Modified isometric crystal high-temperature alloy with cooperatively improved casting performance and mechanical performance and preparation method of modified isometric crystal high-temperature alloy

Abstract

The invention relates to the technical field of isometric crystal high-temperature alloy casting, and discloses a modified isometric crystal high-temperature alloy with casting performance and mechanical performance synergistically improved and a preparation method, and the modified cast high-temperature alloy comprises three different proportions including 0.04% by mass of C, 0.06% by mass of C and 0.08% by mass of C, the preparation method comprises the following steps: putting a graphite rod and an unmodified K4169 master alloy into a vacuum induction melting furnace for mixing, smelting and refining to obtain a modified cast high-temperature alloy; the problems that at present, K4169 high-temperature alloy is generally smelted through median components, and in the production process of existing aero-engine complex-structure castings, particularly thin-wall positions and complex-structure parts are prone to mold filling difficulty, multiple internal loose defects exist and the like are solved. The modified cast superalloy is prepared by optimizing the content of the C element, the flowing mold-filling capacity of the alloy is improved, the loose defect of an alloy casting is reduced, the mechanical property of the alloy is improved, and cooperative improvement of the casting property and the mechanical property of the isometric crystal superalloy is achieved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of equiaxed crystal high-temperature alloy casting, and particularly relates to a modified equiaxed crystal high-temperature alloy with improved casting performance and mechanical performance and a preparation method. BACKGROUND

[0002] High-temperature alloys play a vital role in key components of an aero-engine, especially the most widely used equiaxed crystal casting high-temperature alloy K4169. With the requirements of high performance, high reliability and structure weight reduction of an aero-engine, the complex structure castings of high-temperature alloys gradually develop towards integration, thinning and size accuracy, which leads to the problems of underfilling and many porosity defects in the production process of the conventional high-temperature alloy complex structure parts, and the forming quality of the castings directly affects the performance, service life and structural reliability of the aero-engine, and also seriously affects the production efficiency of the castings. The standard component range of the casting high-temperature alloy K4169 is wide, and the medium value component smelting is generally adopted at present, which cannot meet the design requirements of the aero-engine.

[0003] Therefore, it is urgent to find an alloy component with stronger filling capacity, fewer porosity defects and more excellent mechanical performance within the standard component range. SUMMARY

[0004] In view of the problems of filling difficulty and many internal porosity defects in the production process of the complex structure parts in the prior art, the present application provides a modified equiaxed crystal high-temperature alloy with improved casting performance and mechanical performance and a preparation method, improves the alloy flow filling capacity, reduces the alloy casting porosity defects, improves the alloy mechanical performance, and realizes the synergistic improvement of the casting performance and mechanical performance of the equiaxed crystal high-temperature alloy.

[0005] The present application provides a modified equiaxed crystal high-temperature alloy with improved casting performance and mechanical performance, which comprises the following components:

[0006]

[0007] The above percentages are mass percentages, and the total mass percentage of the components is 100% of the modified equiaxed crystal high-temperature alloy.

[0008] Further, the mass percentage of C is 0.04%, 0.06% or 0.08%.

[0009] Further, the characteristic solidification temperature interval of the modified equiaxed crystal high-temperature alloy decreases with the increase of the C content, and the characteristic solidification temperature interval is ≤72℃.

[0010] Further, under the same casting process, the alloy flow filling capacity test is carried out, and the flow filling length of the modified equiaxed crystal high-temperature alloy is 254mm-286mm.

[0011] Furthermore, room temperature tensile and high temperature endurance tests were carried out under the same conditions, and the modified equiaxed high temperature alloy had a tensile strength of 1055 MPa, a yield strength of 946 MPa, and a high temperature endurance life of 103.1 h.

[0012] The present invention also provides a method for preparing a modified equiaxed grained superalloy with synergistically improved casting properties and mechanical properties. Based on the modified equiaxed grained superalloy with synergistically improved casting properties and mechanical properties as described above, the preparation method specifically comprises:

[0013] preparing graphite rods with a set mass fraction and preparing unmodified K4169 master alloy;

[0014] The graphite rod and the unmodified K4169 master alloy are placed in a vacuum induction melting furnace for combined melting and refining to obtain the modified equiaxed high-temperature alloy.

[0015] Furthermore, the mass fraction of the graphite rod includes three different ratios: 0.04%, 0.06%, and 0.08%.

