A single crystal superalloy turbine blade airfoil and method of manufacture

Abstract

The present application relates to the technical field of turbine blade, and particularly relates to a single crystal high-temperature alloy turbine blade shell and a preparation method thereof, which comprises a sprue cup, a straight sprue, a cross sprue, a slag collecting groove, a seed cavity and a seed growth cavity; wherein the two ends of the straight sprue are connected with the sprue cup and the cross sprue respectively; the seed cavity is perpendicular to the other end of the cross sprue and the inlet channel of the slag collecting groove, and is located below the seed growth cavity; the seed growth cavity is communicated with the seed cavity, the slag collecting groove and the cross sprue respectively. The seed setting mode of the present application eliminates the gap between the seed and the seed cavity, and avoids the seed drawing defects caused by the existence of the gap. Moreover, the length of the seed paste area is significantly reduced by designing the sprue structure and the slag collecting groove, so that the seed drawing defects in the seed drawing process are avoided as much as possible.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of turbine blade, in particular to a single crystal superalloy turbine blade shell and a preparation method thereof. BACKGROUND

[0002] Single crystal superalloy has many advantages, such as excellent high temperature strength, oxidation resistance and creep resistance. In high temperature environment, single crystal superalloy can maintain high strength and stability, so it is widely used in manufacturing turbine blades of aero-engine and gas turbine.

[0003] In the process of manufacturing single crystal superalloy turbine blade, directional solidification technology needs to be used. The directional solidification is realized by pouring alloy liquid into a shell, and then through a specific directional solidification process, the alloy liquid is solidified along a certain direction, so that a turbine blade with single crystal structure is obtained. In the preparation of single crystal, first of all, seeding is needed, so that only one grain enters the mold cavity, and on this basis, the crystal grows slowly into a single crystal blade composed of one grain. Among them, the seed crystal is a common 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 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 lower part of the shell remains solid due to low temperature, and the upper part of the seed crystal melts into liquid under the action of high temperature, and there is a transition zone between the melted and unmelted parts, which is called the paste zone. In the transition zone, crystal nuclei are easy to appear, leading to defects in the blade crystal and causing the failure of single crystal seeding.

[0005] Therefore, how to improve the success rate of single crystal seeding in the preparation of single crystal blades has become a technical problem to be solved at present. SUMMARY

[0006] The present application aims to provide a single crystal superalloy turbine blade shell and a preparation method thereof, to solve the above technical problems.

[0007] To achieve the above-mentioned purpose, the present application provides a single crystal superalloy turbine blade shell, comprising: a sprue cup, a straight runner, a cross runner, a slag collecting groove, a seed crystal cavity, a seed crystal growth cavity;

[0008] Wherein, the two ends of the straight runner are connected with the sprue 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 groove, and is located below the seed crystal growth cavity; the seed crystal growth cavity is communicated with the seed crystal cavity, the slag collecting groove and the cross runner respectively.

[0009] The present application also provides a preparation method of a single crystal superalloy turbine blade shell, comprising:

[0010] Based on the turbine blade dimensions of the single-crystal high-temperature alloy and the thermophysical parameters of the cast alloy, determine the length of the seed crystal scouring section and the length L of the seed crystal completely non-melting section;

[0011] The cavity structure of the single-crystal high-temperature alloy turbine blade shell is determined based on the length of the seed crystal scouring section.

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

[0013] Based on the cavity structure, a single-crystal wax model with seed crystals is coated, dewaxed, and sintered 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 housing, which is used in aero-engines and gas turbines.

[0015] The technical effects and advantages of this invention are as follows:

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

[0017] The seed crystal setting method of this invention eliminates the gap between the seed crystal and the seed crystal cavity (the inner cavity of the shell forms the cavity, and the seed crystal cavity is a part of the cavity), thus avoiding crystal-leading defects caused by the presence of this gap. Moreover, by designing the gating structure and slag collection groove, the length of the seed crystal slurry region is significantly reduced, thereby minimizing the occurrence of crystal-leading defects during the seed crystal lead-in process.

[0018] Other features and advantages of the invention will be set forth in the description which follows, and will be apparent in part from the description, or may be learned by practicing the invention. Attached Figure Description

[0019] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort. Figure 1 This is a schematic diagram of a single-crystal high-temperature alloy turbine blade shell structure.

[0020] Figure labels: 1-pouring cup; 2-sprue; 3-grate; 4-slag collection trough; 5-seed crystal; 6-seed crystal growth chamber. Detailed Implementation

[0021] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0022] It should be noted that the structures, proportions, sizes, etc., illustrated in the accompanying drawings are merely for illustrative purposes to aid those skilled in the art and to facilitate understanding and reading. They are not intended to limit the scope of the invention and therefore have no substantial technical significance. Any modifications to the structure, changes in proportions, or adjustments to size, without affecting the effectiveness and purpose of the invention, should still fall within the scope of the technical content disclosed herein. Furthermore, the terms "upper," "lower," "left," "right," "middle," and "one" used in this specification are merely for clarity and not intended to limit the scope of the invention. Changes or adjustments to their relative relationships, without substantially altering the technical content, should also be considered within the scope of the invention.

