JPS59129739A - Production of alloy - Google Patents

Abstract

PURPOSE:To produce an ingot without variance in quality in the vertical direction and without the decrease in the content of Mg in the stage of refining an Al-Ti-Mg alloy by electroslag refining by charging additionaly slag having a specific compsn. into the alloy during operation. CONSTITUTION:A consumable electrode 4 consisting of an Al, Ti, Mg alloy is suspended in a water-cooled casting mold 1 formed of copper, and after the inside of the casting mold and a hopper 38 contg. a flux 5 is evacuated, gaseous Ar is supplied therein. A flux 5 composed of 20-60% CaF2, 10-40% MgO, 10- 30% Al2O3, 5-30% TiO2 and <20% CaO is put in the mold 1, and a voltage is impressed and conducted between the electrode 4 and a molding board 13 formed of copper in the bottom part to melt the flux and to form molten salg 6. The electrode 4 is dipped in the slag 6, and while the electrode 4 is gradually melted by the Joule heat of the slag 6, the flux 5 is additionally supplied. The decrease, by evaporation, of the Mg contained in the alloy is obviated and an alloy ingot 7 having no variance in quality in the vertical direction thereof is obtd.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing alloys containing Al + Ti and Mg by electroslag melting.

Electroslag melting (hereinafter referred to as ESR) is generally used in the production of Ni-based, Fe-based alloys, or other alloys. In the alloy manufacturing method using ESR, the tip of a consumable electrode with the composition necessary to obtain the target alloy composition is
The flux is placed in the molten slag, and an electric current is applied between the counter electrode and the adjusting plate in the water-cooled copper mold. This is a method of producing an ingot by dropping it and cooling it continuously in a water-cooled copper mold. In addition, the 7lux used for ESH mainly consists of CaF2, Al2O3,
A slack with appropriate addition of CaO is used, and the slack composition is (1) stable at high temperatures (2) low viscosity (3)
) High electrical resistance (4) Stable chemical reaction.

Now, conventionally, alloys containing kl, Ti and Mg are subjected to ES
When manufacturing at R, AI! As for Ti, component segregation in the ingot is particularly significant in the height direction, making it difficult to obtain a product with uniform quality and properties in the height direction.

In addition, Mg, which is effective in improving workability in Ni-based alloys, is oxidized and consumed into the slag during ESR.
Otherwise, it evaporated into the dissolved surrounding air and did not remain in the product, so that no improvement in processability could be expected.

To explain in more detail, in Figure 1, the horizontal axis shows the element concentration in the Ni bath (
This is a graph showing the deoxidation etc. cross line of Ni at 1873 K, taking the bone concentration in the bath (00%) as the vertical axis, and in the case of Ni-based alloys, A7? , Tll Mg
It can be seen that the amount of oxygen in the bath differs for each element, and also varies depending on the concentration in the trench. Therefore, if A/, Ti, and Mg are small in the molten metal, a large amount of oxygen is contained in the bath,
Since he, Tt+ Mg precipitates as oxides during solidification, the amount of impurities in the alloy increases, and as a result, quality tends to vary depending on the position of the ingot.

In addition, in Figure 2, the horizontal axis represents the amount of Mg, and the vertical axis represents the number of twists.
O: 10ppm) during hot (1250℃) alloy
It is a graph showing the relationship between the amount of g and the number of twists. From this figure, the number of twists is about 2 in the absence of Mg, but when the Mg content exceeds about 45 ppm, the number of twists increases suddenly, and reaches a peak at about 75 ppm, meaning that it can withstand about 500 twists. I understand. In this way, Mg is effective in improving hot workability, but Mg has a relatively low boiling point of 1107°C, and its vapor pressure is still high.
It evaporates violently during SR and becomes traces in the ingot.

The present invention has been made to solve these two problems, and is to perform ESR in a non-oxidizing atmosphere, to keep the trenched slag composition constant, and to apply 7 lac in an amount commensurate with the change in slag composition. It is an object of the present invention to provide a manufacturing method using ESR that allows obtaining an alloy containing desired amounts of M and g without vertical component variations by additionally charging .

The method for producing the alloy according to the present invention is based on the weight ratio of CaF220.
~60 staff, Mg010~40 staff, AI! 20310-3
Using a flux consisting of 0%, TlO 25-30%, CaO 20% or less and other unavoidable impurities,
The present invention is characterized in that a consumable electrode containing Kl, Ti, and Mg is electroslag melted in a non-oxidizing atmosphere, and the above-mentioned flux is additionally charged in order to keep the slag composition constant during melting.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The method for producing an alloy according to the present invention will be explained based on drawings showing its implementation state. FIG. 3 is a schematic diagram showing the implementation state of the method of the present invention. For example, 1 in the figure has an inner diameter of 100 mm.
The water-cooled copper mold has a double pipe structure and is supported by a pedestal 2 at an upper flange portion 1b, and a copper surface plate 1 whose lower end flange portion 1a functions as an electrode.
It is sealed by 3. A cooling water flow chamber 16 is formed in the inner and outer pipes 11 and 12, and the cooling water flow chamber 1
A water supply pipe 14.14 and a drain pipe 15.15 are connected to the lower and upper parts of the tank 6, respectively. Furthermore, a vacuum device 3 is connected to the flange portion 1b at the upper end.

