CN114622270A - Method for preparing single crystal high temperature alloy test bar - Google Patents
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- CN114622270A CN114622270A CN202210244049.6A CN202210244049A CN114622270A CN 114622270 A CN114622270 A CN 114622270A CN 202210244049 A CN202210244049 A CN 202210244049A CN 114622270 A CN114622270 A CN 114622270A
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- 239000013078 crystal Substances 0.000 title claims abstract description 280
- 238000012360 testing method Methods 0.000 title claims abstract description 145
- 238000000034 method Methods 0.000 title claims abstract description 35
- 239000000956 alloy Substances 0.000 title claims abstract description 20
- 229910045601 alloy Inorganic materials 0.000 title claims abstract description 18
- 229910000601 superalloy Inorganic materials 0.000 claims abstract description 33
- 238000007711 solidification Methods 0.000 claims description 33
- 230000008023 solidification Effects 0.000 claims description 33
- 238000005520 cutting process Methods 0.000 claims description 26
- 210000001787 dendrite Anatomy 0.000 claims description 17
- 238000004140 cleaning Methods 0.000 claims description 15
- 238000001816 cooling Methods 0.000 claims description 15
- 238000012545 processing Methods 0.000 claims description 10
- 238000004321 preservation Methods 0.000 claims description 4
- 238000009826 distribution Methods 0.000 claims description 3
- 238000004519 manufacturing process Methods 0.000 claims 1
- 238000002360 preparation method Methods 0.000 abstract description 7
- 238000011160 research Methods 0.000 abstract description 4
- 230000009286 beneficial effect Effects 0.000 abstract description 3
- 238000012797 qualification Methods 0.000 abstract description 3
- 238000010438 heat treatment Methods 0.000 description 13
- 230000007547 defect Effects 0.000 description 9
- 238000005530 etching Methods 0.000 description 7
- 238000002425 crystallisation Methods 0.000 description 6
- 230000008025 crystallization Effects 0.000 description 6
- 238000010586 diagram Methods 0.000 description 5
- 230000002349 favourable effect Effects 0.000 description 3
- 239000007788 liquid Substances 0.000 description 3
- 238000005266 casting Methods 0.000 description 2
- 238000005516 engineering process Methods 0.000 description 2
- 239000000463 material Substances 0.000 description 2
- 230000015572 biosynthetic process Effects 0.000 description 1
- 238000005336 cracking Methods 0.000 description 1
- 238000011161 development Methods 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 238000011835 investigation Methods 0.000 description 1
- 230000006911 nucleation Effects 0.000 description 1
- 238000010899 nucleation Methods 0.000 description 1
- 239000002994 raw material Substances 0.000 description 1
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- 238000004781 supercooling Methods 0.000 description 1
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- C—CHEMISTRY; METALLURGY
- C30—CRYSTAL GROWTH
- C30B—SINGLE-CRYSTAL GROWTH; UNIDIRECTIONAL SOLIDIFICATION OF EUTECTIC MATERIAL OR UNIDIRECTIONAL DEMIXING OF EUTECTOID MATERIAL; REFINING BY ZONE-MELTING OF MATERIAL; PRODUCTION OF A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; SINGLE CRYSTALS OR HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; AFTER-TREATMENT OF SINGLE CRYSTALS OR A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; APPARATUS THEREFOR
- C30B11/00—Single-crystal growth by normal freezing or freezing under temperature gradient, e.g. Bridgman-Stockbarger method
- C30B11/14—Single-crystal growth by normal freezing or freezing under temperature gradient, e.g. Bridgman-Stockbarger method characterised by the seed, e.g. its crystallographic orientation
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22C—FOUNDRY MOULDING
- B22C9/00—Moulds or cores; Moulding processes
- B22C9/02—Sand moulds or like moulds for shaped castings
- B22C9/04—Use of lost patterns
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22C—FOUNDRY MOULDING
- B22C9/00—Moulds or cores; Moulding processes
- B22C9/22—Moulds for peculiarly-shaped castings
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
- B22D27/00—Treating the metal in the mould while it is molten or ductile ; Pressure or vacuum casting
- B22D27/04—Influencing the temperature of the metal, e.g. by heating or cooling the mould
- B22D27/045—Directionally solidified castings
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- C—CHEMISTRY; METALLURGY
- C30—CRYSTAL GROWTH
- C30B—SINGLE-CRYSTAL GROWTH; UNIDIRECTIONAL SOLIDIFICATION OF EUTECTIC MATERIAL OR UNIDIRECTIONAL DEMIXING OF EUTECTOID MATERIAL; REFINING BY ZONE-MELTING OF MATERIAL; PRODUCTION OF A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; SINGLE CRYSTALS OR HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; AFTER-TREATMENT OF SINGLE CRYSTALS OR A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; APPARATUS THEREFOR
- C30B29/00—Single crystals or homogeneous polycrystalline material with defined structure characterised by the material or by their shape
- C30B29/10—Inorganic compounds or compositions
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Abstract
The invention discloses a method for preparing a single crystal high-temperature alloy test rod, and belongs to the technical field of research and preparation processes of high-temperature alloy materials of engines. The method adopts the [001] oriented seed crystal and utilizes simple tools to realize the preparation of any oriented test rods and blades such as [011] and [111 ]. [001] The oriented seed crystal is easy to obtain, and the deviation of the seed crystal orientation is easy to detect. The method is easy to realize, simple to operate and high in qualification rate of the preparation of the complex orientation test bar, and is beneficial to the research of the anisotropy of the single crystal superalloy and the preparation of the single crystal turbine blade.