[0016] Furthermore, the vacuum pressure of the vacuum induction melting furnace for melting is set at 1×10 -2 MPa~6×10 - 2 Between MPa.

[0017] Furthermore, the refining temperature of the vacuum induction melting furnace is 1470° C. to 1500° C., and the refining time is 3-5 minutes.

[0018] Furthermore, the components of the unmodified K4169 master alloy include: 0.02% C, 52.5% Ni, 19% Cr, 3.05% Mo, 0.5% Al, 4.9% Nb, 0.9% Ti, impurities ≤0.01%, and the balance Fe.

[0019] The beneficial effects of the present invention are:

[0020] In the present invention, the C element is mainly segregated at the grain boundaries during the solidification process. It is a serious solidification segregation element and forms MC carbides with a face-centered cubic structure with other carbide-forming elements. The carbides formed are mainly distributed in the grain boundary area. The morphology of the carbides mainly depends on the characteristic solidification temperature range of the alloy and the width of the channels between the alloy dendrites. K4169 nickel-based cast high-temperature alloy, the carbides in its cast alloy are mainly MC carbides (NbC, TiC). The addition of the C element will cause other elements such as Nb and Ti to segregate between the dendrites, promote the increase in the size of the MC carbides between the dendrites, thereby occupying the loose formation position between the dendrites, reducing the loose defects of the alloy, and improving the mechanical properties of the alloy. Finally, by optimizing the C element content in the high-temperature alloy to prepare a modified high-temperature alloy, the flow and filling ability of the alloy is improved, the loose defects of the alloy castings are reduced, and the mechanical properties of the equiaxed high-temperature alloy are improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 This is a diagram showing the actual results of the flow filling ability test of the comparative example of the present invention.

[0022] Figure 2 This is a diagram showing the actual results of the flow and filling ability test of Example 1 of the present invention.

[0023] Figure 3 This is a diagram showing the actual results of the flow and filling ability test of Example 2 of the present invention.

[0024] Figure 4 This is a diagram showing the actual results of the flow-filling ability test of Example 3 of the present invention.

[0025] Figure 5 The figure shows the result of physical property parameters obtained by simulation of comparative examples and examples of the present invention.

[0026] Figure 6 The metallographic images of the loose defects at three locations, namely, the riser, 30 mm from the riser, and the midpoint of the spiral, obtained in the comparative example of the present invention.

[0027] Figure 7 This is a metallographic diagram of the loose defects at three locations: the riser, 30 mm from the riser, and the midpoint of the spiral obtained in Example 1 of the present invention.

[0028] Figure 8 This is a metallographic diagram of the loose defects at three locations: the riser, 30 mm from the riser, and the midpoint of the spiral obtained in Example 2 of the present invention.

[0029] Figure 9 This is a metallographic diagram of the loose defects at three locations: the riser, 30 mm from the riser, and the midpoint of the spiral obtained in Example 3 of the present invention.

[0030] Figure 10 It is a diagram of the room temperature stretching results of the comparative example and each example of the present invention.

[0031] The purpose, features and advantages of the present invention will be further described with reference to the accompanying drawings and in conjunction with the embodiments. DETAILED DESCRIPTION

[0032] The technical solutions of the present invention are described in detail below in conjunction with specific embodiments and their accompanying drawings. The embodiments described herein are specific embodiments of the present invention and are used to illustrate the concept of the present invention; these descriptions are explanatory and exemplary and should not be understood as limiting the embodiments of the present invention and the scope of protection of the present invention. In addition to the embodiments described herein, those skilled in the art can also adopt other obvious technical solutions based on the contents disclosed in the claims of this application and its specification, including technical solutions that adopt any obvious replacements and modifications to the embodiments described herein.

[0033] The casting properties of an alloy primarily include its flow-filling capacity and its shrinkage during solidification. The flow-filling capacity directly impacts the formability of alloy structures and complex thin-walled parts, while the shrinkage during solidification can affect the formation of porosity defects, thereby impacting the alloy's mechanical properties. The casting properties of an alloy are primarily determined by the elemental composition and content of the high-temperature alloy, the alloy's thermophysical properties, and the casting process.

