High-homogeneity and high-purity GH4145 alloy for nuclear use and short-process preparation method of high-homogeneity and high-purity GH4145 alloy

Abstract

The invention discloses a nuclear high-homogeneity and high-purity GH4145 alloy and a short-process preparation method thereof. The short-process preparation method comprises the following steps: 1, selecting and pretreating a crucible; 2, preparing raw materials; 3, material distribution; 4, vacuum melting; the content of impurity elements in the alloy is as follows: S is less than or equal to 0.001%, O is less than or equal to 0.001% and N is less than or equal to 0.002%. The inner wall of the magnesia crucible is coated with calcium oxide to react with excessive aluminum, the effects of deep deoxidation, denitrification and desulfurization are achieved, corresponding inclusions are prevented from being formed, nickel-chromium and nickel-niobium intermediate alloys are selected to replace high-melting-point elemental metal chromium and niobium, high-melting-point non-frit is prevented from being formed, the smelting time is effectively shortened, component homogenization is facilitated, and the production efficiency is improved. And through electromagnetic stirring during smelting, components are further homogenized, gas and low-density inclusions are promoted to be discharged, the high-homogeneity and high-purity GH4145 alloy is obtained, short-process preparation is achieved, and the alloy is suitable for fastening bolts and spring components in a pressurized water reactor control rod driving mechanism.

Description

Technical Field

[0001] The invention belongs to the technical field of alloy preparation, and specifically relates to a high-homogeneity and high-purity GH4145 alloy for nuclear use and a short-process preparation method thereof. Background Art

[0002] GH4145 alloy is currently used for fastening bolts and spring components in the control rod drive mechanism of pressurized water reactors due to its good fatigue resistance, radiation resistance, high temperature resistance and corrosion resistance. These fastening bolts and spring components are in direct contact with the primary coolant and are subject to high temperature, high pressure and corrosion of the reactor coolant for a long time. Therefore, they are required to have the above excellent properties and long-term organizational stability to ensure stable service performance.

[0003] GH4145 alloy is a nickel-based high-temperature alloy that is strengthened by aging with γ' phase. The addition of Al, Ti, and Nb elements promotes the formation of Ni3 (Al, Ti, Nb) type γ' phase to achieve aging precipitation strengthening. However, the GH4145 alloy prepared by the existing process has problems with composition uniformity, unstable control of inclusions, harmful gases and impurity content, resulting in large fluctuations in the mechanical properties of the prepared GH4145 alloy products between batches. Therefore, in order to ensure that the GH4145 alloy has stable service performance, it is necessary to accurately control the content and uniformity of alloy elements during the preparation process, reduce the content of inclusions and impurity elements in the alloy, and obtain highly homogeneous and highly purified GH4145 alloy billets.

[0004] Patent publication number CN114635058A discloses a GH4145 alloy electroslag ingot and a manufacturing method thereof. The method prepares a high-purity, large-size, homogenized GH4145 alloy ingot through a four-in-one smelting process of electric furnace + argon oxygen decarburization furnace + ladle refining furnace + electroslag. However, the process flow of this method is too long, the production efficiency is low, and the cost is significantly increased.

[0005] Patent publication number CN105483448A discloses a method for preparing a nuclear nickel-based high-temperature alloy GH4145 wire. The method uses vacuum induction + vacuum consumable dual smelting and casting to form an alloy ingot, forging it into an alloy steel ingot after homogenization, and then hot rolling it into a Ø8mm~12mm wire rod, and finally solid solution, multiple cold drawing and annealing to obtain the GH4145 alloy wire of the required diameter. This method is a small-sized wire produced by a small ingot production process using a double vacuum approach, which is not suitable for the preparation of large-sized nickel-based high-temperature alloy GH4145 ingots. In addition, the patent has no specific requirements for raw materials, and the production process does not control impurity elements and inclusions such as oxygen and nitrogen, and the uniformity and purity of the prepared GH4145 alloy ingot cannot be stably guaranteed. Summary of the invention

