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new technology for producing billets for components from creep-resisting alloys.

by:Earlston     2020-02-09
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Anti-nickel alloy is widely used in the manufacture of components for important applications such as gas turbine engines, several types of knives, molds, blades for metal and other parts processing, working at high temperatures
The main process of producing billet from creep
Refractory alloy is a hot ceramic mold cast in a vacuum induction furnace.
This determines that the labor content of parts manufacturing is very high, and the profitability of production is very low.
At the same time, the casting and process properties of these alloys are poor, and strict requirements for casting quality inevitably lead to low yield and high scrap rate of suitable metals.
A large part of the waste in casting production is represented by irreversible production losses, which makes no sense, especially given the high cost of the alloy and the shortage of components contained in these alloys.
Therefore, it is quite important to develop new technologies for the production of cast parts, while reusing various wastes of creep-resistant alloys of different forms and sizes.
Recently, based on the technology of electroslag melting metal, especially the mold casting of electroslag ingot (EIMC)
Has been widely used from high-
Steel and alloy]1].
This is explained by the economic advantages of producing metals, which are determined by cheaper equipment, low service spending and higher quality parameters.
At the same time, the traditional casting process of electroslag
Anti-alloy, based on the method of re-melting the electrode in the ceramic crucible, then flip and pour the slag-
There are some shortcomings in the metal melting into the mold.
This is mainly due to the \"secondary\" Oxidation of liquid metals that fails to achieve the required chemical composition [2].
First of all, it is impossible to effectively extract elements that are easily oxidized (
Titanium and aluminum)
From G \'-
Determine the main properties of the alloy.
In addition, the cast electroslag iron also has a cylindrical thick-
Granular structure of long primary branch crystal arm [3, 4].
All of these factors do not guarantee the desired use properties of the cast metal.
Therefore, the problem of improving the casting process of electric slag furnace needs to be solved urgently.
Therefore, a new technology of electric furnace casting in inert gas has been developed, including re-melting the electrode in the copper skull melting container at flux, and then pouring into the mold located in the pre-heating furnace, accumulation of liquid metal filled with inert gas. [
Figure 1 slightly]
Therefore, a production complex has been built for the EIMC process (Fig. 1).
The complex includes the following main elements: A-
550 U1 equipment, melting container 2, pre-heating furnace 3, casting mold 4, Gas System 5, TShS-3000-
1 Transformer 6, control box 7.
Control of re-melting parameters using thermal sensors and KSP-
Potential 8.
Knife switch 11, Contactor 9 power supply to this part, and automatic system 10 is used to protect the equipment during short circuit.
The design of the equipment column ensures the stable vertical displacement of the car during movement (
Lower compartment with melting container and upper compartment with consumable electrode)
, And the power supply by single-
Phase single filter circuit.
Oxidation and burn-out of alloy elements are not acceptable in creep re-melting
Chromium resistantnickel alloys.
Therefore, the use of high meltingFluorine flux.
However, the fluorine flux actively interacts with the Crucible lining material (Chrome layer-
Magnesium brick)[5].
Therefore, ceramic melting containers can be used.
Therefore, a copper water-cooled melting container has been developed to ensure the \"disinfection\" conditions of the process for the volume of metal required for re-melting and accumulation.
In order to improve the efficiency of the melting container, the slit-
Just as the recession occurs on the inner surface of the shell, the shell is formed together with the slag skull, and the gas cavity ensures a high thermal resistance of the wall, in order to store the required quantity of liquid metal in the container.
The melting container is fixed on the lower bracket of equipment A. 550U (
Highly controllable)using clamps.
The consumable electrode is placed in the electrode holder.
The electrode is fixed with a screw fixture and can be adjusted in the direction of height.
The support for lateral displacement is used to concentrate the consumable electrode on the shaft of the melting container.
Due to the extensive \"secondary\" Oxidation of alloy elements in casting creep --
Resist the alloy in the air, it is necessary to use the method of pouring the bottom of the melt into the casting mold.
This is achieved using a discharge device consisting of a copper water-cooled substrate with a continuous taper hole, where the current-supplying plug-
Place seeds made of the same material as the consumable electrode. A dead-
The center part of the plug makes the end hole to ensure its melting.
After the accumulation of the required mass for melting, the water supply in the substrate is interrupted, the bridge between the hole and the melting is no longer cooled, and the melting is poured into the mold.