[0034] At present, under the premise of not changing the high-temperature alloy casting process, the casting performance and mechanical properties of the alloy can be improved to a certain extent by changing the composition and content of the alloying elements. For the cast high-temperature alloy K4169, its alloy composition elements are relatively large and the composition range is relatively wide, but the median composition smelting is generally adopted at present. Changing the content of the main alloying elements within the standard range will greatly affect the casting performance of the alloy, but may also deteriorate the mechanical properties of the alloy. Therefore, the present invention chooses to optimize the content of the C element within the standard composition range to improve the flow filling ability of the cast high-temperature alloy, reduce the generation of loose defects, improve the mechanical properties of the high-temperature alloy, and achieve a synergistic improvement in the casting performance and mechanical properties of the alloy, which has great engineering significance for improving the molding quality of complex thin-walled castings of the alloy.

[0035] In the following examples and comparative examples, the present invention selects unmodified K4169 nickel-based casting high-temperature alloy, and prepares a modified high-temperature alloy by optimizing the content of the C element, thereby improving the flow and filling ability of the nickel-based casting high-temperature alloy, reducing porosity defects, improving the mechanical properties of the casting alloy, and achieving a synergistic improvement in the casting performance and mechanical properties of the casting alloy. It should be noted that the unmodified K4169 nickel-based casting high-temperature alloy selected by the present invention is only used to illustrate that the method disclosed herein can achieve a synergistic improvement in the casting performance and mechanical properties of the K4169 casting high-temperature alloy by optimizing the C element content. For unmodified K4169 nickel-based casting high-temperature alloys composed of other component contents, the casting performance and mechanical properties of K4169 can also be improved by this method.

[0036] The present invention provides a modified equiaxed high-temperature alloy with synergistically improved casting performance and mechanical properties, characterized in that it comprises the following components in mass percentage: C is 0.038-0.08%, Ni is 52.5%, Ti is 0.9%, Cr is 19%, Mo is 3.05%, Al is 0.5%, Nb is 4.9%, impurities are ≤0.01%, and the balance is Fe, and the total mass percentage of the above components is 100% of the modified K4169 casting high-temperature alloy.

[0037] In one embodiment, the mass percentages of C are 0.04%, 0.06%, and 0.08%, respectively. The mass percentages of C can also be 0.038%, 0.042%, 0.056%, 0.063%, 0.078%, and 0.08%, but are not limited to the listed values. Other values ​​not listed near these values ​​are also applicable.

[0038] In one embodiment, the characteristic solidification temperature range of the modified equiaxed superalloy decreases with increasing carbon content, and the characteristic solidification temperature range is ≤72°C.

[0039] In one embodiment, the alloy flow filling ability test is carried out under the same casting process, and the flow filling length of the modified equiaxed grain high temperature alloy is 254mm-286mm; room temperature tensile and high temperature endurance tests are carried out under the same conditions, and the tensile strength of the modified equiaxed grain high temperature alloy is 1055MPa, the yield strength is 946MPa, and the high temperature endurance life is 103.1h.

[0040] During solidification, carbon primarily segregates at grain boundaries, a significant solidification segregation element. Together with other carbide-forming elements, it forms face-centered cubic (MC) carbides. The resulting carbides are primarily distributed at grain boundaries, and their morphology depends primarily on the alloy's characteristic solidification temperature range and the width of the interdendritic channels. In the K4169 nickel-based cast superalloy, the carbides in the as-cast alloy are primarily MC carbides (NbC and TiC). Increasing the carbon content alters the interdendritic segregation of other elements, such as Nb and Ti, promoting the increase in the size of interdendritic MC carbides. These carbides occupy interdendritic porosity formation sites and reduce alloy porosity defects.

[0041] The present invention also provides a method for preparing a modified equiaxed grained superalloy with synergistically improved casting properties and mechanical properties. Based on the modified equiaxed grained superalloy with synergistically improved casting properties and mechanical properties as described above, the preparation method specifically comprises:

[0042] S1. Prepare graphite rods with a set mass fraction and prepare unmodified K4169 master alloy;

[0043] The mass fraction of the graphite rod includes three different ratios: 0.04%, 0.06%, and 0.08%. The unmodified K4169 master alloy includes a K4169 nickel-based cast high-temperature alloy with a low C element content, and the specific components include: C is 0.02%, Ni is 52.5%, Cr is 19%, Mo is 3.05%, Al is 0.5%, Nb is 4.9%, Ti is 0.9%, impurities are ≤0.01%, and the balance is Fe.

