Preparation device and preparation method for ultra-pure high-temperature alloy test bar

Abstract

The invention discloses a preparation device and a preparation method for an ultra-pure high-temperature alloy test bar, and belongs to the technical field of high-temperature alloy metallurgy. According to the method, multiple purification measures such as adopting an inner and outer crucible structure, limiting the use frequency of an inner crucible, arranging an impurity collection pit at the bottom of a mold shell, additionally arranging a filter sheet on a pouring cup, cleaning ethanol of the mold shell and preserving heat at high temperature are adopted, and a multi-stage preparation method of mother alloy bar pretreatment, mold shell pretreatment, loading and assembling, smelting and refining and pouring is utilized. The system solves the problems that in a traditional process, many ceramic inclusions exist, in order to avoid introduction of the inclusions, a crucible needs to be replaced frequently, consequently, the disassembling, beating and sintering processes are tedious, the production efficiency is low, the detection period is prolonged, and the cost is increased. The prepared test bar is high in purity, stable in mechanical property and suitable for performance detection and evaluation of high-temperature alloy materials in the fields of aerospace, energy power and the like.

Description

An apparatus and method for preparing ultrapure high-temperature alloy test bars Technical Field

[0001] This invention relates to the field of high-temperature alloy materials and metallurgical technology, specifically to an apparatus and method for preparing ultrapure high-temperature alloy test bars. Background Technology

[0002] High-temperature alloys are special metallic materials that maintain high strength, oxidation resistance, corrosion resistance, and fatigue resistance in high-temperature environments above 600℃. They mainly include three categories: nickel-based, iron-based, and cobalt-based. They are widely used in critical components such as aerospace engine combustion chambers, turbine blades, gas turbine blades, and turbocharger turbines. Mechanical property testing of high-temperature alloy test bars is a crucial step in evaluating the reliability and safety of materials under extreme operating conditions.

[0003] Currently, the conventional method for preparing high-temperature alloy test bars is as follows: alloy rod material is melted in a vacuum induction melting furnace with a ceramic crucible, then poured into a refractory ceramic test bar mold, and finally cut after cooling to form the test bar. However, the existing preparation process has the following problems:

[0004] 1. Ceramic crucibles are prone to interfacial reactions with active elements such as Al and Ti in alloys under high temperature and high vacuum conditions. Furthermore, due to insufficient crucible density and poor thermal shock stability, they are prone to cracking and spalling during use, which leads to refractory material particles entering the molten steel to form inclusions, affecting the purity of the test bar and thus causing distortion in the mechanical property test.

[0005] 2. To avoid the introduction of inclusions, crucibles need to be changed frequently, which makes the disassembly and sintering process cumbersome, resulting in low production efficiency, extended testing cycle and increased costs;

[0006] 3. The test bar shell lacks an effective impurity interception and filtration mechanism during the casting process. Tiny inclusions in the molten steel can easily enter the test bar body, affecting the accuracy of material performance evaluation.

[0007] Therefore, in view of this, we have studied and improved the existing structure and its shortcomings, and proposed a device and method for preparing ultrapure high-temperature alloy test bars, in order to achieve a more practical purpose. Summary of the Invention

[0008] The purpose of this invention is to provide an apparatus and method for preparing ultrapure high-temperature alloy test bars, so as to solve the problems mentioned in the background art.

[0009] To achieve the above objectives, the present invention provides the following technical solution: a method for preparing ultrapure high-temperature alloy test bars, comprising the following steps:

[0010] S1. Pretreatment of master alloy bar stock: The surface of the high-temperature alloy master alloy bar stock is processed to remove oxide scale, inclusions and surface defects to obtain a clean master alloy bar stock.