Description
Technical Field
The invention discloses a method for preparing a single crystal high-temperature alloy test rod, belongs to the technical field of engine high-temperature alloy material research and blade preparation processes, and provides a method for researching anisotropy of single crystal high-temperature alloy and preparing arbitrarily oriented test rods of single crystal high-temperature alloys [011] and [111 ].
Background
Turbine blades are one of the most critical components in turbine engines, and are subjected to harsh operating environments and high temperatures and stresses. The directional solidification technology appeared in the early sixties of the twentieth century is an important milestone in the development process of casting high-temperature alloy, and makes the research and application of casting make breakthrough progress. The columnar crystal formed by directional solidification eliminates a transverse crystal boundary vertical to the main stress axis, and improves the thermal fatigue performance of the alloy; the single crystal has no crystal boundary characteristic, so that the problems of high-temperature crystal boundary weakening, longitudinal crystal boundary cracking and the like do not exist. The single crystal high temperature alloy hollow turbine blade becomes one of the great key technologies of the aeroengine. The single crystal superalloy eliminates substantially all grain boundaries, has excellent high temperature properties, and is widely used as a vane material for aircraft engines and industrial gas turbines.
The single crystal superalloy has a single crystal structure and has significant anisotropy. Numerous researchers have conducted extensive theoretical and experimental investigations into the mechanical behavior of materials under permanent stress and the anisotropic characteristics of single crystal superalloys. The experimental study of the anisotropy of the single crystal superalloy needs to prepare mechanical property test bars with different crystal orientations.
Disclosure of Invention
The purpose of the invention is: a method for preparing a single crystal superalloy test rod is provided for researching the anisotropy of the single crystal superalloy. The method is simple and convenient to operate, and the preparation accuracy and the qualification rate are high.
The technical scheme of the invention is as follows:
a method for preparing a single crystal superalloy test rod comprises preparing a [001] oriented seed crystal, and cutting the side surface of the seed crystal in a specific direction to control the secondary orientation of the seed crystal in a desired direction. And designing and processing a combined tool according to the orientation of the test bar to be prepared. And (4) adopting a combined tool to weld and fix the seed crystal and the test stick wax mold. Then preparing a single crystal wax mould module and a mould shell, and preparing the required test rod with any orientation such as [011] or [111] and the like by directional solidification.
The single crystal turbine blade is used as a structural member, the solidification speed is high, and the growth mode of a solid-liquid interface in the solidification process is dendritic crystal growth. Single crystal superalloys belong to the face centered cubic system, in which the dendrite branches during solidification along the <001> crystal system, i.e. the <001> crystal orientation is the preferred growth direction. Therefore, [001] oriented seed crystals are easily obtained and have high quality. Meanwhile, since the dendrite structure is branched along the <001> crystal orientation, the solidified dendrite structure clearly shows the characteristic of the <001> crystal orientation, and the primary dendrite parallel to the main heat flow direction is the [001] crystal orientation belonging to the <001> crystal system, and the dendrites are arranged in parallel in a bundle shape. The secondary dendrite of the single crystal superalloy appears in a cross section as a cross, and the cross direction is the crystal orientation of [100] and [010 ]. The spacing between the parallel primary dendrite bundles is usually 0.3-0.5 mm. After the single crystal superalloy is corroded, the dendritic structure can be clearly distinguished visually, so that the approximate orientations of the primary dendritic crystal and the secondary dendritic crystal of the [001] oriented single crystal superalloy sample can be distinguished. The cutting of the seed crystal can be roughly positioned, and the cutting has good pointing effect on the accurate positioning cutting of the seed crystal. Then, the three-dimensional orientation of the sample was precisely measured using a diffractometer.
