A screw selector for secondary orientation control of single crystal superalloys
By designing a spiral crystal selector and optimizing its structure and heat flow direction, precise control of the secondary orientation of single-crystal high-temperature alloys was achieved. This solved the problem that traditional crystal selection methods could not control the secondary orientation, improved the consistency of blade lifespan, and reduced production costs.
Patent Information
- Application Number
- CN202610354577.5
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2026-03-23
- Publication Date
- 2026-06-26
AI Technical Summary
Existing technologies cannot effectively control the secondary orientation of single-crystal superalloys, resulting in inconsistent and unpredictable blade lifespan. Traditional crystal selection methods cannot control the secondary orientation, while seed crystal methods are costly and difficult to meet the needs of engineering mass production.
A spiral crystal selector is designed, comprising a crystallization section, a primary orientation screening unit, a secondary orientation control unit, and a single crystal steady-state growth unit. By optimizing the structure and controlling the heat flow direction, precise control of the secondary orientation of single crystal high-temperature alloys can be achieved.
It achieves effective control of secondary orientation, improves the consistency of high-temperature fatigue life and creep life of blades in the same batch, reduces production costs, and is applicable to a variety of single-crystal high-temperature alloy castings.
Smart Images
Figure CN122279755A_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of directional solidification technology of single-crystal superalloys, specifically a spiral crystal selector for secondary orientation control of single-crystal superalloys. Background Technology
[0002] Nickel-based single-crystal superalloys have become key materials for high-temperature core components such as turbine blades of aero-engines due to their excellent high-temperature mechanical properties.
[0003] Due to the significant anisotropy of single-crystal materials, their physical properties (such as elastic modulus and Poisson's ratio) and mechanical response strongly depend on crystal orientation characteristics. During directional solidification, the distribution of secondary orientation in the casting not only directly affects the anisotropy of key physical properties but also determines the evolution of stress concentration-sensitive locations under specific orientation combinations, thus fundamentally impacting the consistency between the high-temperature fatigue life and creep life of the blade. Currently, industrial practice has successfully achieved axial [structure / property] of single-crystal blades. <001> While precise control of orientation (≤10°) is possible, effective control methods are still lacking for secondary orientation, which is equally critical and directly affects the mechanical behavior of blades. The random distribution of secondary orientation can lead to a discrete risk in the service life of blades in the same batch, ultimately causing unpredictability in the service life of blades.
[0004] Currently, the preparation of single-crystal castings mainly employs the crystal selection method and the seed crystal method.
[0005] Selective crystal selection relies on the geometrical blocking effect of spiral or stepped crystal selectors to eliminate other grains through competitive dendrite growth, thereby obtaining near-crystals. <001> Oriented single crystals. This method is simple, low-cost, suitable for mass production, and widely used. However, traditional crystal selection methods can only roughly control the orientation at one stage. <001> Crystal orientation), unable to control secondary orientation ( <100> or <010> This leads to a random distribution of secondary orientations.
[0006] Although the seed crystal method can precisely control the primary and secondary orientation of crystals, it is limited by the long preparation cycle and high cost of seed crystals, and the extremely stringent requirements for temperature field control of directional solidification equipment, making it difficult to meet the needs of low-cost, high-efficiency engineering mass production.
[0007] Therefore, developing a crystal selection device that can effectively control secondary orientation and has engineering application feasibility has become a technical problem that urgently needs to be solved in this field. Summary of the Invention
[0008] The purpose of this invention is to provide a spiral crystal selector for secondary orientation control of single-crystal superalloys, in order to overcome and supplement the shortcomings of existing crystal selection technologies. By optimizing the structural design of existing crystal selectors, the geometric blocking effect and dendrite competitive growth behavior during the crystal selection process are controlled, thereby achieving precise control of the secondary orientation of single-crystal castings.
[0009] The technical solution adopted by the present invention to achieve the above objectives is: a spiral crystal selector for secondary orientation control of single-crystal superalloys, comprising: a crystal initiation section and a spiral crystal selection section coaxially connected from bottom to top;
[0010] The spiral crystal selection section includes: a primary orientation screening unit, a secondary orientation control unit, and a single crystal steady-state growth unit, which are coaxially connected in sequence, and the channel cross-section of each unit is circular.