[0011] S2. Mold shell pretreatment: The inner cavity of the test rod mold shell of the pre-prepared device is rinsed with anhydrous ethanol for no less than 3 times; then the test rod mold shell is placed in a heating furnace and kept at a temperature of 900℃ to 1000℃ for at least 3 hours; the bottom of the test rod mold shell is provided with a hemispherical pit, and a cylindrical clamping platform is provided at the end of the pouring cup, on which a filter plate is placed;

[0012] S3. Loading and Assembly: The master alloy bar material processed in step S1 is placed into the inner crucible of the vacuum induction furnace; the inner crucible is placed inside the outer crucible, and the outer crucible is fixed to the induction coil of the vacuum induction furnace by tamping refractory material. The gap between the inner crucible and the outer crucible is 2 mm to 5 mm, and the gap is filled with aluminum silicate felt; the test bar mold shell processed in step S2 is hoisted into the mold shell cavity of the vacuum induction furnace and positioned.

[0013] S4. Melting and refining: Evacuate the vacuum induction furnace to a vacuum level of 10⁻¹Pa or lower, and then power on the master alloy bar to melt it; after it is completely melted, raise the temperature of the molten steel to 180℃±10℃ above the alloy melting point, and refine it at this temperature for 2 to 3 minutes.

[0014] S5. Casting: The temperature of the refined molten steel is reduced to 130℃±10℃ above the alloy melting point. The area of ​​slag on the surface of the molten steel is evaluated. When the slag area is less than 1%, the temperature of the molten steel is adjusted to the target casting temperature, and the molten steel is cast into the test rod mold shell positioned in step S3 while energized. During the casting process, the molten steel passes through the filter sheet and the hemispherical pit for flow stabilization and impurity collection.

[0015] Furthermore, the radius of the hemispherical recess is 10 mm to 20 mm;

[0016] The diameter of the cylindrical card table is 50 mm to 70 mm;

[0017] The filter is made of zirconium oxide and has a diameter of 49 mm to 69 mm with a porosity of 10 ppi, 20 ppi or 30 ppi.

[0018] Furthermore, the inner crucible is new or has been used no more than three times;

[0019] Both the inner crucible and the outer crucible are made of alumina-based refractory material;

[0020] An apparatus for preparing ultrapure high-temperature alloy test bars, comprising:

[0021] An inner crucible and an outer crucible are nested together, and the inner crucible is detachable and replaceable.

[0022] The test rod mold shell has a protective cover on its top. The test rod mold shell has a gating chamber, a feeding chamber, a first molding chamber, a test rod molding chamber, a second molding chamber, and an impurity collection chamber inside. The upper part of the test rod mold shell has a gating chamber, and the bottom of the gating chamber is connected to the feeding chamber. The bottom of the feeding chamber is connected to the first molding chamber, and the bottom of the first molding chamber is connected to test rod molding chambers around its perimeter. The bottom center of the first molding chamber is connected to the second molding chamber. The upper perimeter of the second molding chamber is connected to multiple sets of test rod molding chambers. An impurity collection chamber is opened in the middle of the bottom wall of the inner cavity of the second molding chamber.

[0023] A filter is embedded at the connection between the gating chamber and the feed chamber.

[0024] Furthermore, the first molding cavity and the second molding cavity are arranged in an I-shape in cross-section;

[0025] The test rod forming cavity is arranged in a circular surrounding shape, and there are eight sets of them;

[0026] The impurity collection chamber is configured as a hemispherical concave pit;

[0027] The filter element has a cylindrical structure, and the filter element and the bottom inner diameter of the first forming cavity are matched.

[0028] The inner cavity of the gating chamber is configured as a frustum-shaped structure, and the inner wall is configured as a sloping structure.

[0029] This invention provides an apparatus and method for preparing ultrapure high-temperature alloy test bars, which have the following beneficial effects:

[0030] 1. In this invention, the entire preparation device adopts an inner and outer crucible structure, which enables rapid replacement of the inner crucible, greatly reduces disassembly and sintering time, and improves production efficiency;

[0031] Limiting the use of the inner crucible to ≤3 times significantly reduces the risk of introducing ceramic inclusions and improves the purity of molten steel.

[0032] 2. In this invention, the impurity collection cavity with a hemispherical recess structure at the bottom of the test rod mold shell has both flow stabilization and impurity collection functions, improving the surface quality and internal purity of the test rod.

[0033] Furthermore, the filter plate installed at the end of the pouring cup in the top pouring chamber further filters out minute inclusions in the molten steel.

