A method for controlling the precipitation of primary carbides during solidification of GH3128 nickel-based high-temperature alloy

Abstract

The present invention provides a method for controlling the precipitation of primary carbides during the solidification process of GH3128 nickel-based high-temperature alloy, and relates to the technical field of alloy production. The method includes a vacuum induction melting process and an electroslag remelting process, wherein in the vacuum induction melting process, a nickel-magnesium alloy is added to the molten steel, and after being melted, it is cast into a casting mold to obtain a vacuum induction ingot; in the electroslag remelting process, the cooling water flow is controlled, quaternary slag is used, and the vacuum induction ingot is used as a consumable electrode for remelting to obtain an electroslag ingot. Adding the nickel-magnesium alloy and using the quaternary slag can help reduce the oxidation and burning of the magnesium element in the electroslag remelting process, while controlling the cooling water flow of the crystallizer can help increase the cooling rate of the molten steel in the molten pool. By coordinated control of the magnesium content and the cooling rate, it is ensured that the primary carbides precipitated during the solidification process of the GH3128 nickel-based high-temperature alloy are small in size and evenly dispersed, thereby improving its high-temperature plasticity and creep life.

Description

Technical Field

[0001] The invention relates to the technical field of alloy production, and in particular to a method for controlling the precipitation of primary carbides during the solidification process of a GH3128 nickel-based high-temperature alloy. Background Art

[0002] GH3128 nickel-based high-temperature alloy is a solid solution strengthened nickel-based deformation high-temperature alloy independently developed by my country based on GH3044 nickel-based high-temperature alloy. It has the advantages of high plasticity and long-lasting creep strength at 950°C, as well as good oxidation resistance and corrosion resistance. It is widely used in the field of aerospace technology, such as key components such as aircraft engine combustion chamber flame tubes and afterburner combustion chamber casings.

[0003] The production process of GH3128 nickel-based high-temperature alloy bars (forgings) is: vacuum induction melting → electroslag remelting → high-temperature forging → intermediate annealing → solution treatment. Due to its high content of chromium, molybdenum and tungsten elements, and its carbon content of about 0.025%, M6C type primary carbides will be formed. In the electroslag remelting process, due to the selective crystallization, the primary carbide segregation phenomenon occurs, and the re-dissolution temperature of the M6C type primary carbide is relatively high, which is difficult to eliminate within the forging and heat treatment temperature range, resulting in the long-term existence of primary carbide strip aggregation in the finished bar, affecting its high-temperature plasticity and creep life. Therefore, controlling the precipitation of primary carbides during the solidification process of GH3128 nickel-based high-temperature alloy has become a key issue that needs to be solved urgently.

[0004] In view of this, the present invention is proposed. Summary of the invention

[0005] The present invention provides a method for controlling the precipitation of primary carbides during the solidification process of GH3128 nickel-based high-temperature alloy, which is used to solve the problem of how to control the precipitation of primary carbides during the solidification process, and finally achieve the purpose of small size and uniform dispersion distribution of primary carbides in GH3128 nickel-based high-temperature alloy.

[0006] The present invention provides a method for controlling the precipitation of primary carbides during the solidification process of GH3128 nickel-based high-temperature alloy, comprising a vacuum induction melting process and an electroslag remelting process, wherein in the vacuum induction melting process, a nickel-magnesium alloy is added to molten steel, and after being melted, the alloy is cast into a casting mold to obtain a vacuum induction ingot;

[0007] In the electroslag remelting process, the cooling water pipe of the crystallizer is connected, and the quaternary slag containing calcium fluoride, calcium oxide, aluminum oxide and magnesium oxide is used as the fixed slag material, and the vacuum induction ingot is used as the consumable electrode for remelting to obtain the electroslag ingot, wherein the cooling water flow Q of the crystallizer is calculated using the following formula 1:

[0008] (1);

[0009] In the above formula H is the heat dissipation coefficient of the crystallizer, kcal / (m 2 ·h·℃); H 1 is the heat dissipation coefficient of the electroslag ingot surface to the crystallizer, kcal / (m 2 ·h·℃); D is the equivalent diameter of the crystallizer, m; Q is the cooling water flow rate of the crystallizer, m 3 / h; r is the radius of the crystallizer cooling water pipe, m.

