Preparation method and application of high-uniformity zirconium alloy cast ingot

Abstract

The invention belongs to the technical field of metal material preparation, and particularly discloses a preparation method and application of a high-uniformity zirconium alloy cast ingot, and the preparation method comprises the following steps: 1) raw material preparation: preparing sponge zirconium and corresponding alloy raw materials according to target cast ingot nominal components; 2) raw material allocation: calculating the weight of sponge zirconium and alloy raw materials according to the weight of a single electrode block; 3) electrode preparation: averagely dividing the distributed sponge zirconium into N (N is greater than or equal to 2) parts, equally dividing the alloy raw material into N-1 parts, staggeredly arranging the N parts and the N-1 parts in a mold cavity of a press to form a laminated structure, pressing to obtain an electrode block, and welding the electrode block into a consumable electrode; and 4) cast ingot smelting: carrying out at least two times of vacuum self-consuming arc smelting by adopting reversing arc-stabilizing current to obtain a target cast ingot. Through the synergistic effect of a series of operations such as reasonable selection of raw materials, careful design of a material distribution mode and precise control of smelting process parameters, the zirconium alloy cast ingot which has high uniformity and can meet nuclear requirements is finally successfully prepared.

Description

Technical Field

[0001] The present invention belongs to the technical field of metal material preparation, and in particular, relates to a preparation method of a high-uniformity zirconium alloy ingot and an application thereof. Background Art

[0002] Zirconium alloy, as an important strategic material, is known as the "first metal of the atomic energy era". It plays a vital role in the field of nuclear energy due to its small thermal neutron absorption cross section, good corrosion resistance and mechanical properties. For example, in nuclear reactors, zirconium alloy is widely used to manufacture key components such as fuel cladding. Its low thermal neutron absorption cross section allows nuclear reactions to be carried out more efficiently and stably, effectively improving energy efficiency. At the same time, its excellent corrosion resistance enables it to operate stably for a long time in a high-temperature, high-pressure and highly corrosive nuclear reactor environment, greatly ensuring the safety and reliability of nuclear reactors.

[0003] At present, there are many zirconium alloy grades that are maturely used and under scientific research at home and abroad. Different grades of zirconium alloys contain alloy elements of different types, different contents and different physical properties. The precise control of each alloy element has certain technical difficulties, such as Sn or Al elements with low melting points, Nb, Mo, Ta, W or C elements with high melting points, gas element O, and Ge, Cu, Si, Ni, Y, Fe, Ti, V, Cr or Hf elements with moderate melting points. These alloy elements are usually added to zirconium alloys through smelting methods. However, in the preparation process of zirconium alloy ingots, there is often a problem of uneven composition inside the ingot, which seriously affects the quality and performance of subsequent products.

[0004] The reason for this unevenness is that the current smelting of zirconium alloy mainly adopts vacuum consumable arc melting. Although this melting technology is relatively mature, in actual operation, there are problems such as improper selection of alloy raw material particle size, shape and type, unreasonable material distribution during electrode pressing, and unsatisfactory setting of melting process parameters, which leads to uneven distribution of chemical composition of the final prepared ingot, making it difficult to meet the strict requirements of high uniformity, and thus adversely affecting the performance of subsequent process products. In order to meet the urgent demand for high uniformity products for key components in the nuclear energy field, a preparation method for high uniformity zirconium alloy ingots needs to be developed.

[0005] In view of this, this invention is proposed. Summary of the invention

[0006] The purpose of the present invention is to overcome the shortcomings of the above-mentioned prior art and provide a method for preparing a high-uniformity zirconium alloy ingot and its application, aiming to solve the problem in the prior art that the final prepared ingot has uneven composition due to improper selection of alloy raw material particle size, shape and type, unreasonable material distribution during electrode pressing, and poor setting of smelting process parameters, making it difficult to meet the demand for high-uniformity products for key components in the nuclear energy field.

[0007] The purpose of the present invention is to be solved by the following technical solutions:

[0008] In one aspect, the present invention provides a method for preparing a high-uniformity zirconium alloy ingot, comprising the following steps:

[0009] Step 1: Raw materials preparation

[0010] Raw materials are prepared according to the nominal composition of the target zirconium alloy ingot, the raw materials include sponge zirconium and alloy raw materials, and the composition of the alloy raw materials includes one or more of the following four categories: Category I is low melting point elements Sn or Al; Category II is high melting point elements Nb, Mo, Ta, W or C; Category III is elements Ge, Cu, Si, Ni, Y, Fe, Ti, V, Cr or Hf with melting points between Category I and Category II; Category IV is O;

[0011] Step 2: Raw Materials Allocation

[0012] According to the target zirconium alloy ingot batching calculation value, batching calculation is performed according to the weight of a single electrode block, and according to the addition method of the alloy raw materials, the weight of the sponge zirconium and alloy raw materials required for a single electrode block is determined;

[0013] Step 3: Electrode preparation

[0014] First, the zirconium sponge dispensed in step 2 is equally divided into N portions, and the alloy raw material dispensed is equally divided into N-1 portions; then the N-1 portions of the alloy raw material and the N portions of the zirconium sponge are alternately arranged in a press die cavity to form a stacked structure; finally, the arranged materials are pressed to obtain an electrode block, and the electrode block is welded into a consumable electrode;

[0015] Wherein, N is a natural number greater than or equal to 2;

[0016] Step 4: Ingot Melting

[0017] The consumable electrode obtained in step 3 is subjected to vacuum consumable arc melting at least twice using a commutated arc stabilizing current to obtain the target zirconium alloy ingot.