[0023] To address the shortcomings of existing technologies, this invention discloses a single-crystal high-temperature alloy turbine blade housing, such as... Figure 1 As shown, it includes: pouring cup 1, sprue 2, glide sprue 3, slag collection tank 4, seed crystal cavity, and seed crystal growth cavity 6.

[0024] The straight gating channel 2 is connected to the pouring cup 1 and the horizontal gating channel 3 at both ends, respectively; the seed crystal cavity is perpendicular to the other end of the horizontal gating channel 3 and the inlet channel of the slag collection tank 4, and is located below the seed crystal growth cavity 6; the seed crystal growth cavity 6 is connected to the seed crystal cavity, the slag collection tank 4 and the horizontal gating channel 3, respectively.

[0025] Among them, the straight pouring channel 2 adopts a tapered shape with a smaller bottom and a larger top, and the tapered shape is 1° to 3°.

[0026] Among them, the cross-sectional area of ​​the horizontal sprue 3 is smaller than the cross-sectional area of ​​the small end of the vertical sprue 2.

[0027] Among them, the slag collection tank 4 receives molten metal with broken dendrites to prevent the broken dendrites from forming crystallization nuclei, and the volume of the slag collection tank 4 is more than 10 times the volume of the seed crystal 5 scouring section.

[0028] Among them, the diameter of the inlet channel of the slag collection trough 4 is greater than the diameter of the horizontal pouring 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 collection trough 4 is 10-20mm, and the height is 15-25mm.

[0029] The distance L between the seed crystal growth cavity 6 and the bottom surface of the single-crystal superalloy turbine blade shell is the length of the completely non-melting section of the seed crystal 5.

[0030] The application further provides a preparation method of the single-crystal superalloy turbine blade shell, comprising the following steps:

[0031] 1. According to the size of the single-crystal superalloy turbine blade and the thermal physical parameters of the pouring alloy, the length of the flushing section of the seed crystal 5 and the length L of the completely non-melting section of the seed crystal 5 are determined.

[0032] Specifically, the length L of the completely non-melting section of the seed crystal 5 is determined according to the thermal physical parameters of the pouring alloy; the length of the seed crystal is determined according to the size of the single-crystal superalloy turbine blade; and the length of the flushing section of the seed crystal 5 is determined according to the length of the seed crystal and the length L of the completely non-melting section of the seed crystal 5.

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

[0034]

[0035] In the formula, T0 is room temperature, T S is the solidus, and f(G) T is a temperature gradient function of the seed crystal relative to temperature.

[0036] 2. The cavity structure of the single-crystal superalloy turbine blade shell is determined according to the length of the flushing section of the seed crystal 5.

[0037] Specifically, the kinetic energy required to be generated when the pouring alloy is poured is calculated according to the length of the flushing section of the seed crystal 5; and the size and position information of the slag runner 4, the sprue 2 and the runner 3 are determined according to the kinetic energy required to be generated when the pouring alloy is poured.

[0038] 3. The seed crystal 5 is placed on a base plate, and a wax mold is prepared.

[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 the single-crystal superalloy turbine blade shell.

[0040] Specifically, the seed crystal is prepared according to the diameter required for preparing the single-crystal superalloy turbine blade, the wax mold and the shell are prepared, and the seed crystal is placed in the wax mold during the preparation of the wax mold to ensure that there is no gap between the side surface of the seed crystal and the seed crystal cavity of the shell to be formed subsequently. Then, the single-crystal wax mold with the seed crystal is subjected to shell coating, dewaxing and sintering to obtain the single-crystal shell with the seed crystal.

[0041] It should be noted that the specific steps in the preparation process of the single-crystal superalloy turbine blade shell, such as shell coating, dewaxing and sintering, are all prior art and will not be described in detail here. For details, please refer to the application No. 201410742333.1.

[0042] The application also provides a single crystal high-temperature alloy turbine blade shell and an application of the single crystal high-temperature alloy turbine blade shell in an aero-engine and a gas turbine.

[0043] In order to eliminate the gap between the seed crystal and the seed crystal cavity, the seed crystal can be put into the wax mold during preparation of the wax mold before coating, and then the single crystal wax mold with the seed crystal is subjected to shell coating, dewaxing and sintering, so that there is no gap between the shell surrounding the seed crystal in the directional solidification process and the seed crystal, and the dendrite nucleation caused by the gap and the filling of the alloy liquid is avoided.

[0044] Meanwhile, in the preparation of the single crystal blade by using the seed crystal, the sprue, the runner, the slag collecting groove and the like are designed to make the pouring metal liquid have kinetic energy capable of flushing away the seed crystal flushing section, reduce or even remove the seed crystal remelting paste zone, make the length of the paste zone between the unmelting part of the seed crystal and the poured alloy liquid as small as possible to form a relatively flat solid-liquid interface, and make the directional solidification grow dendrites on the basis of the interface, so that a good crystal drawing effect is obtained.

