Single-crystal high-temperature alloy turbine blade shell and preparation method

Abstract

The invention relates to the technical field of turbine blades, in particular to a single-crystal high-temperature alloy turbine blade shell and a preparation method thereof.The shell comprises a sprue cup, a sprue, a cross gate, a slag collecting groove, a seed crystal cavity and a seed crystal growth cavity; wherein the two ends of the sprue are respectively connected with the sprue cup and the cross gate; the seed crystal cavity is vertical to the other end of the cross gate and the inlet channel of the slag collecting groove and is positioned below the seed crystal growth cavity; and the seed crystal growth cavity is respectively communicated with the seed crystal cavity, the slag collecting groove and the cross gate. According to the arrangement mode of the seed crystal, a gap between the seed crystal and the seed crystal cavity is eliminated, and the seeding defect caused by the existence of the gap is avoided. And the length of a seed crystal paste area is obviously reduced by designing a pouring gate structure and a slag collecting groove, so that the seeding defect in the seeding process of the seed crystal is avoided as much as possible.

Description

Technical Field

[0001] The present invention relates to the technical field of turbine blades, and in particular to a single crystal high temperature alloy turbine blade shell and a preparation method thereof. Background Art

[0002] Single crystal superalloys have many advantages, such as excellent high temperature strength, oxidation resistance and creep resistance, etc. In high temperature environments, single crystal superalloys can maintain high strength and stability, so they are widely used in the manufacture of turbine blades for aircraft engines and gas turbines.

[0003] Directional solidification technology is required in the process of manufacturing single crystal high-temperature alloy turbine blades. To achieve directional solidification, the alloy liquid is poured into the mold shell, and then a specific directional solidification process is used to solidify the alloy liquid along a certain direction, thereby obtaining a turbine blade with a single grain structure. Among them, when preparing single crystals by directional solidification, seeding is first required so that only one grain enters the mold cavity. On this basis, the crystal slowly and gradually grows into a single crystal blade composed of one grain. Among them, seed crystals are a commonly used seeding method for preparing single crystal turbine blades.

[0004] In the prior art, in order to facilitate the placement of the seed crystal into the mold shell, there is a certain gap between the seed crystal and the seed crystal cavity. A large number of studies have shown that the gap between the seed crystal and the seed crystal cavity is one of the main reasons for the failure of seed crystal seeding. In addition, before the alloy liquid is poured, the seed crystal at the bottom of the mold shell remains in a solid state due to the low temperature, and the upper part of the seed crystal is melted into a liquid state due to the high temperature. There is a transition area between the melted and unmelted parts, that is, the so-called mushy area. In the transition area, crystal nuclei are prone to appear, resulting in blade crystal defects and the failure of single crystal seeding.

[0005] Therefore, how to improve the success rate of single crystal seeding when preparing single crystal blades has become a technical problem that needs to be solved urgently. Summary of the invention

[0006] The object of the present invention is to provide a single crystal high temperature alloy turbine blade shell and a preparation method thereof, so as to solve the above-mentioned technical problems.

[0007] To achieve the above object, the present invention provides a single crystal high temperature alloy turbine blade shell, comprising: a pouring cup, a sprue, a runner, a slag collecting trough, a seed crystal cavity, and a seed crystal growth cavity;

[0008] The two ends of the sprue are connected to the pouring cup and the cross runner respectively; the seed crystal cavity is perpendicular to the other end of the cross runner and the inlet channel of the slag collecting trough, and is located below the seed crystal growth cavity; the seed crystal growth cavity is connected to the seed crystal cavity, the slag collecting trough and the cross runner respectively.

[0009] The present invention also provides a method for preparing a single crystal high temperature alloy turbine blade shell, comprising:

[0010] According to the size of the single crystal high temperature alloy turbine blade and the thermophysical parameters of the casting alloy, the length of the seed crystal flushing section and the length L of the seed crystal completely unmelted section are determined;

[0011] According to the length of the seed crystal scouring section, the cavity structure of the single crystal high-temperature alloy turbine blade shell is determined;

[0012] Place the seed crystal on the base plate and prepare a wax mold;

[0013] Based on the cavity structure, the single crystal wax mold with seed crystal is subjected to shell coating, dewaxing and sintering to obtain a single crystal high-temperature alloy turbine blade shell.

[0014] The present invention also provides an application of a single crystal high temperature alloy turbine blade shell, and the single crystal high temperature alloy turbine blade shell is applied to aircraft engines and gas turbines.

