DE2126435A1 - Nickel alloy with improved high temperature properties and process for their manufacture - Google Patents

Description

Ρ'3996-25 ^ May 27, 1971

Special Metals Corporation

. "Nickel alloy with improved high temperature properties and process for their preparation "...

The invention relates to a nickel alloy, and more particularly to one 'Nickel alloy with improved high temperature properties, as well a process for making such nickel alloys.

Nickel alloys and their use at elevated temperatures have been known for some time. In particular, it is known that nickel alloys can be considerably improved by precipitation hardening, so that not only their useful life is extended, but these alloys can also be used at higher temperatures. Perhaps the best known hardening precipitate in nickel alloys is an intermetallic compound known as the "/ 'phase", which is believed to have the general formula M ₅ (Al, Ti). The symbol "M" in the sense of the invention in the ν 'compound represented by the above general formula means a metal component consisting mainly of nickel, which can be replaced to a certain small extent by chromium and / or molybdenum, the nickel, Probably contains chromium and molybdenum in an approximate atomic ratio of 95: 3 s 2 , *

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'' Despite the generally very good high-temperature properties consists of nickel alloys hardened by / '- grain precipitation of course on Q-around of the constantly increasing requirements In terms of the properties of construction materials, the desire for nickel alloys with even better high-temperature properties, so that the invention is based on the object of a nickel alloy with improved high-temperature properties to provide and to create a process for the production of such nickel alloys.

It has now been found that the already good high-temperature properties of nickel alloys, which essentially consist of 14.2 to 20 wt .- ^ cobalt, 13.7 to 16 wt .- ^ chromium, 3.8 to 5.5 wt. - ^ molybdenum, 2.75 to 3.75% by weight titanium, 3.75 to 4.75% by weight aluminum, 0.005 to 0.035% by weight boron, up to 0.18% by weight carbon , up to 4 wt .- ^ iron, up to 0.5 wt .- <fo zircon, up to 0.5 wt .- 5 ^ hafnium, up to 0.75 wt .- J ^ niobium, up to 0, 5 wt .- ^ rhenium, up to 0.75 wt .- $ tantalum, up to 1.0 wt .- $ manganese, up to 3 wt .- ^ tungsten and up to 0.5 wt .- ^ rare earth metals, E.g. cerium and / or yttrium and / or lanthanum, as well as the remainder essentially consisting of nickel with the usual incidental impurities, can be significantly improved if the nickel alloys are subjected to a treatment through which a special ^ 'grain phase develops or is generated, which consists essentially of randomly distributed, irregularly shaped f ¹ granules with a grain diameter of little it exists as about 0.35 µm.

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The subject of the invention is thus a nickel alloy with improved high temperature properties, consisting essentially of 14.2 "to 20 wt .- ^ cobalt, 13.7 to 16 wt .- ^ chromium, * 3.8 to 5.5 wt .- ^ Molybdenum, 2.75 to 3.75 wt .- $ titanium, 3.75 to 4.75 wt .- ^ aluminum, 0.005 to 0.035 wt .- ^, boron, up to 0.18 wt .- ^ carbon, up to 4 wt .- ^ iron, up to 0.5 wt .- ^ zircon, up to 0.5 wt .- ^ hafnium, up to 0.75 wt .- ρ Job, up to 0.5 wt .- ^ Rhenium, up to 0.75 wt .- ^ tantalum, up to 1.0 wt .- $ manganese, up to 3 wt .- ^ tungsten and up to 0.5 wt .- ^ rare earth metals, as well as the remainder im essentially nickel with the usual impurities, having a substantially made of irregularly shaped, randomly distributed ^ '- grains having a grain size of less than about 0.35 to ¹ y existing grain phase.

Up to now, nickel alloys with the composition specified above often had a <J "grain phase or a structure of oriented cubic ^ 'grains with an edge length of about 0.5 microns. These cubic v 'grains interfered the high temperature properties of the nickel alloys, as they add to it tend to get lost during "a long period of use with" to agglomerate at elevated temperatures and to form rod-like particles or granules in certain crystallographic planes, along which rapid sliding or translation then takes place. The formation of these cubic ^ '- granules was due to the during the second treatment stage in heat treatment processes according to the Prior art, during which the precipitation of the y 'phase or granules was initiated, used high annealing temperatures traced back. For example, at a special

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len known processes with a heat treatment

1) 4-hour annealing at a temperature of 1168.3 ⁰ C and then cooling down,

2) annealing for 4 hours at a temperature of 1079> 4 ° 0 and subsequent. Cooling down, - .

