CN110777284B - High-defect-tolerance single-crystal high-temperature alloy component and preparation method thereof - Google Patents
High-defect-tolerance single-crystal high-temperature alloy component and preparation method thereof Download PDFInfo
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- CN110777284B CN110777284B CN201911170740.9A CN201911170740A CN110777284B CN 110777284 B CN110777284 B CN 110777284B CN 201911170740 A CN201911170740 A CN 201911170740A CN 110777284 B CN110777284 B CN 110777284B
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C19/00—Alloys based on nickel or cobalt
- C22C19/03—Alloys based on nickel or cobalt based on nickel
- C22C19/05—Alloys based on nickel or cobalt based on nickel with chromium
- C22C19/051—Alloys based on nickel or cobalt based on nickel with chromium and Mo or W
- C22C19/057—Alloys based on nickel or cobalt based on nickel with chromium and Mo or W with the maximum Cr content being less 10%
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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
- 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
- C30B11/00—Single-crystal growth by normal freezing or freezing under temperature gradient, e.g. Bridgman-Stockbarger method
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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
- C30B29/52—Alloys
Abstract
The invention discloses a high-defect-tolerance single-crystal high-temperature alloy component and a preparation method thereof, belonging to the technical field of high-temperature alloy materials and investment casting. The element carbon formed by adding and optimizing carbides of Hf, B, Zr, Ti, V and the like forms carbides of different types, so that the grain boundary strength is improved, the tolerance of small-angle grain boundary defects is improved, and the tolerance of internal micropores is improved by Ce, La and the like. Through L1、L2、H1Variation in size among the three produces a single crystal structure having a content of micropores not passing through the inside, by L1And Y1The change of the structure size changes the growth of secondary dendrites in the solidification process of the component, and the preparation of the small-angle grain boundary defects with different angle differences is realized. The invention realizes the quantitative preparation of the solidification defects such as micropores, small-angle grain boundaries and the like in the single crystal high-temperature alloy through the cooperative adjustment of alloy components and the structure of a component.
Description
The technical field is as follows:
the invention relates to the technical field of high-temperature alloy materials and investment casting, in particular to a high-defect-tolerance single-crystal high-temperature alloy component and a preparation method thereof.
Background art:
the single crystal high temperature alloy is an indispensable key structural material for aviation, aerospace, energy, nuclear industry, petrifaction, national defense weaponry and national economic construction. Because the structure of the single crystal high temperature alloy part is very complex, the occurrence of solidification defects such as internal micropores, small-angle crystal boundaries and the like is easily caused in the directional solidification process, thereby influencing the service life of the part. The small-angle crystal boundary is used as a defect structure, the transverse crystal boundary is introduced again, the structural integrity of the single crystal high-temperature alloy blade is damaged, the high-temperature mechanical property of the alloy is obviously reduced, and the high-temperature mechanical property becomes a great hidden danger in the service process of the blade. And the internal micropores enable the stress concentration of the single crystal component in the service process, so that the single crystal component can generate fatigue cracks prematurely. At present, the formation elements of carbon (boron) compounds in the single crystal high-temperature alloy containing rhenium in the second generation and the above generations are less, so that the single crystal component is scrapped once the defects of internal micropores (about 0.25mm) or small-angle crystal boundaries (about 6 degrees) and the like exceeding the specification of the technical standard are formed, and great waste is caused. Firstly, a single crystal superalloy with high defect tolerance is developed, and even if the interior of the alloy has micropores with large sizes and small angle grain boundaries, the alloy can maintain good mechanical properties, and has important significance for controlling the cost of an aeroengine. Secondly, because the single crystal superalloy is directionally solidified, the preparation of large-size internal micropores and small-angle crystal boundaries is very difficult, a sample method capable of preparing solidification defects such as the large-size internal micropores is developed, a component with specific size and defect characteristics is provided for an aero-engine to be examined, and the method has important significance for research and development of the aero-engine and formulation of related technical standards.
