JPH01180924A - Production of alloy - Google Patents

Abstract

PURPOSE: To decrease the amount of a vacuum-melted alloy and to reduce manufacturing costs of an alloy by welding a first metal ingot, prepared by vacuum melting, to a second ingot prepared by air melting and forming a metallic charge for investment casting.

CONSTITUTION: A first alloy, containing Al and Ti in its matrix, is subjected to vacuum melting. An Ni-containing second alloy is melted in the air. Subsequently, an ingot of the first alloy is weld to an ingot of the second alloy and they are joined together mechanically. By this method, a charge for investment casting, composed of an Ni-base alloy containing ≥3% Al and ≥0.1% Ti and satisfying Al+Ti≥12%, can be obtained.

COPYRIGHT: (C)1989,JPO

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application This invention is used in the investment casting industry to manufacture critical components used in the hot stages of turbocharger components for aircraft jet engines and internal combustion engines. This paper relates to the manufacturing process of high-grade alloys.

BACKGROUND OF THE INVENTION Alloys containing various concentrations of aluminum and titanium are currently required in the manufacture of metal parts that must withstand high temperatures and corrosion.

Such alloys are used, for example, in the manufacture of parts for aircraft gas turbine engines. The metallurgical requirements for the metals used to make such parts are so demanding that the metals are called superalloys. The American Institute of Metals defines superalloys as ``alloys developed for use at very high temperatures where relatively high stresses and oxidation resistance are often required.'' Titanium is used more often in sharpeners where an alloy with high strength is required. On the other hand, more aluminum is used when the resulting alloy has a hard oxidation resistance.

The parts that make up the turbocharger unit are currently manufactured by investment casting methods. Alloy ingots are initially manufactured by a vacuum process such as vacuum induction melting. It is then supplied to investment casters in the form of ingots. The ingot is then remelted and cast in a mold to form the desired shape.

Raw materials for the production of superalloys are broadly divided into vacuum melting grades or air melting grades. Vacuum melting grade materials must be of the highest quality and cleanest, and it must be proven that no foreign matter is present in the superalloy, and must be qualified for the specific alloy. Vacuum melting grade metals are produced by a number of different processing techniques.

These processes include vacuum induction melting, vacuum arc remelting, electroflux and eftron beam melting, and other processing methods. To date, vacuum melting grade Special processing was required to produce the raw materials.

In vacuum induction melting, the quality of the alloy mainly depends on the quality of the raw materials. That is, the raw material from which the ingot is formed must be of very high purity compared to the formation of other metallurgical alloys.

This is because many dull materials are not removed in the vacuum induction melting process.

Air-melting grade raw materials may contain some oxide scale or harmful materials that may be removed during air-melting.

Air melting is originally used for refined alloys used in plates, sheets, pertubes and forging stock, or for the production of mask alloys which are remelted by vacuum processing. Airborne melt grade materials have recently been produced by an argon oxygen carbon removal process. Argon oxygen carbon removal (AOD) uses an open vessel fitted with a trunnion lined with magnesite chrome or dolomite refractory bricks. Oxygen and inert gas (argon or nitrogen) are injected by opening the lower tuyere provided in the side wall of the vessel. The heat is generated by exothermic reactions of the bath components and no external heat source is used or required. First, an inert gas containing a large amount of oxygen is blown onto the molten metal. As the carbon content of the dissolved material decreases, the content of oxygen relative to the inert gas is lowered step by step to obtain the most favorable thermodynamic conditions. The AOD process deflows molten metals to very low levels and also removes carbon with very high efficiency. However, this process also removes aluminum titanium. In the manufacture of turbocharger parts, aluminum is indispensable due to the oxidation resistance of the alloy, and titanium is indispensable in the manufacture of parts with sufficient strength. Therefore, conventionally, it has been necessary to manufacture ingots for manufacturing turbocharger parts by a vacuum melting process rather than an AOD process.