[0006] The technical problem to be solved by the present invention is to provide a short-process preparation method for a high-homogeneity and high-purity GH4145 alloy for nuclear use in view of the deficiencies of the above-mentioned prior art. The method adopts a vacuum melting method, and by coating calcium oxide on the inner wall of a magnesium oxide crucible to react with excess aluminum, the effects of deep deoxidation, denitrification and desulfurization are achieved, and the formation of corresponding inclusions is avoided. By selecting nickel-chromium and nickel-niobium intermediate alloys instead of high-melting-point elemental metals chromium and niobium, the formation of high-melting-point infusible blocks is avoided, the melting time is effectively shortened, and it is beneficial to the homogenization of the composition. By performing electromagnetic stirring during the vacuum melting process, the composition is further homogenized and the gas and low-density inclusions are promoted to be discharged, thereby obtaining a high-homogeneity and high-purity GH4145 alloy, and realizing short-process preparation, the problem of long existing process flow and the inability to stably guarantee the uniformity and purity of the alloy is solved.

[0007] In order to solve the above technical problems, the technical solution adopted by the present invention is: a short-process preparation method of a highly homogeneous and highly purified GH4145 alloy for nuclear use, characterized in that the method comprises the following steps:

[0008] Step 1: selecting and pre-treating a crucible: selecting a magnesium oxide crucible, coating the inner wall of the magnesium oxide crucible with calcium oxide, and then drying the crucible to obtain a pre-treated crucible;

[0009] Step 2, raw material preparation: select block NiCr45 master alloy, NiNb65 master alloy, electrolytic nickel, sponge titanium, metallic iron and metallic aluminum as raw materials, and then weigh the raw materials that meet the design composition ratio requirements according to the design composition of the target product GH4145 alloy, and weigh the metallic aluminum separately;

[0010] Step 3, material distribution: part of the nickel metal weighed in the raw material in step 2 is spread on the bottom of the pre-treated crucible in step 1, and the aluminum metal weighed in step 2 is placed near the crucible wall, and then the sponge titanium, iron metal, remaining nickel metal, aluminum metal, block NiCr45 master alloy, and NiNb65 master alloy in the raw material are sequentially added to complete the material distribution;

[0011] Step 4: Vacuum melting: After the material is laid in step 3, vacuum induction melting is performed, and electromagnetic stirring is performed during the vacuum induction melting process, and then the alloy is cast into an ingot to obtain a highly homogeneous and highly purified GH4145 alloy.

[0012] The present invention adopts vacuum induction melting to prepare GH4145 alloy, and selects a magnesium oxide crucible with an inner wall coated with calcium oxide as a melting crucible. During the melting process, the calcium oxide on the inner wall of the crucible reacts with the aluminum added to the alloy raw material to form CaO-saturated CaO·Al2O3 slag, which reduces the activity of Al2O3 and accelerates the reaction between aluminum and oxygen, thereby facilitating deep deoxidation. On the other hand, CaO and Al and S can react simultaneously to form CaS and CaO·Al2O3, which is beneficial to desulfurization. At the same time, the better deoxidation effect also reduces the free oxygen concentration in the molten metal, reduces the oxidation opportunity of other impurities, and further improves the denitrification and desulfurization efficiency. Secondly, the raw materials of the present invention use a material with a melting point and density close to that of the matrix nickel metal (melting point of about 1455°C, density of about 8.9g / cm 3 ) nickel-chromium master alloy (melting point about 1350°C, density about 8.1g / cm 3 ) and nickel-niobium master alloy (melting point about 1290℃, density about 8.7g / cm 3 ), replacing the high-melting-point elemental metal chromium (melting point of about 1907°C) and niobium (melting point of about 2477°C), avoiding the formation of high-melting-point non-melting block inclusions, and effectively reducing the smelting time, reducing the loss of low-melting-point metal aluminum, thereby more accurately controlling the uniformity of alloy elements and components. In addition, the vacuum smelting process of the present invention is accompanied by electromagnetic stirring, which is beneficial to the diffusion of alloy elements, and promotes the floating and discharge of gases and low-density inclusions, further homogenizing the alloy composition and improving the purity of the alloy. Under the above-mentioned combined effects, the present invention prepares a highly homogeneous and highly purified GH4145 alloy, which is suitable for the field of nuclear equipment.

