluminum and atomic
percent titanium Is from 2 to 6, a ratio of atomic percent aluminum to atomic percent
titanium is at least 1.5, and the sum of atomic percent aluminum and atomic percent
titanium divided by atomic percent niobium is from 0.8 to 1.3, wherein the nickel-
base alloy includes.
32. A heat treated 718-type nickel-base alloy including up to 14 weight percent iron and
comprising a matrix comprising ?'-phase precipitates and ?"-phase precipitates, wherein
the ?'-phase precipitates are predominant strengthening precipitates in the nickel-base
alloy, and an amount of grain boundary precipitates sufficient to pin the majority of the
grain boundaries in the matrix, the grain boundary precipitates being selected from the
group consisting of d-phase precipitates, r|-phase precipitates, and mixtures thereof,
and having short, generally rod-shaped morphologies, wherein the nickel-base alloy is
heat treated by:
pre-solution treating the nickel-base alloy at a temperature ranging from
1500°F to 1650°F for a time ranging from 2 to 16 hours;
solution treating the nickel-base alloy for no greater than 4 hours at a solution
temperature ranging from 1725°F to 1850°F,
cooling the nickel-base alloy at a first cooling rate of at least SOOT per hour
after solution treating the nickel-base alloy;
aging the nickel-base alloy in a first aging treatment from 2 hours to 8 hours at
a temperature ranging from 1325°F to 1450°F; and
aging the nickel-base alloy in a second aging treatment for at least 8 hours at
a second aging temperature, the second aging temperature ranging from
1150°F to1300°F.
33. A method of forming an article of manufacture comprising a 718-type nickel-
base alloy including up to 14 weight percent iron, the method comprising:
forming the nickel-base alloy into a desired configuration; and
heat treating the nickel-base alloy, wherein heat treating the nickel-base alloy
comprises:
pre-solution treating the nickel-base alloy at a temperature ranging
from 1500°F to 1650°F for a time ranging from 2 to 16 hours;
solution treating the nickel-base alloy for no greater than 4 hours at a
solution temperature ranging from 1725°F to 1850°F;
cooling the nickel-base alloy at a first cooling rate of at least 800°F per
hour after solution treating the nickel-base alloy;
aging the nickel-base alloy in a first aging treatment from 2 hours to 8
hours at a temperature ranging from 1325°F to 1450°F; and
aging the nickel-base alloy in a second aging treatment for at least 8
hours at a second aging temperature, the second aging
temperature ranging from 1150°F to 1300°F.
34. The method as claimed in claim 32 wherein the nickel-base alloy comprises, in
percent by weight, up to 0.1 carbon, from 12 to 20 chromium, up to 4 molybdenum,
up to 6 tungsten, from 5 to 12 cobalt, up to 14 iron, from 4 to 8 niobium, from 0.6 to
2.6 aluminum, from 0.4 to 1.4 titanium, from 0.003 to 0.03 phosphorus, from 0.003 to
0.015 boron, and nickel; wherein a sum of the weight percent of molybdenum and
the weight percent of tungsten is at least 2 and not more than 8, and wherein a sum
of atomic percent aluminum and atomic percent titanium is from 2 to 6, a ratio of
atomic percent aluminum to atomic percent titanium is at least 1.5, and the sum of
atomic percent aluminum and atomic percent titanium divided by atomic percent
niobium is from 0.8 to 1.3.
35. The nickel-base alloy as claimed in claim 31 wherein the nickel-base alloy has a
notched stress-rupture life of at least 400 hours as measured at 1300°F and 80 ksi,
and a low notch-sensitivity.
36. The nickel-base alloy as claimed in claim 32 wherein the nickel-base alloy has a
notched stress-rupture life of at least 400 hours as measured at 1300°F and 80 ksi,
and a low notch-sensitivity.
39