[0015] Technical effects and advantages of the present invention:

[0016] The present invention discloses a single crystal high temperature alloy turbine blade shell, comprising: a pouring cup, a sprue, a cross runner, a slag collecting groove, a seed crystal cavity, and a seed crystal growth cavity; wherein, the two ends of the sprue are respectively connected to the pouring cup and the cross runner; the seed crystal cavity is perpendicular to the other end of the cross runner and the inlet channel of the slag collecting groove, and is located below the seed crystal growth cavity; the seed crystal growth cavity is respectively connected to the seed crystal cavity, the slag collecting groove and the cross runner.

[0017] The seed crystal arrangement method of the present invention eliminates the gap between the seed crystal and the seed crystal cavity (the inner cavity of the mold shell constitutes the mold cavity, and the seed crystal cavity is a part of the mold cavity), thereby avoiding seeding defects caused by the existence of the gap. In addition, the length of the seed crystal mushy zone is significantly reduced by designing the runner structure and the slag collecting groove, thereby minimizing seeding defects during the seed crystal seeding process.

[0018] Other features and advantages of the present invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are 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. Figure 1 This is a schematic diagram of the single crystal high temperature alloy turbine blade shell structure;

[0020] Figure numerals: 1- pouring cup; 2- sprue; 3- runner; 4- slag collecting trough; 5- seed crystal; 6- seed crystal growth cavity. DETAILED DESCRIPTION

[0021] 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.

[0022] It should be noted that the structures, proportions, sizes, etc. illustrated in the drawings of this specification are only used to match the contents disclosed in the specification for people familiar with this technology to understand and read, and are not used to limit the limiting conditions for the implementation of the present invention, so they have no substantial technical significance. Any modification of the structure, change of the proportion relationship or adjustment of the size should still fall within the scope of the technical content disclosed by the present invention without affecting the effects and purposes that can be achieved by the present invention. At the same time, the terms such as "upper", "lower", "left", "right", "middle" and "one" quoted in this specification are only for the convenience of description, and are not used to limit the scope of the implementation of the present invention. The change or adjustment of their relative relationship should also be regarded as the scope of the implementation of the present invention without substantially changing the technical content.

[0023] To solve the deficiencies of the prior art, the present invention discloses a single crystal high temperature alloy turbine blade shell, such as Figure 1 As shown, it includes: a pouring cup 1, a straight runner 2, a horizontal runner 3, a slag collecting trough 4, a seed crystal cavity, and a seed crystal growth cavity 6.

[0024] Among them, the two ends of the sprue 2 are respectively connected to the pouring cup 1 and the cross runner 3; the seed crystal cavity is perpendicular to the other end of the cross runner 3 and the inlet channel of the slag collecting trough 4, and is located below the seed crystal growth cavity 6; the seed crystal growth cavity 6 is respectively connected to the seed crystal cavity, the slag collecting trough 4 and the cross runner 3.

[0025] The sprue 2 has a taper that is smaller at the bottom and larger at the top, and the taper is 1° to 3°.

[0026] The cross-sectional area of ​​the runner 3 is smaller than the cross-sectional area of ​​the small end of the sprue 2 .

[0027] The slag collecting tank 4 receives the molten metal with broken dendrites to prevent the broken dendrites from forming crystallization cores, and the volume of the slag collecting tank 4 is 10 times greater than the volume of the flushing section of the seed crystal 5 .

[0028] The diameter of the inlet channel of the slag collecting trough 4 is greater than the diameter of the runner 3, and the length of the inlet channel is greater than or equal to the diameter of the inlet channel; the diameter of the inner cavity of the slag collecting trough 4 is 10-20 mm, and the height is 15-25 mm.

[0029] The distance L between the seed crystal growth cavity 6 and the bottom surface of the single crystal high temperature alloy turbine blade shell is the length of the completely unmelted section of the seed crystal 5 .

[0030] The present invention also provides a method for preparing a single crystal high temperature alloy turbine blade shell, comprising:

[0031] 1. According to the size of the single crystal high temperature alloy turbine blade and the thermophysical parameters of the casting alloy, determine the length of the flushing section of the seed crystal 5 and the length L of the completely unmelted section of the seed crystal 5.

[0032] Specifically, it includes: determining the length L of the completely unmelted section of the seed crystal 5 according to the thermophysical properties of the cast alloy; determining the length of the seed crystal according to the size of the single crystal high-temperature alloy turbine blade; determining the length of the flushing section of the seed crystal 5 according to the seed crystal length and the length L of the completely unmelted section of the seed crystal 5.