[0010] In some embodiments, the vacuum induction melting process includes:

[0011] Step 1: Prepare raw materials;

[0012] According to the chemical composition ratio of GH3128 nickel-based high-temperature alloy, metal nickel, metal chromium, metal molybdenum and metal tungsten are loaded into the crucible of the vacuum induction furnace, and high-purity graphite, industrial silicon, electrolytic manganese, aluminum particles, sponge titanium and nickel-magnesium alloy are loaded into the sealed silo in sequence;

[0013] Step 2: Melting;

[0014] Heat the crucible electrically and evacuate the crucible until the raw materials are completely melted;

[0015] Step 3: alloying;

[0016] Add high-purity graphite, industrial silicon and electrolytic manganese to the completely melted molten steel in step 2 in sequence, and then add aluminum particles and sponge titanium in sequence after the molten steel is completely melted;

[0017] Step 4: Adding nickel-magnesium alloy and casting;

[0018] Adjusting the temperature of the molten steel in step 3 and filling the vacuum chamber of the vacuum induction furnace with argon gas;

[0019] When the temperature of the molten steel reaches a preset temperature and the pressure of the vacuum chamber reaches a preset pressure, nickel-magnesium alloy is added to the molten steel, and after being melted, it is cast into a casting mold to obtain a vacuum induction ingot.

[0020] In some embodiments, the electroslag remelting process includes:

[0021] Step 5: Remelting material preparation;

[0022] Preparation of quaternary slag: pre-melting and drying the quaternary slag containing calcium fluoride, calcium oxide, aluminum oxide and magnesium oxide;

[0023] Preparation of consumable electrode: removing the oxide layer of the vacuum induction ingot obtained in step 4 to obtain a consumable electrode;

[0024] Preparation of arc starter: The arc starter is prepared by mixing the chips obtained by turning a consumable electrode with calcium fluoride powder, wherein the mass ratio of the chips to calcium fluoride is 1:1;

[0025] Step 6: Assembling the protective atmosphere electroslag furnace;

[0026] Install the crystallizer, connect the cooling water pipes of the crystallizer and the bottom water tank respectively, and calculate the cooling water flow rate Q of the crystallizer according to formula 1;

[0027] Place the arc starter in the crystallizer, install the consumable electrode on the electrode holding device, open the gas valve and let in argon gas;

[0028] Step 7: electroslag remelting;

[0029] Turn on the power to start the arc, add the quaternary slag that has been pre-melted and dried in step 5 into the crystallizer, start remelting the consumable electrode, and adjust the current and voltage during the remelting process to achieve a relatively stable state;

[0030] After remelting, the electroslag ingot is demoulded.

[0031] In some embodiments, in step 4, the preset temperature is 1400°C to 1450°C.

[0032] In some of the embodiments, in step 4, the preset pressure is 40 kPa to 60 kPa.

[0033] In some of the embodiments, in step 4, the amount of nickel-magnesium alloy added is 6 kg / ton steel to 8 kg / ton steel.

[0034] In some of the embodiments, in step 5, the mass percentages of the quaternary slag are: 45% to 55% calcium fluoride, 18% to 22% calcium oxide, 17% to 21% aluminum oxide, and 10% to 14% magnesium oxide, and the mass ratio of calcium oxide to aluminum oxide is 1 to 1.3.

[0035] In some of the embodiments, in step 6, the cooling water flow rate Q of the crystallizer is controlled according to formula 1 to achieve solidification of the molten steel in the molten pool at a cooling rate of 10°C / min to 30°C / min.

[0036] In some embodiments, the pre-melting process includes:

[0037] Step 51: pre-melting the quaternary slag at 1450° C. to 1600° C. for 10 min to 30 min to obtain a pre-melted slag material;

[0038] The drying process comprises:

[0039] Step 52: The pre-melted slag obtained in step 51 is baked at 400° C. to 800° C. for 4 h to 10 h to obtain a dried slag material.

[0040] In some of the embodiments, in step 5, the mass ratio of the quaternary slag to the consumable electrode is 1:8 to 1:12.

[0041] After adopting the above technical scheme, the present invention has the following beneficial effects compared with the prior art.