The process of making parts from ingots formed by vacuum induction melting is very expensive compared to making them from ingots made by AOD.

The process of forming ingots containing more than about 0.1% aluminum or titanium must be carried out in a vacuum because these materials react with air.

Until now, only such alloys could be produced by vacuum melting. Due to the high cost of raw materials and the high cost of vacuum induction melting itself, the aluminum and titanium-containing ingots used by investment casters to make metal parts are very expensive.

SUMMARY OF THE INVENTION In accordance with the present invention, a method is devised that significantly limits the amount of vacuum induction melt alloy that must be used to make parts by investment casting. According to this invention, the majority of the alloys utilized in the final investment cast parts are made by a method that is significantly cheaper than vacuum induction melting. For example, most alloys containing elements such as chromium, molybdenum, boron, columbium cobalt and nickel can be produced by methods such as AOD. According to this technique, molten alloy is produced by electric arc or air induction, and the molten metal is transferred to a decanter. Oxygen, argon, nitrogen or a mixture of these gases is blown through the decanter to remove unwanted impurities. With AOD, raw material costs are significantly lower than with vacuum induction melting.

This is because, unlike vacuum induction melting, raw materials of considerably lower purity can be utilized from the beginning due to the fact that impurities can be removed.

According to the invention, alloy raw materials excluding reactive elements, such as aluminum and titanium, are refined by AOD and cast into ingots. To obtain the required aluminum and titanium, refined aluminum and titanium are produced in fairly small quantities in a matrix material such as nickel by vacuum induction melting or an equivalent method. Larger and less expensively produced ingots of less reactive elements such as nickel, chromium, molybdenum, columbium and carbon produced by AOD are compared to significantly smaller ingots of nickel, aluminum and titanium alloys in preparation for investment casting. mechanically joined to the The two are joined together to form one ingot and finally melted by investment casting to produce metal parts from an alloy containing appropriate concentrations of aluminum and titanium. These parts therefore exhibit the desirable characteristics contributed by those elements.

Investment casting is the production of metal parts that withstand harsh environments and maintain precise dimensional tolerances by pouring molten metal into specific molds. The metals used to form these parts are quite complex in their chemical structure and are typically purchased in the form of pre-alloyed ingots. Investment casters purchase ingots according to industry specifications. An investment caster acquires a pre-alloyed ingot, melts it and manufactures his parts.

It is widely understood in the investment casting field that the addition of aluminum and titanium to investment casting furnaces is detrimental due to the reactivity of aluminum and titanium.

As a result, the only method accepted to date for investment casting parts containing significant amounts of aluminum and titanium is the use of ingots produced by vacuum induction melting or an equivalent method. It is done through.

The invention exhibits improvements over conventional investment casting techniques. Because, according to the invention, most of the ingot material used to cast the final part is not produced by the expensive vacuum induction melting process, but by the much cheaper AOD process. A small portion of the material used in the investment casting process must be produced by vacuum induction melting or an equivalent method. This ingot is comparable in quality to conventional vacuum-induced ingots.

The method of the invention allows parts to be manufactured by investment casting at significantly lower costs than conventional casting techniques. Similar considerations can be applied to tall melt or realalloy conditions where scrap alloys can be refined by an AOD process with removal of reactive elements. Similar alloys (nickel, chromium, molybdenum, columbium and carbon) can be completely purified by the relatively inexpensive AOD process. Aluminum and titanium (active species) are produced in the final product by mechanically combining small amounts of vacuum-purified nickel, aluminum and titanium alloys with larger ingots of AOD-purified material. It can be reintroduced into the substance. Preferably, much of the alloy of components to be mechanically bonded is provided as a composite ingot, thereby ensuring a suitably compositional alloy from the investment casting process.

E In one broad aspect, the present invention provides for aluminum having a statistical content of about 0.3% or more, about 0.3% or more of aluminum; A method of producing a quantity of a metal alloy containing at least 1% titanium and up to about 12% aluminum and titanium.

