CN118162603A - A device and method for controlling the grain growth direction of a directional or single crystal casting - Google Patents

Abstract

The invention discloses a directional or single crystal casting grain growth direction control device and a control method thereof, belonging to the field of metal casting technology, comprising a device cover, a device base and a water-cooled tray, the water-cooled chassis comprising a water-cooled outer ring, a water-cooled middle ring and a water-cooled inner circle which are sequentially sleeved from the outside to the inside, the water-cooled outer ring is fixed on the top of the device base, a lifting mechanism is arranged in the control chamber, an inlet and outlet are arranged on the top of the device base, a ring mold shell is detachably installed on the top surface of the water-cooled middle ring, a heating rod located at the center of the ring mold shell is installed on the top surface of the water-cooled inner circle, the device cover is fixed on the water-cooled outer ring and covered outside the ring mold shell, a heating body is arranged on the inner wall of the device cover, and a pouring cup is arranged on the top of the device cover. The heating rod and the heating body can improve the temperature gradient during the solidification process of the casting, so that the grain orientation of the casting is good, and it is not easy to produce broken crystals and miscellaneous crystals. Under the action of the water-cooled tray, especially the water-cooled inner circle, the solid-liquid interface morphology can be improved and the generation of defects can be reduced.

Description

A device and method for controlling the grain growth direction of a directional or single crystal casting

Technical Field

The invention relates to the technical field of metal casting, and in particular to a device for controlling the grain growth direction of a directional or single crystal casting and a control method thereof.

Background technique

Directed columnar crystal blades and single crystal blades have significantly improved their longitudinal mechanical properties due to the elimination of transverse grain boundaries, so they are usually used as key hot end castings for aircraft and gas turbines. This type of blade is mainly prepared by rapid solidification (HRS). Although the process is mature and stable, its temperature gradient is low and drops rapidly with the increase of the pulling distance, causing the grain orientation of the casting to deviate from the axial direction and even the appearance of equiaxed crystals. At the same time, in actual production, due to the different mold shell structures, the mold shell has negative and positive surfaces, and the solid-liquid interface of the casting is bent and deformed, which can easily lead to increased grain orientation deviation and broken crystals in the casting, seriously reducing the comprehensive performance of the casting.

Summary of the invention

The purpose of the present invention is to solve the above-mentioned technical problems and provide a device for controlling the grain growth direction of a directional or single crystal casting and a control method thereof. Under the action of a heating rod and a heating body, heat can be provided to the inner and outer sides of the casting for insulation during pouring, thereby increasing the temperature gradient of the casting during directional solidification, refining its growing structure, improving performance, producing directional and single crystal castings with good grain orientation, and not prone to producing broken crystals and miscellaneous crystals. Under the action of a water-cooled tray, especially a water-cooled inner circle, the center of the casting is cooled, the solid-liquid interface of the casting can be kept stable and not tilted, the solid-liquid interface morphology can be improved, the probability of differently oriented grains appearing at the edges and corners of large platforms of single crystal castings can be reduced, the qualified rate of directional or single crystal castings can be improved, and the generation of defects can be reduced.

To achieve the above-mentioned purpose, the present invention provides the following scheme: The present invention discloses a device for controlling the grain growth direction of directional or single crystal castings, comprising a device cover, a device base with a control chamber therein, and a water-cooled tray with an axis vertically arranged, the water-cooled chassis comprising a water-cooled outer ring, a water-cooled middle ring and a water-cooled inner circle which are tightly sleeved from the outside to the inside in sequence, the water-cooled outer ring is fixedly connected to the top of the device base, a lifting mechanism for independently driving the water-cooled middle ring and the water-cooled inner circle to rise and fall is arranged in the control chamber, an inlet and outlet for the water-cooled middle ring and the water-cooled inner circle to enter and exit the control chamber is arranged on the top of the device base, an annular mold shell is detachably mounted on the top surface of the water-cooled middle ring, a heating rod coaxially located at the center of the annular mold shell is mounted on the top surface of the water-cooled inner circle, the device cover is fixed on the water-cooled outer ring and is covered outside the annular mold shell, a heating body located around the annular mold shell is arranged on the inner wall of the device cover, and a pouring cup for pouring into the annular mold shell is mounted on the top of the device cover.