[0044] S2. Putting the graphite rod and the unmodified K4169 master alloy into a vacuum induction melting furnace for combined melting and refining to obtain the modified equiaxed high-temperature alloy.

[0045] In one embodiment, the vacuum pressure of the vacuum induction melting furnace for melting is set at 1×10 -2 MPa~6×10 -2 MPa, for example, it can be 1×10 -2 MPa, 2×10 -2 MPa, 3×10 -2 MPa, 4×10 -2 MPa, 5×10 -2 MPa or 6×10 -2 MPa, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0046] In one embodiment, the vacuum induction melting furnace is refined at a temperature of 1470 °C to 1500 °C, for example, it can be 1470 °C, 1475 °C, 1480 °C, 1485 °C, 1490 °C or 1500 °C, but not limited to the listed values, other values not listed in the range are also applicable.

[0047] The refining time of the vacuum induction melting furnace is 3-5 min, for example, it can be 3 min, 4 min or 5 min, but not limited to the listed values, other values not listed in the range are also applicable.

[0048] In order to make the purpose, technical scheme and advantages of the present application more clear and explicit, the technical scheme and principles of the present application are further explained and described below by specific examples and in conjunction with the drawings. It should be noted that the following specific examples are only illustrative, and the protection scope of the present disclosure is not limited thereto.

[0049] Example 1

[0050] This example provides a modified cast high-temperature alloy, which includes a C component in the modified cast high-temperature alloy with a mass percentage of 0.04%, and other alloy element contents are taken as the median value of the standard component range. The alloy component content of the modified cast high-temperature alloy is shown in Table 1.

[0051] Table 1

[0052] C(％) Ni(%) Ti(%) Cr(％) Mo (%) Al(％) Nb(%) Fe(%) Impurities (%) 0.04 52.5 0.9 19.0 3.05 0.5 4.9 margin ≤0.01

[0053] Example 2

[0054] This example provides a modified cast high-temperature alloy, which includes a C component in the modified cast high-temperature alloy with a mass percentage of 0.06%, and other alloy element contents are taken as the median value of the standard component range. The alloy component content of the modified cast high-temperature alloy is shown in Table 2.

[0055] Table 2

[0056] C(％) Ni(%) Ti(%) Cr(％) Mo (%) Al(％) Nb(%) Fe(%) Impurities (%) 0.06 52.5 0.9 19.0 3.05 0.5 4.9 margin ≤0.01

[0057] Example 3

[0058] This example provides a modified cast high-temperature alloy, which includes a C component in the modified cast high-temperature alloy with a mass percentage of 0.08%, and other alloy element contents are taken as the median value of the standard component range. The alloy component content of the modified cast high-temperature alloy is shown in Table 3.

[0059] Table 3

[0060] C(％) Ni(%) Ti(%) Cr(％) Mo (%) Al(％) Nb(%) Fe(%) Impurities (%) 0.08 52.5 0.9 19.0 3.05 0.5 4.9 margin ≤0.01

[0061] Comparative Example

[0062] This comparative example provides an unmodified cast high-temperature alloy. The difference from Example 1 is that the unmodified alloy has a lower C element content, which is around 0.02%. A low-C content K4169 nickel-based cast high-temperature alloy is obtained, and its alloy component contents are shown in Table 4.

[0063] Table 4

[0064] C(％) Ni(%) Ti(%) Cr(％) Mo (%) Al(％) Nb(%) Fe(%) Impurities (%) 0.02 52.5 0.9 19.0 3.05 0.5 4.9 margin ≤0.01

[0065] The modified cast superalloys obtained in Examples 1 to 3 of the present invention and the unmodified K4169 nickel-based cast superalloy of the comparative example were subjected to flow and filling ability tests, porosity defect statistics, and mechanical property tests. The methods for the flow and filling ability tests, porosity defect statistics, and mechanical property tests are as follows:

[0066] (1) Flow filling capacity test

[0067] like Figure 1-4 The graphs below show the actual results of flow-filling capability tests for the comparative example and Examples 1-3, respectively. These tests were conducted using a self-developed spiral mold with a spiral section thickness of 3mm and a height of 10mm. The mold was held at 980°C, the pouring temperature was 1450°C, and the pouring rate was 0.5 kg / s. The length of the alloy liquid filling the spiral section after solidification was used to characterize its flow-filling capability. The flow-filling capability was determined by removing the spiral alloy test specimens from the mold and measuring their streamline length.

