CN114619021A - Method for casting integral equiaxial fine-grained blade disc by mechanical oscillation method - Google Patents

Abstract

The invention discloses a method for casting an integral equiaxial fine-grained bladed disk by adopting a mechanical oscillation method, and belongs to the field of precision casting of high-temperature alloy integral bladed disks. The method is characterized in that a die shell rotates in the positive and negative directions under vacuum, the die shell can be braked and reversed rapidly, the solidified dendritic crystal tissue is broken by utilizing the rotation and rapid emergency braking force, nucleation is promoted in non-solidified molten steel, and the purpose of integral fine grains is achieved. The device can be used for producing fine-grained structural components of engine casings of aviation, aerospace, combustion engines and the like, integrated fine-grained cast turbines of disks and other fine-grained cast precision castings.

Description

A method for casting integral equiaxed fine-grain blisks by mechanical oscillation method

technical field

The invention relates to the technical field of casting superalloy integral blisk precision casting, in particular to a method for casting an integral equiaxed fine-grain blisk by using a mechanical oscillation method.

Background technique

Casting superalloy integral precision casting technology is a major development in the aviation and aerospace casting industry, and its applications are becoming more and more extensive, from integral turbine rotors, guide impellers, nozzle rings to complex diffuser casings, diffusion casings, combustion The casing, turbine casing and fan frame can all be formed by precision casting. More and more integral precision castings are used to replace forgings, forging and casting assemblies and machining assemblies, which can not only improve the performance of parts, effectively reduce the weight of the engine, improve the performance and reliability of the engine, but also greatly improve the performance of the engine. Production efficiency, reduce manufacturing costs, and bring very obvious economic benefits.

Since the 1980s, the development and application of foreign superalloy integral precision casting technology has been extremely rapid, and the integral blade casting technology of nickel-based, cobalt-based and other superalloys has appeared one after another. Coarse grains make the performance of the alloy uneven, the fluctuation is large, and it is easy to produce loose casting.

In order to refine superalloy grains, refining methods such as thermal control method, chemical method and kinetic method (mechanical method) have been developed in foreign countries. The characteristics of the thermal control method are to reduce the refining temperature and time, retain the carbides, and at the same time reduce the pouring temperature, accelerate the cooling, and limit the grain growth; the chemical method is to add a solid nucleating agent to the melt to form a large number of heterogeneous crystal nuclei; The kinetic law is to agitate the melt by rotating the mold and mechanical vibration to refine the grains. However, there are certain limitations and defects in the application of the above process methods. For example, the thermal control method has the disadvantage that it is difficult to remove bubbles and inclusions, which reduces the purity of the casting and makes it difficult to cast large parts. Temperature control limits its application. In mechanical applications, it is difficult to use mechanical force to make the melt movement uniform and is limited by the shape of the part. The disadvantage of the chemical method is that it is difficult to control the chemical composition, and the nucleating agent is easy to form oxides and cause fatigue sources. In general, the fine grains obtained by the above methods are not effective in improving the properties of the alloy.

SUMMARY OF THE INVENTION

In order to solve the problem in the prior art that the integral casting fine-grained blade cannot be prepared by the dynamic method, the purpose of the present invention is to provide a method for casting the integral equiaxed fine-grained blisk by using the mechanical oscillation method. A variety of precision fine-grained castings are prepared by induction melting, pouring, rotary oscillation, rapid nucleation, and rapid cooling and solidification.

For achieving the above object, the technical scheme adopted in the present invention is as follows:

A method for casting an integral equiaxed fine-grain leaf disk by using a mechanical oscillation method. Through the forward and reverse rotation of the mold shell and emergency braking, the solidified dendrite structure can be broken, and the nucleation can be promoted in the unsolidified molten steel to achieve the purpose of overall fine grain, thereby preparing the overall equiaxed fine grain leaf disk .

The mechanically rotating and oscillating fine-grain casting furnace includes a rotatable water-cooled chassis, and a mold shell is fixed above the rotatable water-cooled chassis, and the action of the mold shell is driven by the rotation and braking of the water-cooled chassis.

The mold case is provided with a cavity protrusion on the lower surface of the base, and the cavity protrusion is adapted to the groove on the water-cooled chassis, and the base of the mold case is fixed on the water-cooled chassis by bolts.

The preparation method of the mold shell is as follows: the first layer and the subsequent reinforcement layers are prepared on the wax mold, and the mold shell surface layer is made of 200 mesh Al ₂ O ₃ powder and cobalt aluminate refiner according to 85:15. The reinforcement layer is sanded with 80 mesh Al ₂ O ₃ powder, and silica sol is used for dipping between each layer of sand. Spare shell.