Preferably, the heating rod is a graphite heating rod.

Preferably, a heat-insulating layer is provided on the inner wall of the equipment housing.

Preferably, it is characterized in that the heating body is a magnetic heating body, and a heating coil for providing an induced magnetic field for the magnetic heating body is provided on the outer wall of the device cover.

Preferably, the water-cooled middle ring and the water-cooled inner circle are interlocked by a locking mechanism.

Preferably, the locking mechanism comprises locking bolts and bolt ear plates correspondingly arranged on the water-cooled middle ring and the water-cooled inner circle.

Preferably, the lifting mechanism comprises a pull-out rod capable of being lifted up and down, the bottom wall of the water-cooled inner circle is coaxially connected to one of the pull-out rods, and the bottom wall of the water-cooled middle ring is connected to two pull-out rods arranged on both sides of its axis.

Preferably, the pull-out rod is a hollow rod, one end of the pull-out rod of the water-cooled inner circle is connected to the water-cooled inner circle, and the other end is provided with a cooling water gate, and one end of the two pull-out rods of the water-cooled middle ring are connected to the water-cooled middle ring, and the other end is respectively provided with a cooling water inlet and a cooling water outlet.

Also disclosed is a method for controlling the grain growth direction of a directional or single crystal casting, comprising the following steps:

S1. Install the above-mentioned directional or single crystal casting grain growth direction control device in a holding furnace, and connect the pouring cup with the melting chamber;

S2, the holding furnace and the smelting chamber are evacuated, the smelting chamber is smelted, and the smelting time is set to keep the temperature, the molten alloy liquid is poured into the annular mold shell through the pouring cup, the heating body and the heating rod are heated and kept warm, and after the pouring is completed, the preset rest time is set to stand, and then the heating rod and the heating body are turned off;

S3, cooling water is injected into the water-cooled outer ring, the water-cooled middle ring and the water-cooled inner circle. The water-cooled middle ring descends first. After the casting is pulled out, the water-cooled inner circle descends to the same horizontal position as the water-cooled middle ring. After the temperature of the annular mold shell is cooled to below the preset cooling temperature, the annular mold shell is taken out to obtain a directional casting or a single crystal casting.

Preferably, the temperature during smelting is controlled at 1500-1570°C, and the preset insulation time is 3-5 minutes; the temperature during pouring is controlled at 1480-1550°C, and the preset standing time is 2-5 minutes; the preset cooling temperature is 100°C.

Compared with the prior art, the present invention has achieved the following technical effects:

In the control device of the present invention, the heating rod and the heating body can provide heat for the inner and outer sides of the casting for insulation, thereby improving the temperature gradient of the casting during the directional solidification process, refining the growing structure, and improving the performance. The directional and single crystal castings produced by this technology have good grain orientation and are not prone to broken crystals and mixed crystals. The water-cooled inner circle in the water-cooled tray can cool the center of the casting, making the solid-liquid interface of the casting stable and not tilted, improving the solid-liquid interface morphology, reducing the probability of differently oriented grains appearing at the edges and corners of large platforms of single crystal castings, improving the qualified rate of directional or single crystal castings, and reducing the occurrence of defects.

BRIEF DESCRIPTION OF THE DRAWINGS

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

FIG1 is a schematic diagram of the internal structure of a device for controlling the grain growth direction of a directional or single crystal casting;

FIG2 is a schematic diagram of the structure of the water cooling tray when viewed from above;

Figure 3 is a schematic diagram of the motion process of the control device (the water-cooled middle ring descends first);

FIG4 is a schematic diagram of the motion process of the control device (the water-cooled middle ring and the water-cooled inner circle descend synchronously);

Figure 5 shows the solid-liquid interface of the casting under different processes (a heating with heating rod and central water cooling, b heating with heating rod, c traditional HRS method);

Figure 6 shows the grain orientation of the castings under different processes (a heating with heating rod and central water cooling, b heating with heating rod, c traditional HRS method).