[0011] The primary orientation is screened by the spiral channel structure of the primary orientation screening unit, the secondary orientation is regulated by the horizontal channel structure of the secondary orientation control unit, and the single crystal steady-state growth is maintained by the single crystal steady-state growth unit, thereby achieving coordinated control of the primary and secondary orientations of the single crystal high-temperature alloy.
[0012] Wherein, the primary orientation represents the crystallographic orientation. <001> Crystal orientation, i.e., the preferred crystal growth direction of a single-crystal superalloy;
[0013] The secondary orientation represents the crystallographic concept. <010> Crystal orientation refers to the orientation of a crystal in a cross-section perpendicular to its primary orientation.
[0014] The crystallizing segment has a cylindrical structure with a diameter of 15-30 mm and a height of 20-35 mm;
[0015] The center of the upper end face of the crystallizing section is coaxially connected to the center of the lower end face of the spiral crystallizing section, which is used to form multiple fine grains in the early stage of directional solidification, providing a source of grains for the subsequent screening by the spiral crystallizing section.
[0016] The channel cross-sectional diameters of the primary orientation screening unit, the secondary orientation control unit, and the single crystal steady-state growth unit are consistent, with a diameter range of 5 to 8 mm. The coaxiality at the connection between adjacent units is ≤ ±0.1 mm, ensuring that the dendrites do not experience orientation shift or growth interruption during continuous growth between units.
[0017] The channel of the primary orientation screening unit is formed by a spiral along the crystal selector. <001> The crystal orientation is swept along the crystal axis, and its helical lead is 20-25 mm.
[0018] The spiral of the primary orientation screening unit and <001> The crystal orientation axial angle is 35° to 45°, the axial height of the primary orientation screening unit is 10 to 15 mm, and the inner wall of the channel is a smooth arc surface.
[0019] The spiral channel eliminates interference through geometric blocking effect. <001> The grains with significantly deviated orientations, while utilizing a spiral trajectory to guide the direction of heat flow, provide... <001> Oriented dendrites provide a preferred growth path, enabling initial screening for orientation.
[0020] The secondary orientation control unit is a horizontally arranged straight pipe structure;
[0021] The secondary orientation control unit is smoothly connected to the outlet end of the primary orientation screening unit on the same axis. Its axial length is 15-20 mm, and the channel cross-section is circular with a diameter of 5-8 mm.
[0022] The horizontal pipe structure changes the heat flow during the directional solidification process from vertical to horizontal, causing dendrites to grow laterally within the horizontal pipe. Through the synergistic effect of heat flow direction regulation and geometric constraints, the growth advantage of the target secondary orientation dendrites is enhanced, while the competitive growth of non-target secondary orientation dendrites is suppressed, thus achieving precise control over secondary orientation.
[0023] The channel of the single crystal steady-state growth unit is formed by a spiral along the crystal selector. <001> Crystalline axial sweep forming, with a helical lead of 12–18 mm, and <001> The crystal orientation axial angle is 45° to 50°, the axial height of the single crystal steady-state growth unit is 10 to 15 mm, and the inner wall of the channel is a smooth arc surface;
[0024] The single-crystal steady-state growth unit guides the dendrites, after secondary orientation control, back through a spiral channel structure. <010> Growing along the crystal axis eliminates orientation disturbances that may be introduced by horizontal channels, ensuring that the single crystal grows along the crystal axis. <010> The crystal orientation and the target secondary orientation continue to grow in a steady state, avoiding orientation shift or growth defects.
[0025] The spiral lead of the primary orientation screening unit is different from that of the single-crystal steady-state growth unit (5), and the spiral lead of the primary orientation screening unit is different from that of the single-crystal steady-state growth unit (5). <001> The crystal orientation axial angle is smaller than that of the helix of the single crystal steady-state growth unit. <001> Crystalline axial angle; a gradient transition from primary orientation selection to steady-state growth is achieved through differentiated spiral parameter design.