[0013] In the vacuum induction melting process of the present invention, the bottom and middle of the crucible become high temperature areas due to poor heat dissipation conditions. Therefore, some metal nickel (1455°C), sponge titanium (1660°C), metal iron (1539°C) and remaining nickel with relatively high melting points are placed in the bottom of the crucible, and sponge titanium (4.54 g / cm 2 ) is placed between the metal nickel and the metal iron, which is beneficial to the homogenization of the elements after the later melting. Then the low-melting-point metal aluminum, block NiCr45 master alloy, and NiNb65 master alloy are placed on the upper part of the crucible to improve the uniformity of smelting.

[0014] The above-mentioned short-process preparation method of a highly homogeneous and highly purified GH4145 alloy for nuclear use is characterized in that the coating thickness of the calcium oxide in step 1 is 1 mm to 3 mm; the temperature of the drying treatment is 600°C to 700°C, and the time is 15 min to 30 min. The present invention controls the coating thickness of the calcium oxide, and controls the temperature and time of the drying treatment to fully remove the calcium oxide bound water, ensure the drying of the magnesium oxide crucible and the coated calcium oxide, and is beneficial to the subsequent deoxidation, denitrification and desulfurization.

[0015] The short-process preparation method of a high-homogeneity and high-purity GH4145 alloy for nuclear use is characterized in that the mass purity of the raw material block NiCr45 master alloy, NiNb65 master alloy, electrolytic nickel, sponge titanium, metal iron and metal aluminum in step 2 is greater than 99.9% and the size is 10mm to 100mm. The present invention strictly controls the purity and size of the raw materials, which, on the one hand, facilitates the uniformity of the composition during the distribution and subsequent melting, and on the other hand, ensures that the final product GH4145 alloy has low impurity content and high purity.

[0016] The above-mentioned short-process preparation method of a highly homogeneous and highly purified GH4145 alloy for nuclear use is characterized in that the mass of the additionally weighed metal aluminum in step 2 is 0.5% of the total mass of the raw material. The 0.5% aluminum weighed externally reacts with the calcium oxide on the inner wall of the crucible during the smelting process to form CaO-saturated CaO·Al2O3 slag, which, on the one hand, reduces the activity of Al2O3 and accelerates the reaction between aluminum and oxygen, thereby facilitating deep deoxidation; on the other hand, CaO and Al and S can react simultaneously to form CaS and CaO·Al2O3, which is beneficial to desulfurization; at the same time, the better deoxidation effect also reduces the free oxygen concentration in the molten metal, reduces the oxidation opportunities of other impurities, and further improves the denitrification and desulfurization efficiency.

[0017] The above-mentioned short-process preparation method of high-homogeneity and high-purity GH4145 alloy for nuclear use is characterized in that the mass of the part of metal nickel described in step three accounts for 1 / 2 of the mass of all metal nickel in the raw material.

[0018] The short-process preparation method of a high-homogeneity and high-purity GH4145 alloy for nuclear use is characterized in that the vacuum induction melting process described in step 4 is: first evacuate to 0.005Pa~0.001Pa, then fill in argon gas with a mass purity of more than 99.99% to 0.1Pa for washing, repeat the evacuation and argon washing process twice, and then smelt, the smelting temperature is 1500℃~1700℃, and keep warm for 20min~40min after melting. The present invention avoids the gas existing in the furnace chamber from contaminating the alloy during the smelting process through two washing processes and high vacuum during smelting; at the same time, the appropriate smelting temperature and smelting time can ensure uniform melting of the raw materials, avoid insufficient smelting temperature and time, resulting in incomplete melting of the alloy and uneven diffusion of alloy elements, or large burnout of low-melting-point elements due to excessively high smelting temperature and long smelting time.

[0019] The above-mentioned short-process preparation method of a highly homogeneous and highly purified GH4145 alloy for nuclear use is characterized in that the voltage of the electromagnetic stirring accompanying the vacuum induction melting process in step 4 is 100V to 150V, and the current is 4kA to 5kA. The present invention facilitates the diffusion of alloy elements and promotes the floating and discharge of gas and low-density inclusions by performing electromagnetic stirring within the above parameter range during vacuum melting, further homogenizing the composition of the GH4145 alloy and improving the purity of the GH4145 alloy.