Explanation of the accompanying drawings: 1. Equipment cover; 2. Equipment base; 3. Water-cooled outer ring; 4. Water-cooled middle ring; 5. Water-cooled inner circle; 6. Ring-shaped mold shell; 7. Heating rod; 8. Heating body; 9. Heating coil; 10. Pouring cup; 11. Pull rod; 12. Insulation layer; 13. Insulation pad; 14. Telescopic cylinder; 15. Connecting frame; 16. Guide frame; 17. Locking bolt; 18. Positioning seat.

Detailed ways

The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

Example 1

The present embodiment provides a device for controlling the grain growth direction of directional or single crystal castings, as shown in Figures 1 to 6, including a device housing 1, a device base 2, and a water-cooled tray. The axis of the water-cooled tray is arranged vertically, and the water-cooled tray is mainly composed of a water-cooled outer ring 3, a water-cooled middle ring 4, and a water-cooled inner circle 5. The water-cooled outer ring 3, the water-cooled middle ring 4, and the water-cooled inner circle 5 are sequentially arranged from the outside to the inside and fit each other. The bottom surface of the water-cooled outer ring 3 is fixedly connected to the top of the device base 2. A control chamber is provided in the device base 2, and a lifting mechanism is provided in the control chamber. The lifting mechanism is used to independently drive the water-cooled middle ring 4 and the water-cooled inner circle 5 to rise and fall, which can control the water-cooled middle ring 4 and the water-cooled inner circle 5 to rise and fall respectively, and can also control the water-cooled middle ring 4 and the water-cooled inner circle 5 to rise and fall synchronously. An inlet and outlet connected to the control chamber are provided at the top of the device base 2. When the water-cooled middle ring 4 and the water-cooled inner circle 5 are lifted and lowered under the drive of the lifting mechanism, they can enter and exit the control chamber through the inlet and outlet. The top surface of the water-cooled middle ring 4 is detachably mounted with an annular mold shell 6, and the top surface of the water-cooled inner circle 5 is mounted with a heating rod 7. Preferably, the heating rod 7 can also be detachably mounted, such as providing a positioning seat 18 on the water-cooled inner circle 5, and providing a positioning hole on the positioning seat 18 for the heating rod 7 to be plugged in. The heating rod 7 is vertically arranged and located at the center of the annular mold shell 6. The equipment cover 1 is fixedly connected to the top surface of the water-cooled outer ring 3, and the equipment cover 1 covers the annular mold shell 6 therein. A pouring cup 10 is installed on the top of the equipment cover 1, and the molten metal can be poured into the annular mold shell 6 through the pouring cup 10. Preferably, the pouring cup 10 is detachably mounted on the top of the equipment cover 1, such as providing a snap device on the equipment cover 1 to clamp the pouring cup 10. A plurality of heating bodies 8 are arranged on the inner wall of the equipment cover 1, and the plurality of heating bodies 8 are arranged around the annular mold shell 6.

working principle:

The control device is installed in a heat-insulating furnace, the pouring cup 10 is connected to the smelting chamber, the heat-insulating furnace and the smelting chamber are evacuated, and the smelting crucible is used to smelt the metal. After the smelting is completed, the alloy liquid is poured into the annular mold shell 6 through the pouring cup 10. After the alloy liquid reaches the annular mold shell 6, the heating rod 7 and the heating body 8 will keep the alloy liquid in the annular mold shell 6 warm. After standing for a certain period of time, the heating rod 7 and the heating body 8 are turned off to complete the pouring, and then cooling water is injected into the water-cooled outer ring 3, the water-cooled middle ring 4 and the water-cooled inner circle 5. Then, the water-cooled middle ring 4 first descends, and the water-cooled inner circle 5 remains stationary. The water-cooled middle ring 4 drives the annular mold shell 6 to descend, and the casting is pulled. During the pulling process, the water-cooled inner circle 5 will cool the center of the casting. After the casting is pulled, the water-cooled inner circle 5 will descend to the same horizontal position as the water-cooled middle ring 4. Then, after the temperature of the annular mold shell 6 is cooled to below the preset cooling temperature, the annular mold shell 6 is taken out to obtain a directional casting or a single crystal casting. Preferably, the water-cooled middle ring 4 and the water-cooled inner circle 5 descend at a constant rate.