And cutting the seed crystal by linear cutting according to the diffraction test result. When cutting, the seed crystal is cut into a rod shape with a square cross section, the axis of the square rod-shaped seed crystal is parallel to the [001] crystal direction, and the square side of the cross section is respectively parallel to the [100] and [010] crystal directions. Because the crystal orientations of the [100] and the [010] have equivalent symmetry, the crystal structures are completely the same. When the wax patterns are combined, the mistake proofing treatment is not needed to be considered.
The length of the rod-shaped seed crystal is 25-35 mm, and the length of the seed crystal is required to ensure that part of the seed crystal is molten and only part of the seed crystal is molten in the directional solidification process. The seed crystal, which remains solid, provides a core for further growth so that subsequent solidification results in a sample oriented in accordance with the seed crystal. The length of the seed crystal is in a proper range, and is as short as possible on the premise of ensuring the core function of dendritic crystal growth, so that the directional solidification efficiency is improved.
The directional solidification from bottom to top, from the solidification point of view, the smaller the sudden change of the cross section is, the more favorable the growth of dendrite is; from this point of view, it is desirable that the cross-sectional area of the seed crystal be large, and the cross-sectional area closer to the test rod is more favorable for dendrite growth. However, the larger the seed crystal, the larger the circumference of the cross-section, and correspondingly, the larger the contact interface with the shell, the greater the chance of crystal defects. Therefore, the cross-sectional area of the seed crystal is moderate. According to the invention, the side length of the cross section of the seed crystal is selected to be 4-5 mm. The sharp edges of the square radiate heat more quickly and are easy to overcool, so that crystal defects are easy to generate. The sharp edge rounding is beneficial to reducing solidification supercooling at the sharp edge and reducing the probability of mixed crystals, and the fillet radius is 0.3-0.5 mm.
The seed crystal is cut from the single crystal sample with enough size by adopting a linear cutting mode, the required shape can be accurately obtained by adopting the linear cutting, and raw materials can be obviously saved compared with mechanical processing. The recast layer is remained on the surface of the wire-electrode cutting, and becomes a favorable position for phase change nucleation at high temperature. And after the seed crystal is cut, carrying out macroscopic deep etching to remove a recast layer generated in the linear cutting process and reduce the possibility of crystal defect formation.
In order to accurately control the orientation of the test bar, the spatial angle of the seed crystal and the axis of the test bar is controlled according to the distribution relation of different crystal orientations according to the orientation of the test bar required to be prepared, so that the wax pattern combined tool is designed and processed. The cavity for placing the seed crystal on the combined tool has the axis positioned in the [001] crystal direction, and the square plane for positioning the seed crystal and rotating the seed crystal is parallel to the [100] and [010] crystal directions. And (3) positioning the axis of the cavity of the test bar wax mold on the combined tool to be parallel to the crystal orientation of the single crystal test bar to be prepared. The tool is adopted to combine and fix the seed crystal and the test stick wax mold. Then, a test bar wax mold module is combined, and a shell is prepared.
And (2) putting the prepared mould shell into a directional solidification furnace, heating to 1500-1600 ℃, pouring the monocrystalline alloy liquid melted to 1500-1600 ℃ into the mould shell, drawing at the speed of 2-7 mm/min until the whole monocrystalline test bar is solidified, then taking out the mould shell containing the monocrystalline test bar after vacuum breaking, and carrying out air cooling or placing the mould shell into a heat-insulating bucket for heat-insulating cooling.
And cutting, cleaning and carrying out heat treatment on the die set after shell cleaning, and accurately measuring the orientation deviation degree of the test bar by adopting a diffractometer for later use.
The invention has the beneficial effects that: the invention provides a method for preparing a single crystal superalloy [011] or [111] arbitrarily oriented test rod by adopting [001] oriented seed crystals, which is used for researching the anisotropy of the single crystal superalloy or preparing a single crystal turbine blade. The method is simple and intuitive to operate, and the accuracy and the qualification rate of the preparation are high.