[0042] 1. In the vacuum induction melting process, adding nickel-magnesium alloy to the molten steel at low melt pool temperature and high vacuum chamber pressure can reduce the vapor pressure of magnesium and increase the boiling point of magnesium, thereby increasing the magnesium yield and making the vacuum induction ingot have an appropriate amount of magnesium.

[0043] 2. In the electroslag remelting process, the use of quaternary slag with low melting temperature and low viscosity can reduce the oxidation and burning of magnesium in the consumable electrode, so that the electroslag ingot has an appropriate amount of magnesium and good surface quality, and maximizes the role of magnesium in refining and uniformly dispersing primary carbides. On this basis, the cooling rate during the solidification process is appropriately increased to inhibit the precipitation and growth of primary carbides.

[0044] 3. The primary carbide size of the GH3128 nickel-based high-temperature alloy in this application is small and the distribution is more evenly dispersed, which is not only beneficial to improve the high-temperature plasticity and creep life of the GH3128 nickel-based high-temperature alloy, but also the high-temperature alloy obtained after smelting can be directly subjected to high-temperature forging without homogenization treatment, thereby reducing energy consumption and production costs and improving production efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] Figure 1 is a comparison diagram of the metallographic structures of the electroslag ingots of Examples 1 to 3 and Comparative Examples 1, 2 and 6;

[0046] Figure 2 is a comparison diagram of the average diameters of primary carbides in the electroslag ingots of Examples 1 to 3 and Comparative Examples 1, 2 and 6;

[0047] Figure 3 It is a schematic diagram of the relationship between the cooling water flow rate of the crystallizer and the heat dissipation coefficient of the crystallizer. DETAILED DESCRIPTION

[0048] The technical solution of the present invention will be clearly and completely described below in conjunction with the embodiments. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0049] Example 1

[0050] The present invention discloses a method for controlling the precipitation of primary carbides during the solidification process of GH3128 nickel-based high-temperature alloy, which comprises vacuum induction melting and electroslag remelting, specifically:

[0051] 1) Vacuum induction melting process

[0052] Vacuum induction melting of GH3128 nickel-based high-temperature alloy is carried out in a vacuum induction furnace with a furnace capacity of 50kg, a maximum operating temperature of 1750℃ and an ultimate vacuum degree of 0.5Pa.

[0053] The vacuum induction melting process includes the following steps:

[0054] Step 1: Prepare the ingredients

[0055] According to the chemical composition ratio of GH3128 nickel-based high-temperature alloy, the required raw materials are weighed, and metal nickel, metal chromium, metal molybdenum, and metal tungsten are loaded into the crucible of the vacuum induction furnace, and high-purity graphite, industrial silicon, electrolytic manganese, aluminum particles, sponge titanium, and nickel-magnesium alloy are loaded into the sealed material bin in sequence, wherein the mass percentage of nickel element in the nickel-magnesium alloy is 80%, the mass percentage of magnesium element is 20%, and the purity of other raw materials is above 99%;

[0056] Step 2: Melting

[0057] Turn on the cooling water, heat up the furnace electrically, and start the vacuum pump to evacuate the furnace until the vacuum pressure is less than 5 Pa. When the raw materials in the crucible are completely melted, turn off the vacuum pump.

[0058] Step 3: Alloying

[0059] Add high-purity graphite, industrial silicon and electrolytic manganese to the molten steel in step 2 in sequence, and then add aluminum particles and sponge titanium in sequence after melting, and keep the temperature for 5 minutes to make it completely melted;

[0060] Step 4: Adding nickel-magnesium alloy and casting

[0061] Using a thermocouple to measure the temperature, adjust the temperature of the molten steel in step 3 to 1400° C. to 1420° C., and fill the vacuum chamber of the induction furnace with argon gas to maintain the vacuum chamber pressure at 50 kPa;

[0062] When the temperature of the molten steel reaches the preset temperature and the pressure of the vacuum chamber reaches the preset pressure and remains stable, 300 g of nickel-magnesium alloy is added to the molten steel, kept warm for 2 minutes, and cast into a mold after being melted to obtain a vacuum induction ingot.

[0063] 2) The electroslag remelting process includes:

[0064] The electroslag remelting of GH3128 nickel-based high-temperature alloy is carried out in a protective atmosphere electroslag furnace with a furnace capacity of 50 kg.