The invention content is as follows:
the invention aims to provide a single crystal high-temperature alloy component with high defect tolerance and a preparation method thereof, and aims to solve the problems that (1) the existing single crystal high-temperature alloy has small solidification defect tolerance, is sensitive to solidification defects such as internal micropore size, small angle grain boundary and the like, and once the solidification defect is formed in the alloy, the performance of the single crystal alloy is rapidly reduced to influence the performance of an aeroengine; (2) the single crystal high temperature alloy is prepared by adopting a directional solidification mode, and the method has good feeding property, so that the preparation of large-size internal micropores and small-angle crystal boundaries in a single crystal component is very difficult; (3) at present, due to the lack of a proper means for preparing the components with the solidification defects such as internal micropores with specific sizes, the standards of high-temperature components of aero-engines are mostly established by referring to foreign standards, and the fundamental reason is that single crystal components without specific solidification defects in China can be examined by related design units. The method for preparing the high-temperature alloy material and the member thereof, which are researched and developed by the invention, can provide a basis for selecting the single-crystal high-temperature alloy material, guide the design and production of the single-crystal high-temperature alloy member and reduce the manufacturing cost and the development period of the single-crystal member.
In order to achieve the purpose, the technical scheme adopted by the invention is as follows:
a single crystal superalloy component having a high defect tolerance, the single crystal superalloy component having a chemical composition, in weight percent, as follows:
0.12 to 0.18% of C, 4.3 to 5.6% of Cr, 5.6 to 6.3% of Al, 8.0 to 10.0% of Co, 0.8 to 1.4% of Mo, 7.7 to 9.3% of W, 1.4 to 1.8% of Nb, 3.5 to 4.5% of Ta, 3.5 to 4.5% of Re, 0.001 to 0.005% of Y, 0.005 to 0.03% of Hf, 0.005 to 0.03% of Zr, less than or equal to 0.2% of Ti, 0.001 to 0.1% of V, 0.001 to 0.0055% of Ce, 0.001 to 0.0045% of La, and the balance of Ni and inevitable impurities.
In the chemical components of the single crystal superalloy component, O is less than or equal to 0.02wt.%, N is less than or equal to 0.02wt.%, S is less than or equal to 0.004 wt.%, and B is less than or equal to 0.008 wt.%.
In the chemical components of the single crystal high-temperature alloy component, the total content of Hf and Zr elements is more than or equal to 0.02 wt.%.
In the chemical components of the single crystal superalloy component, the sum of Ti and V is more than or equal to 0.001 wt% and less than or equal to 0.3 wt%.
In the chemical components of the single crystal high temperature alloy component, Ce/La is less than or equal to 1.
In the chemical composition of the single crystal superalloy component, O + N is less than or equal to 0.03 wt%.
The preparation method of the single crystal high temperature alloy component with high defect tolerance adopts a directional solidification process to prepare the single crystal high temperature alloy component with high defect tolerance, and specifically comprises the following steps:
(1) mixing the raw materials according to the alloy components, and preparing a master alloy by utilizing vacuum induction melting;
(2) designing an alloy component structure and an auxiliary pouring system structure, wherein the auxiliary pouring system structure comprises a spiral crystal selector, a vertical channel and an inclined channel with an included angle theta with the vertical channel; the upper ends of the vertical channel and the inclined channel are both connected with alloy components, and the lower ends of the vertical channel and the inclined channel are both connected with a spiral crystal selector (comprising a crystal leading section and a crystal selecting section);
(3) preparing a metal mold and a ceramic (corundum) mold shell according to the alloy component structure and the auxiliary pouring system structure designed in the step (2) (connecting an auxiliary pouring system wax mold with the alloy component wax mold, coating ceramic slurry on the wax mold and preparing the ceramic mold shell); the bottom of the mould shell (the crystal leading section) is placed on a copper water-cooling crystallizer;
(4) performing directional solidification in a directional solidification furnace by adopting a spiral crystal selection method to obtain a single crystal high-temperature alloy component with high defect tolerance; the defects include internal micropores and small-angle grain boundaries; wherein: the alloy pouring temperature in the directional solidification is 1520 and 1580 ℃, and the pulling speed is 5 mm/min.
In the above step (2), the alloy member includes a middle section, and both ends of the middle section are of a rectangular parallelepiped structure, wherein: the length of the middle section of the alloy component is L1The length of the two rectangular end parts (along the length direction of the middle part of the component) is L2The end of the rectangular block is H1；
In the auxiliary pouring system, the vertical channel is cylindrical, and the diameter of the vertical channel is Y1(ii) a The upper end of the vertical channel is connected to the central position of the middle section of the alloy component; the upper ends of the two inclined channels are respectively connected to the bottom centers of the end parts of the alloy component cuboid; a crystal leading section at the lower part of the spiral crystal selector and a crystal selecting section at the upper part of the spiral crystal selector; the lower ends of the vertical channel and the two inclined channels are connected with the upper part of the crystal selection section.