The heating rod 7 heats and insulates the center of the annular mold shell 6, and the heating body 8 can heat and insulate the periphery of the annular mold shell 6, which can improve the temperature field of the negative and positive surfaces of the annular mold shell 6, improve the temperature gradient of the negative surface of the casting, increase the refractory elements of the high-generation single crystal alloy and the oriented columnar crystal alloy, and the increase in temperature gradient can not only reduce element segregation, but also make the casting more conducive to oriented grain growth during the competitive growth process of the crystal selection section, improve the growth direction of the crystal, and reduce the broken crystals on the surface of the casting. The water-cooled inner circle 5 in the water-cooled tray cools the center of the casting, which can keep the solid-liquid interface of the casting horizontal and not tilted, improve the solid-liquid interface morphology, reduce the probability of different oriented grains appearing at the corners of the large platform of the single crystal casting, improve the qualified rate of oriented or single crystal castings, and reduce the generation of defects.

Control experiment:

Experiment 1: Vacuuming, the temperature of the molten alloy is controlled at 1500-1570℃, the holding time is 3-5min, the pouring temperature is 1480-1550℃, the heating rod 7 and the heating body 8 are heated and kept warm, and the standing time is 2-5min. After the pouring is completed, the water-cooled middle ring 4 first descends synchronously at a certain rate, and the water-cooled inner circle 5 remains motionless. When the casting is completely pulled out, the water-cooled inner circle 5 is quickly pulled to the same horizontal position as the water-cooled middle ring 4. When the temperature of the annular mold shell 6 drops below 100℃, the annular mold shell 6 is removed, the pouring process is completed, and a directional casting or a single crystal casting is obtained. The solid-liquid interface of the obtained casting is shown in a of Figure 5, and the grain orientation is shown in a of Figure 6.

Experiment 2: Vacuuming, the temperature of the smelting alloy is controlled at 1500-1570℃, the holding time is 3-5min, the pouring temperature is 1480-1550℃, the heating rod 7 and the heating body 8 are heated and kept warm, and the standing time is 2-5min. After the pouring is completed, the water-cooled middle ring 4 and the water-cooled inner circle 5 are synchronously lowered at a certain rate. When the casting is completely pulled out, the temperature of the annular mold shell 6 drops below 100℃, the annular mold shell 6 is removed, the pouring process is completed, and a directional casting or a single crystal casting is obtained. The solid-liquid interface of the obtained casting is shown in b in Figure 5, and the grain orientation is shown in b in Figure 6.

Experiment 3:

Evacuate the casting, control the temperature of the smelting alloy at 1500-1570°C, keep warm for 3-5 minutes, and set the pouring temperature at 1480-1550°C. Heat the heating body 8 and keep warm. Do not start the heating rod 7. Leave it to stand for 2-5 minutes. After the pouring is completed, the water-cooled middle ring 4 and the water-cooled inner circle 5 drop synchronously at a certain rate. When the casting is completely pulled out, wait for the temperature of the annular mold shell 6 to drop below 100°C, remove the annular mold shell 6, and the pouring process is completed to obtain a directional casting or a single crystal casting. The solid-liquid interface of the casting is shown in c in Figure 5, and the grain orientation is shown in c in Figure 6.