The fine-grain casting process includes the following steps:

(1) Fix the mold shell on the rotating water-cooled chassis, close the furnace door, lower the holding furnace to completely cover the mold shell, evacuate the furnace to below 3Pa, heat the holding furnace to 1240°C, and keep the mold shell for 2 hours;

(2) The smelting furnace is powered on to start smelting. When the molten steel is completely dissolved, when the molten steel temperature reaches 1600 °C, refining is performed for 5 minutes;

(3) After the refining is finished, the power is cut off to cool down until the molten steel solidifies and begins to conjunctiva, and then the molten steel is powered on again to melt the molten steel. When the molten steel rises to 1480-1510 °C, pour it;

(4) After pouring, the molten steel rests in the shell for 3-15 seconds, and the water-cooled chassis starts to move. After rotating in one direction for 30-180 seconds, brake quickly for 1-5 seconds, and then rotate in the opposite direction to oscillate. 30-180 seconds, then emergency braking again, and turning in the opposite direction again, and so on.

In step (4), the unidirectional rotation speed is 100-200 rpm, and the overall rotation and oscillation time is 6-15 minutes.

The overall fine-grain casting leaf disk prepared by the method of the invention has an average crystal grain size of less than 2 mm and uniform crystal grains.

The beneficial effects of the present invention are:

1. By adopting the overall fine-grain casting leaf disk process of the present invention, a small equiaxed crystal integral casting leaf disk with an average grain size of less than 2 mm can be prepared, and the inclined columnar crystal structure formed by gravity casting of the blade under vacuum can be eliminated.

2. The overall casting blisk prepared by the fine-grain casting process of the present invention is anatomically sampled, and the medium temperature performance of the alloy and the anatomical sampling structure performance of the original gravity casting blisk are greatly improved, and the dispersion degree is reduced.

3. The present invention adopts the mechanical vibration fine-grained casting furnace, combined with the special casting process, to obtain an ideal overall fine-grained casting leaf disk, and its fine-grained structure can especially improve the service performance of high-temperature alloy castings at medium and low temperature (≤760°C). Obviously, on the one hand, the low-cycle fatigue life of the casting can be more than doubled, and the uniformity of the alloy structure and composition can be effectively improved, and the dispersion of the mechanical property data of the casting can be reduced, thereby improving the design tolerance and reliability of the casting. (see Table 1 for data).

Description of drawings:

Fig. 1 is the mold shell used in the mechanically oscillating fine-grain casting furnace of the present invention.

Figure 2 shows the fixed connection between the shell and the rotatable water-cooling plate in the mechanically oscillating fine-grain casting furnace.

FIG. 3 is the cast blisk prepared in Example 1. FIG.

FIG. 4 is the cast blisk prepared in Example 2. FIG.

FIG. 5 is the cast blisk prepared in Example 3. FIG.

FIG. 6 is the cast blisk prepared in Example 4. FIG.

FIG. 7 is the cast blisk prepared in Example 5. FIG.

FIG. 8 is the cast blisk prepared in Example 6. FIG.

FIG. 9 shows the cast blisk prepared in Example 7. FIG.

FIG. 10 is the cast blisk prepared in Example 8. FIG.

FIG. 11 is the cast blisk prepared in Example 9. FIG.

Fig. 12 shows the anatomical grain structure of the integrally cast blisk body by gravity casting under vacuum.

Detailed ways:

The present invention will be described in detail below with reference to the accompanying drawings.

The device used for preparing the equiaxed fine-grained leaf disk for casting in the present invention is a mechanically rotating and oscillating fine-grained casting furnace (patent with the application number of 201110004318.3 for structural parameters of the casting furnace), which includes a rotatable water-cooled turntable, and the mold shell can be fixed on the rotating device, As shown in Fig. 1-2, a protrusion with a cavity is provided on the lower bottom surface of the base of the mold case, which is used for fixing the mold case to the rotatable water-cooled chassis. The upper part of the water-cooled chassis is provided with a groove, the protrusion with a cavity matches the shape and size of the groove, and is detachably connected by bolts.

The preparation method of the mold shell is as follows: coating and hanging paint on the wax mold, the first layer is formed by mixing 200 mesh Al ₂ O ₃ powder and cobalt aluminate refiner in a weight ratio of 85:15; The eleventh layer is the reinforcement layer. The reinforcement layer is sanded with 80 mesh Al ₂ O ₃ powder. Between each layer of sand, silica sol is used to dip the slurry. The obtained shell is ready for use.