The Invention discloses a method of heat treating a 718-type nickel-base alloy
comprising: pre-solution treating the nickel-base alloy wherein an amount of at least
one grain boundary precipitate selected from the group consisting of δ-phase
precipitates and η-phase precipitates is formed within the nickel-base alloy, the at
least one grain boundary precipitate having a short, generally rod-shaped
morphology; solution treating the nickel-base alloy wherein substantially all γ'-phase
precipitates and γ"-phase precipitates in the nickel-base alloy are dissolved while at
least a portion of the amount of the at least one grain boundary precipitate is
retained; cooling the nickel-base alloy after solution treating the nickel-base alloy at a
first cooling rate sufficient to suppress formation of γ'-phase and γ"-phase
precipitates in the nickel-base alloy; aging the nickel-base alloy in a first aging
treatment wherein primary precipitates of γ'-phase and γ"-phase are formed in the
nickel-base alloy; and aging the nickel-base alloy in a second aging treatment
wherein secondary precipitates of γ'-phase and γ"-phase are formed in the nickel-
base alloy, the secondary precipitates being finer than the primary precipitates;
wherein after heat treating the nickel-base alloy, the nickel-base alloy has a matrix
comprising γ'-phase precipitates and γ"-phase precipitates, wherein the γ'-phase
precipitates are predominant strengthening precipitates in the nickel-base alloy, and
an amount of grain boundary precipitates sufficient to pin the majority of the grain
boundaries in the matrix, the grain boundary precipitates being selected from the
group consisting of δ-phase precipitates, η-phase precipitates, and mixtures thereof,
and having short, generally rod-shaped morphologies.

Documents:

00855-kolnp-2006-abstract.pdf

00855-kolnp-2006-assignment.pdf

00855-kolnp-2006-claims.pdf

00855-kolnp-2006-correspondence others.pdf

00855-kolnp-2006-cover letter.pdf

00855-kolnp-2006-description(complete).pdf

00855-kolnp-2006-drawings.pdf

00855-kolnp-2006-form 1.pdf

00855-kolnp-2006-form 3.pdf

00855-kolnp-2006-from 5.pdf

00855-kolnp-2006-international publication.pdf

00855-kolnp-2006-international search authority report.pdf

00855-kolnp-2006-pct form.pdf

00855-kolnp-2006-priority document.pdf

855-KOLNP-2006-ABSTRACT 1.1.pdf

855-KOLNP-2006-ABSTRACT-1.2.pdf

855-KOLNP-2006-CANCELLED DOCOMENT-1.1.pdf

855-KOLNP-2006-CANCELLED PAGE.pdf

855-KOLNP-2006-CLAIMS 1.1.pdf

855-KOLNP-2006-CLAIMS-1.2.pdf

855-KOLNP-2006-DESCRIPTION COMPLETE 1.1.pdf

855-KOLNP-2006-DESCRIPTION COMPLETE-1.2.pdf

855-KOLNP-2006-FORM 1-1.2.pdf

855-KOLNP-2006-FORM 1.1.pdf

855-KOLNP-2006-FORM 3.1.pdf

855-KOLNP-2006-FORM-27.pdf

855-kolnp-2006-granted-abstract.pdf

855-kolnp-2006-granted-assignment.pdf

855-kolnp-2006-granted-claims.pdf

855-kolnp-2006-granted-correspondence.pdf

855-kolnp-2006-granted-description (complete).pdf

855-kolnp-2006-granted-drawings.pdf

855-kolnp-2006-granted-examination report.pdf

855-kolnp-2006-granted-form 1.pdf

855-kolnp-2006-granted-form 18.pdf

855-kolnp-2006-granted-form 3.pdf

855-kolnp-2006-granted-form 5.pdf

855-kolnp-2006-granted-gpa.pdf

855-kolnp-2006-granted-reply to examination report.pdf

855-kolnp-2006-granted-specification.pdf

855-KOLNP-2006-OTHERS-1.1.pdf

855-KOLNP-2006-OTHERS.pdf

855-KOLNP-2006-PCT PRIORITY DOCUMENT NOTIFICATION.pdf

855-KOLNP-2006-PETITION UNDER RULE 137.pdf

855-KOLNP-2006-REPLY F.E.R.pdf

855-KOLNP-2006-REPLY TO EXAMINATION REPORT.pdf

abstract-00855-kolnp-2006.jpg


Patent Number 235652
Indian Patent Application Number 855/KOLNP/2006
PG Journal Number 19/2010
Publication Date 07-May-2010
Grant Date 07-May-2010
Date of Filing 06-Apr-2006
Name of Patentee ATI PROPERTIES INC
Applicant Address 1600 NE OLD SALEM ROAD, P.O.BOX 460 ALBANY, OR 97321
Inventors:
# Inventor's Name Inventor's Address
1 CAO, WEI-DI 6922 KERSFIELD PLACE, CHARLOTTE, NC 28227
2 KENNEDY, RICHARD, L.. 206 MACEDONIA CHURCH ROAD, MONROE, NC 28112
PCT International Classification Number C22C 19/05
PCT International Application Number PCT/US2004/031760
PCT International Filing date 2004-09-28
PCT Conventions:
# PCT Application Number Date of Convention Priority Country
1 10/679,899 2003-10-06 U.S.A.