In the step (2), L is more than 11/L2＜3，1＜H1/L2< 5, and L1Is 10-40mm, L20.5-10mm, H120-45mm, by pair L1、L2And H1The size among the three is regulated and controlled to realize the control of the feeding channel in the directional solidification process, and further realize the regulation and control of the size of the micropores in the component.
In the step (2), the diameter Y of the vertical passage10.5-10mm, L is more than 11/Y1< 4, by pairing Y1And L1The size is regulated and controlled, so that the dendrites meet at different degrees, and the preparation of the small-angle grain boundary defects with different angle differences is realized.
The design idea of the invention is as follows:
1. on the basis of traditional alloy components, the invention adds and optimizes carbide forming elements such as Hf, B, Zr, Ti, V and the like to enable the carbide forming elements to form different types of carbides with carbon in the alloy, thereby improving the grain boundary strength and the tolerance of small-angle grain boundary defects, improving the grain boundary and interface purity of the alloy by adding elements such as Ce, La and the like, and improving the tolerance of internal micropores.
2. The traditional thought is that the rare earth elements Ce and La have the function of purifying the grain boundary, and the invention utilizes the function of purifying the internal micropores and the matrix interface of the rare earth elements Ce and La. Because the internal micropores in the directional solidification are formed by insufficient final solidification feeding, trace impurity elements are easy to segregate and the interface of the internal micropores and the matrix, so that the internal micropores and the matrix interface are easy to form microcracks in the deformation process. According to the invention, the content of the rare earth elements Ce and La is optimized, the purity of the interface between the internal micropores and the matrix is improved, and the enrichment of trace impurity elements is reduced, so that the critical value of crack initiation is improved.
3. Because the high-generation single crystal high-temperature alloy is lack of carbide forming elements, the mechanical property of the alloy can be obviously reduced due to the formation of a small-angle grain boundary. The method adds a small amount of Hf, Zr, Ti, V and other elements into the single-crystal high-temperature alloy, optimizes the appearance, content and type of carbide in the single-crystal high-temperature alloy by adjusting the content of carbide elements of different types, fully utilizes the action of N element in the alloy, promotes the precipitation of carbide by means of the preferential nucleation of N atoms and Ti atoms, and realizes the controllable appearance of the carbide.
4. In the directional solidification process, the sample has better feeding capacity due to the solidification of the melt from bottom to top, large-size internal micropores are difficult to prepare in the sample, and carbides are preferentially precipitated in a liquid phase in the solidification process. Secondly, by changing the structure of the specimen, the fluidity of the liquid metal is changed, the feeding ability is reduced, and finally, large-sized internal micropores are formed in the specimen due to insufficient feeding.
5. If the traditional plate-shaped sample is adopted and the sample required by the performance experiment is cut in the upper transverse direction, the actual test is the transverse mechanical performance, and the actual mechanical performance of the single crystal cannot be well reflected. According to the invention, through the optimization of the sample structure and by means of the competitive growth concept, the secondary dendrite in the gauge length section of the sample in the invention is rapidly grown, and finally, a structure similar to that of the traditional directional solidification alloy sample is formed, and the performance of the sample prepared by adopting the method can be equivalent to that of the traditional method.
6. By adjusting the middle seeding part of the sample, the solid/liquid adjustment in the directional solidification process can be realized, so that the dendritic crystals at two sides form a controllable small-angle crystal boundary in the convergence process, and finally the control of the large-size internal micropores and the small-angle crystal boundary is realized.
The invention has the advantages and beneficial effects that:
1. at present, the Re-containing single crystal high-temperature alloy has high cost, less carbide elements and less purifying element content in the component design, so that the tolerance of the alloy to defects such as large-size internal micropores, small-angle grain boundaries and the like is low, and once the defect performance is detected, the service life of the alloy can be greatly reduced, thereby seriously influencing the qualification rate of high-temperature parts. The invention can obviously improve the defect tolerance of the single crystal superalloy by adding the carbide element and the purification element.
2. The single crystal high temperature alloy material obtained by the invention has high endurance strength limit and creep limit, good high temperature oxidation resistance and thermal corrosion resistance, high thermal stability, and good thermal fatigue resistance and mechanical fatigue resistance even if the single crystal high temperature alloy material contains a certain amount of defects.