[0026] A spiral crystal selector is used in a directional solidification system. The overall structure of the spiral crystal selector is located below a square casting, and the upper end of the spiral crystal selector is coaxially connected to the bottom of the cavity of the square casting.
[0027] The top surface of the crystallizing section of the spiral crystal selector is connected to the water-cooled chassis of the directional solidification system, and the outlet of the single crystal steady-state growth unit is smoothly connected to the bottom inlet of the cavity of the square casting.
[0028] The directional solidification system includes a heating zone, a transition zone, and a cooling zone; the spiral crystal selector is located across the boundary between the heating zone and the transition zone.
[0029] A riser and a gating system are provided above the square casting. The riser is connected to the top of the cavity of the square casting and is used for feeding and venting. Through the coordinated operation of the spiral crystal selector, the square casting, the riser and the directional solidification system, the alloy melt is directionally solidified from bottom to top and flows through the spiral crystal selector, the square casting and the riser in sequence, finally obtaining a single crystal high-temperature alloy casting with secondary orientation control.
[0030] The method for preparing single-crystal superalloy castings using the spiral crystal selector includes the following steps:
[0031] Step S1: Install the spiral crystal selector into the directional solidification system, so that the lower end of the spiral crystal selector is connected to the water-cooled chassis of the directional solidification system, and the upper end of the spiral crystal selector is the outlet of the single crystal steady-state growth unit. The outlet is smoothly connected to the bottom inlet of the cavity of the square casting.
[0032] Step S2: Pour the molten single-crystal superalloy into the crystallization section, filling the entire cavity of the spiral crystal selector and the square casting.
[0033] Step S3: Start the directional solidification system, control the solidification process parameters, and make the alloy melt solidify directionally from bottom to top, flowing sequentially through the crystallization section, the primary orientation screening unit, the secondary orientation control unit, and the single crystal steady-state growth unit.
[0034] Step S4: In the primary orientation screening unit, the geometric blocking effect of the spiral channel is used to eliminate those that are already in the primary orientation. <001> Grains with crystal orientation deviations greater than a threshold are selected to identify dendrites with a dominant primary orientation.
[0035] Step S5: In the secondary orientation control unit, the heat flow direction is changed from vertical to horizontal by using a horizontal straight pipe structure, which promotes the growth of dendrites along the lateral direction. Through the synergistic effect of heat flow direction regulation and geometric constraints, the growth advantage of the target secondary orientation dendrites is enhanced and the competitive growth of non-target secondary orientation dendrites is suppressed.
[0036] Step S6: In the single crystal steady-state growth unit, the dendrites are guided back to the primary orientation axis for growth using the spiral channel, eliminating the orientation disturbance that may be introduced by the horizontal channel, and maintaining the steady-state growth of the single crystal along the primary orientation and the target secondary orientation.
[0037] Step S7: After solidification, a single-crystal high-temperature alloy casting with controlled secondary orientation is obtained.
[0038] The present invention has the following beneficial effects and advantages:
[0039] 1. This invention uses a horizontal straight pipe structure of a secondary orientation control unit to change the directional solidification heat flow from vertical to horizontal, forcing dendrites to grow laterally. Combined with geometric constraints, it enhances the growth advantage of the target secondary orientation and suppresses competition from non-target orientations. For the first time, it has achieved effective control of secondary orientation in the crystal selection method, filling the technical gap that the traditional crystal selection method cannot control secondary orientation.
[0040] 2. This invention eliminates the need for expensive seed crystals; secondary orientation control can be achieved simply by optimizing the crystal selector structure. The spiral crystal selector features consistent channel diameters across all units and a coaxiality of ≤±0.1mm, ensuring continuous dendrite growth without deviation. Furthermore, it is compatible with existing directional solidification processes, offering both high precision and low cost.