The method includes forming a first ingot containing all the aluminum and titanium to alloy in a nickel matrix by vacuum melting. Thereafter, a second air melt grade ingot is added to the AOD
All other non-reactive elements formed by the process and necessary to produce the desired alloy are included. Next, the first
and a second ingot are mechanically joined together, for example by welding, and then remelted to produce an investment casting having a specific chemistry.

The invention can also be applied to metallurgical processes for alloys with other reactive metals. For example, in another aspect, the invention may be considered a method of producing a quantity of a metal alloy containing less than about 15% overall of reactive elements selected from the group consisting of titanium, tantalum, zircon, and hafnium. The process includes forming a first metal ingot by vacuum induction melting a first insert containing a total amount of reactive element in a cobalt matrix. A second metal ingot is formed from a second insert of cobalt-containing air-soluble grade material. The first and second ingots are mechanically bonded together and then melted together by an investment caster.

In processing metal alloys including aluminum and titanium, the amount of nickel in the first ingot is preferably
The total amount of aluminum and titanium in them is less than. In metallurgical processes for alloys containing reactive elements, the amount of cobalt in the first insert is at least equal to the total amount of reactive elements therein. In processing alloys containing aluminum and titanium, the ratio of aluminum to titanium in the alloy is preferably about 1:11 and about 11
:1. In processing metal alloys according to the invention containing reactive elements, the reactive elements preferably do not exceed 15% of the total alloy material. Any single specific reactive element is typically present in a concentration between 0.005% and 10%.

The invention will be explained more clearly and in more detail with reference to the following examples.

EXAMPLES Example 1 According to the present invention, a quantity of nickel-based alloy for investment casting is produced. The total amount of material that becomes the investment casting contains aluminum, titanium, and nickel, with the nickel being about 0.3% or more aluminum and about 0.3% aluminum. Contains 1% or more of titanium and has a total of 1
Contains less than 2% aluminum and titanium.

According to the invention, the first metal ingot includes a total amount of aluminum and titanium and includes an amount of nickel approximately equal to the total amount of aluminum and titanium. The first
The ingot is formed by vacuum induction melting. The ratio of aluminum to titanium may vary between 1:11 and 11:1. A typical composition of elemental concentrations in the material of the first ingot is shown in Table 1.

(Left below) Table 1 Element (wt, %) Minimum amount Maximum amount Suitable amount C,
05,08 Zr, 50. 70. 8O
A 1 88.00 42.00 40
．． 00T i 5.80 6.50
B,0ON i BAL B
AL BA Lo 200
ppm LAPN 20
0ppm LAPS n
20ppm LAPP b
2Oppm LAP A material having a composition as shown in Table 1 must be melted in a zirconia melt.

Several abbreviations are used in Table 1 and the following tables. These are BAL, which represents the remaining amount, LAP, which represents the lowest possible concentration, and ppm, which represents parts per million.
It is.

A second ingot of air melt grade containing nickel is also made. The elemental composition of typical exemplary materials used to make the second ingot is shown in Table 2.

(Margins below) Table 2 Elements (wt, %) Minimum amount Maximum amount Preferred amount C,
10, 15, 13 Si LAP, 20
LAPMn LAP, 20
LAPCr 1B, 00 '1B
,50 16.20M o 4,50
5.20 5.00Cb 2.20
2.70 2.80B, 0
08. 015. 012Fe
LAP, 50 LAPN i
BAL BAL BALC
u LAP, 20 L
APW LAP, 20
LAPCo LAP 1.00
LAPP b LAP lop
pm LAPAg LAP
10ppm LAPS n LA
P 1oppm LAPB i
LAP, 5ppm LAPOL
AP 50ppm LAPN
LAP 50ppm LAP=
19-2 ingots may be formed by air casting (AOD) or other methods that produce air melt grade material.

Next, the first and second ingots are mechanically joined. The first ingot accounts for only 15% of the total weight of the two ingots, and the weight of the second ingot accounts for 85% of the total weight.