3. According to the method, according to the problem that large-size internal micropores are not easily formed in the process of solidifying the single crystal high-temperature alloy, the preparation problem of the large-size internal micropores in the single crystal high-temperature alloy is realized through the combination optimization of alloy components and a sample structure, basic data are provided for the formulation of defect standards of single crystal components of aero-engines, and evaluation results of the method can be used as the basis for alloy selection, single crystal component preparation process parameters and casting head design.
4. The invention can not only realize the quantitative control of the size of the large-size internal micropore, but also realize the quantitative control of the small-angle crystal boundary and the cooperative regulation and control of the large-size internal micropore and the small-angle crystal boundary.
5. The method is simple to operate, reasonable in design, strong in operability, low in cost and beneficial to popularization and application, and the cost in the research and development and production processes of the single crystal high-temperature alloy part can be obviously reduced.
Description of the drawings:
FIG. 1 is a schematic structural view of a variable cross-section alloy member and an auxiliary runner system according to the present invention.
FIG. 2 is a schematic microstructure of a cross-section of an alloy component.
FIG. 3 is a graph of internal pores in a single crystal superalloy sample.
In the figure: 1-an alloy member; 2-an oblique channel; 3-a vertical channel; 4-alloy member ends; 5-selecting a crystal section; 6-crystal introduction section.
The specific implementation mode is as follows:
the invention is described in detail below with reference to the figures and examples.
The experimental master alloy is smelted by a 5kg vacuum induction furnace, the Re granule precast block is placed at the bottom of a crucible, and then elements such as Ni, Co, Mo, W, Nb, Ta and the like are sequentially added. And (4) heating to about 1500 ℃, turning off the vacuum pump and filling argon, continuing heating until the mixture is completely melted, vacuumizing, refining and discharging. Casting into a master alloy ingot with the size of phi 80 multiplied by 500mm, and then polishing to remove oxide skin and cutting into proper blocks for preparing single crystal samples.
The single crystal sample is prepared on a vacuum induction furnace by a spiral crystal selection method, and the contents of elements such as Hf, Zr, Ti, V, Ce, La and the like are not easy to control, so the elements are added in the directional solidification process. The drawing speed of the crystallizer is steplessly adjustable within the range of 1-800 mm/min. The preparation of the directional solidification sample is carried out on a directional solidification furnace, the experimental mould shell is a corundum shell, the mould shell is placed on a copper water-cooled crystallizer, the prepared master alloy is filled into a CaO composite crucible, the directional solidification furnace is pumped into a vacuum state, the mould shell is heated by power transmission, after the alloy is melted, the temperature of the alloy melt is measured by a W-Re galvanic couple, the casting is carried out at 1600 ℃, the heat preservation is carried out for 5 minutes, and then the drawing is carried out at a preset speed, so as to prepare the directional solidification sample.
As shown in FIG. 1, the invention designs a variable cross-section alloy component structure and designs an auxiliary pouring system with a specific structure, wherein the auxiliary pouring system structure comprises a spiral crystal selector, a vertical channel 3 and an inclined channel 2 with an included angle theta with the vertical channel; the upper ends of the vertical channel 3 and the inclined channel 2 are both connected with alloy components, and the lower ends of the vertical channel and the inclined channel are both connected with a spiral crystal selector (comprising a crystal leading section 6 and a crystal selecting section 5);
preparing a metal mold according to the designed alloy component structure and the auxiliary pouring system structure, connecting the auxiliary pouring system wax mold with the alloy component wax mold, coating the ceramic slurry on the wax mold, and manufacturing a ceramic mold shell (corundum mold shell); the bottom of the mould shell (the crystal leading section) is placed on a copper water-cooled crystallizer.
The alloy member 1 includes a middle section, two end portions 4 of the middle section are of a rectangular parallelepiped structure, wherein: the length of the middle section of the alloy component is L1The length (along the length direction of the middle section of the component) of the two cuboid end parts 4 is L2The end of the rectangular block is H1；
In the auxiliary pouring system, the vertical channel is cylindrical, and the diameter of the vertical channel is Y1(ii) a The upper end of the vertical channel is connected to the central position of the middle section of the alloy component; the upper ends of the two inclined channels are respectively connected to the bottom centers of the end parts of the alloy component cuboid; a crystal leading section at the lower part of the spiral crystal selector and a crystal selecting section at the upper part of the spiral crystal selector; the lower ends of the vertical channel and the two inclined channels are connected with the upper part of the crystal selection section.