The vacuum device 3 includes a header 399 attached to the flange portion 1b at the upper end of the water-cooled copper mold 1, and a vacuum exhaust pipe 31 that connects the header 39 with a vacuum pump (not shown). An inert gas supply pipe 32 connected to the middle of the vacuum exhaust pipe 31. It consists of an exhaust pipe 33 and the like connected to a header 39. The upper opening of the header 39 is closed with a lid 35 having a hole through which a consumable electrode 4 having an outer diameter of 50 mm mainly composed of Fe, Ni+Cr'c can be inserted, and a seal ring 34 is provided in the hole.

Vacuum exhaust pipe 3-1. Inert gas supply'! The trachea 33 is provided with stop valves 31V, 32V, and 33V, respectively, and the vacuum exhaust pipe 31 is equipped with a pressure gauge 36° and a vacuum pressure gauge 37. A flux supply device 38 is attached to the header 39, and a 7-six feeder 38 is connected to the hopper 38a containing the flux 5.
K is provided to supply flux 5 through b. A pipe 38e connected midway through the evacuation pipe 31 is connected to the upper part of the hopper 38a in order to maintain the same atmosphere inside the hopper 38a as the inside of the water-cooled copper mold 1. Further, the upper end of the hopper 38a is sealed by a lid 38 (1).

Next, a procedure for producing an alloy using the apparatus configured as described above will be explained. With the tip of the consumable electrode 4 containing Ae, Ti, and Mg passed through the lid 35 on the header 39, that is, with the hole closed, the stop valves 32V and 33
V is closed, the stop valve 31V is opened, a vacuum is drawn by a vacuum pump (not shown), and an appropriate amount of flux 5 whose composition has been selected in advance is poured into the water-cooled steel mold 1 by measuring it using a vacuum pressure gauge 37. 10-" inside the hopper 38a
Torr, then close the stop valve 31V, and then close the stop valve 32V.
By opening the door, Ar gas is introduced into the water-cooled copper mold 1 and into the hopper 38a, and the pressure is measured using the pressure gauge 36.
Torr. This provides a pressurized Ar gas atmosphere with a low oxygen potential. In this atmosphere, the flux 5 in the hole-ku-38a was transferred to the 7-lux feeder 38.
In b, the ingot V-shaped IT is cut out at a rate of 50 kg, and initially charged into the water-cooled copper mold 1 via the supply pipe 38c, and the tip of the consumable electrode 4 is placed in the 7 lux 5, as shown in the figure. Electricity is applied between the consumable electrode 4 and the copper surface plate 13 by a non-consumable power source, and the flux 5 is melted to generate slag 6. The tip of the consumable electrode 4, which is controlled to be always located in the slag 6, is melted by Joule heat in the slag 6, but at this time it reacts with the slag 6 and changes the composition of the slag 6. The change in slag 6 composition will be detailed later, but
Since this is undesirable in producing a uniform alloy, it is prevented by continuously charging flux 5 into the ESR.

Further, the tip of the melted consumable electrode 4 drips down into the slag 6 and accumulates in an unsolidified molten metal pool 8 in the water-cooled copper mold 1, which is continuously cooled to form an ingot 7.

It goes without saying that instead of continuously charging the 7 lux 5, the flux 5 may be charged intermittently so that the composition of the slag 6 remains constant.

Next, the reasons for limiting the composition of the flux 5 used in the present invention will be described. First, to explain MgO, Mg contained in the consumable electrode 4 reacts with the oxide in the slag 6 according to equation (1), is oxidized, and is trapped in the slag 6.

X+ eMxOy= X0ey+exM −(
11 However, X: Aj', Ti and MgM
Metal MXOy in the varnish slag Oxide in the varnish slag Therefore, in order to balance the Mg contained in the consumable electrode 4 and the MgO in the slag 6, it is necessary to appropriately add MgO to the flux 5. In order to effectively reduce the oxidation loss of Mg, the lower limit was set to 10%.

Moreover, if it exceeds 40%, the melting point will rise and smooth operation will be hindered, so it was set in the range of 10 to 40%.

AI! 203 for the same reason as MgO, that is, A1g contained in the consumable electrode 4! In order to effectively reduce oxidation loss, the lower limit was set to 10 inches. The upper limit is AI! The increase in 203 causes a decrease in electrical conductivity and an increase in melting point,
Since it would interfere with smooth operations, it was set at 30 inches.