[0041] 3. The primary orientation screening unit and the single-crystal steady-state growth unit of this invention adopt differentiated spiral parameter design: the former uses a large lead and a small included angle to quickly eliminate deviations. <001> The latter, with its small lead and large angle, smoothly guides the dendrites back to their original position. <001> Axial growth eliminates orientation disturbances introduced by horizontal pipes and avoids growth defects.
[0042] 4. This invention enables strict control of the primary orientation of the casting. <001> The crystal orientation and secondary orientation are also controlled and consistent, eliminating the mechanical property dispersion caused by the random distribution of secondary orientation in the traditional crystal selection method, and significantly improving the consistency of key properties such as the transverse elastic modulus and high-temperature creep life of blades in the same batch.
[0043] 5. Applicable to various single-crystal high-temperature alloys such as DD413, as well as castings such as test bars, blades, and thin-walled test pieces; the directional solidification process parameters have a wide adjustment range and strong adaptability. Attached Figure Description
[0044] Figure 1 A structural diagram of the spiral crystal selector of the present invention;
[0045] Figure 2 A schematic diagram of the spiral crystal selection section of this invention;
[0046] Figure 3 A schematic diagram of the structural connection of the square casting of the present invention;
[0047] Figure 4 Schematic diagram of the directional solidification system of the present invention;
[0048] Among them, 1 is the spiral crystal selection section; 2 is the crystal initiation section; 3 is the primary orientation screening unit; 4 is the secondary orientation control unit; 5 is the single crystal steady-state growth unit; 6 is the spiral crystal selector; 7 is the square casting; 8 is the riser; and 9 is the directional solidification system. Detailed Implementation
[0049] The present invention will now be described in further detail with reference to the accompanying drawings and embodiments.
[0050] Heat transfer is the core control element in the solidification process, and the directional solidification of alloys requires the control of unidirectional heat flow at the solidification front. In the fabrication of single-crystal blades, the coordinated use of molds and processes ensures that heat flow is transferred vertically from top to bottom, guaranteeing the directional solidification and growth of the single-crystal superalloy from bottom to top. Based on this principle, this invention optimizes the structure of the crystal selector, altering the direction of heat flow and transforming the traditional vertical heat dissipation mode into a parallel heat dissipation mode. This provides a more efficient lateral expansion growth path for dendrites with better secondary orientation, ultimately achieving precise control over the secondary orientation of single-crystal castings.
[0051] The present invention will be further discussed below through two embodiments.
[0052] Example 1:
[0053] This embodiment provides a spiral crystal selector 6 for secondary orientation control of single-crystal superalloys, the structure of which is as follows: Figure 1 , Figure 2 As shown.
[0054] like Figure 1 As shown, the spiral crystal selector 6 consists of a crystal initiation section 2 and a spiral crystal selection section 1 from bottom to top, and the two are coaxially connected. The crystal initiation section 2 is a cylindrical structure with a diameter of 20 mm and a height of 25 mm. It is used to form multiple fine grains in the early stage of directional solidification, providing a source of grains for subsequent screening.
[0055] In this invention, primary orientation represents crystallographic representation. <001> Crystal orientation refers to the preferred crystal growth direction of a single-crystal superalloy; secondary orientation refers to the direction of crystallographic growth. <010> Crystal orientation refers to the orientation of a crystal in a cross-section perpendicular to its primary orientation.
[0056] The spiral crystal selection section 1 is the core functional section, and from bottom to top, it is coaxially connected to the primary orientation screening unit (3), the secondary orientation control unit 4, and the single crystal steady-state growth unit 5. The channel cross-section of each unit is circular, and the diameter is consistent, which is 6mm in this embodiment. The coaxiality at the connection between adjacent units is controlled to ≤±0.1mm to ensure that the dendrites do not shift in orientation or have their growth interrupted during continuous growth between units.
[0057] like Figure 2As shown, the channel of the primary orientation screening unit 3 is formed by a spiral along the crystal selector. <001> Crystalline axial sweep forming, helical lead of 22mm, and... <001> The crystal orientation axial angle is 40°, the unit cell axial height is 12mm, and the inner wall of the channel is a smooth arc surface. This spiral channel eliminates interference from other crystals through geometric blocking effects. <001> Grains with significantly deviated crystal orientations, while simultaneously utilizing helical trajectories to guide heat flow, for <001> Crystal orientation dendrites provide a preferred growth path, enabling preliminary screening of primary orientations.