In summary, it can be seen from Figure 5 that the inclination angle of the solid-liquid interface in Experiment 3 (traditional HRS method) is too large, while in Experiment 1, by adding a water cooling system and adding a heating rod 7 in the middle of the annular mold shell 6, the solid-liquid interface is significantly flat. At the same time, it can also be seen that the length of the mushy zone (i.e., the middle area between TL and TS) in Experiment 1 (central heating plus central water cooling process) is the shortest among the three experiments. There is a semi-liquid and semi-solid area between the liquid phase and the solid, which is called the mushy zone. The crystallization temperature range is related to the alloy composition and process. Therefore, when the same alloy is used, the temperature gradient of the heating rod 7 plus central water cooling is the largest. The temperature gradient at the solid-liquid interface can be obtained by the formula GL=(TL-TS)/L, where TL represents the liquid phase temperature at the solid-liquid interface front, TS represents the solidified solid temperature, and L represents the length of the mushy zone. It can be seen from Figure 6 that in Experiment 1 (central heating plus central water cooling process), the proportion of grains with a growth orientation less than 15° is the largest, and its grain orientation is better. In Experiment 2 (only the central heating process is set), the grain orientation deviation is increased. In Experiment 3 (traditional HRS method), the grain orientation generally exceeds 15°. Therefore, the heating rod 7 plus the center water cooling process not only changes the solid-liquid interface morphology, but also increases the temperature gradient at the solid-liquid interface front, and at the same time, optimizes the growth direction of the grains and reduces the probability of defect formation.

Further, in this embodiment, as shown in FIGS. 1 to 6 , the temperature at the annular formwork 6 is monitored by a temperature sensor, and the temperature sensor is installed on the outer wall of the annular formwork 6 .

Furthermore, in this embodiment, as shown in FIG. 1 to FIG. 6 , the water-cooled outer ring 3 , the water-cooled middle ring 4 and the water-cooled inner ring 5 are all made of copper.

In this embodiment, as shown in FIG. 1 to FIG. 6 , the heating rod 7 is a graphite heating rod.

In this embodiment, as shown in FIG. 1 to FIG. 6 , a heat-insulating layer 12 is provided on the inner wall of the equipment housing 1 .

Furthermore, in this embodiment, as shown in Figures 1 to 6, a thermal insulation pad 13 is provided on the top surface of the device base 2, and the heating body 8 and the thermal insulation layer 12 are installed on the thermal insulation pad 13 to separate the heating body 8 and the thermal insulation layer 12 from the device base 2.

In this embodiment, as shown in Figures 1 to 6, the heating body 8 is a magnetic heating body. A heating coil 9 is provided on the outer wall of the device housing 1. The heating coil 9 provides an induced magnetic field for the magnetic heating body. When the magnetic heating body senses the magnetic field, eddy currents are generated and converted into resistance heating.

In this embodiment, as shown in Figures 1 to 6, the water-cooled middle ring 4 and the water-cooled inner circle 5 are interlocked by a locking mechanism. Locking the water-cooled middle ring 4 and the water-cooled inner circle 5 by the locking mechanism is more conducive to the synchronous lifting of the water-cooled middle ring 4 and the water-cooled inner circle 5. When the water-cooled middle ring 4 and the water-cooled inner circle 5 do not need to be lifted and lowered synchronously, the locking mechanism can be unlocked.

Further, in this embodiment, as shown in Figures 1 to 6, the locking mechanism includes a locking bolt 17 and a bolt ear plate (not shown). The water-cooled middle ring 4 and the water-cooled inner circle 5 are provided with bolt ear plates correspondingly. The locking bolt 17 is screwed into the bolt ear plate on the water-cooled middle ring 4 and the corresponding bolt ear plate on the water-cooled inner circle 5 to lock the water-cooled middle ring 4 and the water-cooled inner circle 5. The locking bolt 17 is screwed off to unlock the water-cooled middle ring 4 and the water-cooled inner circle 5.