[0033] The length L of the completely unmelted section of the seed crystal 5 is determined by the following formula:

[0034]

[0035] Where T0 is room temperature, T S is the solidus, f(G) T is the temperature gradient function within the seed relative to the temperature.

[0036] 2. According to the length of the scouring section of the seed crystal 5, the cavity structure of the single crystal high-temperature alloy turbine blade shell is determined.

[0037] Specifically, it includes: calculating the kinetic energy required to be generated when pouring the alloy according to the length of the flushing section of the seed crystal 5; and determining the size and position information of the slag collecting trough 4, the sprue 2 and the runner 3 according to the kinetic energy required to be generated when pouring the alloy.

[0038] 3. Place the seed crystal 5 on the base plate and prepare a wax mold.

[0039] 4. Based on the cavity structure, the single crystal wax mold with the seed crystal 5 is subjected to shell coating, dewaxing, and sintering to obtain a single crystal high-temperature alloy turbine blade shell.

[0040] Specifically, it includes: preparing seed crystals according to the seed crystal diameter required for preparing single crystal high-temperature alloy turbine blades, preparing wax molds and shell molds. When preparing the wax mold, the seed crystals are placed to ensure that there is no gap between the side of the seed crystal and the seed crystal cavity of the shell mold that is subsequently formed. Then, the single crystal wax mold with seed crystals is coated, dewaxed, and sintered to obtain a single crystal shell mold with seed crystals.

[0041] It should be noted that the specific steps in the single crystal high temperature alloy turbine blade shell preparation process, such as shell coating, dewaxing, sintering, etc. are all existing technologies and will not be introduced in detail here. For details, see application number 201410742333.1.

[0042] The present invention also provides an application of a single crystal high temperature alloy turbine blade shell, and the single crystal high temperature alloy turbine blade shell is applied to aircraft engines and gas turbines.

[0043] In order to eliminate the matching gap between the seed crystal and the seed crystal cavity, the present invention can place the seed crystal when preparing the wax mold before coating, and then the single crystal wax mold with the seed crystal is subjected to shell coating, dewaxing and sintering. In this way, there is no gap between the shell surrounding the seed crystal and the seed crystal during the directional solidification process, thereby avoiding the dendrite nucleation caused by alloy liquid filling due to the existence of gaps in many existing technologies.

[0044] At the same time, when seed crystals are used to prepare single crystal blades, the pouring molten metal is given kinetic energy to flush out the seed crystal flushing section by designing structures such as the straight runner, the cross runner, and the slag collecting trough, thereby reducing or even removing the seed crystal remelting paste area, and making the length of the paste area between the unmelted part of the seed crystal and the poured alloy liquid as small as possible to form a relatively flat solid-liquid interface. Directed solidification is carried out on the basis of this interface to grow dendrites, thereby obtaining a good seeding effect.

[0045] In order to better explain the present scheme, examples are also provided below.

[0046] Example

[0047] A method for preparing a shell of a DD6 alloy blade comprises the following steps:

[0048] Due to the weak core and other reasons, the directional solidification temperature of the blade is lower than 1500℃. According to the previous formula, the unmelted length of the seed crystal is 10mm.

[0049] The seed crystal diameter is 2mm and the seed crystal length is 15mm according to the blade size. The seed crystal is placed when preparing the wax mold to ensure that there is no gap between the side of the seed crystal and the seed crystal cavity of the shell to be formed later. The single crystal wax mold with the seed crystal is then coated, dewaxed, and sintered to obtain a single crystal shell mold with the seed crystal.

[0050] In order to obtain sufficient kinetic energy, the proportions of the cavity structure near the seed crystal need to be set as follows: the diameter of the slag collecting trough 4 is 12mm, the height is 20mm, the diameter of the slag collecting trough entrance channel is 4mm, and the length is 4mm; the diameter of the cross runner 3 is 3mm, and the length is 4.5mm; the diameter of the small end of the straight runner 2 is 5mm; the straight runner adopts a taper with a small bottom and a large top, and the taper is 1°.

[0051] During the preparation of the blade, the seeding structure is designed to eliminate most of the mushy area during the casting process, forming a relatively flat solid-liquid interface in the seed crystal. Directional solidification is carried out on the basis of this interface to grow dendrites, thereby obtaining a good seeding effect. At the same time, the slag collecting tank 4 is used to receive the molten metal with broken dendrites, avoiding the formation of crystal cores by broken dendrites. 410 blades were prepared using this seeding method, with a seeding success rate of more than 97%.