[0018] Furthermore, in step 2, the four types of alloy raw materials are added respectively in the following ways:

[0019] Type I alloying materials are added via alloys containing Sn or Al;

[0020] Type II alloy raw materials are added through pure elements or compounds containing corresponding elements;

[0021] Class III alloy raw materials are added with pure elements;

[0022] Type IV alloy raw materials are added with the help of O-containing compounds;

[0023] Wherein, when the type II alloy raw material or the type IV alloy raw material is added in the form of a compound, the content of impurity elements introduced by the compound should not exceed the upper limit value of the content of the impurity elements in the target zirconium alloy ingot.

[0024] Further, in step 2, the type I alloy raw material includes Zr-Sn, Zr-Al or Zr-Sn-Al master alloy;

[0025] When the Class II alloy raw materials are corresponding compounds, they include Zr-Nb, AlMo, AlTa, WO3 or Cr3C2; the content of corresponding Al, O and Cr elements introduced into the compounds AlMo, AlTa, WO3 or Cr3C2 should not exceed the upper limit value of the content of Al, O and Cr elements in the target zirconium alloy ingot.

[0026] The type IV alloy raw material includes ZrO2.

[0027] Furthermore, the Zr-Sn, Zr-Al or Zr-Sn-Al master alloy in the type I alloy is in the form of spherical blocks;

[0028] When the Class II alloy raw material is a pure element, it is in powder form, and the powder particle size is less than or equal to 30 μm; when the Class II alloy raw material is a corresponding compound, Zr-Nb is in crumb form, and AlMo, AlTa, WO3 or Cr3C2 is in powder form or granular form;

[0029] The Class III alloy raw material is in the form of foil, flake, granule, block, chip or powder;

[0030] The type IV alloy raw material is ZrO2 powder.

[0031] Furthermore, before arranging the alloy raw materials, a layer of zirconium foil is laid on the lower layer of the alloy raw materials. After the arrangement is completed, another layer of zirconium foil is laid on the upper layer of the alloy raw materials, and the cross-sectional size of each layer of the zirconium foil laid should be the same as the cross-sectional size of the press cavity.

[0032] Furthermore, in step 3, when N=2, the raw materials include two portions of zirconium sponges, one portion of alloy raw materials and two layers of zirconium foils, and the specific cross-arrangement and stacked structure formed are as follows:

[0033] First, a portion of zirconium sponge is laid on the bottom layer of the press cavity; then a layer of zirconium foil is laid on the upper surface of the zirconium sponge, and an alloy raw material is arranged on the zirconium foil; finally, another layer of zirconium foil is laid on the alloy raw material, and another portion of zirconium sponge is laid on the top layer.

[0034] It should be noted that, since the weight of zirconium foil is extremely light, it indicates that its weight proportion in the entire zirconium alloy ingot preparation system is extremely small, so that its influence on the overall weight is almost negligible, and therefore, in the actual batching process, its weight can be completely ignored. In addition, the added zirconium foil will not introduce any impurities relative to the target zirconium alloy ingot, and will not have any negative effect on the purity and quality of the final product.

[0035] Furthermore, in step three, when the alloy raw materials are arranged, the intermediate alloy block is arranged first, then the non-chip raw materials are arranged, and finally the chip raw materials are arranged, and the distance between all the arranged raw materials and the edge of the press cavity is greater than or equal to 30 mm; wherein, when arranging the powdered raw materials, the two or more powdered raw materials after distribution should be mixed evenly.

[0036] Furthermore, in the step 4, when the consumable electrode is subjected to three vacuum consumable arc melting using a commutated arc stabilizing current, the specific melting process is as follows:

[0037] The ingot diameter of the first vacuum consumable arc melting is 220mm to 360mm, the arc stabilization current is 3A to 6A, and the switching time interval is 20s to 40s.

[0038] The ingot diameter of the second vacuum consumable arc melting is Ф280mm~Ф450mm, the arc stabilization current is 5A~8A, and the switching time interval is 20s~40s;

[0039] The ingot diameter of the third vacuum consumable arc melting is Ф360mm~Ф550mm, the arc stabilization current is 7A~10A, and the switching time interval is 20s~40s.

[0040] Furthermore, in the step 4, when entering the feeding stage at the end of the third smelting, the arc stabilizing current in the feeding stage is 4A to 6A, and the commutation time interval is 20s to 40s.

[0041] On the other hand, the present invention provides an application of a high-uniformity zirconium alloy ingot, wherein the high-uniformity zirconium alloy ingot is prepared based on the above-mentioned preparation method, and the high-uniformity zirconium alloy ingot is used to prepare nuclear fuel structural parts, such as nuclear fuel cladding.