In the present invention, L1Is 10-40mm, L20.5-10mm, H120-45mm while defining 1 < L1/L2＜3，1＜H1/L2< 5, by pairing L1、L2And H1The size among the three is regulated and controlled to realize the control of the feeding channel in the directional solidification process, and further realize the regulation and control of the size of the micropores in the component.
In the present invention, the diameter Y of the vertical passage1Is 0.5-10mm, limit 1 < L1/Y1< 4, by pairing Y1And L1The size is regulated and controlled, so that the dendrites meet at different degrees, and the preparation of the small-angle grain boundary defects with different angle differences is realized.
Example 1
The composition of the present example is shown in table 1, and the alloy has a certain amount of carbide forming elements and rare earth elements added to the original alloy composition (table 2), wherein the total amount of Hf + Zr elements is 0.02wt.%, the weight of Ti + V is 0.09 wt.%, Ce/La is 1, and O + N is less than or equal to 0.021 wt.%. The carbide content of the superalloy is increased by adding a small amount of carbide-forming elements. In addition, by changing the size in the structure of the sample, the internal micropores with large size in the alloy are reduced, and a certain amount of small-angle grain boundaries are formed, wherein L1Size 10mm, L2Size 0.5mm, H1The size is 20mm, Y1Is 0.5mm in diameter. Melting paraffin at 50 ℃, injecting the molten paraffin into a single crystal component metal mould with a thermal insulation riser through a paraffin injection machine, combining wax patterns completely, coating wax on the combined wax patterns after slurry coating and drying, and sintering the wax patterns after slurry coating, sand spraying and dewaxing to prepare the corundum mould shell, wherein the sintering temperature is 850 ℃, the sintering time is 1 hour, and the thickness of the middle section membrane shell of the sample is 20 percent thinner than that of the two ends so as to increase heat dissipation.
And then performing directional solidification in a vacuum directional furnace, wherein the single crystal preparation process comprises the steps of performing directional solidification under the conditions that the vacuum degree is 0.01Pa, the casting temperature of the alloy is 1550 ℃, and the pulling speed is 5mm/min, and performing mechanical processing on samples of two alloy components after warp cutting and heat treatment to obtain the standard mechanical property test bar. FIG. 2 is a schematic view showing the microstructure of the cross section of the alloy structural member of this embodiment. FIG. 3 is a graph of internal pores in a single crystal superalloy sample. The alloy test bars were subjected to mechanical property tests, and the test results are shown in table 3.
Table 1 alloy composition of example 1, wt.%
| C | Cr | Al | Co | Mo | Nb | W | Ta | Re | Y | Hf | Zr | Ti | V |
| 0.16 | 4.4 | 5.65 | 9.4 | 1.3 | 1.4 | 8.8 | 4.0 | 3.8 | 0.003 | 0.01 | 0.01 | 0.05 | 0.04 |
| Ce | La | B | S | O | N | Ni | |||||||
| 0.003 | 0.003 | 0.003 | 0.002 | 0.001 | 0.02 | Surplus |
TABLE 2 original alloy composition in wt.%
| C | Cr | Al | Co | Mo | Nb | W | Ta | Re | Y | RE | Ni |
| 0.16 | 4.4 | 5.65 | 9.4 | 1.3 | 1.4 | 8.8 | 4.0 | 3.8 | 0.003 | 0.008 | Surplus |
TABLE 3 example 1 alloy structural member 100 hours proof strength/MPa
As shown in Table 3, the single crystal alloy containing the micropore defects has the same endurance performance as the original alloy at the intermediate temperature and 980 ℃, is slightly lower than the original alloy at 1100 ℃, and also has better internal micropore defect resistance.