[0065] The electroslag remelting process includes the following steps:

[0066] Step 5: Remelting Material Preparation

[0067] Preparation of quaternary slag: The quaternary slag containing calcium fluoride, calcium oxide, aluminum oxide and magnesium oxide was pre-melted at 1550°C for 20 minutes and then baked at 600°C for 7 hours. The mass percentages of the final quaternary slag were: calcium fluoride 49.10%, calcium oxide 21.57%, aluminum oxide 18.68%, magnesium oxide 10.65%, and the mass ratio of calcium oxide to aluminum oxide was 1.15;

[0068] Preparation of consumable electrode: removing the oxide layer of the vacuum induction ingot obtained in step 4 to obtain a consumable electrode prepared into 80 mm;

[0069] Preparation of arc starter: The arc starter is prepared by mixing the chips obtained by turning a consumable electrode with calcium fluoride powder, wherein the mass ratio of the chips to calcium fluoride is 1:1;

[0070] Step 6: Protective atmosphere electroslag furnace assembly

[0071] Select Diameter D For a 160 mm crystallizer, connect the cooling water pipes (50 mm) of the crystallizer and the bottom water tank respectively. Calculate the cooling water flow rate Q of the crystallizer using formula (1): Figure 3 Then adjust the flow meter to control the cooling water flow rate at 2-3m 3 / h; place the arc starter in the crystallizer and install the consumable electrode on the electrode clamping device; open the gas valve to introduce argon gas into the crystallizer, and maintain the flow rate at 40L / min;

[0072] Step 7: Electroslag Remelting

[0073] Lower the consumable electrode, energize and strike an arc, add the quaternary slag that has been pre-melted and dried in step 5 into the crystallizer through the feeding port, the mass ratio of the quaternary slag to the consumable electrode is 1:10, start remelting the consumable electrode, adjust the current and voltage during the remelting process, and stabilize them at 2kA~3kA and 30V~38V respectively;

[0074] After remelting is completed, the electroslag ingot is demoulded.

[0075] Example 2

[0076] The difference between this embodiment and embodiment 1 is that:

[0077] Step 4: Adding nickel-magnesium alloy and casting

[0078] Using a thermocouple to measure the temperature, adjust the temperature of the molten steel in step 3 to 1400° C. to 1420° C., and fill the vacuum chamber of the induction furnace with argon gas to maintain the vacuum chamber pressure at 50 kPa;

[0079] When the temperature of the molten steel reaches the preset temperature and the pressure of the vacuum chamber reaches the preset pressure and remains stable, 400 g of nickel-magnesium alloy is added to the molten steel, kept warm for 2 minutes, and cast into a mold after being melted to obtain a vacuum induction ingot.

[0080] Example 3

[0081] The difference between this embodiment and embodiment 1 is that:

[0082] Select Diameter D For a 160 mm crystallizer, connect the cooling water pipes (50 mm) of the crystallizer and the bottom water tank respectively. Calculate the cooling water flow rate Q of the crystallizer using formula (1): Figure 3 Then adjust the flow meter to control the cooling water flow rate at 3-4m 3 / h; place the arc starter in the crystallizer and install the consumable electrode on the electrode clamping device; open the gas valve to introduce argon gas into the crystallizer, and maintain the flow rate at 40L / min;

[0083] Comparative Example 1

[0084] The difference between this comparative example and Example 1 is:

[0085] Step 4: Adding nickel-magnesium alloy and casting

[0086] Using a thermocouple to measure the temperature, adjust the temperature of the molten steel in step 3 to 1400° C. to 1420° C., and fill the vacuum chamber of the induction furnace with argon gas to maintain the vacuum chamber pressure at 50 kPa;

[0087] When the temperature of the molten steel reaches a preset temperature and the pressure in the vacuum induction furnace reaches a preset pressure and remains stable, the molten steel is cast into a casting mold to obtain a vacuum induction ingot.

[0088] Comparative Example 2

[0089] The difference between this embodiment and embodiment 1 is that:

[0090] Step 4: Adding nickel-magnesium alloy and casting

[0091] Using a thermocouple to measure the temperature, adjust the temperature of the molten steel in step 3 to 1400° C. to 1420° C., and fill the vacuum chamber of the induction furnace with argon gas to maintain the vacuum chamber pressure at 50 kPa;

[0092] When the temperature of the molten steel reaches the preset temperature and the pressure of the vacuum chamber reaches the preset pressure and remains stable, 200 g of nickel-magnesium alloy is added to the molten steel, kept warm for 2 minutes, and cast into a mold after being melted to obtain a vacuum induction ingot.