[0042] Compared with the prior art, the present invention has the following beneficial effects:

[0043] The preparation method provided by the present invention is improved in the following aspects compared with the existing zirconium alloy ingot preparation technology:

[0044] First, the present invention has made innovative optimizations in the classification and addition of alloy raw materials, effectively solving the problem of uneven ingot composition caused by differences in alloy element characteristics and improving the chemical uniformity of the ingot. For example, for low-melting-point Class I elements (such as Sn and Al), intermediate alloys (Zr-Sn, Zr-Al or Zr-Sn-Al) are selected to increase their melting points and change their physical properties, greatly enhancing the uniformity of the elements in the ingot; for high-melting-point Class II metals (Nb, Mo, etc.), there are two ways of adding pure elements and compounds to ensure full melting and uniform composition; for Class III alloys with moderate melting points, pure elements are directly added, and the material shapes are diverse, which improves production efficiency; for Class IV gas element O, ZrO2 powder is selected. That is, different addition methods and raw material forms are used to enable various elements to be more evenly distributed during the smelting process.

[0045] Second, the present invention is ingenious in the electrode preparation process, especially the cross-layered arrangement of zirconium sponge and alloy raw materials and the use of zirconium foil, which ensures that the materials are evenly distributed in the consumable electrode, laying the foundation for the uniform composition of the ingot. The specific reasons are as follows: Experiments show that the arrangement of zirconium sponge sandwiching alloy raw materials can not only ensure uniform composition but also improve the efficiency of material distribution; at the same time, zirconium foil with the same cross-sectional size as the press cavity is laid on the bottom and top of the alloy raw materials to avoid the risks caused by bottom leakage and top impact during pressing, and reduce composition deviation; in addition, the materials are laid in a specific order (first the intermediate alloy sphere, then the non-chip-shaped raw materials, and finally the chip-shaped raw materials) to facilitate uniform placement and adjustment, and control the raw materials to be no less than 30mm from the edge of the cavity to ensure uniform axial distribution, and reserve a moving distance to prevent material loss during pressing.

[0046] Third, the present invention has made a breakthrough in the smelting process. Through multiple smelting and precise control of the arc stabilization current and the switching time interval, the uniformity and quality of the ingot are further improved. This is because the timed switching of the arc stabilization current stirring direction weakens the momentum accumulation, reduces the depth of the molten pool, shortens the existence time of the liquid phase, increases the solidification rate, reduces solute migration and element segregation, strengthens the molten liquid convection, and promotes the uniformity of liquid phase composition and temperature; at the same time, as the number of smelting increases, the ingot shape becomes larger, and the stirring magnetic field strength is gradually increased to fully homogenize the alloy elements; in addition, in the shrinkage feeding stage, due to the serious segregation of the equiaxed crystal zone around the shrinkage hole, as the molten pool depth and the cross-sectional area of ​​the molten pool decrease, the arc stabilization current is reduced, the solid phase flow and segregation are reduced, and the alloy elements are further promoted to be homogenized.

[0047] In summary, the present invention significantly improves the composition uniformity of zirconium alloy ingots through all-round innovative improvements in the classification and addition of alloy raw materials, electrode preparation methods and smelting processes, providing a high-quality material foundation and technical support for the nuclear energy field. BRIEF DESCRIPTION OF THE DRAWINGS

[0048] The accompanying drawings are incorporated in and constitute a part of this specification and, together with the description, serve to explain the principles of the present invention.

[0049] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, for ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0050] Figure 1 is a flow chart of the preparation method of the present invention;

[0051] Figure 2 It is a schematic diagram of the main view of the arrangement of the zirconium sponge and alloy raw materials in the present invention;

[0052] Figure 3 yes Figure 2 Middle AA top view schematic diagram;

[0053] Among them: 1 is zirconium sponge; 2 is zirconium foil; 3 is alloy raw material; 31 is intermediate alloy block; 32 is non-chip-shaped raw material; 33 is chip-shaped raw material. DETAILED DESCRIPTION

[0054] Exemplary embodiments will be described in detail herein, examples of which are shown in the accompanying drawings. When the following description refers to the drawings, the same numbers in different drawings represent the same or similar elements unless otherwise indicated. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with the present invention. Instead, they are merely examples of devices consistent with some aspects of the present invention as detailed in the appended claims.

[0055] In order to enable those skilled in the art to better understand the technical solution of the present invention, the present invention is further described in detail below with reference to the accompanying drawings.

[0056] See also Figure 1 The present invention provides a method for preparing a high-uniformity zirconium alloy ingot, which specifically comprises the following steps:

[0057] Step 1. Raw material preparation: prepare raw materials according to the nominal composition of the target zirconium alloy ingot, the raw materials include sponge zirconium and alloy raw materials, the composition of the alloy raw materials includes one or more of the following four categories: Category I is low melting point elements Sn or Al; Category II is high melting point elements Nb, Mo, Ta, W or C; Category III is elements Ge, Cu, Si, Ni, Y, Fe, Ti, V, Cr or Hf with a melting point between Category I and Category II; Category IV is O.