3) Annealing for 24 hours at a temperature of 843.3 ° G and repeated cooling, as well

4) annealing for 16 hours at a temperature of 76O ⁰ C and subsequent cooling carried out, that is, in the second heat treatment stage · or. at the second glow. a: temperature of 1079.4 ° C applied, where, as has been found according to the invention, cubic grains precipitate. - ■

According to the invention this formation of coarse comparatively cubic j -'- Eörnchen essentially in that applied during the second stage of the heat treatment or during the second annealing an annealing temperature of at most 101o C ⁰ avoided "is."

The above-described and other tasks, features and advantages of the invention emerge from the description and the claims and are particularly good from the following Description should be understood in conjunction with the accompanying drawing.

In the drawing is:

Figure 1 is a diagram in which the elongation in percent of two nickel alloy samples is plotted against the time that a relative to the second stage (hereinafter referred to as Aus-10 9 8 5 1/10 8 6

Seheidungsglühung) were subjected to different heat treatments, with one pro. be a 4-hour Ausscheidungsglühung at 1079j4 was performed ° C and the other for 8 hours at 926.7 Ausscheidungsglühung ⁰ C; ".

FIG. 2 a photomicrograph (enlargement factor 7200) of a nickel alloy, which undergoes a heat treatment with a 4-hour precipitation anneal Was subjected to 1079.4 ° G;

FIG. 3 a photomicrograph (enlargement factor 72OO) a nickel alloy that undergoes heat treatment was subjected to a precipitate anneal for 8 hours at 926.7 ° C;

Figure 4 is a photomicrograph (Ve'rgrösserungsfaktor 72OO) a nickel alloy, which was subjected to a heat treatment for 8 hours at 954.4 Ausscheidungsglühung ⁰ C;
and ·

FIG. 5 shows a photomicrograph ("magnification factor 7200") of a nickel alloy which has been subjected to a heat treatment with a precipitation annealing at 954.4 ⁰ O for 24 hours.

The nickel alloys of the invention preferably have one ^ "- grain phase consisting essentially of / '- granules with a Diameter of less than 0.25 ^ m. You can also nickel alloys according to the invention contain other precipitates, e.g. granules of the formula "M-'g ^ Cg", in which M 'in the Re- · gel is chromium, which improves the grain boundary ductility,

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It should be noted that too. Nickel alloys of the foregoing specified composition as according to the invention or preferred nickel alloys according to the invention are to be considered which

/
contain a certain small proportion of ^ ¹ granules with a grain size of more than 0.35 or 0.25 / im, provided that the proportion of such ^ ¹ granules is less than about 5 percent by volume.

In preferred nickel alloys of the invention, the grain size of the>'grains is mostly in a range from 0.1 to 0.25 μm.

To explain the "nickel alloys according to the invention" Reference is made to Table I below, in the preferred ranges for the composition of nickel alloys according to the invention are specified.

Table I - .'..._

EIe- Preferred area Preferred area Preferred area ment I II III (wt. - #) (wt .- ^) (ffew ..- #. *

C 0.03-0.10 0.03-0.09 0.05-0.09

Co 17-20 16-18 14.25-16.25

Or 14-16 14-16 "14-15.25

Mo 4.5 - 5.5 4.5 - 5.5 3.9 - 4.9

Ti 2.75-3.75 3.35-3.65 3.0-3.7

Al 3.75 -4.75 3.85-4.15 4-4.6

Fe 4 max. ■ 0.5 max.. 0.5 max.

B 0.025-0.035 0.02-0.03 0.012-0.02

Zr 0.06 max. 0.10 max, 0.06 max.

Mn 0.15 max. 0.15 max. 0.15 max.

Ni remainder remainder remainder

As already mentioned, the invention also relates to a method to produce essentially from 14.2 to

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20 wt% cobalt, 13.7 to 16 wt% chromium, 3.8 to 5.5 wt% molybdenum, 2.75 to 3.75 wt% titanium, 3.75 "to 4 , 75 wt .- ^
Aluminum, 0.005 to 0.035 weight percent boron, up to 0.18 weight percent
Carbon, up to 4 wt .- ^ iron, up to 0.5 wt .- ^ zircon,
up to 0.5 wt. - ^c ß> hafnium, up to 0.75 wt .- $ niobium, up to
0.5 wt .- ^ rhenium, up to 0.75 wt .- $ tantalum, up to 1.0 wt .- $ manganese, up to 3 wt .- $ ΐ / bfram and up to 0.5 wt .- $ rare earth metals such as cerium and / or yttrium and / or lanthanum, and the balance in the ^r A \ e sent lic hen · nickel with usual impurities
existing lithium alloys with improved high temperature properties.