Example 2
The composition of the alloy of this example is shown in table 4, and a certain amount of carbide-forming elements and rare earth elements are added to the original alloy composition (table 2), wherein the total amount of Hf + Zr elements is 0.06 wt.%, the Ti + V accounts for 0.3wt.%, and O + N is less than or equal to 0.021 wt.%, unlike example 1, the alloy composition of this example is characterized in that the carbide-forming elements are added to the upper limit, and the rare earth elements are also added to the upper limit. The carbide content of the superalloy is increased by adding a small amount of carbide-forming elements. In addition, by changing the size in the structure of the sample, the internal micropores with large size in the alloy are reduced, and a certain amount of small-angle grain boundaries are formed, wherein L1Size 10mm, L2Size 0.5mm, H1The size is 20mm, Y1Is 0.5mm in diameter. Melting paraffin at 50 deg.C, and passing through paraffin injection machineInjecting molten paraffin into a pre-designed single crystal component metal mold with a heat-insulating riser, combining wax patterns completely, coating wax on the combined wax pattern after slurry coating is dried, coating the wax, then performing slurry coating, sand spraying and dewaxing on the wax pattern, and sintering to prepare the corundum mold shell, wherein the sintering temperature is 850 ℃, the sintering time is 1 hour, and the thickness of the middle section of the corundum mold shell is 20% thinner than that of the two ends of the corundum mold shell so as to increase heat dissipation. And then performing directional solidification in a vacuum directional furnace, wherein the single crystal preparation process comprises the steps of performing directional solidification under the conditions that the vacuum degree is 0.01Pa, the casting temperature of the alloy is 1550 ℃, and the pulling speed is 5mm/min, performing mechanical property test after the samples of the two alloy components are subjected to warp cutting and heat treatment, and performing mechanical property test, wherein the test results are shown in table 5.
Table 4 alloy composition of example 2, wt.%
| C | Cr | Al | Co | Mo | Nb | W | Ta | Re | Y | Hf | Zr | Ti | V |
| 0.16 | 4.4 | 5.65 | 9.4 | 1.3 | 1.4 | 8.8 | 4.0 | 3.8 | 0.005 | 0.03 | 0.03 | 0.2 | 0.1 |
| La | Ce | B | S | O | N | Ni | |||||||
| 0.0055 | 0.0045 | 0.008 | 0.001 | 0.001 | 0.002 | Surplus |
TABLE 5 example 2 alloy structural member 100 hours proof stress/MPa
Table according to table 5, the single crystal alloys containing micro-porosity defects according to the present invention showed durability comparable to that of the original alloys at 760 ℃, 980 ℃ and 1100 ℃, and showed good resistance to internal micro-porosity defects.
Example 3
The alloy composition of this example was the same as that of example 2, and the sample structure was dimensionedAnd adjusting to ensure that solidification defects such as small-angle crystal boundaries, internal micropores and the like exist in the sample at the same time. The composition of the present example is shown in table 6, and the alloy is obtained by adding a certain amount of carbide-forming elements and rare earth elements to the original alloy composition (table 2), wherein the total amount of Hf + Zr elements is 0.06 wt.%, the weight of Ti + V is 0.3wt.%, and O + N is less than or equal to 0.021 wt.%, and the composition is characterized in that the carbide-forming elements are added to the upper limit, and the rare earth elements are also added to the upper limit. The carbide content of the superalloy is increased by adding a small amount of carbide-forming elements. In addition, by changing the size in the structure of the sample, the internal micropores with large sizes in the alloy are reduced, and a certain amount of small-angle grain boundaries are formed. L is1The size is 40mm, L2Size 0.5mm, H1The size is 20mm, Y1Is 0.5mm in diameter. Melting paraffin at 50 ℃, injecting the molten paraffin into a single crystal component metal mould with a thermal insulation riser through a paraffin injection machine, combining wax patterns completely, coating wax on the combined wax patterns after slurry coating and drying, and sintering the wax patterns after slurry coating, sand spraying and dewaxing to prepare the corundum mould shell, wherein the sintering temperature is 850 ℃, the sintering time is 1 hour, and the thickness of the middle section membrane shell of the sample is 20 percent thinner than that of the two ends so as to increase heat dissipation. And then performing directional solidification in a vacuum directional furnace, wherein the single crystal preparation process comprises the steps of performing directional solidification under the conditions that the vacuum degree is 0.01Pa, the casting temperature of the alloy is 1550 ℃, and the pulling speed is 5mm/min, performing mechanical property test after the samples of the two alloy components are subjected to warp cutting and heat treatment, and performing mechanical property test, wherein the test results are shown in Table 7.
TABLE 6 alloy composition of example 3, wt.%
| C | Cr | Al | Co | Mo | Nb | W | Ta | Re | Y | Hf | Zr | Ti | V |
| 0.16 | 4.4 | 5.65 | 9.4 | 1.3 | 1.4 | 8.8 | 4.0 | 3.8 | 0.005 | 0.03 | 0.03 | 0.2 | 0.1 |
| La | Ce | B | S | O | N | Ni | |||||||
| 0.0055 | 0.0045 | 0.008 | 0.001 | 0.001 | 0.002 | Surplus |
TABLE 7 100 hours proof Strength/MPa for alloy structural members of example 3
Table 7 shows that the single crystal alloys of the present invention containing micro-porosity defects and small angle grain boundaries exhibit good creep resistance at 760 ℃ and 980 ℃, while the endurance performance at 1100 ℃ is slightly lower than that of the original alloys, showing good resistance to internal micro-porosity defects and small angle grain boundary defects.