Description of the drawings:
FIG. 1 is a schematic diagram showing the position of a single crystal superalloy [011] orientation test rod prepared by using a [001] orientation seed crystal
FIG. 2 is a schematic diagram showing the position of a [111] oriented test rod for preparing a single crystal superalloy by using a [001] oriented seed crystal
FIG. 3 is a schematic diagram showing the position of a single crystal superalloy [112] orientation test rod prepared by using a [001] orientation seed crystal
FIG. 4 is a schematic diagram showing the position of a [124] oriented test rod for preparing a single crystal superalloy by using a [001] oriented seed crystal
FIG. 5 is a schematic diagram showing the position of a single crystal superalloy [258] orientation test rod prepared by using [001] orientation seed crystals
Detailed Description
By using the [001] oriented seed crystal and controlling the spatial angle between the seed crystal and the axial line of the test rod according to the distribution relation of different crystal orientations, the test rods with any orientations such as [011] and [111] are obtained.
Firstly, preparing [001] oriented seed crystal, and designing and processing a combined tool according to the orientation of a test rod to be prepared. And (4) adopting a combined tool to weld and fix the seed crystal and the test stick wax mold. Then preparing a single crystal wax mould module and a mould shell, and preparing the required test rod with any orientation such as [011] or [111] and the like by directional solidification.
Selecting a single crystal superalloy sample with good single crystal integrity and sufficient size, and visually judging primary and secondary approximate orientations according to the dendritic crystal form; and accurately measuring the primary and secondary orientations of the seed crystal by using a diffractometer. When the seed crystal is cut, the direction of the parallel dendrite beam is taken as the primary orientation [001] and is parallel to the axial direction of the rod-shaped seed crystal. The section of the seed crystal is square, the side length of the square cross section is 5mm, the sharp edge of the square is rounded, and the radius of the fillet is 0.3-0.5 mm. The side faces of the square rod-shaped seed crystal are parallel to the secondary orientation [010] or [100], respectively. The length of the rod-shaped seed crystal is 25-35 mm, and after the seed crystal is cut, macroscopic deep etching is carried out to remove a recasting layer generated in the linear cutting process. The recast layer contains higher energy and is easy to cause crystallization defects in the directional solidification process.
In order to accurately control the orientation of the test bar, a wax mold combined tool is designed and processed. A seed crystal cavity and a test rod cavity groove are formed in the upper plane of the combined tool, the seed crystal and the test rod wax mold are positioned by the groove, and the axes of the two cavities are parallel to the plane of the tool. The longitudinal section of the seed crystal cavity groove is right-angled triangle, and the longitudinal section of the test rod cavity groove is arc. Two straight edges of the right triangle of the tool locate the side of the seed crystal in the wax mold combination process. According to the three-dimensional orientation of the test bar to be prepared, determining an included angle alpha between a straight-side plane of a right-angled triangular seed crystal cavity and a tool plane and an included angle beta between the seed crystal cavity and a cavity groove axis of the test bar, and determining the orientation of the single crystal test bar according to the two angles.
The tool is adopted to combine and fix the seed crystal and the test stick wax mold. Then, a test bar wax pattern module is combined, and a shell is prepared.
And (2) putting the prepared mould shell into a directional solidification furnace, heating to 1500-1600 ℃, pouring the monocrystalline alloy liquid melted to 1500-1600 ℃ into the mould shell, drawing at the speed of 2-7 mm/min until the whole monocrystalline test bar is solidified, then taking out the mould shell containing the monocrystalline test bar after vacuum breaking, and carrying out air cooling or placing the mould shell into a heat-insulating bucket for heat-insulating cooling.
And cutting, cleaning and carrying out heat treatment on the die set after shell cleaning, and accurately measuring the orientation deviation of the test bar by adopting a diffractometer for later use.
Example 1
Preparing a [011] orientation test rod by using the [001] orientation seed crystal.
Firstly, preparing [001] oriented seed crystal, and designing and processing a combined tool according to the orientation of a test rod to be prepared. And (4) adopting a combined tool to weld and fix the seed crystal and the test stick wax mold. Then preparing a single crystal wax mould module and a shell, and preparing the required [011] orientation test rod by directional solidification.
Selecting a single crystal superalloy sample with good single crystal integrity and sufficient size, and visually judging primary and secondary approximate orientations according to the dendritic crystal form; and accurately measuring the primary and secondary orientations of the seed crystal by using a diffractometer. When the seed crystal is cut, the direction of the parallel dendrite beam is taken as the primary orientation [001] and is parallel to the axial direction of the rod-shaped seed crystal. The section of the seed crystal is square, the side length of the square cross section is 4.5mm, the sharp edge of the square is rounded, and the radius of the fillet is 0.4 mm. The side faces of the square rod-shaped seed crystal are parallel to the secondary orientation [010] or [100], respectively. The length of the rod-shaped seed crystal is 30mm, and macroscopic deep etching is carried out after the seed crystal is cut so as to remove a recast layer generated in the linear cutting process. The recast layer contains higher energy and is easy to cause crystallization defects in the directional solidification process.