The method of the invention essentially comprises a two- or three-stage heat treatment, that is to say that a nickel alloy of the composition specified above is subjected to two or three annealing operations, each of which is followed by cooling. As a result of this heat treatment, a structure of J "grains or a ^ ¹ grain phase is produced in the nickel alloy, which consists essentially of randomly distributed, irregularly shaped y'-grains with a diameter of less than about 0.35 μm." · .--

The first stage of the method of the invention characterizing heat treatment (solution annealing) is used, a sufficiently large proportion of coarse ^ Granules, the lung during the herstel, form of the alloy, for example during casting and machining,
to bring into (solid) solution. The ^ '- granules begin at
a temperature of about 1093.3 ⁰ C to go (+ 13.9 ⁰ C, depending on the accuracy of the annealing furnace used) in solution, the solution process is complete at about 1162.8 ⁰ C. The in

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Individual cases applicable solution treatment depends "on the intended end use of nickel alloy from. For alloys to be used at an operating temperature of more than 982.2 ⁰ C, it is recommended, preferably a solution annealing temperature of about 1162.8 0 apply as practical in substantially all coarse ^ Granules which do not contribute to the strength of the alloy, to be placed in solution. for alloys to be at 76o ⁰ O, used at operating temperatures of less than 982.2 ⁰ G, for example ', it is sometimes It is expedient and recommended to use a solution annealing temperature of 1093.3 to 1162.8 ⁰ O, at which only partial dissolution takes place, since lower solution annealing temperatures lead to nickel alloys with a finer grain size.

The second stage of the heat treatment characterizing the process of the invention (precipitation annealing) is used to initiate and effect the formation of randomly distributed, irregularly shaped fine ^ -korns and a grain boundary ^{exclusion of M 1} 23 ^C 6 (K ¹ is usually chromium) produce, through which the grain boundary ductility is improved. The precipitation annealing is a time and temperature dependent process. Longer annealing times are required at lower temperatures, while the annealing times are shorter at higher annealing temperatures. The annealing temperature is pulled downwards by at 815.6 ⁰ C a limit since it wäre- uneconomical "taking into account the required then annealing times to operate at lower annealing temperatures. The upper Glühtemperaturgrenze is in Ausscheidungsglühung about 1010 ° C because ,. M. ' _o , Cg at this one

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Temperature begins to go into solution and since the formation of cubic ^ '- granule is accelerated at higher temperatures.

The Ausscheidungsglühung is preferably carried out at a temperature between about 871.1 and about 982.2 ⁰ C. No specific range can be given with regard to the annealing time, as the annealing time depends on too many variables, such as the temperature and the thickness of the material being treated.

In the heat treatment carried out according to the invention, the third annealing is a contingency measure that is preferably used but is not absolutely necessary. It serves to secrete additional M'p ^ Cg granules and is carried out at a temperature low enough to preclude harmful growth of ^ 'granules. The temperature range in which this annealing is preferably carried out is 732.2 to 787.8 ⁰ G.

The examples illustrate the invention.

Several samples (A, B, C and D) are melted and heat treated, after which photomicrographs are taken for each. Samples A and B are also each tested for their creep behavior at 982.2 ° and under a tensile stress of 11.25 kp / mm. All samples mentioned consist essentially of 0.08% by weight of carbon, 16.9% by weight of cobalt, 15.1% by weight of -4> chromium, 5.0% by weight of molybdenum, 3.47% by weight ^ Titanium, 4.0 wt .- ^ aluminum, 0.027 wt .- ^ boron and the remainder of nickel with usual impurities »

The sample A is subjected to the following heat treatment:

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1) annealing for 4 hours at 1168.3 ° C and cooling in air;

2) (precipitation annealing) annealing for 4 hours at 1079.4 ° C and Cooling in, air;

3) annealing for 24 hours at 843.3 ° C and cooling in air? and .

4) Annealing for 16 hours at 760 ^° C. and cooling in air.

The sample B is subjected to the following heat treatment:

1) 4-hour annealing at 1168.3 ⁰ C and cooling in air;

2) (precipitation annealing) annealing for 8 hours at 926.7 ° C and Cooling in air;

and

3) Anneal at 76O ⁰ G for 16 hours and cool in air.

The sample C undergoes the same heat treatment as the sample B

subject, whereby, in deviation therefrom, only the intermediate annealing, that is to say the second or precipitation annealing at 954.4 ⁰ O is carried out.