The fine-grain casting process is as follows:

Fix the mold shell on the rotating water-cooled chassis, close the furnace door, lower the holding furnace to the bottom of the mold shell, completely cover the mold shell, evacuate the furnace to less than 3Pa, turn on the holding furnace heating device, heat the holding furnace, and keep the heat preservation. The furnace is heated to 1240°C and kept for 2 hours. After the holding furnace is kept for 2 hours, the smelting furnace is powered on to start smelting. When the molten steel is completely dissolved and the temperature of the molten steel reaches 1600°C, refining is performed for 5 minutes. Until the molten steel solidifies and begins to conjunctiva, send electricity again to melt the molten steel. When the molten steel rises to 1480-1510 ℃, pour it. After pouring, let it stand for 3-15 seconds, control the action of the rotatable water-cooled chassis, and rotate 30-180 in one direction. Seconds later, brake quickly, braking time is 1-5 seconds, then rotate in the opposite direction for 30-180 seconds, then emergency brake again, and rotate in the opposite direction again, and so on and so forth, the total vibration time is 6-15 minutes The unidirectional rotation speed is 100-200 rpm.

Examples 1-9:

Examples 1-9 The alloy composition, process parameters and the state of the cast integral equiaxed fine-grained leaf disk are shown in Table 1. Table 2 shows the comparison of the tensile properties of the integral blisk prepared by the present invention and the sampling of the existing gravity casting blisk disk.

The cast blisks prepared in Examples 1-9 are shown in Figures 3-11, and the anatomical grain structure of the integrally cast blisks by gravity casting under vacuum is shown in Figure 12.

Table 1

Table 2 Comparison of tensile properties of integral blisk disk samples

Claims (7)

1. a method that adopts mechanical oscillation method to cast the integral equiaxed crystal-fine leaf disk, it is characterized in that: the method is to prepare the integral equiaxed crystal-fine leaf disk by adopting the mechanical rotating vibration fine-grain casting furnace and the fine-grain casting process, and the casting process In the vacuum condition, the solidified dendritic structure is broken by the forward and reverse rotation of the mold shell and emergency braking can be performed, and the nucleation is promoted in the unsolidified molten steel, so as to achieve the purpose of overall fine-graining, thereby preparing the overall Isometric fine-grained leaf disk. 2. The method for casting an integral equiaxed fine-grain leaf disk by mechanical oscillation method according to claim 1, characterized in that: the mechanical rotational oscillation fine-grain casting furnace comprises a rotatable water-cooled chassis, and the mold shell is fixed on the rotatable water-cooled chassis. On the rotating water-cooled chassis, the action of the shell is driven by the rotation and braking of the water-cooled chassis. 3 . The method for casting an integral equiaxed fine-grain leaf disk by mechanical oscillation method according to claim 2 , wherein the shell is provided with a cavity protrusion on the lower surface of the base, and the cavity protrusion is different from the cavity protrusion. 4 . The grooves on the water-cooled chassis are adapted, and the base of the mold shell is fixed on the water-cooled chassis by bolts. 4. the method for casting integral equiaxed fine-grain leaf disk by mechanical oscillation method according to claim 2, is characterized in that: the preparation method of described shell is: prepare the first level layer and each subsequent layer on the wax mold. The reinforcement layer, the shell surface layer is made of 200 mesh Al ₂ O ₃ powder and cobalt aluminate refiner mixed in a weight ratio of 85:15; the reinforcement layer is 80 mesh Al ₂ O ₃ powder sprinkled with sand, each layer of sand Silica sol is used for dipping in between, and after coating to eleven layers, silica sol is used for dipping, drying and dewaxing, and the obtained shell is used for later use. 5. the method that adopts mechanical oscillation method to cast integral equiaxed fine-grain leaf disk according to claim 2, is characterized in that: described fine-grain casting process comprises the steps: (1) Fix the mold shell on the rotating water-cooled chassis, close the furnace door, lower the holding furnace to completely cover the mold shell, evacuate the furnace to below 3Pa, heat the holding furnace to 1240°C, and keep the mold shell for 2 hours; (2) The smelting furnace is powered on to start smelting. When the molten steel is completely dissolved, when the molten steel temperature reaches 1600 °C, refining is performed for 5 minutes; (3) After the refining is finished, the power is cut off to cool down until the molten steel solidifies and begins to conjunctiva, and then the molten steel is powered on again to melt the molten steel. When the molten steel rises to 1480-1510 °C, pour it; (4) After pouring, the molten steel rests in the shell for 3-15 seconds, and the water-cooled chassis starts to move. After rotating in one direction for 30-180 seconds, brake quickly for 1-5 seconds, and then rotate in the opposite direction to oscillate. 30-180 seconds, then emergency braking again, and turning in the opposite direction again, and so on. 6. the method that adopts mechanical oscillation method to cast integral equiaxed fine-grain leaf disk according to claim 5, is characterized in that: in step (4), one-way rotational speed is 100-200 rev/min, and overall rotational oscillation time 6-15 minutes. 7. The method for casting an integral equiaxed fine-grained leaf disk using a mechanical oscillation method according to claim 5, characterized in that: the overall fine-grained casting leaf disk prepared by the method has an average grain size of the disc body less than 2 mm or less, The grains are uniform.

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