In order to accurately control the orientation of the test bar, a wax mold combined tool is designed and processed. Set up the chamber way recess of seed crystal chamber way and test rod on the combination frock upper plane, the axis of two chamber ways all is on a parallel with the frock plane. The longitudinal section of the seed crystal cavity groove is right-angled triangle, and the longitudinal section of the test rod cavity groove is arc. Two straight edges of the right triangle of the tool locate the side of the seed crystal in the wax mold combination process. And determining that the included angle between the straight-side plane of the right-angled triangular seed crystal cavity channel and the plane of the tool is 0 degree, namely preparing the rectangular groove. And determining the angle included angle between the axes of the seed crystal cavity channel and the cavity channel groove of the test rod to be 45 degrees, and determining the orientation of the single crystal test rod according to the two angles. The spatial position relationship between the seed crystal and the test rod is schematically shown in FIG. 1.
The tool is adopted to combine and fix the seed crystal and the test rod wax mold. Then, a test bar wax pattern module is combined, and a shell is prepared.
And (2) putting the prepared mould shell into a directional solidification furnace, heating to 1550 ℃, pouring a three-generation single crystal high-temperature alloy DD9 which is melted to 1570 ℃ into the mould shell, drawing at the speed of 3.5mm/min until the whole single crystal test bar is solidified, taking out the mould shell containing the single crystal test bar after vacuum breaking, and carrying out air cooling or placing the mould shell into a heat-insulating barrel for heat preservation and cooling.
And cutting, cleaning and heat treating the module after shell cleaning, and accurately measuring the orientation deviation of the test bar by adopting a diffractometer for later use.
Example 2
Preparing a [111] orientation test rod by using the [001] orientation seed crystal.
Firstly, preparing [001] oriented seed crystal, and designing and processing a combined tool according to the orientation of a test rod to be prepared. And (4) adopting a combined tool to weld and fix the seed crystal and the test stick wax mold. Then preparing a single crystal wax mould module and a shell, and preparing the required [111] orientation test rod by directional solidification.
Selecting a single crystal superalloy sample with good single crystal integrity and sufficient size, and visually judging primary and secondary approximate orientations according to the dendritic crystal form; and accurately measuring the primary and secondary orientations of the seed crystal by using a diffractometer. When the seed crystal is cut, the direction of the parallel dendrite beam is taken as the primary orientation [001] and is parallel to the axial direction of the rod-shaped seed crystal. The section of the seed crystal is square, the side length of the square cross section is 4mm, the sharp edge of the square is rounded, and the radius of the fillet is 0.3 mm. The side faces of the square rod-shaped seed crystal are parallel to the secondary orientation [010] or [100], respectively. The length of the rod-shaped seed crystal is 35mm, and macroscopic deep etching is carried out after the seed crystal is cut so as to remove a recast layer generated in the linear cutting process. The recast layer contains higher energy and is easy to cause crystallization defects in the directional solidification process.
In order to accurately control the orientation of the test bar, a wax mold combined tool is designed and processed. A seed crystal cavity and a cavity groove of the test rod are formed in the upper plane of the combined tool, and the axes of the two cavities are parallel to the plane of the tool. The longitudinal section of the seed crystal cavity groove is right-angled triangle, and the longitudinal section of the test rod cavity groove is arc. Two straight edges of the right triangle of the tool locate the side of the seed crystal in the wax mold combination process. And determining that the included angle between the straight-side plane of the right-angled triangular seed crystal cavity channel and the plane of the tool is 45 degrees, namely preparing a rectangular groove. And determining that the included angle between the seed crystal cavity channel and the cavity channel axis of the test rod is 54.7 degrees, and determining the orientation of the single crystal test rod according to the two angles. The spatial position relationship between the seed crystal and the test rod is schematically shown in FIG. 2
The tool is adopted to combine and fix the seed crystal and the test stick wax mold. Then, a test bar wax pattern module is combined, and a shell is prepared.
And (2) putting the prepared mould shell into a directional solidification furnace, heating to 1570 ℃, pouring the three-generation single crystal alloy DD9 melted to 1570 ℃ into the mould shell, drawing at the speed of 2mm/min until the whole single crystal test bar is solidified, then taking out the mould shell containing the single crystal test bar after vacuum breaking, and carrying out air cooling or placing the mould shell into a heat-insulating barrel for heat preservation and cooling.
And cutting, cleaning and carrying out heat treatment on the die set after shell cleaning, and accurately measuring the orientation deviation of the test bar by adopting a diffractometer for later use.