[0058] Step 2. Raw material allocation: According to the target zirconium alloy ingot ingredient calculation value, the ingredient calculation is performed according to the weight of a single electrode block. At the same time, according to the addition method of the alloy raw materials, the weight of the sponge zirconium (the weight of the sponge zirconium is the weight of a single electrode block minus the weight of the four types of alloy raw materials contained) and the weight of the alloy raw materials required for a single electrode block are determined.

[0059] Step 3, electrode preparation: first, divide the zirconium sponge allocated in step 2 into N (N is a natural number greater than or equal to 2) portions, and divide the alloy raw material allocated into N-1 portions; then, alternately arrange the N-1 portions of alloy raw material and the N portions of zirconium sponge in the press cavity to form a stacked structure; finally, press the arranged materials to obtain an electrode block, and weld the electrode block into a consumable electrode.

[0060] Step 4: Ingot melting: The consumable electrode obtained in step 3 is subjected to vacuum consumable arc melting at least twice with a commutated stable arc current to obtain a target zirconium alloy ingot.

[0061] Specifically, in steps one and two, the present invention has made innovative optimizations in the classification and addition of alloy raw materials. The alloy raw materials required for the target zirconium alloy ingot are divided into four categories according to their melting points. Among them, the melting points of Sn and Al elements in Category I are relatively low, at 231°C and 660°C respectively. They are very easy to flow during smelting and are prone to cause regional segregation. Therefore, Zr-Sn, Zr-Al or Zr-Sn-Al intermediate alloys are selected for addition to preliminarily alloy the single elements Sn and Al, thereby increasing the melting points of Sn and Al, changing their physical properties, and greatly improving the uniformity of the elements in the ingot. The high-melting-point metals Nb, Mo, Ta, W or C in Category II have very high melting points. On the one hand, powders with a particle size of less than 30 μm can be selected for addition to ensure that the high-melting-point materials are fully melted during the smelting process without inclusions, ensuring the molten metal. Uniformity after smelting; on the other hand, corresponding compounds such as AlMo, AlTa, WO3, Cr3C2 or Zr-Nb can be selected, wherein Zr-Nb is in the form of crumbs, and AlMo, AlTa, WO3 or Cr3C2 is in the form of powder or granules. This method can reduce the melting point of the single substance and improve the uniformity of the composition after smelting; the melting point of Class III alloy raw materials is between Class I and Class II, and can be smelted uniformly without preparing into intermediate alloys again. It can be directly added as pure single substances, and the material has various shapes, such as foil, sheet, granular, block, crumb or powder, etc., thereby improving production efficiency; Class IV alloy raw materials are gaseous elements O, which are added as ZrO2 powder. In short, the present invention significantly improves the uniformity of distribution of various elements during the smelting process by optimizing the alloy materials and adopting the most suitable raw material addition method for smelting.

[0062] In step three, the present invention adopts the method of cross-arranging alloy raw materials and sponge zirconium, which effectively improves the uniformity of alloy elements in consumable electrodes and lays the foundation for the uniformity of ingot composition. Specifically, zirconium foil with the same cross-sectional size as the cross-sectional size of the press cavity is laid at the bottom and top of the alloy raw material to prevent the powder from leaking from the bottom of the electrode block and the impact of the upper layer of sponge zirconium on the alloy raw material during the pressing, causing it to move to the edge of the mold and cause the risk of leakage. At the same time, when laying the material, the intermediate alloy block is arranged first, and then the non-chip-like raw material (such as powder or granular, etc.) is arranged, and finally the chip-like raw material is arranged, which is convenient for adjusting the uniformity of each material. When laying the material, the distance between the alloy raw material and the edge of the cavity is controlled to be not less than 30mm, and sufficient distance is reserved for the movement of the material at the moment of pressing, so as to avoid the loss of the alloy raw material caused by the material being squeezed and moved to the edge of the cavity during pressing. In addition, when arranging the powdered raw material, the two or more powdered raw materials after distribution should be mixed evenly.

[0063] In step four, the present invention has made innovations in the smelting process. Specifically, taking three vacuum consumable arc melting as an example, the process is as follows: the ingot diameter of the first vacuum consumable arc melting is Ф220mm~Ф360mm, the arc stabilizing current is 3A~6A, and the commutation time interval is 20s~40s; the ingot diameter of the second vacuum consumable arc melting is Ф280mm~Ф450mm, the arc stabilizing current is 5A~8A, and the commutation time interval is 20s~40s; the ingot diameter of the third vacuum consumable arc melting is Ф360mm~Ф550mm, the arc stabilizing current is 7A~10A, and the commutation time interval is 20s~40s. When entering the feeding stage at the end of the third melting, the arc stabilizing current in the feeding stage is 4A~6A, and the commutation time interval is 20s~40s. That is, the three melting processes all use the reversing arc stabilizing current, and the stirring direction of the arc stabilizing current is switched regularly, which reduces the depth of the molten pool, increases the solidification speed, inhibits the segregation of alloy elements, and improves the uniformity of the ingot composition. In addition, when entering the shrinkage feeding stage, the arc stabilizing current is reduced, which reduces the occurrence of segregation and promotes the homogenization of alloy elements in the molten pool during the shrinkage feeding stage.