[0020] At the same time, the present invention also discloses a highly homogeneous and highly purified GH4145 alloy for nuclear use prepared by the above method, characterized in that the main element components of Ni, Cr, Al, Ti, Fe, and Nb in the GH4145 alloy are evenly distributed without segregation, and the mass percentages of key impurity elements are: S≤0.001%, O≤0.001%, and N≤0.002%.

[0021] The GH4145 alloy prepared by the present invention has the characteristics of high homogenization, high purity and low impurity content, and the alloy elements are evenly distributed, without the inclusion of unmelted blocks formed by high melting point single metal and the inclusion of impurity elements such as oxygen, nitrogen and sulfur, and the content of impurity elements is low. The fastening bolts and spring components in the control rod drive mechanism of the pressurized water reactor prepared by using the alloy billet can ensure the excellence and stability of its service performance.

[0022] Compared with the prior art, the present invention has the following advantages:

[0023] 1. The present invention adopts a magnesium oxide crucible with an inner wall coated with calcium oxide in the vacuum induction melting process of preparing GH4145 alloy, and utilizes calcium oxide to react with excess aluminum metal to perform deoxidation, denitrification and desulfurization, thereby reducing the impurity content and the corresponding inclusion content; adopts nickel-chromium and nickel-niobium master alloys to replace high-melting-point elemental metals chromium and niobium, thereby avoiding the formation of high-melting-point non-melting block inclusions, effectively reducing the melting time, reducing the loss of low-melting-point metal aluminum, and thus more accurately controlling the uniformity of alloy elements and components; and performs electromagnetic stirring during the vacuum melting process, which is beneficial to the diffusion of alloy elements, and promotes the floating and discharge of gas and low-density inclusions, thereby further homogenizing the alloy components and improving the purity of the alloy.

[0024] 2. The GH4145 alloy prepared by the present invention has the characteristics of high homogenization, high purity and low impurity content. The alloy elements are evenly distributed, and there are no inclusions of unmelted blocks formed by high-melting point single metals and inclusions formed by impurity elements such as oxygen, nitrogen, and sulfur. The impurity element content is low, and it is suitable for fastening bolts and spring components in the control rod drive mechanism of a pressurized water reactor to ensure the superiority and stability of the component performance.

[0025] 3. Compared with the preparation of GH4145 electroslag ingots by the four-in-one process of electric furnace + argon oxygen decarburization furnace + ladle refining furnace + electroslag, the present invention only uses vacuum induction melting process to prepare high-homogeneity and high-purity GH4145 alloy, with a short process flow, high production efficiency and significantly reduced costs.

[0026] 4. Compared with the conventional vacuum induction + vacuum consumable dual smelting and casting into alloy ingots, the present invention coats the crucible wall with calcium oxide and adds excess aluminum for deep deoxidation, denitrification and desulfurization. Combined with the raw materials, an intermediate alloy with a melting point and density close to that of the base metal nickel is used for smelting, which is more conducive to uniform composition, reducing impurity content and improving alloy purity.

[0027] 5. The method for preparing the highly homogeneous and highly purified GH4145 alloy of the present invention is simple and effective, and is suitable for large-scale and mass industrial production.

[0028] The technical solution of the present invention is further described in detail below through the accompanying drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 This is a scan image of the GH4145 alloy prepared in Example 1 of the present invention.

[0030] Figure 2 This is the distribution diagram of Ni element in the GH4145 alloy prepared in Example 1 of the present invention.

[0031] Figure 3 This is the distribution diagram of Cr element in the GH4145 alloy prepared in Example 1 of the present invention.

[0032] Figure 4 This is the Al element distribution diagram in the GH4145 alloy prepared in Example 1 of the present invention.

[0033] Figure 5 This is the distribution diagram of Ti element in the GH4145 alloy prepared in Example 1 of the present invention.

[0034] Figure 6 This is the distribution diagram of Fe element in the GH4145 alloy prepared in Example 1 of the present invention.