The latter has a large riser Part 4, which accepts the liquid flux as a hot riser, which equates the temperature of the solidified casting and prevents the formation of a contraction cavity in it.
Castings can be produced using metal molds and ceramic molds.
Use the sealing part to ensure the tightness of the contact between the casting mold and the substrate.
By controlling the electronic system of the valves placed in the pipe, ensure that the water supply and stop entering the internal cavity of the Crucible substrate.
In order to reduce the temperature gradient between the liquid metal and the casting mold and avoid the formation of the structure of the different particle size coating, it is necessary to use the electric pre-heating furnace, with the shape of the box, lined with chrome-
Magnesium brick, the heating element is installed on the inner surface of the box.
Special holes through which shielding gas passes (argon)
The supply is made at the bottom of the furnace. [
Figure 2:
The casting mold placed in the heating furnace is centered on the shaft of the molten plugseed.
Use a special bellows device to prevent atmospheric air from penetrating into the space between the melting containers of the heating furnace.
Chromel control for preheating temperature-
Kepel and KSP-
Equipment 4 times. The inert gas (argon)
Is supplied to the furnace to protect the melting area from atmospheric air. [
Figure 3 slightly]
When pouring liquid metal into parts of the casting mold by bottom pouring, it is necessary to ensure that the axis of the pouring funnel and the axis of the melting container are coaxial with the melting plug placed in the bottom plate.
Consumable electrodes are produced from rejected parts of a single melt, welded together through ar-
A protective arc welded into bundles.
The Kh12N65K5V5M5Yu5YZ alloy has been developed by the technology.
Start melting with liquid under ANF-
1p flow is characterized by the lowest oxidation capacity compared to various active alloy elements such as titanium and aluminum that control mechanical properties and long-term properties
Long-term strength of nickel alloys.
The best re-melting conditions are: U = 39 v, I = 2700. . . 2900 A.
Kh12N65K5V5M5Yu5T3 alloy belongs to the multi-element creep of cast composite alloy-
Alloy resistant.
The main hardening phase is [gamma]\'-
Phase represented by inter-metal compounds [(Ni, Co). sub. 3](Al, Ti), and carbides.
Therefore, the properties of cast alloys depend on their chemical and phase composition.
Chemical analysis shows that, in terms of the main alloy elements, the composition of the ar slag casting alloy poured at the bottom of the molten layer only slightly changes to meet the requirements of technical conditions (Table 1).
The properties of the casting alloy produced by bottom pouring in ar are studied, and with vacuum-
Induction casting (VIC).
Use these methods to remove samples from the cast ingot for testing and optical inspection.
Test results of specimens (Table 2)
The results show that the mechanical properties of castings produced by electroslag casting are similar to those produced by vacuum induction casting.
At the same time, the strength of the castings produced by electroslag casting is even slightly higher than that produced by vacuum induction casting.
This can be explained by the amount of hardening [gamma]\'-
The phase in these castings is 850 [degrees]
C is roughly at the same level, and the performance of the cast metal is determined by the change of particle size and morphology of the carbide (Fig. 2)[3].
Macro analysis-
The microstructure of Kh12n65k5m5m5yu5t3 alloy shows that the macro-organizational size of castings produced by vacuum induction casting is 1. 0-3.
5mm, in the casting produced by the electric furnace casting, 2-4 mm.
Obviously, this is related to the overheating of the melt in the melting container (Figure 3).
The average particle size of complex carbide in castings produced by electroslag casting is 3-6 [micro]
M, maximum size up to 30 [micro]
M, and in the casting produced by vacuum induction casting, it is 100 (m (
In portrait).
Obviously, this is for the long term. term strength.
The best combination of structure and performance of Kh12N65K5V5M5Yu5T3 alloy is at 1600-1620[degrees]C.
This system leads to the formation of structures with the best carbide (2-4 [micro]m)
, Evenly distributed in the matrix of the alloy.
The microstructure of this alloy is characterized by the fine and tight precipitation [gamma]-[gamma]
Distribution of co-crystal, carbide in space between crystal axes and fine dispersion precipitation [gamma]\'-phase.
The experimental results were used as the basis for the development of electroslag casting technology for Erfurt cutting machine blade components, thus greatly improving the durability of hot cutting of rolling materials-Strength steel.
References [1. ]Paton B. E. and Medo W. T.
Carter, pouring from the bottom of the ESR furnace (Proc. Int.
Seminar on electric furnace re-melting technology and equipment, Kiev, May 1517, 2001, pp. 61-63.
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