Example 4
The structural size of the sample is adjusted, so that solidification defects such as small-angle crystal boundaries, internal micropores and the like exist in the sample at the same time. The composition of the present example is shown in table 8, and the alloy is obtained by adding a certain amount of carbide-forming elements and rare earth elements to the original alloy composition (table 2), wherein the total amount of Hf + Zr elements is 0.05 wt.%, the weight of Ti + V is 0.25 wt.%, and O + N is less than or equal to 0.021 wt.%, and the composition is characterized in that the carbide-forming elements are added to the upper limit, and the rare earth elements are also added to the upper limit. The carbide content of the superalloy is increased by adding a small amount of carbide-forming elements. In addition, by changing the size in the structure of the sample, the internal micropores with large sizes in the alloy are reduced, and a certain amount of small-angle grain boundaries are formed. L is1The size is 40mm, L2Size 10mm, H1The size is 45mm, Y1Is 10mm in diameter. Melting paraffin at 50 ℃, injecting the molten paraffin into a single crystal component metal mould with a thermal insulation riser through a paraffin injection machine, combining wax patterns completely, coating wax on the combined wax patterns after slurry coating and drying, and sintering the wax patterns after slurry coating, sand spraying and dewaxing to prepare the corundum mould shell, wherein the sintering temperature is 850 ℃, the sintering time is 1 hour, and the thickness of the middle section membrane shell of the sample is 20 percent thinner than that of the two ends so as to increase heat dissipation. Then carrying out directional solidification in a vacuum directional furnace, wherein the single crystal preparation process comprises the steps of controlling the vacuum degree to be 0.01Pa and pouring the alloy at the casting temperatureThe directional solidification is carried out at 1550 ℃ and the drawing speed of 5mm/min, samples of two alloy components are subjected to wire cutting and heat treatment, standard mechanical property test bars are machined, and mechanical property tests are carried out, wherein the test results are shown in table 9.
TABLE 8 alloy composition of example 4, wt.%
| C | Cr | Al | Co | Mo | Nb | W | Ta | Re | Y | Hf | Zr | Ti | V |
| 0.16 | 4.4 | 5.65 | 9.4 | 1.3 | 1.4 | 8.8 | 4.0 | 3.8 | 0.005 | 0.025 | 0.025 | 0.15 | 0.1 |
| La | Ce | B | S | O | N | Ni | |||||||
| 0.0055 | 0.0035 | 0.007 | 0.001 | 0.001 | 0.002 | Surplus |
TABLE 9 100 hours proof Strength/MPa for alloy structural members of example 2
As shown in Table 9, the single crystal alloy containing the micro-pore defects and the small angle grain boundaries of the invention has better creep resistance under the conditions of 760 ℃ and 980 ℃, the mechanical property difference of the single crystal alloy and the original alloy component alloy is less than 10%, the endurance property at 1100 ℃ is slightly lower than that of the original alloy and is only 35MPa, and the single crystal alloy has better resistance to the internal micro-pore defects and the small angle grain boundaries.
The working process and the result of the invention are as follows:
according to the method, according to the problem that large-size internal micropores are not easily formed in the process of solidifying the single crystal high-temperature alloy, the preparation problem of the large-size internal micropores in the single crystal high-temperature alloy is realized through the combination optimization of alloy components and a sample structure, basic data are provided for the formulation of defect standards of single crystal components of aero-engines, and evaluation results of the method can be used as the basis for alloy selection, single crystal component preparation process parameters and casting head design. The method is simple to operate, reasonable in design, strong in operability, low in cost and beneficial to popularization and application, and the cost in the research and development and production processes of the single crystal high-temperature alloy part can be obviously reduced.
The embodiment result shows that the preparation method has the characteristics of simple preparation process, low cost and the like, can solve the problem of low tolerance of the large-size internal micropore and small-angle grain boundary of the single crystal superalloy, realizes the design and defect preparation of the high-defect-tolerance single crystal superalloy material through the improvement of the component optimization and preparation method, is favorable for the research and development of the single crystal superalloy material, and provides a basis for the establishment of the defect standard of an actual aero-engine.