[0058] The secondary orientation control unit 4 is a horizontally positioned straight pipe structure, smoothly coaxially connected to the outlet end of the primary orientation screening unit 3. Its axial length is 18 mm, and the channel cross-section is circular with a diameter of 6 mm. This horizontal pipe structure changes the heat flow during directional solidification from a vertical to a horizontal direction, causing dendrites to grow laterally within the horizontal pipe. Through the synergistic effect of heat flow direction control and geometric constraints, it enhances the growth advantage of the target secondary orientation dendrites and suppresses the competitive growth of non-target secondary orientation dendrites, achieving precise control over secondary orientation.
[0059] The channel of the single crystal steady-state growth unit 5 is formed by a spiral along the crystal selector. <001> Crystalline axial sweep forming, with a helical lead of 15mm, and... <001> The crystal orientation axial angle is 48°, the unit axial height is 12mm, and the inner wall of the channel is a smooth arc surface. This unit guides the dendrites, after secondary orientation control, back through a spiral channel structure. <001> Growing along the crystal axis eliminates orientation disturbances that may be introduced by horizontal channels, ensuring that the single crystal grows along the crystal axis. <001> The crystal orientation and the target secondary orientation continue to grow in a steady state, avoiding orientation shift or growth defects.
[0060] In this embodiment, the spiral lead (22mm) of the primary orientation screening unit 3 is greater than the spiral lead (15mm) of the single crystal steady-state growth unit 5, and the spiral of the primary orientation screening unit 3 is... <001> The crystal orientation axial angle (40°) is less than that of the helix of the single crystal steady-state growth unit 5. <001> The crystal orientation axial angle (48°) is achieved through differentiated spiral parameter design to realize a gradient transition from primary orientation screening to steady-state growth.
[0061] Example 2:
[0062] This embodiment provides a method for directional solidification of single-crystal superalloys using the spiral crystal selector 6 described in Embodiment 1, using DD413 nickel-based single-crystal superalloy as the material, and preparing a square cross-section test bar 7 as a casting.
[0063] like Figure 3 , Figure 4As shown, the spiral crystal selector 6 is located below the square casting 7, and its upper end is coaxially connected to the bottom of the cavity of the square casting 7. The lower end of the spiral crystal selector 6 is connected to the water-cooled chassis of the directional solidification system 9, and the upper end of the spiral crystal selector 6 is the outlet of the single crystal steady-state growth unit 5, which is smoothly connected to the inlet at the bottom of the cavity of the square casting 7.
[0064] The directional solidification system 9 includes a heating zone, a transition zone, and a cooling zone. The spiral crystal selector 6 is located across the boundary between the heating zone and the transition zone to ensure a reasonable temperature gradient is formed during directional solidification.
[0065] A riser 8 and a gating system are also provided above the square casting 7. The riser 8 is connected to the top of the cavity of the square casting 7 and is used for feeding and venting.
[0066] The method for directional solidification using the above-mentioned apparatus includes the following steps:
[0067] Step S1: Install the spiral crystal selector 6 in the directional solidification system 9, so that the lower end of the spiral crystal selector 6 is connected to the water-cooled chassis of the directional solidification system 9, and the upper end of the spiral crystal selector 6 is the outlet of the single crystal steady growth unit 5. The outlet is smoothly connected to the bottom inlet of the cavity of the square casting 7.
[0068] Step S2: Pour the molten DD413 alloy into the crystallization section 2, filling the cavity of the spiral crystal selector 6 and the square casting 7. The pouring temperature is 1500-1550℃.
[0069] Step S3: Start the directional solidification system 9 and control the solidification process parameters: pulling rate is 6 mm / min, heating zone temperature is 1520℃, cooling zone temperature is 25℃, and temperature gradient is 40℃ / cm. The alloy melt is then directionally solidified from bottom to top, flowing sequentially through the crystallization section 2, the primary orientation screening unit 3, the secondary orientation control unit 4, and the single crystal steady-state growth unit 5.