In this embodiment, as shown in Figures 1 to 6, the lifting mechanism includes a pull rod 11, and the pull rod 11 can be lifted up and down. A pull rod 11 is coaxially connected to the bottom wall of the water-cooled inner circle 5. Two pull rods 11 are connected to the bottom wall of the water-cooled middle ring 4, and the two pull rods 11 are arranged on both sides of the axis of the water-cooled middle ring 4. By pulling down the three pull rods 11 at the same time, the water-cooled middle ring 4 and the water-cooled inner circle 5 can be synchronously lowered. The lifting and lowering of the pull rod 11 can be achieved by a telescopic cylinder 14, that is, the cylinder body of the telescopic cylinder 14 is fixed in the control chamber of the equipment base 2, and a connecting frame 15 is fixedly connected to the piston rod of the telescopic cylinder 14. The connecting frame 15 is fixedly connected to the pull rod 11, and the lifting and lowering of the pull rod 11 is achieved by the extension and retraction of the piston rod of the telescopic cylinder 14. Specifically, the telescopic cylinder 14 can be a pneumatic cylinder, a hydraulic cylinder or an electric cylinder.

In this embodiment, as shown in FIGS. 1 to 6 , the pull rod 11 is a hollow rod. One end of the pull rod 11 on the water-cooled inner circle 5 is connected to the water-cooled inner circle 5, and the other end is provided with a cooling water gate, through which the coolant is fed in and discharged. One end of the two pull rods 11 of the water-cooled middle ring 4 is connected to the water-cooled middle ring 4, and the other end is provided with a cooling water inlet and a cooling water outlet, respectively. The coolant enters through the cooling water inlet of one of the pull rods 11, and then is discharged through the cooling water outlet of the other pull rod 11.

Furthermore, in this embodiment, as shown in Figures 1 to 6, a guide frame 16 is installed in the control chamber of the equipment base 2, and three guide holes are provided on the guide frame 16. The axes of the guide holes are vertically arranged, and the positions of the three guide holes correspond to the positions of the three pull-out rods 11. The three pull-out rods 11 are respectively inserted into the three guide holes to ensure stable vertical lifting of the pull-out rods 11.

Example 2

This embodiment provides a method for controlling the grain growth direction of a directional or single crystal casting, as shown in FIGS. 1 to 6 , comprising the following steps:

S1. Install the directional or single crystal casting grain growth direction control device in Example 1 in a holding furnace, and connect the pouring cup 10 with the melting chamber;

S2, the holding furnace and the smelting chamber are evacuated, the smelting chamber is smelted, and the smelting is kept warm for a preset holding time, the molten alloy liquid is poured into the annular mold shell 6 through the pouring cup 10, the heating body 8 and the heating rod 7 are heated and kept warm, and after the pouring is completed, the preset standing time is set to stand, and then the heating body 8 and the heating rod 7 are turned off;

S3, the water-cooled middle ring 4 descends first, and when the casting is pulled out, the water-cooled inner circle 5 descends to the same horizontal position as the water-cooled middle ring 4, and cooling water is injected into the water-cooled outer ring 3, the water-cooled middle ring 4 and the water-cooled inner circle 5. After the temperature of the annular mold shell 6 is cooled to below the preset cooling temperature, the annular mold shell 6 is taken out to obtain a directional casting or a single crystal casting.

This control method improves the temperature gradient of the casting during directional solidification, refines the growing structure, and improves the performance. The directional and single crystal castings produced by this technology have good grain orientation, are not prone to broken crystals and miscellaneous crystals, have a stable solid-liquid interface without tilting, and can effectively improve the solid-liquid interface morphology. The qualified rate of directional or single crystal castings is high and the defects are few. For relevant proof, refer to the control experiment in Example 1.

Further, in this embodiment, the temperature during smelting is controlled at 1500-1570°C, and the preset holding time is 3-5 minutes; the temperature during pouring is controlled at 1480-1550°C, and the preset standing time is 2-5 minutes; the preset cooling temperature is 100°C, that is, when the temperature is below 100°C, the annular mold shell 6 is taken out. Of course, the above parameters are only reference values and can be adjusted according to specific needs.

The present invention uses specific examples to illustrate the principles and implementation methods of the present invention. The above examples are only used to help understand the method and core ideas of the present invention. At the same time, for those skilled in the art, according to the ideas of the present invention, there will be changes in the specific implementation methods and application scope. In summary, the content of this specification should not be understood as limiting the present invention.