[0035] Figure 7 This is the distribution diagram of Nb element in the GH4145 alloy prepared in Example 1 of the present invention. DETAILED DESCRIPTION

[0036] Example 1

[0037] This embodiment includes the following steps:

[0038] Step 1, crucible selection and pretreatment: select a magnesium oxide crucible, and coat the inner wall of the magnesium oxide crucible with a thickness of 2 mm of calcium oxide, and then perform a drying treatment at a temperature of 650° C. for 20 min to obtain a pretreated crucible;

[0039] Step 2, raw material preparation: select block NiCr45 master alloy, NiNb65 master alloy, electrolytic nickel plate, sponge titanium, metallic iron and metallic aluminum as raw materials, and then weigh the raw materials that meet the design composition ratio requirements according to the design composition of the target product GH4145 alloy, and weigh the metallic aluminum separately; the mass purity of the raw materials block NiCr45 master alloy, NiNb65 master alloy, electrolytic nickel plate, sponge titanium, metallic iron and metallic aluminum is greater than 99.9%, and the size is 10mm~100mm; the mass of the metallic aluminum separately weighed is 0.5% of the total mass of the raw materials;

[0040] Step 3, material distribution: a portion of the metal nickel plate accounting for 1 / 2 of the mass of all the metal nickel in the raw material in step 2 is spread on the bottom of the pre-treated crucible in step 1, and the metal aluminum weighed in step 2 is placed near the crucible wall, and then the sponge titanium, metal iron, remaining metal nickel plate, metal aluminum, block NiCr45 master alloy, and NiNb65 master alloy in the raw material are sequentially placed to complete the material distribution;

[0041] Step 4, vacuum melting: after the material is laid in step 3, vacuum induction melting is carried out, and electromagnetic stirring is performed during the vacuum induction melting process, and then it is cast into an ingot to obtain a high-homogeneity and high-purity GH4145 alloy; the vacuum induction melting process is: first evacuate to 0.005Pa~0.001Pa, and then fill with argon gas with a mass purity of more than 99.99% to 0.1Pa for gas washing, repeat the vacuum extraction and argon gas washing process twice, and then melt, the melting temperature is 1600°C, and the heat is kept for 30 minutes after melting; the voltage of the electromagnetic stirring accompanied by the vacuum induction melting process is 130V and the current is 4.5kA.

[0042] The impurity elements of the GH4145 alloy prepared in this embodiment were detected, and the results are shown in Table 1 below:

[0043] Table 1 Impurity element content (wt%) of GH4145 alloy prepared in this example

[0044] element S O N content 0.001 0.001 0.002

[0045] As can be seen from Table 1, the impurity elements in the GH4145 alloy are very low, especially oxygen, nitrogen and sulfur elements. It is used for fastening bolts and spring components in the control rod drive mechanism of a pressurized water reactor, which can ensure the superiority and stability of service performance.

[0046] Figure 1This is a scan of the GH4145 alloy prepared in this example. Figure 2 to Figure 7 They are the distribution diagrams of Ni, Cr, Al, Ti, Fe and Nb elements in the GH4145 alloy prepared in this embodiment, combined with Figure 1 and Figure 2 to Figure 7 It can be seen that all alloying elements in the GH4145 alloy are uniformly distributed as a whole, there is no segregation, and no high-melting-point infusible block inclusions are formed.

[0047] Example 2

[0048] This embodiment includes the following steps:

[0049] Step 1, crucible selection and pretreatment: select a magnesium oxide crucible, and coat the inner wall of the magnesium oxide crucible with a thickness of 1 mm of calcium oxide, and then perform a drying treatment at a temperature of 600° C. for 30 min to obtain a pretreated crucible;

[0050] Step 2, raw material preparation: select block NiCr45 master alloy, NiNb65 master alloy, electrolytic nickel plate, sponge titanium, metallic iron and metallic aluminum as raw materials, and then weigh the raw materials that meet the design composition ratio requirements according to the design composition of the target product GH4145 alloy, and weigh the metallic aluminum separately; the mass purity of the raw materials block NiCr45 master alloy, NiNb65 master alloy, electrolytic nickel plate, sponge titanium, metallic iron and metallic aluminum is greater than 99.9%, and the size is 10mm~100mm; the mass of the metallic aluminum separately weighed is 0.5% of the total mass of the raw materials;