[0070] Step S4: In the primary orientation screening unit 3, the geometric blocking effect of the spiral channel is used to eliminate those with primary orientation (i.e., ...). <001> For grains whose orientation deviates by more than 5°, dendrites with primary orientation dominance are selected.
[0071] Step S5: In the secondary orientation control unit 4, the heat flow direction is changed from vertical to horizontal using a horizontal straight pipe structure, causing dendrites to grow laterally. Through the synergistic effect of heat flow direction control and geometric constraints, the target secondary orientation (i.e., <100> or <010> The growth advantage of dendrites in one of the crystal orientations inhibits the competitive growth of non-target secondary orientation dendrites.
[0072] Step S6: In the single crystal steady-state growth unit 5, the dendrites are guided back to the primary orientation axis for growth using the spiral channel, eliminating the orientation disturbance that may be introduced by the horizontal channel, and maintaining the steady-state growth of the single crystal along the primary orientation and the target secondary orientation.
[0073] Step S7: After solidification, a single-crystal high-temperature alloy square cross-section test bar with controlled secondary orientation is obtained.
[0074] The spiral crystal selector and directional solidification method provided by this invention are applicable to various grades of nickel-based single-crystal superalloys such as DD413, DD406, and CMSX-4, as well as various casting forms such as test bars, turbine blades, guide vanes, and thin-walled test pieces. The directional solidification process parameters can be adjusted within a wide range: pulling speed 3–10 mm / min, heating zone temperature 1500–1550℃, cooling zone temperature 20–30℃, and temperature gradient 20–60℃ / cm.
[0075] In summary, this invention provides a spiral crystal selector and its directional solidification method for controlling secondary orientation of single-crystal superalloys. This device, through the coordinated operation of a crystal initiation section, a primary orientation screening unit, a secondary orientation control unit, and a single-crystal steady-state growth unit, achieves effective control of secondary orientation in a crystal selection method for the first time. Specifically, the secondary orientation control unit employs a horizontal straight pipe structure, changing the directional solidification heat flow from vertical to horizontal, forcing dendrites to expand laterally. Combined with geometric constraints, this enhances the growth advantage of the target secondary orientation and suppresses competition from non-target orientations. The primary orientation screening unit and the single-crystal steady-state growth unit employ differentiated spiral parameter designs to achieve a gradient transition from primary orientation screening to steady-state growth, eliminating orientation disturbances and avoiding growth defects.
[0076] This invention eliminates the need for expensive seed crystals, achieving secondary orientation control simply by optimizing the crystal selector structure. It combines high precision with low cost, exhibits good compatibility with existing directional solidification production lines, and shows promising prospects for engineering applications. The primary orientation of the resulting castings is strictly controlled within... <001> The crystal orientation and secondary orientation are also controlled and consistent, eliminating the mechanical property dispersion caused by the random distribution of secondary orientation in the traditional crystal selection method, significantly improving the consistency of key performance of castings in the same batch, and applicable to various single crystal high temperature alloys and casting forms such as test bars, blades, and thin-walled test pieces.
[0077] Those skilled in the art will understand that the above description is merely a preferred embodiment of the present invention, and the features described in the various embodiments and / or claims of this disclosure can be combined or combined in various ways, even if such combinations or combinations are not explicitly described in this disclosure. This is not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.
[0078] Although preferred embodiments of the invention have been described, those skilled in the art, upon learning the basic inventive concept, can make other changes and modifications to these embodiments. Therefore, the appended claims are intended to be interpreted as including both the preferred embodiments and all changes and modifications falling within the scope of the invention. Clearly, those skilled in the art can make various alterations and modifications to the invention without departing from its spirit and scope. Thus, if these modifications and modifications of the invention fall within the scope of the claims and their equivalents, the invention is also intended to include these modifications and modifications.