Similarly, regarding TiO2, Ti contained in the consumable electrode 4
In order to effectively reduce oxidation loss, the lower limit was set at 5%. Further, the upper limit was set at 30 in order to suppress the rise in melting point.

Next, CaF2 is a basic component of 7lux 5 for ESR, and in order to maintain the melting point and electrical conductivity, CaF2 is 20 to 60%
The range of If CaF2 is less than 20%, the necessary melting point and electrical conductivity cannot be secured, and CaF2 is less than 6%.
If it exceeds 0%, the required Ar, 03°TiO2+
Electric conductivity increases in balance with CaO.

CaO is contained in order to fix this S and prevent the reaction, since S which is inevitably mixed in the flux 5 reacts with Mg contained in the consumable electrode 4 and prevents the required product components from being obtained. It is something that can be done. In addition, CaO is used to maintain appropriate melting point, electrical conductivity, and viscosity, and if a large amount of CaO is used, the melting point of flux 5 will rise and smooth operation will be hindered. The range was up to 20 inches depending on the S level.

When using the method of the present invention such as diagonal top-up, variations in composition in the height direction of the ingot can be reduced, and Mg can be included to improve hot workability.

That is, Fe+Nt+Cr is the main component, and Al, Ti, and Mg must be included in the alloy.
'rt, ESR using Mg-containing consumable electrodes
When performing Fe , Nt+ The oxidation of the consumable electrode mainly composed of Cr is carried out, resulting in Fe, N
i. Lower oxides of Cr are produced and mixed into the slag, causing a change in the slag composition and resulting in a decrease in alloy quality. However, when ESR is performed in a non-oxidizing atmosphere as in the present invention, the above-mentioned lower oxides are not generated and changes in the slag composition are reduced.

In addition, the metal and slag that make up the consumable electrode come into contact with the slag when the consumable electrode melts, when the consumable electrode drips and settles in the slag after melting, and when the molten metal pool that is still unsolidified in the water-cooled copper mold comes into contact with the slag. Generally, Al + Ti and Mg (Da
However, in the case of the present invention, flux is additionally charged to create a state in which a large amount of slag exists, so the reaction equilibrium follows the slag composition, and eventually the ingot Variations in composition will be suppressed. By adding additional flux, the Mg that easily evaporates is compensated for, so the required amount of Mg is maintained in the ingot.
can be contained.

Next, an example of the method of the present invention will be described in the case of a Ni-based alloy. The flux compositions, consumable electrodes, and ingot compositions of Examples 1, 2.3 of the method of the present invention are shown in Table 1. As a comparative example, a known typical flux (70%
CaF2-30'% A1203). In this comparative example, Al contained in the pole is consumed ↑ and remains in the ingot, but Ti and aluminum become traces, which is not preferable.

On the other hand, in Example 1.2.3 of the present invention using a flux containing MgO, Al2O3°TiO2,
Mg, kl: Ti remain in the ingot.

In particular, Mg, whose content differs in each example,
By additionally charging 72 Tx in a non-oxidizing atmosphere, an ideal condition is obtained in which the consumable electrode is not oxidized and the slag composition does not change, making it an efficient consumable electrode! Mg of
The ingot will contain approximately the same amount as the above amount. The same applies to kl + Tt. Also, due to the above reasons, the bottom of the ingot.

Mg in central part 1 head, AI! It is clear from the examples shown in Table 1 that the composition of + Ti was also made uniform.

As described in detail above, the method of the present invention is an At-containing compound with good mechanical properties and hot workability. + It is a metallurgically ideal manufacturing method for homogeneously manufacturing Ti and Mg alloys, and it does not contain AI! .

It is extremely useful in the production of Ti and Mg alloys.

[Brief explanation of the drawing]

Figure 1 is a graph showing the deoxidation equidistant line of Ni in 1873, Figure 2 is a graph showing the relationship between M, gt and the number of twists of a 75%Ni-15%Cr alloy, and Figure 3 is a graph showing the number of twists. FIG. 2 is a schematic diagram showing the implementation state of the invention method. 1...Water-cooled copper mold 2. Rack 3...Vacuum equipment
4... Consumable electrode 5... Flux 6... Slag 7... Ingot or alloy 38... Flux supply device 38b... Flux feeder Patent applicant Sumitomo Metal Industries Co., Ltd. Patent attorney Kawa Noboru No

Claims (1)

[Claims] 1. In a method of producing an alloy by electroslag melting, CaF, 20-60%, Mg010 by weight
~40%, AI! , 0310~30chi, Ti025~3
Electroslag melting of a consumable electrode containing Kl + Ti and Ti in a non-oxidizing atmosphere is carried out using a slack consisting of 0% Ti, Cab' 20% or less and other unavoidable impurities, and the slag composition during melting is kept constant. A method for producing an alloy, characterized in that the slack is additionally charged as needed.