[0093] Comparative Example 3

[0094] The difference between this comparative example and Example 1 is:

[0095] Step 4: Adding nickel-magnesium alloy and casting

[0096] Using a thermocouple to measure the temperature, adjust the temperature of the molten steel in step 3 to 1500°C to 1520°C, and fill the vacuum chamber of the induction furnace with argon gas to maintain the vacuum chamber pressure at 50 kPa;

[0097] When the temperature of the molten steel reaches the preset temperature and the pressure of the vacuum chamber reaches the preset pressure and remains stable, 300 g of nickel-magnesium alloy is added to the molten steel, kept warm for 2 minutes, and cast into a mold after being melted to obtain a vacuum induction ingot.

[0098] Comparative Example 4

[0099] The difference between this comparative example and Example 1 is:

[0100] Step 4: Adding nickel-magnesium alloy and casting

[0101] Using a thermocouple to measure the temperature, adjust the temperature of the molten steel in step 3 to 1400° C. to 1420° C., and fill the vacuum chamber of the induction furnace with argon gas to maintain the vacuum chamber pressure at 30 kPa;

[0102] When the temperature of the molten steel reaches the preset temperature and the pressure of the vacuum chamber reaches the preset pressure and remains stable, 300 g of nickel-magnesium alloy is added to the molten steel, kept warm for 2 minutes, and cast into a mold after being melted to obtain a vacuum induction ingot.

[0103] Comparative Example 5

[0104] The difference between this comparative example and Example 1 is:

[0105] Step 5: Remelting Material Preparation

[0106] Preparation of quaternary slag: The quaternary slag containing calcium fluoride, calcium oxide, aluminum oxide and magnesium oxide was pre-melted at 1550°C for 20 minutes and then baked at 600°C for 7 hours. The mass percentages of the quaternary slag were: calcium fluoride 49.22%, calcium oxide 17.19%, aluminum oxide 22.40%, magnesium oxide 10.47%, and the mass ratio of calcium oxide to aluminum oxide was 0.77.

[0107] Preparation of consumable electrode: removing the oxide layer of the vacuum induction ingot obtained in step 4 to obtain a consumable electrode prepared into 80 mm;

[0108] Preparation of arc starter: The arc starter is obtained by mixing the chips obtained by turning a consumable electrode with calcium fluoride powder, wherein the mass ratio of the chips to the calcium fluoride is 1:1.

[0109] Comparative Example 6

[0110] The difference between this embodiment and embodiment 1 is that:

[0111] Select a crystallizer with a diameter of 160 mm, connect the cooling water pipes (50 mm) of the crystallizer and the bottom water tank respectively, and calculate the cooling water flow of the crystallizer by formula (1), as follows: Figure 3 Then adjust the flow meter to control the cooling water flow rate at 1-2m 3 / h; place the arc starter in the crystallizer and install the consumable electrode on the electrode clamping device; open the gas valve to introduce argon gas into the crystallizer, and maintain the flow rate at 40L / min;

[0112] Indicator testing

[0113] The magnesium content detection results in the vacuum induction casting ingots and the magnesium yield calculation results in Examples 1 to 3 and Comparative Examples 1 to 6 are shown in Table 1, the mass fractions of each element in the electroslag ingots are shown in Table 2, and the magnesium yield calculation results in the electroslag ingots are shown in Table 3, wherein the magnesium yield in the vacuum induction casting ingots is calculated by formula (2), and the magnesium yield in the electroslag ingots is calculated by formula (3).