[0064] In order to further verify the efficacy of the present invention, the inventors conducted the following experiments:

[0065] Example 1 (Preparation of a zirconium alloy ingot with a nominal composition of Zr-Sn-Fe-Cr-OC)

[0066] The preparation method of the zirconium alloy ingot in this embodiment is as follows:

[0067] 1) Raw material preparation: Prepare materials according to the nominal composition of the target zirconium alloy ingot Zr-Sn-Fe-Cr-OC (wherein Sn=0.8%, Fe=0.1%, Cr=0.1%, O=0.12%, C=0.01%).

[0068] 2) Raw material allocation: The ingredients are calculated based on the weight of a single electrode block of 60kg. Among them, the Sn element is added through Zr-Sn master alloy, Fe uses pure Fe chips, Cr uses pure Cr particles, O is added with the help of ZrO2 powder, and C uses pure C powder (particle size less than 30μm). According to calculations, a single electrode block requires 0.8kg of Zr-Sn master alloy, 0.05kg of Fe chips, 0.06kg of Cr particles, 0.16kg of ZrO2 powder, 0.006kg of C powder, and 58.92kg of zirconium sponge.

[0069] 3) Electrode preparation: Divide the zirconium sponge 1 into 2 equal portions, each weighing 29.46 kg. First, arrange 29.46 kg of zirconium sponge 1 in the press cavity, and then place zirconium foil 2 with the same cross-sectional size as the press cavity on the upper layer of the bottom layer of zirconium sponge 1. Then arrange the alloy raw material 3. When arranging, first place the intermediate alloy block 31, that is, the Zr-Sn intermediate alloy; then place the evenly mixed non-chip-like raw material 32, in the order of arranging ZrO2 powder and C powder first, and then Cr particles; finally arrange the chip-like raw material 33, that is, Fe chips. Moreover, the distance between all arranged alloy raw materials 3 and the edge of the cavity is not less than 30 mm. After the alloy raw material 3 is arranged, lay another layer of zirconium foil 2 on the upper layer, and then add the remaining 29.46 kg of zirconium sponge 1 into the press cavity. After the materials are laid out in this way, a five-layer structure of zirconium sponge 1 → zirconium foil 2 → alloy raw material 3 → zirconium foil 2 → zirconium sponge 1 is formed in the press cavity from bottom to top, as shown in FIG. Figure 2 , 3 Finally, the electrode is pressed and the electrode block is welded into a consumable electrode.

[0070] 4) Ingot smelting: During the first smelting, the ingot diameter is 220 mm, the arc stabilizing current is 3 A, and the switching time interval is 20 s; during the second smelting, the ingot diameter is 280 mm, the arc stabilizing current is 5 A, and the switching time interval is 20 s; during the third smelting, the ingot diameter is 360 mm, the arc stabilizing current is 7 A, and the switching time interval is 20 s; at the end of the third smelting, when entering the feeding stage, the arc stabilizing current is 4 A, and the switching time interval is 20 s. After the smelting is completed, a zirconium alloy ingot with a nominal composition of Zr-Sn-Fe-Cr-OC is obtained.

[0071] Example 2 (Preparation of a zirconium alloy ingot with a nominal composition of Zr-Sn-Fe-Cr-Si-O-Al-Ta)

[0072] The preparation method of the zirconium alloy ingot in this embodiment is as follows:

[0073] 1) Raw material preparation: Prepare materials according to the nominal composition of the target zirconium alloy ingot Zr-Sn-Fe-Cr-Si-O-Al-Ta (wherein Sn=0.7%, Fe=0.2%, Cr=0.1%, Si=0.01%, O=0.10%, Al=0.02%, Ta=0.02%).

[0074] 2) Raw material allocation: The ingredients are calculated based on the weight of a single electrode block of 50kg. Among them, Sn and Al elements are added using Zr-Sn-Al master alloy, Fe uses pure Fe chips, Cr and Si use pure Cr particles and Si particles, O is added with the help of ZrO2 powder, and Ta is added using AlTa powder. According to calculations, a single electrode block requires 0.58kg of Zr-Sn-Al master alloy, 0.09kg of Fe chips, 0.05kg of Cr particles, 0.005kg of Si particles, 0.10kg of ZrO2 powder, 0.017kg of AlTa powder, and 49.16kg of zirconium sponge.