[0068] The flow filling ability test results of each example and comparative example are shown in Table 5.

[0069] Table 5

[0070]

[0071] As can be seen from Table 5, the modified cast high-temperature alloy prepared in the present invention by optimizing the C element content is compared with the comparative example K4169 nickel-based cast high-temperature alloy. When the C element content is optimized to 0.06%, the flow filling ability of the modified cast high-temperature alloy is improved by 41% compared with the flow filling ability of the unmodified K4169 nickel-based cast high-temperature alloy.

[0072] (2) Statistics of loose defects

[0073] like Figure 6-9 As shown, the spiral specimen obtained by the above-mentioned flow filling ability test was used to take samples at the cross sections of the spiral specimen at the riser, 30 mm of the spiral and the midpoint of the spiral. Then, the specimen was prepared and the porosity defects were counted under an optical microscope to determine the porosity defects.

[0074] The statistical results of the loose areas of each example and comparative example are shown in Table 6.

[0075] Table 6

[0076]

[0077] As can be seen from Table 6, the modified cast high-temperature alloy prepared by optimizing the C element content in the present invention has a porosity area percentage of 0.79% when the C content is 0.06%, which is the lowest compared to the unmodified K4169 nickel-based cast high-temperature alloy, and the shrinkage area is reduced by about 81%.

[0078] (3) Mechanical properties test

[0079] Standard heat treatment and mechanical property tests were performed on the modified cast superalloys obtained in Examples 1 to 3 and the unmodified K4169 nickel-based cast superalloy of the comparative example.

[0080] 1) Heat treatment adopts K4169 standard heat treatment. The specific process and parameters of the heat treatment process include:

[0081] a. Homogenization: The homogenization temperature is 1095°C, the holding time is 1.5h, and air-cooled to room temperature;

[0082] b. Solution treatment: The solution treatment temperature is 950 ° C, the holding time is 1h, and air cooling to room temperature;

[0083] c. Graded aging treatment: The primary aging treatment temperature is 720°C, and the holding time is 8 hours. Then the temperature is lowered to the secondary aging temperature of 620°C at a cooling rate of 50°C / h, and the temperature is kept for 8 hours, and then air-cooled to room temperature.

[0084] 2) Mechanical properties tests include room temperature tensile testing and 650℃ / 620MPa endurance testing. Universal tensile testing machine and high temperature endurance creep testing machine were used to carry out room temperature tensile testing and 650℃ / 620MPa endurance testing respectively. Figure 10 The tensile strength, yield strength, elongation and rupture time of the modified high-temperature alloy and the unmodified cast high-temperature alloy were measured respectively.

[0085] The room temperature stretching results of each example and comparative example are shown in Table 7.

[0086] Table 7

[0087]

[0088] As can be seen from Table 7, the modified cast high-temperature alloy prepared by optimizing the C element content in the present invention, compared with the unmodified K4169 nickel-based cast high-temperature alloy, when the C content is 0.06%, the modified cast high-temperature alloy has a room temperature tensile strength of 1055 MPa, a yield strength of 946 MPa, and an elongation of 6%, and all properties are superior to those of the unmodified high-temperature alloy.

[0089] In the present invention, Example 2 and the comparative example with the best casting performance and the highest tensile performance were selected to conduct a 650°C / 620MPa endurance test. The endurance life results of Example 2 and the comparative example are shown in Table 8.

[0090] Table 8

[0091] Alloy Type Duration (h) Example 2 103.1 Comparative Example 17.5

[0092] As can be seen from Table 8, the modified cast high-temperature alloy prepared by optimizing the C element content in the present invention has a durability life of 103.1 h compared to the unmodified K4169 nickel-based cast high-temperature alloy when the C content is 0.06%, which is significantly better than the 17.5 h of the unmodified high-temperature alloy, and the durability life is increased by about 83.0%.

[0093] By optimizing the C content, the K4169 nickel-based casting high-temperature alloy is modified to improve the flow and filling ability of the K4169 nickel-based casting high-temperature alloy, reduce porosity defects, and improve the mechanical properties of the high-temperature alloy. The main reasons for achieving a synergistic improvement in casting performance and mechanical properties are as follows:

[0094] When the casting process parameters remain the same, the change of C element content mainly affects the flow and filling ability of the alloy by affecting the physical properties of the alloy. Among them, specific heat, surface tension, viscosity, solidification temperature range, etc. will have a greater impact on the flow and filling ability of the alloy.