[0034] 3. In this invention, a protective cover of the same size is provided on the top of the test rod mold shell. The protective cover of the same material is resistant to high temperature and can be used repeatedly. It can also prevent unexpected external materials from falling into the mold shell during the heating and hoisting process.

[0035] 4. The present invention uses anhydrous ethanol cleaning and high-temperature insulation process to eliminate residual impurities and moisture inside the mold shell and prevent defects such as air holes. Attached Figure Description

[0036] The disclosure of this invention will become more readily understood with reference to the accompanying drawings. It will be readily understood by those skilled in the art that these drawings are merely illustrative of the technical solutions of this invention and are not intended to limit the scope of protection of this invention. In the drawings:

[0037] Figure 1 is a schematic diagram of the overall structure of an apparatus for preparing ultrapure high-temperature alloy test bars according to the present invention.

[0038] Figure 2 is a schematic diagram of the three-dimensional structure of a test rod mold shell for an ultra-pure high-temperature alloy test rod preparation device according to the present invention.

[0039] Figure 3 is a cross-sectional assembly diagram of the test rod mold shell of the present invention for the preparation device of ultrapure high temperature alloy test rod.

[0040] In the diagram: 1. Inner crucible; 2. Protective cover; 3. Outer crucible; 4. Test rod mold shell; 401. Gating chamber; 402. Feeding chamber; 403. First forming chamber; 404. Test rod forming chamber; 405. Second forming chamber; 406. Impurity collection chamber; 5. Filter plate. Detailed Implementation

[0041] In the description of this invention, unless otherwise stated, "a plurality of" means two or more; the terms "upper," "lower," "left," "right," "inner," "outer," "front end," "rear end," "head," "tail," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing the invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the invention. Furthermore, the terms "first," "second," "third," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0042] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "connected" and "linked" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0043] An apparatus for preparing ultrapure high-temperature alloy test bars includes an inner crucible 1 and an outer crucible 3 that are nested together, wherein the inner crucible 1 is detachable and replaceable.

[0044] The test rod mold shell 4 is covered with a protective cover 2 on its top. The test rod mold shell 4 is provided with a gating chamber 401, a feeding chamber 402, a first molding chamber 403, a test rod molding chamber 404, a second molding chamber 405 and an impurity collection chamber 406 inside. The upper part of the test rod mold shell 4 is provided with a gating chamber 401, and the bottom of the gating chamber 401 is connected to the feeding chamber 402. The bottom of the feeding chamber 402 is connected to the first molding chamber 403, and the bottom of the first molding chamber 403 is surrounded by test rod molding chambers 404. The bottom middle of the first molding chamber 403 is connected to the second molding chamber 405. The upper periphery of the second molding chamber 405 is connected to multiple sets of test rod molding chambers 404. The impurity collection chamber 406 is opened in the middle of the bottom wall of the inner cavity of the second molding chamber 405.

[0045] A filter 5 is embedded at the connection between the gating chamber 401 and the feeding chamber 402;

[0046] Two crucibles, an inner and an outer crucible, are used. The outer crucible is fixed to the vacuum induction furnace coil with refractory material. The inner crucible 1 is placed inside the outer crucible 3, with a gap of 2-5 mm between the two crucibles, which is secured by aluminum silicate felt. The inner crucible 1 can be quickly replaced, avoiding the inefficiency of using a traditional single crucible, which requires removing the refractory material and breaking the crucible each time it is replaced. Furthermore, the use of the inner crucible is limited to no more than 3 times, solving the problem that repeated use of a traditional single crucible introduces ceramic inclusions into the molten steel, reducing the purity of the molten steel and leading to test bar failure.

[0047] Example 1

[0048] A 6 kg IN713C high-temperature alloy master alloy (chemical composition qualified) with a diameter of 80 mm after being polished by a grinding wheel was selected and placed in a new crucible inside a vacuum induction furnace. The test bar mold (containing a 50 mm diameter, 30 ppi filter) was then hoisted into the vacuum induction furnace mold cavity after being rinsed three times with anhydrous ethanol and held at 900°C for 3 hours in a muffle furnace. After adjusting the mold position, a vacuum of 0.5 Pa was evacuated, and melting was initiated. After the master alloy bar was completely melted, the temperature was raised to 1480°C and refined for 2 minutes. The temperature was then lowered to 1440°C, and the slag grade of the molten steel was determined by photographing. The temperature was then adjusted to 1460°C, and the molten steel was poured into the test bar mold while energized. After cutting the test bar mold, the IN713C alloy tensile properties were tested using a universal tensile testing machine, as shown in Table 1.