Sample D is also subjected to the same heat treatment as sample B, with the difference being that only the intermediate annealing or *. Ausscheidungsglühung "is performed at 954.4 ⁰ C with an annealing time of 24 hours ·

The results of the creep tests performed on Samples A and B. are shown in Figure 1, in which the elongation or Lengthening in percent is plotted against time. From the in The test results shown in FIG. 1 show that when subjected to a heat treatment according to the invention Sample B is the creep speed in the second section, the means the most commonly used characteristic value for construction corners,

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substantially constant creep rate, less than that of Sample A which was subjected to a conventional prior art heat treatment. The creep speed in the second test or creep speed section was 0.006 / hour and 0.04 / hour for samples B and A, respectively. A part ("structural element) for which a maximum elongation of $ 1 is required , would have a useful life of only 10 hours at an operating temperature of 982.2 ⁰ C and a tensile stress of 11.25 kgf / mm if it were made of a nickel alloy of the composition given above that had the same heat treatment as the sample A "while the useful life would be about 110 hours if a heat treatment corresponding to that of Sample B were applied. Sample B thus shows an improvement of 11: 1 over Sample A.

The reproduced in the! Figures 2 and 3 are photomicrographs (magnification of respectively 7200) show the different morphology or the different microstructures of the samples A and B. In Figure 2 (photomicrograph of Irobe A) are oriented cubic ^ ¹ -Körnehen with an edge length of about 0.5 µm (whereby some of the ^ '- grains look triangular or trapezoidal due to the grain orientation and the surface section), while the j -' grain phase structure shown in FIG consists essentially of randomly distributed, irregularly shaped ^ ¹ granules with a diameter of less than about 0.25 microns. These photomicrographs clearly show that the

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lower creep speed in the second creep speed section in the case of sample B, it can be traced back to its special morphology or its special structure, which " from the special heat treatment applied according to the invention results,

The microphotographs shown in FIGS. 4 and 5 show how, in the heat treatment according to the invention, the annealing temperature used in the precipitation annealing and the annealing duration used influence the size of the>'grains. Sample C, which was subjected to a heat treatment which differs from that of sample B le. Only in that an annealing temperature of 954 ° 4 0 instead of an annealing temperature of 926.7 ° C was used in the precipitation annealing, has greater ^ ' Granules than sample B, while sample D, which was subjected to a heat treatment that differed from the heat treatment used in sample 0 only in that an annealing time of 24 hours instead of just 8 hours was used for the precipitation annealing, was in turn larger £ granules than sample C. Samples C and D are shown in FIGS. 4 and 5, respectively, enlarged 7200 times. .

A few more samples (Samples, E, P, G, and H) are melted and heat treated, whereupon they are respectively at 898.9 ° E and with subjected to a tensile strength test of 24.61 kgf / mm.

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The samples E ″ to H each essentially consist of 0.05 wt .- $ carbon, 17.5 wt .- $ cobalt, 14.5 wt .- $ chromium, 4.5% by weight molybdenum, 3.19% by weight titanium, 4.20% by weight aluminum, 0.028 wt% boron and the remainder essentially nickel with usual Impurities, the sample E is the following heat treatment. subject to:

1) annealing at 1168.3 C for 4 hours and cooling in air;

2) annealing for 4 hours at 1079.4 ° C. and cooling in air;

3) Annealing for 24 hours at a temperature of 843.3 ° C and cooling in air;

and

4) Annealing at 760 C for 16 hours and cooling in air.

The sample F is subjected to the following heat treatment:

1) annealing for 4 hours at 1168.3 ° C. and cooling in air;

2) (precipitation annealing) annealing for 4 hours at 926.7 C and Cooling in air;

3) Annealing for 16 hours at 76O ⁰ C and cooling in air.

Samples G and H are subjected to the same heat treatment as sample ¥ , with the only difference being that an annealing period of 8 or 16 hours is used for precipitation annealing.

The tensile strength tests with samples E, P, G and H The results obtained are shown in Table II below.

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■■ - 14 - lifespan, 2126435 Hours. * Table II 110.5 sample 115.1 E. 141.7 P. 126.2 G H

* Average value of 2 irobodies

From the. The values given in Table II show that they were subjected to a heat treatment according to the invention Samples F ·, G and H have a higher service life than that Have sample E which is one common in the prior art Subject to heat treatment.

For example, it has a heat treatment according to the invention subjected sample G at 898.9 C and a tensile load of 24.61 kp / mm an average service life of 141.7 hours, while that tested for comparison, after Prior art heat-treated sample E under the same conditions only had an average life of 110.5 hours.