Example 3
Preparing a [112] orientation test rod by using the [001] orientation seed crystal.
Firstly, preparing [001] oriented seed crystal, and designing and processing a combined tool according to the orientation of a test rod to be prepared. And (4) adopting a combined tool to weld and fix the seed crystal and the test stick wax mold. Then preparing a single crystal wax mould module and a shell, and preparing the required [112] orientation test rod by directional solidification.
Selecting a single crystal superalloy sample with good single crystal integrity and sufficient size, and visually judging primary and secondary approximate orientations according to the dendritic crystal form; and accurately measuring the primary and secondary orientations of the seed crystal by using a diffractometer. When the seed crystal is cut, the direction of the parallel dendrite beam is taken as the primary orientation [001] and is parallel to the axial direction of the rod-shaped seed crystal. The section of the seed crystal is square, the side length of the square cross section is 5mm, the sharp edge of the square is rounded, and the radius of the fillet is 0.5 mm. The side faces of the square rod-shaped seed crystal are parallel to the secondary orientation [010] or [100], respectively. The length of the rod-shaped seed crystal is 25mm, and after the seed crystal is cut, macroscopic deep etching is carried out to remove a recast layer generated in the linear cutting process. The recast layer contains higher energy and is easy to cause crystallization defects in the directional solidification process.
In order to accurately control the orientation of the test bar, a wax mold combined tool is designed and processed. A seed crystal cavity and a cavity groove of the test rod are formed in the upper plane of the combined tool, and the axes of the two cavities are parallel to the plane of the tool. The longitudinal section of the seed crystal cavity groove is right-angled triangle, and the longitudinal section of the test rod cavity groove is arc. Two straight edges of the right triangle of the tool locate the side of the seed crystal in the wax mold combination process. And determining that the included angle between the straight-side plane of the right-angled triangular seed crystal cavity channel and the plane of the tool is 45 degrees, namely preparing a rectangular groove. And determining that the included angle between the seed crystal cavity channel and the cavity channel groove axis of the test rod is 35.3 degrees, and determining the orientation of the single crystal test rod according to the two angles. The spatial position relationship between the seed crystal and the test rod is schematically shown in FIG. 3
The tool is adopted to combine and fix the seed crystal and the test stick wax mold. Then, a test bar wax pattern module is combined, and a shell is prepared.
And (2) putting the prepared mould shell into a directional solidification furnace, heating to 1570 ℃, pouring the second-generation monocrystal high-temperature alloy DD6 which is melted to 1500 ℃ into the mould shell, drawing at the speed of 5.5mm/min until the whole monocrystal test rod is solidified, taking out the mould shell containing the monocrystal test rod after vacuum breaking, and carrying out air cooling or placing the mould shell into a heat-insulating barrel for heat preservation and cooling.
And cutting, cleaning and carrying out heat treatment on the die set after shell cleaning, and accurately measuring the orientation deviation of the test bar by adopting a diffractometer for later use.
Example 4
Preparing a [124] orientation test rod by using the [001] orientation seed crystal.
Firstly, preparing [001] oriented seed crystal, and designing and processing a combined tool according to the orientation of a test rod to be prepared. And (4) adopting a combined tool to weld and fix the seed crystal and the test stick wax mold. Then preparing a single crystal wax mould module and a shell, and preparing the required prepared [124] orientation test rod by directional solidification.
Selecting a single crystal superalloy sample with good single crystal integrity and sufficient size, and visually judging primary and secondary approximate orientations according to the dendritic crystal form; and accurately measuring the primary and secondary orientations of the seed crystal by using a diffractometer. When the seed crystal is cut, the direction of the parallel dendrite beam is taken as the primary orientation [001] and is parallel to the axial direction of the rod-shaped seed crystal. The section of the seed crystal is square, the side length of the square cross section is 4mm, the sharp edge of the square is rounded, and the radius of the fillet is 0.3 mm. The side faces of the square rod-shaped seed crystal are parallel to the secondary orientation [010] or [100], respectively. The length of the rod-shaped seed crystal is 35mm, and macroscopic deep etching is carried out after the seed crystal is cut so as to remove a recast layer generated in the linear cutting process. The recast layer contains higher energy and is easy to cause crystallization defects in the directional solidification process.