[0049]

[0050] Conclusion of Example 1: The IN713C high-temperature alloy test bar prepared by the method of this invention significantly exceeded the standard requirements in terms of room temperature tensile strength (Rm), yield strength (Rp0.2), elongation after fracture (δ), and reduction of area (ψ). This indicates that multiple purification measures, including surface pretreatment of the master alloy bar, use of a new inner crucible, rinsing with anhydrous ethanol and high-temperature calcination of the mold shell, and casting filtration, effectively reduced the inclusion content in the test bar, resulting in a high-purity test bar, thus providing a true and excellent characterization of the mechanical properties of the alloy material.

[0051] Example 2

[0052] A 100mm diameter IN38LC high-temperature alloy master alloy (chemical composition tested and qualified) was selected after lathe finishing. Weighing 6 kg, the bar was placed in a crucible (used once) inside a vacuum induction furnace. A test bar mold shell (containing a 50mm diameter, 20ppi filter) was then hoisted into the vacuum induction furnace mold shell cavity after being rinsed four times with anhydrous ethanol and held at 950°C for 3 hours in a muffle furnace. After adjusting the mold shell position, a vacuum of 0.3 Pa was evacuated, and melting was initiated. Once the master alloy bar was completely melted, the temperature was raised to 1500°C and refined for 3 minutes. The temperature was then lowered to 1450°C, and the slag grade of the molten steel was determined by photographing. The temperature was then adjusted to 1465°C, and the molten steel was poured into the test bar mold shell under energized conditions. After cutting the test bar mold shell, the tensile properties of the IN738LC alloy were tested using a universal tensile testing machine, as shown in Table 2.

[0053]

[0054] Example 2 Conclusion: Using the method of the present invention, even after the inner crucible has been reused once, the high-temperature tensile properties of the prepared IN738LC high-temperature alloy test bar at 650℃ still far exceed the standard requirements, especially exhibiting excellent high-temperature plasticity. This proves that the inner and outer crucible structure adopted in the present invention and the strategy of limiting the number of times the inner crucible can be used (≤3 times) can effectively control ceramic inclusions introduced by crucible erosion while ensuring production efficiency (reducing frequent replacements), thus ensuring the performance purity and reliability of the test bar under high-temperature testing conditions.

[0055] In conclusion, the two embodiments above demonstrate that the "Apparatus and Method for Preparing Ultra-Pure High-Temperature Alloy Test Bars" provided by this invention, through a systematic purity control design (coordinated material, crucible, shell, and filter) and a quickly replaceable inner crucible structure, successfully solves the problems of performance distortion caused by numerous inclusions in test bars and low efficiency due to cumbersome crucible replacement in traditional methods. The test bars prepared by this method exhibit stable and excellent mechanical properties, accurately reflecting the intrinsic properties of high-temperature alloy materials, and are suitable for fields requiring extremely high material purity and accuracy in performance evaluation.

[0056] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any changes or substitutions that can be conceived by those skilled in the art within the technical scope disclosed in the present invention without creative effort should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of protection defined in the claims.