[0045] In order to better explain the present scheme, the following also provides an embodiment.

[0046] Embodiment

[0047] A method for preparing a shell of a certain DD6 alloy blade, specifically comprising the following steps:

[0048] Due to the weakness of the core and the like, the directional solidification temperature of the blade is lower than 1500℃, and the unmelting length of the seed crystal is 10mm according to the previous formula calculation.

[0049] According to the size of the blade, the diameter of the seed crystal is 2mm, and the length of the seed crystal is 15mm. The seed crystal is put into the wax mold during preparation of the wax mold, so as to ensure that there is no gap between the side surface of the seed crystal and the seed crystal cavity of the shell formed subsequently. Then, the single crystal wax mold with the seed crystal is subjected to shell coating, dewaxing and sintering to obtain a single crystal shell mold group with the seed crystal.

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

[0051] In the blade preparation process, by designing the seeding structure, most of the paste zone is eliminated in the pouring process, and a relatively flat solid-liquid interface is formed in the seed crystal. Directional solidification is carried out on the basis of the interface to grow dendrites, thereby obtaining good seeding effect. At the same time, the slag collecting groove 4 is used to receive the molten metal with fragmented dendrites, thereby avoiding the formation of crystallization cores after the fracture of the dendrites. The 410 blades are prepared by using the seeding mode, and the seeding success rate is more than 97%.

[0052] Finally, it should be noted that the above only describes the preferred embodiments of the present application and is not intended to limit the present application. Although the present application has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions recorded in the foregoing embodiments or make equivalent replacements to some technical features, as long as they are within the spirit and principles of the present application. Any modification, equivalent replacement, improvement, etc. made shall be included in the protection scope of the present application.

Claims

1. A single-crystal high-temperature alloy turbine blade housing, characterized in that, include: Pour cup (1), sprue (2), glide sprue (3), slag collection tank (4), seed crystal cavity, seed crystal growth cavity (6); The straight gating channel (2) is connected to the pouring cup (1) and the horizontal gating channel (3) at both ends respectively; the seed crystal cavity is perpendicular to the other end of the horizontal gating channel (3) and the inlet channel of the slag collection tank (4), and is located below the seed crystal growth cavity (6); the seed crystal growth cavity (6) is connected to the seed crystal cavity, the slag collection tank (4) and the horizontal gating channel (3) respectively; The sprue (2) adopts a taper with a smaller bottom and a larger top, with a taper range of 1° to 3°. The end of the sprue (2) that connects to the gutter (3) is the small taper end, and the cross-sectional area of ​​the gutter (3) is smaller than the cross-sectional area of ​​the small taper end of the sprue (2). The diameter of the inlet channel of the slag collection trough (4) is greater than the diameter of the horizontal pouring trough (3), and the length of the inlet channel is greater than or equal to the diameter of the inlet channel; The volume of the slag collection tank (4) is greater than 10 times the volume of the seed crystal (5) scouring section. The seed crystal cavity divides the seed crystal into two sections: the outer section is the seed crystal scouring section, and the inner section is the seed crystal completely non-melting section.

2. The single-crystal high-temperature alloy turbine blade housing according to claim 1, characterized in that, The diameter of the inner cavity of the slag collection tank (4) is 10-20mm and the height is 15-25mm.

3. The single-crystal high-temperature alloy turbine blade housing 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 non-melting section of the seed crystal (5).

4. A method for preparing a turbine blade shell based on any one of the single-crystal high-temperature alloys according to claims 1-3, characterized in that, include: Based on the dimensions of the single-crystal superalloy turbine blades and the thermophysical parameters of the cast alloy, the lengths of the seed crystal scouring section and the completely non-melting section of the seed crystal are determined, specifically including: The length of the completely non-melting section of the seed crystal is determined based on the thermophysical properties of the cast alloy. The seed crystal length is determined based on the dimensions of the single-crystal high-temperature alloy turbine blades; The length of the seed crystal scouring section is determined based on the length of the seed crystal and the length of the completely non-melting section of the seed crystal. Based on the length of the seed crystal scouring section, the cavity structure of the single-crystal high-temperature alloy turbine blade shell is determined, including: calculating the kinetic energy required to be generated during alloy casting based on the length of the seed crystal scouring section; and determining the size and location information of the slag collection tank, sprue, and runner based on the kinetic energy required to be generated during alloy casting. Place the seed crystal on the base and prepare a wax model. When preparing the wax model, place the seed crystal in to ensure that there is no gap between the side of the seed crystal and the seed crystal cavity of the shell that is subsequently formed. Based on the cavity structure, a single-crystal wax model with seed crystals is coated, dewaxed, and sintered to obtain a single-crystal high-temperature alloy turbine blade shell.

5. An application of a turbine blade housing based on any one of claims 1-3, characterized in that, Applications of the single-crystal high-temperature alloy turbine blade housing in aero-engines or gas turbines.

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