In order to accurately control the orientation of the test bar, a wax mold combined tool is designed and processed. A seed crystal cavity and a cavity groove of the test rod are formed in the upper plane of the combined tool, and the axes of the two cavities are parallel to the plane of the tool. The longitudinal section of the seed crystal cavity groove is right-angled triangle, and the longitudinal section of the test rod cavity groove is arc. Two straight edges of the right triangle of the tool locate the side of the seed crystal in the wax mold combination process. And determining that the included angle between the straight-side plane of the right-angled triangular seed crystal cavity channel and the plane of the tool is 26.6 degrees, namely preparing a rectangular groove. And determining that the included angle between the seed crystal cavity channel and the cavity channel groove axis of the test rod is 29.2 degrees, and determining the orientation of the single crystal test rod according to the two angles. The spatial position relationship between the seed crystal and the test rod is schematically shown in FIG. 4
The tool is adopted to combine and fix the seed crystal and the test stick wax mold. Then, a test bar wax pattern module is combined, and a shell is prepared.
And (2) putting the prepared mould shell into a directional solidification furnace, heating to 1570 ℃, pouring the second-generation single crystal high-temperature alloy DD6 which is melted to 1530 ℃ into the mould shell, drawing at the speed of 6mm/min until the whole single crystal test rod is solidified, taking out the mould shell containing the single crystal test rod after vacuum breaking, and carrying out air cooling or placing the mould shell into a heat-insulating bucket for heat-insulating and cooling.
And cutting, cleaning and carrying out heat treatment on the die set after shell cleaning, and accurately measuring the orientation deviation of the test bar by adopting a diffractometer for later use.
Example 5
Preparing a [258] orientation test rod by using the [001] orientation seed crystal.
Firstly, preparing [001] oriented seed crystal, and designing and processing a combined tool according to the orientation of a test rod to be prepared. And (4) adopting a combined tool to weld and fix the seed crystal and the test stick wax mold. Then preparing a single crystal wax mould module and a shell, and preparing the required [258] orientation test rod by directional solidification.
Selecting a single crystal superalloy sample with good single crystal integrity and sufficient size, and visually judging primary and secondary approximate orientations according to the dendritic crystal form; and accurately measuring the primary and secondary orientations of the seed crystal by using a diffractometer. When the seed crystal is cut, the direction of the parallel dendrite beam is taken as the primary orientation [001] and is parallel to the axial direction of the rod-shaped seed crystal. The section of the seed crystal is square, the side length of the square cross section is 4mm, the sharp edge of the square is rounded, and the radius of the fillet is 0.3 mm. The side faces of the square rod-shaped seed crystal are parallel to the secondary orientation [010] or [100], respectively. The length of the rod-shaped seed crystal is 35mm, and macroscopic deep etching is carried out after the seed crystal is cut so as to remove a recast layer generated in the linear cutting process. The recast layer contains higher energy and is prone to cause crystallization defects during directional solidification.
In order to accurately control the orientation of the test bar, a wax mold combined tool is designed and processed. A seed crystal cavity and a cavity groove of the test rod are formed in the upper plane of the combined tool, and the axes of the two cavities are parallel to the plane of the tool. The longitudinal section of the seed crystal cavity groove is right-angled triangle, and the longitudinal section of the test rod cavity groove is arc. Two straight edges of the right triangle of the tool locate the side of the seed crystal in the wax mold combination process. And determining that the included angle between the straight-side plane of the right-angled triangular seed crystal cavity channel and the plane of the tool is 21.8 degrees, namely preparing a rectangular groove. And determining that the included angle between the seed crystal cavity channel and the cavity channel groove axis of the test rod is 33.9 degrees, and determining the orientation of the single crystal test rod according to the two angles. The spatial position relationship between the seed crystal and the test rod is schematically shown in FIG. 5
The tool is adopted to combine and fix the seed crystal and the test stick wax mold. Then, a test bar wax mold module is combined, and a shell is prepared.
And (2) putting the prepared mould shell into a directional solidification furnace, heating to 1600 ℃, pouring the third-generation single crystal high-temperature alloy DD9 melted to 1600 ℃ into the mould shell, drawing at the speed of 5mm/min until the whole single crystal test bar is solidified, then breaking vacuum, taking out the mould shell containing the single crystal test bar, and carrying out air cooling or placing the mould shell into a heat-insulating bucket for heat-insulating and cooling.
And cutting, cleaning and carrying out heat treatment on the die set after shell cleaning, and accurately measuring the orientation deviation of the test bar by adopting a diffractometer for later use.