Claims

1. A method for preparing ultrapure high-temperature alloy test bars, characterized in that, Includes the following steps: S1. Pretreatment of master alloy bar: The surface of the high-temperature alloy master alloy bar is processed to remove oxide scale, inclusions and surface defects to obtain a clean master alloy bar; S2. Pretreatment of mold shell: The inner cavity of the test bar mold shell (4) of the pre-prepared device is rinsed with anhydrous ethanol for no less than 3 times; then the test bar mold shell (4) is placed in a heating furnace and kept at a temperature of 900°C to 1000°C for at least 3 hours; the bottom of the test bar mold shell (4) is provided with a hemispherical pit and the end of the pouring cup is provided with a cylindrical support. A filter sheet is placed on the cylindrical platen; S3. Loading and assembly: The master alloy bar material processed in step S1 is placed in the inner crucible (1) of the vacuum induction furnace; the inner crucible is placed inside the outer crucible (3), and the outer crucible is fixed to the induction coil of the vacuum induction furnace by ramming refractory material. The gap between the inner crucible (1) and the outer crucible (3) is 2 mm to 5 mm, and the gap is filled with aluminum silicate felt; the test bar mold shell (4) processed in step S2 is hoisted into the mold shell cavity of the vacuum induction furnace and positioned. S4. Melting and refining: Vacuum the vacuum induction furnace to a vacuum level of 10⁻¹Pa or lower, and then power on the master alloy bar to melt it; after it is completely melted, raise the temperature of the molten steel to 180℃±10℃ above the alloy melting point, and refine it at this temperature for 2 to 3 minutes; S5. Casting: Lower the temperature of the refined molten steel to 130℃±10℃ above the alloy melting point, and evaluate the slag area on the surface of the molten steel; when the slag area is less than 1%, adjust the temperature of the molten steel to the target casting temperature, and pour the molten steel into the test bar mold shell (4) positioned in step S3 while energized; during the casting process, the molten steel passes through the filter plate (5) for filtration and the hemispherical pit for flow stabilization and impurity collection.

2. The preparation method according to claim 1, characterized in that, In step S2, the radius of the hemispherical recess is 10 mm to 20 mm; the diameter of the cylindrical card plate is 50 mm to 70 mm; the filter sheet is made of zirconium oxide, with a diameter of 49 mm to 69 mm and a porosity of 10 ppi, 20 ppi or 30 ppi.

3. The preparation method according to claim 1, characterized in that, In step S3, the inner crucible (1) is a new crucible or a crucible that has been used no more than 3 times; the inner crucible (1) and the outer crucible (3) are both made of alumina-based refractory material.

4. The preparation method according to claim 1, characterized in that, In step S1, the surface processing is performed by grinding with a grinding wheel, grinding with a sandbag, or turning with a lathe.

5. The preparation method according to claim 1, characterized in that, In step S2, the test rod mold shell (4) is also equipped with a protective cover of the same material. During the pretreatment and hoisting of the test rod mold shell (4), the protective cover covers the gating cavity (401). The surface material of the test rod mold shell (4) is zircon sand powder, and the surface material is fused silica sand powder.

6. An apparatus for implementing the method according to any one of claims 1-5, characterized in that, include: An inner crucible (1) and an outer crucible (3) are nested together. The inner crucible (1) is detachable and replaceable. A test rod mold shell (4) is provided with a protective cover (2) on the top. The test rod mold shell (4) is provided with a gating chamber (401), a feeding chamber (402), a first molding chamber (403), a test rod molding chamber (404), a second molding chamber (405), and an impurity collection chamber (406). The upper part of the test rod mold shell (4) is provided with a gating chamber (401), and the bottom of the gating chamber (401) is connected to the feeding chamber (402). The bottom of the feeding chamber (402) is connected to the first forming chamber (403), and the bottom of the first forming chamber (403) is connected to the test rod forming chamber (404) around its perimeter. The bottom of the first forming chamber (403) is connected to the second forming chamber (405) at its middle end. The upper perimeter of the second forming chamber (405) is connected to multiple sets of the test rod forming chambers (404). An impurity collection chamber (406) is provided at the middle end of the bottom wall of the inner cavity of the second forming chamber (405). A filter plate (5) is embedded at the connection between the gating chamber (401) and the feeding chamber (402).

7. The apparatus according to claim 6, characterized in that, The first molding cavity (403) and the second molding cavity (405) are arranged in an I-shape in cross-section; the test rod molding cavity (404) is arranged in a circular surrounding shape and is provided in eight groups; the impurity collection cavity (406) is set in a hemispherical pit shape; the filter (5) has a cylindrical structure, and the bottom inner diameter of the filter (5) and the first molding cavity (403) are matched with each other; the inner cavity of the gating chamber (401) is set in a frustum shape and the inner wall is set in a sloping structure.

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