[0075] 3) Electrode preparation: Divide the zirconium sponge 1 into 2 equal portions, each weighing 24.58 kg. First, arrange 24.58 kg of zirconium sponge 1 in the press cavity, and then place zirconium foil 2 with the same cross-sectional size as the press cavity on the upper layer of the bottom layer of zirconium sponge 1. Then arrange the alloy raw material 3. When arranging, first place the intermediate alloy block 31, that is, the Zr-Sn-Al intermediate alloy; then place the evenly mixed non-chip-like raw material 32, in the order of arranging ZrO2 powder and AlTa powder first, and then arranging Cr particles and Si particles; finally arrange the chip-like raw material 33, that is, Fe chips. In addition, the distance between all arranged alloy raw materials 3 and the edge of the cavity is not less than 30 mm. After the alloy raw material 3 is arranged, a layer of zirconium foil 2 is laid on the upper layer, and then the remaining 24.58 kg of zirconium sponge 1 is added to the press cavity. After the materials are laid out in this way, a five-layer structure of zirconium sponge 1 → zirconium foil 2 → alloy raw material 3 → zirconium foil 2 → zirconium sponge 1 is formed from bottom to top in the press cavity, as shown in FIG. Figure 2 , 3 Finally, the electrode is pressed and the electrode block is welded into a consumable electrode.

[0076] 4) Ingot smelting: During the first smelting, the ingot diameter is Ф360mm, the arc stabilizing current is 6A, and the reversing time interval is 40s; during the second smelting, the ingot diameter is Ф450mm, the arc stabilizing current is 8A, and the reversing time interval is 40s; during the third smelting, the ingot diameter is Ф550mm, the arc stabilizing current is 10A, and the reversing time interval is 40s; at the end of the three smeltings, when entering the feeding stage, the arc stabilizing current is 6A, and the reversing time interval is 40s. After the smelting is completed, a zirconium alloy ingot with a nominal composition of Zr-Sn-Fe-Cr-Si-O-Al-Ta is obtained.

[0077] Example 3 (Preparation of a zirconium alloy ingot with a nominal composition of Zr-Sn-Fe-Cr-O-Hf-W)

[0078] The preparation method of the zirconium alloy ingot in this embodiment is as follows:

[0079] 1) Raw material preparation: Prepare materials according to the nominal composition of the target zirconium alloy ingot Zr-Sn-Fe-Cr-O-Hf-W (wherein Sn=0.9%, Fe=0.15%, Cr=0.12%, O=0.11%, Hf=0.02%, W=0.02%).

[0080] 2) Raw material allocation: The ingredients are calculated based on the weight of a single electrode block of 55kg. Among them, the Sn element is added through Zr-Sn master alloy, Fe uses pure Fe chips, Cr uses pure Cr particles, O is added with the help of ZrO2 powder, Hf is added using pure Hf particles, and W is added using pure W powder (particle size less than 30μm). According to calculations, a single electrode block uses 0.83kg of Zr-Sn master alloy, 0.07kg of Fe chips, 0.07kg of Cr particles, 0.13kg of ZrO2 powder, 0.011kg of Hf particles, 0.011kg of W powder, and 53.89kg of sponge zirconium.

[0081] 3) Electrode preparation: Divide the zirconium sponge 1 into 3 equal parts, each weighing 17.963 kg, and divide the alloy raw material into 2 equal parts. The specific materials are as follows:

[0082] First, 17.963 kg of zirconium sponge 1 was placed in the press cavity. Then, zirconium foil 2 having the same cross-sectional size as the press cavity was placed on the upper layer of the bottom layer of zirconium sponge 1.

[0083] Next, the first alloy raw material 3 is arranged. When arranging, the intermediate alloy block 31, i.e., the Zr-Sn intermediate alloy, is placed first; then the non-chip-shaped raw material 32, which is mixed evenly, is placed, in the order of first arranging ZrO2 powder and W powder, then arranging Cr particles and Hf particles, and finally arranging the chip-shaped raw material 33, i.e., Fe chips. Moreover, the distance between all the arranged alloy raw materials and the edge of the mold cavity is not less than 30 mm.

[0084] Finally, after the first portion of alloy raw material 3 is arranged, zirconium foil 2, the second portion of 17.963 kg of sponge zirconium 1, zirconium foil 2, another portion of alloy raw material 3 (arranged in the same way as before), zirconium foil 2, and the last portion of 17.963 kg of sponge zirconium 1 are laid on the upper layer in sequence. After laying out the materials in this way, a 9-layer structure of sponge zirconium 1 → zirconium foil 2 → alloy raw material 3 → zirconium foil 2 → sponge zirconium 1 → zirconium foil 2 → alloy raw material 3 → zirconium foil 2 → sponge zirconium 1 is formed from bottom to top in the press cavity (not shown in the figure). Finally, the electrode is pressed and the electrode block is welded into a consumable electrode.

[0085] 4) Ingot smelting: During the first smelting, the ingot diameter is 280 mm, the arc stabilizing current is 4.5 A, and the reversing time interval is 30 s; during the second smelting, the ingot diameter is 360 mm, the arc stabilizing current is 6.5 A, and the reversing time interval is 30 s; during the third smelting, the ingot diameter is 450 mm, the arc stabilizing current is 8.5 A, and the reversing time interval is 40 s; at the end of the third smelting, when entering the feeding stage, the arc stabilizing current is 5 A, and the reversing time interval is 30 s. After the smelting is completed, a zirconium alloy ingot with a nominal composition of Zr-Sn-Fe-Cr-O-Hf-W is obtained.