Claims (6)
1. A high defect tolerant single crystal superalloy component, comprising: the single crystal superalloy component comprises the following chemical components in percentage by weight:
0.12-0.18% of C, 4.3-5.6% of Cr, 5.6-6.3% of Al, 8.0-10.0% of Co, 0.8-1.4% of Mo, 7.7-9.3% of W, 1.4-1.8% of Nb, 3.5-4.5% of Ta, 3.5-4.5% of Re, 0.001-0.005% of Y, 0.005-0.03% of Hf, 0.005-0.03% of Zr, less than or equal to 0.2% of Ti, 0.001-0.1% of V, 0.001-0.0055% of Ce, 0.001-0.0045% of La, and the balance of Ni and inevitable impurities;
the preparation method of the single crystal high-temperature alloy component with high defect tolerance is to prepare the single crystal high-temperature alloy component with high defect tolerance by adopting a directional solidification process, and comprises the following steps:
(1) mixing the raw materials according to the alloy components, and preparing a master alloy by utilizing vacuum induction melting;
(2) designing an alloy component structure and an auxiliary pouring system structure, wherein the auxiliary pouring system structure comprises a spiral crystal selector, a vertical channel and an inclined channel with an included angle theta with the vertical channel; the upper ends of the vertical channel and the inclined channel are both connected with alloy components, and the lower ends of the vertical channel and the inclined channel are both connected with a spiral crystal selector;
(3) preparing a metal mold and a ceramic mold shell according to the alloy component structure and the auxiliary pouring system structure designed in the step (2); the bottom of the mould shell is placed on a copper water-cooling crystallizer;
(4) performing directional solidification in a directional solidification furnace by adopting a spiral crystal selection method to obtain a single crystal high-temperature alloy component with high defect tolerance; wherein: the alloy pouring temperature in the directional solidification is 1520 and 1580 ℃, and the pulling speed is 5 mm/min;
in the step (2), the alloy member includes a middle section, and two ends of the middle section are of a rectangular parallelepiped structure, wherein: the length of the middle section of the alloy component is L1The length of the two rectangular end parts is L2The end of the rectangular block is H1；
In the auxiliary pouring system, the vertical channel is cylindrical, and the diameter of the vertical channel is Y1(ii) a The upper end of the vertical channel is connected to the central position of the middle section of the alloy component; the upper ends of the two inclined channels are respectively connected to the bottom centers of the end parts of the alloy component cuboid; a crystal leading section at the lower part of the spiral crystal selector and a crystal selecting section at the upper part of the spiral crystal selector; the lower ends of the vertical channel and the two inclined channels are connected with the upper part of the crystal selection section;
in the step (2), L is more than 11/L2＜3，1＜H1/L2< 5, and L1Is 10-40mm, L20.5-10mm, H120-45mm, by pair L1、L2And H1The size of the three components is regulated and controlled to realize the control of a feeding channel in the directional solidification process, so that the size of micropores in the component is regulated and controlled;
in the step (2), the diameter Y of the vertical channel10.5-10mm, L is more than 11/Y1< 4, by pairing Y1And L1The size is regulated and controlled, so that the dendrites meet at different degrees, and the preparation of the small-angle grain boundary defects with different angle differences is realized.
2. The high defect tolerant single crystal superalloy component of claim 1, wherein: in the chemical components of the single crystal superalloy component, O is less than or equal to 0.02wt.%, N is less than or equal to 0.02wt.%, S is less than or equal to 0.004 wt.%, and B is less than or equal to 0.008 wt.%.
3. The high defect tolerant single crystal superalloy component of claim 1 or 2, wherein: in the chemical components of the single crystal high-temperature alloy component, the total content of Hf and Zr elements is more than or equal to 0.02 wt.%.
4. The high defect tolerant single crystal superalloy component of claim 1 or 2, wherein: in the chemical components of the single crystal superalloy component, the sum of Ti and V is more than or equal to 0.001 wt% and less than or equal to 0.3 wt%.
5. The high defect tolerant single crystal superalloy component of claim 1 or 2, wherein: in the chemical components of the single crystal high temperature alloy component, Ce/La is less than or equal to 1.
6. The high defect tolerant single crystal superalloy component of claim 2, wherein: in the chemical composition of the single crystal superalloy component, O + N is less than or equal to 0.03 wt%.
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