The two ingots remain mechanically connected to each other until the investment casting part is manufactured.

Table 3 shows the elemental concentrations of the composite material that is to become an investment casting when the two ingots are combined into one ingot and melted. The columns showing weight % ranges indicate preferred ranges of the weights of some elements in the total amount to be made into investment castings. The preferred weight column indicates the preferred percentage by weight of each element within the possible range of weight concentrations. The column designated as 1st ingot making up 15% of the composite indicates the preferred percentage of the element in the first ingot. The column for the second ingot, which accounts for 85% of the weight of the composite, shows the percent concentration by weight of the element in the second ingot. The column related to composite materials shows the element concentration in the total amount of material to be made into an investment casting. The elemental concentration obtained in the manufacture of composite materials is AM
It complies with the S-5391 industry standard, which previously met only alloys made by vacuum induction melting.

(Left below) Table 3 2nd ingot 1st ingot Composite material range (
Wt, %) Suitable concentration 85% 1
5% 100% A1 5.50-8.50 6
．． 00 40.00
6.00B, 005-. 015. 010
．． 012. 0
10C,08-,20,12,13,11 Cb 1.80-2.80 2,20 2
．． 60 2.21Co
1. OOX LAP'
LAPCr 12.0-
14.0 13.8 16.20
13.77Cu, 20x
L.A.P.
LAPFe 2.50x LAP
LAPMn
, 25x LAP
LAPMo 3.8-5
．． 2 4,25 5.00
4.25Ni 74.00 74
．． 0 77JO53,4073,70P
, 015x LAP
LAPS, 015
L.A.P.
LAPSi, 50x LAP
L.A.P.
T i , 50-1.00. 90
6.00. 90Z r
, 05-. 15. 09
．． 60. 09 Example 2 The method of this invention is not limited to nickel-based alloys. The metallurgical method of the invention can also be applied to alloys of similar metals, such as cobalt alloys. Cobalt alloys contain little or no aluminum or titanium.

Certain reactive element additives in cobalt-based alloys are those commonly used to strengthen the metal alloy. For example, zircon and titanium can be added as these elements are useful in strengthening the alloy. Other reactive elements can be used in small amounts to achieve other desirable properties in the metal alloy.

According to an aspect of the invention relating to the production of cobalt-based alloys, a first insert containing the entire amount of reactive element in the cobalt matrix is vacuum induction melted.

Table 4 Element (wt, %) Minimum amount Maximum amount Suitable amount C,
03,06,05 T i 1,90 2.20 2
．． OZ r 4.90 5.20
5.0T a 34.00 36.0
35. OCoBAL
BALCLAP 200ppm
LAPN LAP 200ppm
LAPS n LAP 20p
pm LAPP b LAP
A second insert of air-soluble grade material containing 20 ppm LAP cobalt was also produced in a zirconia crucible. Typical elemental concentration specifications for the second insert are listed in Table 5.

(Left below) Table 5 C, 60, 70, 66 Co BAL BAL Cr 2B, 0 27.0 2B, 6F e
LAP 1.5x 1.5xMn LAP
, 10x , 10xN i 10.5 11.5
11.0P LAP, 015x, 01
5xS LAP, 015x, 015xS
i LAP, 40x, 40xB
LAP, 0IOx, 010xW 7.20
8.20 7.77Pb LAP 10ppm
LAPA g LAP loppm LA
PS n LAP loppm LAPBi
LAP, 5ppm LAPOLAP 50
ppm LAP N LAP 50ppm LAP Table 6 shows the elemental composition of mechanically bonded materials forming alloys for investment casting. The Range column in Table 6 indicates preferred ranges of weight concentrations of several elements in the final product. The adjacent column shows preferred elemental concentrations within the range of the first column. The preferred weight concentration of the first ingot represents 10% of the total weight of the combined ingots and is listed in the next adjacent column. Similarly, the preferred weight concentration of the second ingot represents 90% of the total weight of the combined ingot and is indicative of the preferred weight concentration of the elements. The last column shows all 100% weights of the mechanically combined ingots and represents the final elemental concentration achieved when the first and second ingots are combined into one ingot and remelted. It shows. The alloys having the weight concentrations shown in the Composite column of Table 6 meet industrial specifications for PWA-647F. This specification can only be met by using metal alloys that have been perfectly processed by vacuum induction melting.