[0086] Example 4 (Preparation of a zirconium alloy ingot with a nominal composition of Zr-Sn-Fe-Cr-O-Mo)

[0087] The preparation method of the zirconium alloy ingot in this embodiment is as follows:

[0088] 1) Raw material preparation: Prepare materials according to the nominal composition of the target zirconium alloy ingot Zr-Sn-Fe-Cr-O-Mo (wherein Sn=0.8%, Fe=0.12%, Cr=0.13%, O=0.13%, Mo=0.02%).

[0089] 2) Raw material allocation: The weight of a single electrode block is 55kg. Among them, the Sn element is added through Zr-Sn master alloy, Fe uses pure Fe chips, Cr uses pure Cr particles, O is added with ZrO2 powder, and Mo uses pure Mo powder (particle size less than 30μm). According to calculations, a single electrode block requires 0.73kg of Zr-Sn master alloy, 0.06kg of Fe chips, 0.07kg of Cr particles, 0.17kg of ZrO2 powder, 0.006kg of Mo powder, and 53.96kg of zirconium sponge.

[0090] 3) Electrode preparation: Divide the zirconium sponge 1 into 2 equal portions, each weighing 26.98 kg. First, arrange 26.98 kg of zirconium sponge 1 in the press cavity, and then place zirconium foil 2 with the same cross-sectional size as the press cavity on the upper layer of the bottom layer of zirconium sponge 1. Then arrange the alloy raw material 3. When arranging, first place the intermediate alloy block 31, that is, the Zr-Sn intermediate alloy; then place the evenly mixed non-chip-like raw material 32, in the order of arranging ZrO2 powder and Mo powder first, and then Cr particles; finally arrange the chip-like raw material 33, that is, Fe chips. Moreover, the distance between all arranged alloy raw materials 3 and the edge of the cavity is not less than 30 mm. After the alloy raw material 3 is arranged, lay another layer of zirconium foil 2 on the upper layer, and then add the remaining 26.98 kg of zirconium sponge 1 into the press cavity. After the materials are laid out in this way, a five-layer structure of zirconium sponge 1 → zirconium foil 2 → alloy raw material 3 → zirconium foil 2 → zirconium sponge 1 is formed from bottom to top in the press cavity, as shown in FIG. Figure 2 , 3Finally, the electrode is pressed and the electrode block is welded into a consumable electrode.

[0091] 4) Ingot smelting: During the first smelting, the ingot diameter is 280 mm, the arc stabilizing current is 4.5 A, and the switching time interval is 30 s; during the second smelting, the ingot diameter is 360 mm, the arc stabilizing current is 6.5 A, and the switching time interval is 30 s; at the end of the second smelting, when entering the feeding stage, the arc stabilizing current is 5 A, and the switching time interval is 30 s. After the smelting is completed, a zirconium alloy ingot with a nominal composition of Zr-Sn-Fe-Cr-O-Mo is obtained.

[0092] In order to verify the uniformity of the zirconium alloy ingot prepared by the preparation method of the present invention, the inventors sampled and analyzed 9 points of the zirconium alloy ingots obtained after smelting in Examples 1 to 4, including the center of the head end face, the head end face R / 2, the edge of the head end face, the upper side wall, the middle side wall, the lower side wall, the center of the tail end face, the tail end face R / 2, and the edge of the tail end face. The extreme value and relative standard deviation of each element are shown in Tables 1 and 2 below:

[0093] Table 1 Extreme value of each element of zirconium alloy ingots prepared in Examples 1 to 4 (%)

[0094]

[0095]

[0096] Table 2 Relative standard deviation of each element of zirconium alloy ingots prepared in Examples 1 to 4 (%)

[0097]

[0098] From the relative standard deviation results of various elements in the zirconium alloy ingot samples prepared in Examples 1 to 4, it can be seen that various alloy elements in the target ingot prepared by the present invention are evenly distributed.

[0099] In summary, the present invention can successfully prepare ingots with uniform chemical composition and meet the demand for high uniformity products through the synergistic effects of reasonable selection of raw materials, careful design of material distribution methods, and precise control of smelting process parameters.

[0100] The above description is only a specific embodiment of the present invention, so that those skilled in the art can understand or implement the present invention. Various modifications to these embodiments will be apparent to those skilled in the art, and the general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the present invention.

[0101] It should be understood that the present invention is not limited to what has been described above and that various modifications and changes may be made without departing from its scope. The scope of the present invention is limited only by the appended claims.

Claims

1. A method for preparing a high-uniformity zirconium alloy ingot, characterized in that: The following steps are involved: Step 1: Raw materials preparation Raw materials are prepared according to the nominal composition of the target zirconium alloy ingot, the raw materials include sponge zirconium and alloy raw materials, and the composition of the alloy raw materials includes one or more of the following four categories: Category I is low melting point elements Sn or Al; Category II is high melting point elements Nb, Mo, Ta, W or C; Category III is elements Ge, Cu, Si, Ni, Y, Fe, Ti, V, Cr or Hf with melting points between Category I and Category II; Category IV is O; Step 2: Raw Materials Allocation According to the target zirconium alloy ingot batching calculation value, batching calculation is performed according to the weight of a single electrode block, and according to the addition method of the alloy raw materials, the weight of the sponge zirconium and alloy raw materials required for a single electrode block is determined; Step 3: Electrode preparation First, the zirconium sponge dispensed in step 2 is equally divided into N portions, and the alloy raw material dispensed is equally divided into N-1 portions; then the N-1 portions of the alloy raw material and the N portions of the zirconium sponge are alternately arranged in a press die cavity to form a stacked structure; finally, the arranged materials are pressed to obtain an electrode block, and the electrode block is welded into a consumable electrode; Wherein, N is a natural number greater than or equal to 2; Step 4: Ingot Melting The consumable electrode obtained in step 3 is subjected to vacuum consumable arc melting at least twice using a commutated arc stabilizing current to obtain the target zirconium alloy ingot.