Claims
1. A spiral crystal selector for secondary orientation control of single-crystal superalloys, characterized in that, include: The crystallizing section (2) and the spiral crystallizing section (1) are coaxially connected from bottom to top. The spiral crystal selection section (1) includes: a primary orientation screening unit (3), a secondary orientation control unit (4), and a single crystal steady-state growth unit (5), which are connected coaxially in sequence, and the channel cross-section of each unit is circular; The primary orientation is screened by the spiral channel structure of the primary orientation screening unit (3), the secondary orientation is regulated by the horizontal channel structure of the secondary orientation control unit (4), and the single crystal steady-state growth is maintained by the single crystal steady-state growth unit (5), thereby realizing the coordinated control of the primary and secondary orientations of the single crystal high-temperature alloy. Wherein, the primary orientation represents the crystallographic orientation. <001> Crystal orientation, i.e., the preferred crystal growth direction of a single-crystal superalloy; The secondary orientation represents the crystallographic concept. <010> Crystal orientation refers to the orientation of a crystal in a cross-section perpendicular to its primary orientation.
2. The spiral crystal selector for secondary orientation control of single-crystal superalloys according to claim 1, characterized in that, The crystallizing segment (2) has a cylindrical structure with a diameter of 15-30 mm and a height of 20-35 mm; The center of the upper end face of the crystallizing section (2) is coaxially connected to the center of the lower end face of the spiral crystallizing section (1), which is used to form multiple fine grains in the early stage of directional solidification, providing a source of grains for the subsequent screening of the spiral crystallizing section (1).
3. A spiral crystal selector for secondary orientation control of single-crystal superalloys according to claim 1, characterized in that, The channel cross-sectional diameters of the primary orientation screening unit (3), the secondary orientation control unit (4), and the single crystal steady-state growth unit (5) are consistent, with a diameter range of 5 to 8 mm. The coaxiality at the connection between adjacent units is ≤ ±0.1 mm, ensuring that the dendrites do not experience orientation shift or growth interruption during continuous growth between units.
4. A spiral crystal selector for secondary orientation control of single-crystal superalloys according to claim 1, characterized in that, The channel of the primary orientation screening unit (3) is formed by a spiral along the crystal selector. <001> The crystal orientation is swept along the crystal axis, and its helical lead is 20-25 mm. The spiral of the first orientation screening unit (3) and <001> The crystal orientation axial angle is 35° to 45°, the axial height of the primary orientation screening unit (3) is 10 to 15 mm, and the inner wall of the channel is a smooth arc surface; The spiral channel eliminates interference through geometric blocking effect. <010> Grains with significantly deviated crystal orientations, while simultaneously utilizing helical trajectories to guide heat flow, for <010> Crystal orientation dendrites provide a preferred growth path, enabling preliminary screening of primary orientations.
5. A spiral crystal selector for secondary orientation control of single-crystal superalloys according to claim 1, characterized in that, The secondary orientation control unit (4) is a horizontally arranged straight pipe structure; The secondary orientation control unit (4) is smoothly connected to the outlet end of the primary orientation screening unit (3) on the same axis. Its axial length is 15-20 mm, and the channel cross-section is circular with a diameter of 5-8 mm. The horizontal pipe structure changes the heat flow during the directional solidification process from vertical to horizontal, causing dendrites to grow laterally within the horizontal pipe. Through the synergistic effect of heat flow direction regulation and geometric constraints, the growth advantage of the target secondary orientation dendrites is enhanced, while the competitive growth of non-target secondary orientation dendrites is suppressed, thus achieving precise control over secondary orientation.
6. A spiral crystal selector for secondary orientation control of single-crystal superalloys according to claim 1, characterized in that, The channel of the single crystal steady-state growth unit (5) is formed by a spiral along the crystal selector. <001> Crystalline axial sweep forming, with a helical lead of 12–18 mm, and <001> The crystal orientation axial angle is 45° to 50°, the axial height of the single crystal steady-state growth unit (5) is 10 to 15 mm, and the inner wall of the channel is a smooth arc surface; The single-crystal steady-state growth unit (5) guides the dendrites after secondary orientation control back through a spiral channel structure. <010> Growing along the crystal axis eliminates orientation disturbances that may be introduced by horizontal channels, ensuring that the single crystal grows along the crystal axis. <010> The crystal orientation and the target secondary orientation continue to grow in a steady state, avoiding orientation shift or growth defects.