[0052] Finally, it should be noted that the above is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, it is still possible for those skilled in the art to modify the technical solutions described in the aforementioned embodiments or to make equivalent substitutions for some of the technical features therein. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A single crystal high temperature alloy turbine blade shell, characterized in that: include: A pouring cup (1), a sprue (2), a horizontal runner (3), a slag collecting trough (4), a seed crystal cavity, and a seed crystal growth cavity (6); The two ends of the sprue (2) are respectively connected to the pouring cup (1) and the runner (3); the seed crystal cavity is perpendicular to the other end of the runner (3) and the inlet channel of the slag collecting trough (4), and is located below the seed crystal growth cavity (6); the seed crystal growth cavity (6) is respectively connected to the seed crystal cavity, the slag collecting trough (4) and the runner (3).

2. The single crystal high temperature alloy turbine blade shell according to claim 1, characterized in that: The two ends of the sprue (2) have different tapers; The end of the sprue (2) connected to the runner (3) is a small taper end.

3. The single crystal high temperature alloy turbine blade shell according to claim 2, characterized in that: The taper range is 1°~3°.

4. The single crystal high temperature alloy turbine blade shell according to claim 2, characterized in that: The cross-sectional area of ​​the runner (3) is smaller than the cross-sectional area of ​​the small-taper end of the sprue (2).

5. The single crystal high temperature alloy turbine blade shell according to claim 1, characterized in that: The volume of the slag collecting tank (4) is greater than 10 times the volume of the flushing section of the seed crystal (5); The seed crystal cavity divides the seed crystal into two sections: the section outside the cavity is the seed crystal flushing section, and the section inside the cavity is the seed crystal completely unmelted section.

6. The single crystal high temperature alloy turbine blade shell according to claim 1, characterized in that: The diameter of the inlet channel of the slag collecting trough (4) is greater than the diameter of the runner (3), and the length of the inlet channel is greater than or equal to the diameter of the inlet channel; the diameter of the inner cavity of the slag collecting trough (4) is 10-20 mm, and the height is 15-25 mm.

7. The single crystal high temperature alloy turbine blade shell according to claim 1, characterized in that: The distance L between the seed crystal growth cavity (6) and the bottom surface of the single crystal high temperature alloy turbine blade shell is the length of the completely unmelted section of the seed crystal (5).

8. A method for preparing a single crystal high temperature alloy turbine blade shell according to any one of claims 1 to 7, characterized in that: include: According to the size of the single crystal high temperature alloy turbine blade and the thermophysical parameters of the casting alloy, the length of the seed crystal flushing section and the length L of the seed crystal completely unmelted section are determined; According to the length of the seed crystal scouring section, the cavity structure of the single crystal high-temperature alloy turbine blade shell is determined; Place the seed crystal on the base plate and prepare a wax mold; Based on the cavity structure, the single crystal wax mold with seed crystal is subjected to shell coating, dewaxing and sintering to obtain a single crystal high-temperature alloy turbine blade shell.

9. The method according to claim 8, characterized in that According to the size of the single crystal high temperature alloy turbine blade and the thermophysical parameters of the casting alloy, the length of the seed crystal flushing section and the length L of the seed crystal completely unmelted section are determined, including: Determine the length L of the completely unmelted section of the seed crystal according to the thermophysical parameters of the cast alloy; Determine the seed crystal length according to the size of the single crystal high temperature alloy turbine blade; The length of the seed crystal flushing section is determined based on the length of the seed crystal and the length L of the seed crystal's completely unmelted section.

10. The method according to claim 9, characterized in that The length L of the seed crystal's completely unmelted section is determined by the following formula: Where T0 is room temperature, T S is the solidus, f(G) T is the temperature gradient function within the seed relative to the temperature.

11. The method according to claim 8, characterized in that According to the length of the seed crystal flushing section, the cavity structure of the single crystal high-temperature alloy turbine blade shell is determined, including: According to the length of the seed crystal scouring section, calculate the kinetic energy required to pour the alloy; The size and position information of the slag trough, sprue and runner are determined according to the kinetic energy required to be generated when pouring the alloy.

12. An application of a single crystal high temperature alloy turbine blade shell according to any one of claims 1 to 7, characterized in that: The single crystal high temperature alloy turbine blade shell is used in aircraft engines and gas turbines.

Images