[0051] Step 3, material distribution: a portion of the metal nickel plate accounting for 1 / 2 of the mass of all the metal nickel in the raw material in step 2 is spread on the bottom of the pre-treated crucible in step 1, and the metal aluminum weighed in step 2 is placed near the crucible wall, and then the sponge titanium, metal iron, remaining metal nickel plate, metal aluminum, block NiCr45 master alloy, and NiNb65 master alloy in the raw material are sequentially placed to complete the material distribution;

[0052] Step 4, vacuum melting: after the material is laid in step 3, vacuum induction melting is carried out, and electromagnetic stirring is performed during the vacuum induction melting process, and then it is cast into an ingot to obtain a high-homogeneity and high-purity GH4145 alloy; the vacuum induction melting process is: first evacuate to 0.005Pa~0.001Pa, and then fill with argon gas with a mass purity of more than 99.99% to 0.1Pa for gas washing, repeat the vacuum extraction and argon gas washing process twice, and then melt, the melting temperature is 1500°C, and the temperature is kept for 40 minutes after melting; the voltage of the electromagnetic stirring accompanied by the vacuum induction melting process is 100V and the current is 4kA.

[0053] The impurity elements of the GH4145 alloy prepared in this embodiment were detected, and the results are shown in Table 2 below:

[0054] Table 2 Impurity element content of GH4145 alloy prepared in this example (wt%)

[0055] element S O N content 0.001 0.001 0.002

[0056] As can be seen from Table 2, the impurity elements in the GH4145 alloy are very low, especially oxygen, nitrogen and sulfur elements. It is used for fastening bolts and spring components in the control rod drive mechanism of a pressurized water reactor, which can ensure the superiority and stability of service performance.

[0057] After testing, all alloy elements in the GH4145 alloy prepared in this embodiment are uniformly distributed as a whole, without segregation and without forming high-melting-point infusible block inclusions.

[0058] Example 3

[0059] This embodiment includes the following steps:

[0060] Step 1, crucible selection and pretreatment: select a magnesium oxide crucible, and coat the inner wall of the magnesium oxide crucible with a thickness of 3 mm of calcium oxide, and then perform a drying treatment at a temperature of 700° C. for 15 min to obtain a pretreated crucible;

[0061] Step 2, raw material preparation: select block NiCr45 master alloy, NiNb65 master alloy, electrolytic nickel plate, sponge titanium, metallic iron and metallic aluminum as raw materials, and then weigh the raw materials that meet the design composition ratio requirements according to the design composition of the target product GH4145 alloy, and weigh the metallic aluminum separately; the mass purity of the raw materials block NiCr45 master alloy, NiNb65 master alloy, electrolytic nickel plate, sponge titanium, metallic iron and metallic aluminum is greater than 99.9%, and the size is 10mm~100mm; the mass of the metallic aluminum separately weighed is 0.5% of the total mass of the raw materials;

[0062] Step 3, material distribution: a portion of the metal nickel plate accounting for 1 / 2 of the mass of all the metal nickel in the raw material in step 2 is spread on the bottom of the pre-treated crucible in step 1, and the metal aluminum weighed in step 2 is placed near the crucible wall, and then the sponge titanium, metal iron, remaining metal nickel plate, metal aluminum, block NiCr45 master alloy, and NiNb65 master alloy in the raw material are sequentially placed to complete the material distribution;

[0063] Step 4, vacuum melting: after the material is laid in step 3, vacuum induction melting is carried out, and electromagnetic stirring is performed during the vacuum induction melting process, and then it is cast into an ingot to obtain a high-homogeneity and high-purity GH4145 alloy; the vacuum induction melting process is: first evacuate to 0.005Pa~0.001Pa, and then fill with argon gas with a mass purity of more than 99.99% to 0.1Pa for gas washing, repeat the vacuum extraction and argon gas washing process twice, and then melt, the melting temperature is 1700°C, and the heat is kept for 20 minutes after melting; the voltage of the electromagnetic stirring accompanied by the vacuum induction melting process is 150V and the current is 5kA.

[0064] The impurity elements of the GH4145 alloy prepared in this embodiment were detected, and the results are shown in Table 3 below:

[0065] Table 3 Impurity element content of GH4145 alloy prepared in this example (wt%)

[0066] element S O N content 0.0003 0.0002 0.001

[0067] As can be seen from Table 3, the impurity elements in the GH4145 alloy are very low, especially oxygen, nitrogen and sulfur elements. It is used for fastening bolts and spring components in the control rod drive mechanism of a pressurized water reactor, which can ensure the superiority and stability of service performance.