[0095] Regarding alloy specific heat, under conditions of equal mass and superheat, the greater the alloy's specific heat, the more heat released during solidification, the longer it remains liquid, and thus improves the alloy's flow and filling ability. In the K4169 nickel-based casting superalloy, increasing the C content causes the alloy's peak specific heat to first increase and then decrease, showing a similar trend to the alloy's flow and filling ability.

[0096] Regarding the surface tension of the alloy liquid, since the alloy liquid does not wet the mold shell, the liquid surface in the thin-walled part of the mold is convex. Surface tension creates resistance directed toward the liquid interior, resulting in reduced flow and filling ability of the alloy. In the K4169 nickel-based casting superalloy, increasing the carbon content decreases the surface tension. The lower the surface tension of the alloy, the less resistance to the flow of the alloy liquid, which helps improve the flow and filling ability of the alloy.

[0097] Regarding the viscosity of the alloy liquid, the lower the viscosity of the alloy melt, the more conducive it is to the alloy's flow and filling ability. In the K4169 nickel-based casting high-temperature alloy, as the carbon content increases, the alloy's viscosity tends to gradually decrease, which is more conducive to improving the alloy's flow and filling ability.

[0098] The solidification temperature range of the K4169 nickel-based cast superalloy lies within a wide crystallization temperature range. Its flow stops when the alloy melt temperature drops below the liquidus temperature, causing solid phase precipitation and dendrite growth. As the alloy melt temperature continues to decrease, the viscosity of the alloy melt increases, and the alloy flow rate decreases. When the dendrites in the K4169 nickel-based cast superalloy overlap to form a continuous dendrite network, and the remaining alloy melt pressure cannot overcome the resistance of this dendrite network, the K4169 nickel-based cast superalloy stops flowing. When the alloy melt stops flowing, the dendrites overlap, forming numerous microscopic melt pools between the dendrites. As the temperature further decreases, the alloy in the microscopic melt pools solidifies and shrinks. The remaining liquid phase is unable to feed these microscopic melt pools due to blocked feeding channels between the dendrites, resulting in porosity defects. Therefore, delaying the dendrite overlap time of the K4169 nickel-based cast superalloy can effectively improve the alloy's flow and filling capacity, reduce porosity defects in alloy castings, and improve the mechanical properties of the superalloy.

[0099] Table 9 shows the solidification temperature range test results of various examples and comparative examples.

[0100] Table 9

[0101]

[0102] As shown in Table 9, the solidification temperature range of the alloy gradually decreases as the C content increases. For the K4169 nickel-based casting high-temperature alloy with a modified C content of 0.06%, its solidification temperature range is lower than that of the comparative example and Example 1, so its flow filling ability is higher; while the solidification temperature range of the 0.06% C content is larger than that of Example 3, but the C content in Example 3 is higher, and the interdendritic carbide content is higher, which interacts with other physical parameters to form the test results, such as Figure 5 The physical property parameter results obtained from the comparative example and example simulation are shown.

[0103] Therefore, when the C content is within 0.06%, the alloy's flow-filling ability becomes increasingly better as the C content increases. This is mainly because changes in the C content cause changes in the alloy's physical properties, which improves the alloy's flow-filling ability. However, excessive C content can reduce the alloy's flow-filling ability. This is mainly because excessive C content significantly increases the amount of carbides in the alloy. The precipitation of excessive carbides hinders the flow of the alloy liquid, thereby reducing the alloy's flow-filling ability.

[0104] Porosity defects are primarily caused by volume shrinkage during solidification. After dendrites overlap during solidification, the interdendritic feeding channels become blocked, and insufficient liquid in the interdendritic region prevents feeding of the last solidified interdendritic region, leading to the formation of porosity defects. Porosity defects in castings reduce the effective stress-bearing area and concentrate stress at shrinkage sites and cavities, resulting in reduced mechanical properties.

[0105] The possible reason why increasing the C content reduces the alloy's porosity percentage and improves its mechanical properties is that, when shrinkage defects are high, increasing the C content increases the carbide content in the alloy. During solidification, carbides can fill the pores between dendrites through later growth, reducing porosity defects. Reducing shrinkage defects within high-temperature alloys improves the alloy's tensile and durability properties. However, increasing the C content when defects are low increases the alloy's porosity defects. This is likely because the growth of excessive carbides hinders the flow of the alloy liquid, thereby preventing the alloy liquid from feeding the tiny internal molten pool. This increases the porosity defects in the alloy and reduces the tensile and durability properties of the high-temperature alloy.