From the above description of the invention based on specific, Various other modifications and possible applications are readily apparent to those skilled in the art of the invention, which is therefore not intended to be restricted to the specific examples described.

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Claims (1)

P 3996-25 May 27, 1971 Patent claims 1. Nickel alloy with improved high temperature properties, consisting essentially of 14.2 to 20% by weight cobalt, 13.7 to 16% by weight chromium, 3.8 to 5.5 Gov /.-# molybdenum, 2.75 to 3.75 wt .- ^ titanium, 3.75 to 4.75 weight .- ^ aluminum, 0.005 to 0.035 wt .- # boron, up to 0.18 wt .- ^ carbon, up to 4 e \ r ^{- c} / o iron, up to 0.5% by weight zirconium, up to 0.5% by weight hafnium, up to 0.75% by weight > niobium, up to 0.5% by weight / o rhenium, up to 0.75 wt .- $ tantalum, up to 1.0 wt .- $ manganese, up to 3 wt. -io Yfolfram and up to 0.5 wt .- ^ rare Srdmetalle, as well as ^{The remainder, essentially nickel with the usual impurities, with a ^ 1} grain phase consisting essentially of irregularly shaped, randomly distributed <f "grains with a grain size of less than about 0.35 JMi. 2. Nickel alloy according to claim 1, characterized in that the ^ ¹ granules are smaller than about 0.25 JAm. 3. Nickel alloy according to claim 2, characterized in that the y granules are about 0.1 to 0.25 µm in size. 4. Nickel alloy according to at least one of claims 1 to 3, characterized in that it consists essentially of 0.003 to .0.10 wt .- $ carbon, 17 to 20 wt .- $ cobalt, 14 to 16 wt .- # chromium, 4.5 to 5.5 wt .- $ molybdenum, 2.75 to 3.75 wt .- $ / & titanium, 3.75 to 4.75 wt .- $ aluminum, 0.025 to 0.035 wt .- $ boron, up to 4 wt ^C / _O iron, up to 0.06 parts by weight fo zirconium and up to 0.15 wt .- ^ manganese, and, as the balance nickel with incidental impurities. . 109851/1086 5. Nickel alloy according to at least one of claims 1 "to 3, characterized in that it consists essentially of 0.03 Tdis 0.09 wt .- # carbon, 16 to 18 wt .-% cobalt, 14 to 16 wt .- ^ Chromium, 4.5 to 5.5% by weight molybdenum, 3.35 to 3.65% by weight titanium * 3.85 to 4.15% by weight aluminum, 0.02 to 0.03% by weight .- $ »boron, up to 0.5 wt .- $ iron, up to 0.10 part by weight 5» zirconium and up to 0.15 wt .- $ ^o manganese, and, as the balance nickel with usual Impurities. 6.! Thick! Alloy according to at least one of claims 1 to 3, characterized in that it consists essentially of 0.05 to 0.09 wt .- ^ carbon, 14.25 to 16.25 wt .- ^ cobalt, 14 up to 15.25 weight percent ohm, 3.9 to 4.9 weight percent molybdenum, 3.0 to 3.7 weight percent titanium, 4.0 to 4.6 weight percent aluminum, 0.012 up to 0.02 wt .- $ boron, up to 0.5 wt .- ^ iron, up to 0.06 wt. zircon, and up to 0.15 wt. -fo Hangan, and, as the balance nickel with usual impurities consists. 7. Process for the production of nickel alloys according to at least one of claims 1 to 6, characterized in that a nickel alloy of the corresponding composition is first annealed at a temperature of at least about 1093.3 ° C in order to bring coarse j * granules into solution (Solution heat treatment), the nickel alloy after the solution heat treatment "cools" and then anneals at a temperature of about 815.6 to about 1010 C in order to initiate and bring about the formation of fine y -grains (precipitation annealing). irregularly shaped / '- grains with a grain size of less than about 0.35 µm forms existing ^' - grain phase. 10 9851/1086 C, ancestors according to claim 7, characterized in that α ι · .-- ·. Solution treatment at a temperature of about 1093.3 to about 1162.8 ⁰ G is carried out. 9 · A method according to claim 1, characterized in that the solution annealing at a temperature of at least a etv 1162.8 G ⁰ is performed /. In 10. "The method according to any one of claims 7 to 9" in that the Ausscheidungsglühung at a temperature of etv / a 871.1 to 982.2 etv a ⁰ C is performed /. 11. The method according to at least one of claims 7 to Lö, characterized in that the nickel alloy is subjected to a further annealing at a temperature of about 732.2 to about 787.8 ⁰ C after the precipitation annealing. 109851/1086 SAD Lee on the side