(Left below) Table 6 2nd ingot 1st ingot Composite material iJ
(Wt, %) Suitable concentration 90%10%1
00%B, 010x LAP
,010xC,
55-, 65, 60, 6B
, 60Co BAL BAL
BAL BAL
BALCr 22.50-24.24 24.0
0 2B, 6 2
3.94W 6.5-7.5 7.0
7.77 7. OF
e 1.50x LAP LA
P 1.5xMn
, 10x LAP LAP
, 10xN i 9.
0-11.0 10.0 11.0
9.90P, 015
X LAP LAP
, 015xS , 015x
LAP LAP
, 015xSi, 40xL
AP LAP
, 40xTi, 15-. 30. 20
-2.0. 20
Zr, 30-, [io, 50-5.0
．． 50Ta 3.0-4.0 3
．． 5-35.0
3.50 By using the metallurgical method of the invention, significant savings can be achieved in the production of alloys suitable for use in investment casting of superalloy components. Only a small portion of the material used to cast the final part must be produced by an expensive vacuum induction melting process. The remainder can be manufactured from much cheaper air-soluble grade materials.

Undoubtedly, those familiar with the metallurgical processing of advanced alloys
Numerous variations and modifications of this invention will become readily apparent. Therefore, the scope of this invention should not be limited by the specific examples listed herein;
Rather, it is defined by the claims.

fi↑? \ One step

Claims (13)

[Claims] (1) A method for producing a nickel-based alloy for investment casting that contains about 0.3% or more aluminum and about 0.1% or more titanium, and the total of aluminum and titanium is 12% or less. forming a first metal ingot containing aluminum and titanium in a nickel matrix by vacuum melting; forming a second air-melted ingot containing nickel; and the second ingot by welding to create an investment casting charge. (2) The ratio of aluminum to titanium is approximately 1:11
and 11:1. The method according to claim 1, further comprising the step of: (3) producing the second ingot by argon oxygen decarburization. The method of claim 1, further comprising the step of: (4) making the first ingot by vacuum induction melting. (5) A method for producing an alloy containing about 0.3% or more aluminum, about 0.1% or more titanium, and in which the total amount of aluminum and titanium is 12% or less, the method comprising vacuum melting. forming a first metal ingot containing all of the aluminum and titanium for the alloy in a nickel matrix by forming a second metal ingot that is an air-soluble material and containing nickel; and the step of mechanically joining the second ingot. (6) The method according to claim 5, wherein the amount of nickel in the first ingot is greater than or equal to the total amount of aluminum and titanium. 7. The method of claim 5, wherein the ratio of aluminum to titanium in the alloy is between about 1:11 and about 11:1. The method according to claim 5, further comprising the step of: (8) producing the second ingot by argon oxygen decarburization. The method according to claim 5, further comprising the step of: (9) making the first ingot by vacuum induction melting. (10) a total of about 15 reactive elements selected from the group consisting of titanium, tantalum, zirconium and hafnium;
% or less, comprising the steps of: creating a first metal ingot by vacuum induction melting a first charge containing a predetermined amount of a reactive element in a cobalt matrix; A method comprising the steps of: making a second metal ingot from a second charge of air-soluble material containing; and mechanically joining the first ingot and the second ingot by welding. The method according to claim 10, further comprising the step of: (11) producing the second ingot by argon oxygen decarburization. 12. The method of claim 10, further comprising the step of: (12) making the first ingot by vacuum induction melting. 13. The method of claim 10, wherein the amount of cobalt in the first charge is greater than or equal to the total amount of the reactive elements.