2. The method for preparing a high uniformity zirconium alloy ingot according to claim 1, characterized in that: In step 2, the four types of alloy raw materials are added respectively in the following ways: Type I alloying materials are added via alloys containing Sn or Al; Type II alloy raw materials are added through pure elements or compounds containing corresponding elements; Class III alloy raw materials are added with pure elements; Type IV alloy raw materials are added with the help of O-containing compounds; Wherein, when the type II alloy raw material or the type IV alloy raw material is added in the form of a compound, the content of impurity elements introduced by the compound should not exceed the upper limit value of the content of the impurity elements in the target zirconium alloy ingot.

3. The method for preparing a high uniformity zirconium alloy ingot according to claim 2, characterized in that: In step 2, the type I alloy raw material includes Zr-Sn, Zr-Al or Zr-Sn-Al master alloy; When the Class II alloy raw materials are corresponding compounds, they include Zr-Nb, AlMo, AlTa, WO3 or Cr3C2; The type IV alloy raw material includes ZrO2.

4. The method for preparing a high uniformity zirconium alloy ingot according to claim 3, characterized in that: The Zr-Sn, Zr-Al or Zr-Sn-Al master alloy in the Class I alloy is in the form of spherical blocks; When the Class II alloy raw material is a pure element, it is in powder form, and the powder particle size is less than or equal to 30 μm; When the Class II alloy raw materials are corresponding compounds, Zr-Nb is in the form of chips, and AlMo, AlTa, WO3 or Cr3C2 is in the form of powder or granules; The Class III alloy raw material is in the form of foil, flake, granule, block, chip or powder; The type IV alloy raw material is ZrO2 powder.

5. The method for preparing a high uniformity zirconium alloy ingot according to claim 1, characterized in that: In step three, before arranging the alloy raw materials, a layer of zirconium foil is laid on the lower layer of the alloy raw materials. After the arrangement is completed, another layer of zirconium foil is laid on the upper layer of the alloy raw materials, and the cross-sectional size of each layer of the zirconium foil laid should be the same as the cross-sectional size of the press cavity.

6. The method for preparing a high uniformity zirconium alloy ingot according to claim 1, characterized in that: In step 3, when N=2, the raw materials include two portions of zirconium sponge, one portion of alloy raw material and two layers of zirconium foil, and the specific cross-arrangement and stacked structure formed are as follows: First, a portion of zirconium sponge is laid on the bottom layer of the press cavity; then a layer of zirconium foil is laid on the upper surface of the zirconium sponge, and an alloy raw material is arranged on the zirconium foil; finally, another layer of zirconium foil is laid on the alloy raw material, and another portion of zirconium sponge is laid on the top layer.

7. The method for preparing a high uniformity zirconium alloy ingot according to claim 1, characterized in that: In step three, when the alloy raw materials are arranged, the intermediate alloy block is arranged first, then the non-chip raw materials are arranged, and finally the chip raw materials are arranged. The distance between all the arranged raw materials and the edge of the press cavity is greater than or equal to 30 mm; wherein, when the powdered raw materials are arranged, the two or more powdered raw materials after distribution should be mixed evenly.

8. The method for preparing a high uniformity zirconium alloy ingot according to claim 1, characterized in that: In the step 4, when the consumable electrode uses a commutated arc-stabilizing current to perform vacuum consumable arc melting three times, the specific melting process is as follows: The ingot diameter of the first vacuum consumable arc melting is 220mm to 360mm, the arc stabilization current is 3A to 6A, and the switching time interval is 20s to 40s. The ingot diameter of the second vacuum consumable arc melting is Ф280mm~Ф450mm, the arc stabilization current is 5A~8A, and the switching time interval is 20s~40s; The ingot diameter of the third vacuum consumable arc melting is Ф360mm~Ф550mm, the arc stabilization current is 7A~10A, and the switching time interval is 20s~40s.

9. The method for preparing a high uniformity zirconium alloy ingot according to claim 8, characterized in that: In the step 4, when entering the feeding stage at the end of the third smelting, the arc stabilizing current in the feeding stage is 4A to 6A, and the switching time interval is 20s to 40s.

10. An application of a high uniformity zirconium alloy ingot, characterized in that: The high-uniformity zirconium alloy ingot is prepared based on the preparation method according to any one of claims 1 to 9, and the high-uniformity zirconium alloy ingot is used to prepare nuclear fuel structural parts.

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