[0106] Therefore, optimizing the C element content in the K4169 nickel-based casting high-temperature alloy to 0.06% can improve the alloy's flow and filling ability, reduce the alloy's porosity defects, and improve the alloy's mechanical properties, thereby achieving a synergistic improvement in the casting performance and mechanical properties of the casting high-temperature alloy to meet the needs of complex structural parts of advanced aero-engines.

[0107] It should be noted that, in this document, the terms "comprises," "includes," or any other variations thereof are intended to encompass non-exclusive inclusion, such that a process, apparatus, article, or method comprising a series of elements includes not only those elements but also other elements not explicitly listed, or elements inherent to such process, apparatus, article, or method. In the absence of further limitations, an element defined by the phrase "comprising a ..." does not exclude the presence of other identical elements in the process, apparatus, article, or method comprising the element.

[0108] The above description is only a preferred embodiment of the present invention and does not limit the patent scope of the present invention. Any equivalent structure or equivalent process transformation made by using the contents of the present invention description and drawings, or directly or indirectly applied in other related technical fields, are also included in the patent protection scope of the present invention.

Claims

1. A modified equiaxed high-temperature alloy with synergistically improved casting performance and mechanical properties, characterized in that: Includes the following components: The above percentages are by mass, and the total mass percentage of the modified equiaxed high-temperature alloy is 100%.

2. The modified equiaxed high-temperature alloy with synergistically improved casting performance and mechanical properties according to claim 1, characterized in that: The mass percentages of C are 0.04%, 0.06% and 0.08% respectively.

3. The modified equiaxed high-temperature alloy with synergistically improved casting performance and mechanical properties according to claim 2, characterized in that: The characteristic solidification temperature range of the modified equiaxed high-temperature alloy decreases with increasing C content, and the characteristic solidification temperature range is ≤72°C.

4. The modified equiaxed high-temperature alloy with synergistically improved casting performance and mechanical properties according to claim 2, characterized in that: The flow filling ability test of the alloy was carried out under the same casting process. The flow filling length of the modified equiaxed high-temperature alloy was 254 mm to 286 mm.

5. The modified equiaxed high-temperature alloy with synergistically improved casting performance and mechanical properties according to claim 2, characterized in that: Room temperature tensile and high temperature endurance tests were carried out under the same conditions. The modified equiaxed high temperature alloy had a tensile strength of 1055 MPa, a yield strength of 946 MPa, and a high temperature endurance life of 103.1 h.

6. A method for preparing a modified equiaxed high-temperature alloy with synergistically improved casting performance and mechanical properties, characterized in that: The modified equiaxed high-temperature alloy with synergistically improved casting properties and mechanical properties according to any one of claims 1 to 5, wherein the preparation method specifically comprises: preparing graphite rods with a set mass fraction and preparing unmodified K4169 master alloy; The graphite rod and the unmodified K4169 master alloy are placed in a vacuum induction melting furnace for combined melting and refining to obtain the modified equiaxed high-temperature alloy.

7. The method for preparing a modified equiaxed high-temperature alloy with synergistically improved casting performance and mechanical properties according to claim 6, characterized in that: The mass fraction of the graphite rod includes three different proportions: 0.04%, 0.06% and 0.08%.

8. The method for preparing a modified equiaxed high-temperature alloy with synergistically improved casting performance and mechanical properties according to claim 6, characterized in that: The vacuum pressure of the vacuum induction melting furnace for melting is set at 1×10 -2 MPa~6×10 - 2 Between MPa.

9. The method for preparing a modified equiaxed high-temperature alloy with synergistically improved casting performance and mechanical properties according to claim 6, characterized in that: The vacuum induction melting furnace is used for refining at a temperature of 1470° C. to 1500° C., and the refining time is 3 to 5 minutes.

10. The method for preparing a modified equiaxed high-temperature alloy with synergistically improved casting performance and mechanical properties according to claim 6, characterized in that: The components of the unmodified K4169 master alloy include: 0.02% C, 52.5% Ni, 19% Cr, 3.05% Mo, 0.5% Al, 4.9% Nb, 0.9% Ti, impurities ≤0.01%, and the balance Fe.

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