7. A spiral crystal selector for secondary orientation control of single-crystal superalloys according to claim 1, characterized in that, The spiral lead of the primary orientation screening unit (3) is different from that of the single-crystal steady-state growth unit (5), and the spiral lead of the primary orientation screening unit (3) is different from that of the single-crystal steady-state growth unit (5). <001> The crystal orientation axial angle is smaller than that of the helix of the single-crystal steady-state growth unit (5) and <001> Crystalline axial angle; a gradient transition from primary orientation selection to steady-state growth is achieved through differentiated spiral parameter design.
8. A spiral crystal selector for secondary orientation control of single-crystal superalloys according to claim 1, used in a directional solidification system (9), characterized in that, The spiral crystal selector (6) is located below the square casting (7), and the upper end of the spiral crystal selector (6) is coaxially connected to the bottom of the cavity of the square casting (7). The top surface of the crystallization section (2) of the spiral crystal selector (6) is connected to the water-cooled chassis of the directional solidification system (9), and the outlet of the single crystal steady growth unit (5) is smoothly connected to the bottom inlet of the cavity of the square casting (7). The directional solidification system (9) includes a heating zone, a transition zone, and a cooling zone; the spiral crystal selector (6) is located across the boundary between the heating zone and the transition zone. A riser (8) and a gating system are provided above the square casting (7). The riser (8) is connected to the top of the cavity of the square casting (7) for feeding and venting. Through the coordinated cooperation of the spiral crystal selector (6), the square casting (7), the riser (8) and the directional solidification system (9), the alloy melt is directionally solidified from bottom to top. It passes through the spiral crystal selector (6), the square casting (7) and the riser (8) in sequence, and finally obtains a single crystal high-temperature alloy casting with secondary orientation control.
9. A method for preparing single-crystal superalloy castings using the spiral crystal selector according to any one of claims 1-8, characterized in that, Includes the following steps: Step S1: Install the spiral crystal selector (6) in the directional solidification system (9), so that the lower end of the spiral crystal selector (6) is connected to the water-cooled chassis of the directional solidification system (9), and the upper end of the spiral crystal selector (6) is the outlet of the single crystal steady growth unit (5), which is coaxially and smoothly connected to the bottom inlet of the cavity of the square casting (7). Step S2: Pour the molten single-crystal high-temperature alloy into the crystallization section (2), filling the cavity of the entire spiral crystal selector (6) and the square casting (7); Step S3: Start the directional solidification system (9), control the solidification process parameters, and make the alloy melt solidify directionally from bottom to top, flowing sequentially through the crystallization section (2), the primary orientation screening unit (3), the secondary orientation control unit (4), and the single crystal steady-state growth unit (5). Step S4: In the primary orientation screening unit (3), the geometric blocking effect of the spiral channel is used to eliminate those that are already in the primary orientation. <001> Grains with crystal orientation deviations greater than a threshold are selected to identify dendrites with a dominant primary orientation. Step S5: In the secondary orientation control unit (4), the heat flow direction is changed from vertical to horizontal by using a horizontal straight pipe structure, which promotes the growth of dendrites along the lateral direction. Through the synergistic effect of heat flow direction regulation and geometric constraint, the growth advantage of the target secondary orientation dendrites is enhanced and the competitive growth of non-target secondary orientation dendrites is suppressed. Step S6: In the single crystal steady-state growth unit (5), the dendrites are guided back to the primary orientation axis for growth using the spiral channel, eliminating the orientation disturbance that may be introduced by the horizontal pipe, and maintaining the steady-state growth of the single crystal along the primary orientation and the target secondary orientation. Step S7: After solidification, a single-crystal high-temperature alloy casting with controlled secondary orientation is obtained.