[0068] After testing, all alloy elements in the GH4145 alloy prepared in this embodiment are uniformly distributed as a whole, without segregation and without forming high-melting-point infusible block inclusions.

[0069] The above is only a preferred embodiment of the present invention and does not limit the present invention in any way. Any simple modification, change and equivalent change made to the above embodiment according to the technical essence of the invention still falls within the protection scope of the technical solution of the present invention.

Claims

1. A short-process preparation method for high-homogeneity and high-purity GH4145 alloy for nuclear use, characterized in that: The method comprises the following steps: Step 1: selecting and pre-treating a crucible: selecting a magnesium oxide crucible, coating the inner wall of the magnesium oxide crucible with calcium oxide, and then drying the crucible to obtain a pre-treated crucible; Step 2, raw material preparation: select block NiCr45 master alloy, NiNb65 master alloy, electrolytic nickel, sponge titanium, metallic iron and metallic aluminum as raw materials, and then weigh the raw materials that meet the design composition ratio requirements according to the design composition of the target product GH4145 alloy, and weigh the metallic aluminum separately; Step 3, material distribution: part of the nickel metal weighed in the raw material in step 2 is spread on the bottom of the pre-treated crucible in step 1, and the aluminum metal weighed in step 2 is placed near the crucible wall, and then the sponge titanium, iron metal, remaining nickel metal, aluminum metal, block NiCr45 master alloy, and NiNb65 master alloy in the raw material are sequentially added to complete the material distribution; Step 4: Vacuum melting: After the material is laid in step 3, vacuum induction melting is performed, and electromagnetic stirring is performed during the vacuum induction melting process, and then the alloy is cast into an ingot to obtain a highly homogeneous and highly purified GH4145 alloy.

2. A short-process preparation method for a highly homogeneous and highly purified GH4145 alloy for nuclear use according to claim 1, characterized in that: The coating thickness of the calcium oxide in step 1 is 1 mm to 3 mm; the temperature of the drying treatment is 600° C. to 700° C., and the time is 15 min to 30 min.

3. The short-process preparation method of a high-homogeneity and high-purity GH4145 alloy for nuclear use according to claim 1 is characterized in that: The mass purity of the raw material blocks NiCr45 master alloy, NiNb65 master alloy, electrolytic nickel, sponge titanium, metallic iron and metallic aluminum in step 2 is greater than 99.9%, and the size is 10 mm to 100 mm.

4. The short-process preparation method of a high-homogeneity and high-purity GH4145 alloy for nuclear use according to claim 1 is characterized in that: The mass of the additionally weighed metal aluminum in step 2 is 0.5% of the total mass of the raw materials.

5. The short-process preparation method of a high-homogeneity and high-purity GH4145 alloy for nuclear use according to claim 1 is characterized in that: The mass of the partial metallic nickel described in step 3 accounts for 1 / 2 of the mass of all metallic nickel in the raw material.

6. The short-process preparation method of a high-homogeneity and high-purity GH4145 alloy for nuclear use according to claim 1 is characterized in that: The vacuum induction melting process described in step 4 is: first evacuate to 0.005Pa~0.001Pa, then fill in argon gas with a mass purity of more than 99.99% to 0.1Pa for washing, repeat the vacuuming and argon washing process twice, and then melt at a melting temperature of 1500℃~1700℃, and keep warm for 20min~40min after melting.

7. The short-process preparation method of a high-homogeneity and high-purity GH4145 alloy for nuclear use according to claim 1 is characterized in that: The voltage of the electromagnetic stirring during the vacuum induction melting process in step 4 is 100V to 150V, and the current is 4kA to 5kA.

8. A highly homogeneous and highly purified GH4145 alloy for nuclear use prepared by the method according to any one of claims 1 to 7, characterized in that: The main elements of Ni, Cr, Al, Ti, Fe and Nb in the GH4145 alloy are evenly distributed without segregation, and the mass percentages of key impurity elements are: S≤0.001%, O≤0.001%, and N≤0.002%.

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