Claims (10)

1. The utility model provides a directional or monocrystalline casting grain growth direction control equipment, its characterized in that includes equipment housing, the equipment base that is equipped with the control cavity in the interior and the vertical water-cooling tray that sets up of axis, the water-cooling chassis includes the water-cooling outer loop, the water-cooling zhong and the water-cooling is interior that closely overlaps in proper order from outside to interior, water-cooling outer loop fixed connection is in the top of equipment base, be equipped with in the control cavity and be used for independently driving the water-cooling zhong with the elevating system that the water-cooling is interior goes up and down, the top of equipment base is equipped with confession the water-cooling zhong with the water-cooling is interior business turn over the access of control cavity, the annular form is installed to the top detachable of water-cooling zhong, the coaxial heating rod that is located annular form center is installed to the top surface of water-cooling inside circle, the equipment housing is fixed on the water-cooling outer loop and covers and is established outside the annular form, be equipped with on the inner wall of equipment housing and be located annular form heating member all around, the top of equipment housing installs and is used for to the pouring cup in the annular form.

2. The directional or single crystal casting grain growth direction control apparatus of claim 1 wherein the heating rod is a graphite heating rod.

3. The directional or monocrystalline casting grain growth direction control apparatus of claim 1, wherein the inner wall of the apparatus housing is provided with a heat preservation layer.

4. A directional or monocrystalline casting grain growth direction control apparatus in accordance with any of claims 1-3, characterized in that the heating body is a magnetic heating body, and heating coils providing induction magnetic fields for the magnetic heating body are provided on the outer wall of the apparatus housing.

5. A directional or monocrystalline casting grain growth direction control apparatus in accordance with any of claims 1-3, the water-cooled middle ring and the water-cooled inner circle being interlocked by a locking mechanism.

6. The directional or monocrystalline casting grain growth direction control apparatus of claim 5, wherein the locking mechanism comprises locking bolts and bolt lugs correspondingly disposed on the water-cooled middle ring and the water-cooled inner circle.

7. A directional or monocrystalline casting grain growth direction control apparatus in accordance with any of claims 1-3, the lifting mechanism comprising a lifting rod capable of lifting up and down, the bottom wall of the water-cooled inner circle being coaxially connected with one of the lifting rods, the bottom wall of the water-cooled middle ring being connected with two of the lifting rods separately disposed on either side of its axis.

8. The directional or monocrystalline casting grain growth direction control apparatus of claim 7, wherein the draw bars are hollow bars, one end of the draw bar of the water-cooled inner circle is communicated with the water-cooled inner circle, the other end is provided with a cooling water gate, one end of the two draw bars of the water-cooled middle ring is communicated with the water-cooled middle ring, and the other end is respectively provided with a cooling water inlet and a cooling water outlet.

9. A method for controlling the grain growth direction of a directional or monocrystalline casting, comprising the steps of:

s1, installing the directional or monocrystalline casting grain growth direction control equipment according to any one of claims 1 to 8 in a holding furnace, and communicating a pouring cup with a smelting chamber;

S2, vacuumizing a heat preservation furnace and a smelting chamber, smelting in the smelting chamber, installing a preset heat preservation time for heat preservation, pouring smelted alloy liquid into the annular mould shell through a pouring cup, heating and heat preservation are carried out on a heating body and a heating rod, after pouring, installing a preset standing time for standing, and then closing the heating rod and the heating body;

S3, injecting cooling water into the water-cooling outer ring, the water-cooling middle ring and the water-cooling inner circle, wherein the water-cooling middle ring descends firstly, the water-cooling inner circle descends to the same horizontal position as the water-cooling middle ring after the casting is pulled, and the annular mould shell is taken out after the annular mould shell is cooled to below the preset cooling temperature, so as to obtain the directional casting or the monocrystal casting.

10. The method for controlling the grain growth direction of a directional or single crystal casting according to claim 9, wherein the temperature is controlled to 1500-1570 ℃ during smelting, and the preset holding time is 3-5min; the temperature is controlled to 1480-1550 ℃ during casting, and the preset standing time is 2-5min; the preset cooling temperature is 100 ℃.