Claims (9)
1. A method for preparing a single crystal superalloy test rod is characterized in that: firstly, preparing [001] oriented seed crystals, and designing and processing a combined tool according to the orientation of a test rod to be prepared; adopting a combined tool to weld and fix the seed crystal and the test bar wax mold; then preparing a single crystal wax mould module and a shell, and preparing a required [011] or [111] arbitrarily oriented test rod by directional solidification; preparing a [011] or [111] arbitrarily oriented test rod by utilizing easily obtained [001] oriented seed crystals and matching with a tool, wherein the method comprises the following steps:
firstly, selecting a single crystal high-temperature alloy sample with good single crystal integrity and enough size, and visually judging primary and secondary approximate orientations according to the form of dendrite;
a second part for accurately measuring the primary and secondary orientations of the seed crystal by using a diffractometer;
thirdly, cutting the rodlike seed crystal with the square cross section according to the test result, enabling the axial direction of the seed crystal to be parallel to the [001] crystal direction, and enabling the side surface of the seed crystal to be respectively parallel to the [010] crystal direction and the [100] crystal direction;
fourthly, designing and processing a wax mold combined tool according to the orientation of the test bar to be prepared;
fifthly, fixing the test rod wax mold and the seed crystal by using a tool, and then combining the test rod wax mold module;
and sixthly, preparing a shell and directionally solidifying and pouring a single crystal test rod.
2. A method for preparing a single crystal superalloy test rod as in claim 1, wherein the [001] oriented seed crystal is used, and the [011], [111] arbitrarily oriented test rod is obtained by controlling the spatial angle of the seed crystal and the test rod axis according to different crystal orientation distribution relations.
3. A method of producing a single crystal superalloy test rod as in claim 1, wherein the cutting of the seed crystal is performed with a direction of a parallel dendrite bundle as a primary orientation [001] parallel to an axis of the rod-shaped seed crystal, and the seed crystal has a square cross-section.
4. A method for preparing a single crystal superalloy test rod as in claim 1 or 3, wherein the side length of the square cross section is 4 to 5mm, the sharp edge of the square is rounded, and the fillet radius is 0.3 to 0.5 mm.
5. A method of producing a single crystal superalloy test rod as claimed in claim 1 or 3, wherein the sides of the square rod shaped seed crystal are parallel to the secondary orientation [010] or [100], respectively.
6. A method for preparing a single crystal superalloy test rod as in claim 1 or 3, wherein the length of the square rod shaped seed crystal is 25 to 35 mm.
7. A method of making a single crystal superalloy test rod as in claim 1, wherein after the seed cut is completed, a macro etch back is performed to remove a recast layer created during the wire cut.
8. The method of claim 1, wherein the mold shell is placed in a directional solidification furnace, heated to 1500-1600 ℃, and the single crystal alloy melt melted to 1500-1600 ℃ is poured into the mold shell, and then pulled at a speed of 2-7 mm/min until the whole single crystal test rod is completely solidified, and then the mold shell containing the single crystal test rod is taken out after breaking vacuum, and then air-cooled or placed in a heat-preserving container for heat preservation and cooling.
9. The method for preparing a single crystal superalloy test rod according to claim 1 or 7, wherein the die set is cut, cleaned, heat treated after cleaning, and the degree of orientation deviation of the test rod is accurately measured by a diffractometer for later use.
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| CN101205573A (en) * | 2007-12-17 | 2008-06-25 | 北京航空航天大学 | Method for preparing Co based single-crystal refractory alloy by employing combination of seed crystal method and screw selecting method |
| CN107059133A (en) * | 2017-01-04 | 2017-08-18 | 西北工业大学 | A kind of accurate control single-crystal orientation selects crystal method |
| CN109317616A (en) * | 2018-11-27 | 2019-02-12 | 安徽应流航源动力科技有限公司 | 3 D tropism can essence control high temperature alloy single crystal blade seed crystal preparation method |
| CN112695377A (en) * | 2020-12-10 | 2021-04-23 | 北航（四川）西部国际创新港科技有限公司 | Shuttering and method for preparing [011] or [111] oriented single crystal high-temperature alloy |
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Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101205573A (en) * | 2007-12-17 | 2008-06-25 | 北京航空航天大学 | Method for preparing Co based single-crystal refractory alloy by employing combination of seed crystal method and screw selecting method |
| CN107059133A (en) * | 2017-01-04 | 2017-08-18 | 西北工业大学 | A kind of accurate control single-crystal orientation selects crystal method |
| CN109317616A (en) * | 2018-11-27 | 2019-02-12 | 安徽应流航源动力科技有限公司 | 3 D tropism can essence control high temperature alloy single crystal blade seed crystal preparation method |
| CN112695377A (en) * | 2020-12-10 | 2021-04-23 | 北航（四川）西部国际创新港科技有限公司 | Shuttering and method for preparing [011] or [111] oriented single crystal high-temperature alloy |
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