[0114]

[0115]

[0116] Table 1 Magnesium content (mass fraction / %) and its yield (%) in vacuum induction casting ingots (electrodes)

[0117] Example indicators Example indicators Example 1 Example 2 Example 3 Comparative Example 1 Example 2 Comparative Example 3 Comparative Example 4 Comparative Example 5 Comparative Example 6 Magnesium content 0.063 0.081 0.058 0 0.039 0.043 0.035 0.057 0.060 Yield 52.50 50.63 48.33 0 48.75 35.83 29.17 47.50 50.00

[0118] Table 2 Chemical composition of electroslag ingot (mass fraction / %)

[0119] Example C Si Mn Al Ti Cr W Mo Mg Ni Example 1 0.022 0.17 0.30 0.68 0.63 20.1 8.48 8.35 0.0136 margin Example 2 0.024 0.19 0.30 0.72 0.65 20.2 8.52 8.26 0.0184 margin Example 3 0.023 0.17 0.27 0.66 0.60 20.2 8.41 8.39 0.0121 margin Comparative Example 1 0.022 0.19 0.30 0.71 0.61 20.3 8.56 8.43 0 margin Comparative Example 2 0.021 0.17 0.28 0.66 0.63 20.3 8.17 8.43 0.0072 margin Comparative Example 3 0.021 0.16 0.31 0.68 0.65 20.0 8.34 8.29 0.0077 margin Comparative Example 4 0.024 0.18 0.29 0.73 0.65 20.4 8.49 8.52 0.0064 margin Comparative Example 5 0.025 0.16 0.26 0.69 0.66 20.4 8.32 8.31 0.0051 margin Comparative Example 6 0.022 0.18 0.29 0.69 0.62 20.2 8.37 8.47 0.0143 margin

[0120] Table 3 Recovery rate of magnesium in electroslag ingot (electrode) (%)

[0121] Example Example 1 Example 2 Example 3 Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 Comparative Example 5 Comparative Example 6 Yield 21.59 22.72 20.86 0 18.46 17.90 18.29 8.95 23.83

[0122] From Table 2, Figure 1 and Figure 2It can be seen that in the vacuum induction melting process, Comparative Example 1 did not add nickel-magnesium alloy to the molten steel, and Comparative Example 2 added 200g of nickel-magnesium alloy to the molten steel. The magnesium content in the electroslag ingot was 0% and 0.0072% respectively. The segregation phenomenon of primary carbides in the alloy was very serious, and the size was large, and effective control of primary carbides could not be achieved. However, in Example 1 and Example 2, 300g to 400g of nickel-magnesium alloy was added to the molten steel in the vacuum induction melting process, and the magnesium content in the electroslag ingot could be controlled at 0.01% to 0.02%. At this time, the size of the primary carbides in the alloy was small and evenly dispersed, achieving effective control of the primary carbides in the alloy. If the addition amount of nickel-magnesium alloy continues to increase, the magnesium content in the electroslag ingot will continue to increase, but a large amount of Ni2Mg phase will appear in the alloy, which will significantly deteriorate the hot working properties and creep properties of the alloy. Therefore, the magnesium content in the GH3128 nickel-based high-temperature alloy is controlled at 0.01% to 0.02%, that is, the addition amount of the nickel-magnesium alloy is 6kg / ton of steel to 8kg / ton of steel, which can ensure that the primary carbides in the alloy are fine and evenly dispersed.

[0123] It can be seen from Tables 1 and 2 that in Comparative Example 3, due to improper control of the molten steel temperature in the vacuum induction melting process, the vapor pressure of magnesium in the molten steel increased, resulting in a large amount of volatilization; in Comparative Example 4, due to the failure to fill the vacuum chamber with sufficient argon gas in the vacuum induction melting process, the boiling point of magnesium in the molten steel was reduced, and a large amount of volatilization was also generated. Therefore, the magnesium recovery rate in the vacuum induction ingots of Comparative Examples 3 and 4 is significantly lower than that of Example 1, resulting in the magnesium content in the electroslag ingots of Comparative Examples 3 and 4 being lower than that of Example 1, and thus unable to achieve effective control of primary carbides in the alloy. It can be seen that in the vacuum induction melting process, when 6kg / ton of steel to 8kg / ton of steel of nickel-magnesium alloy is added to the molten steel at a molten pool temperature of 1400℃ to 1450℃ and a vacuum chamber pressure of 40kPa to 60kPa, the magnesium recovery rate in the GH3128 nickel-based high-temperature alloy is significantly improved to about 50%.

[0124] It can be seen from Table 3 that in Comparative Example 5, since no suitable quaternary slag is selected in the electroslag remelting process, the activity of magnesium oxide in the slag is lower than that in Example 1, and the activity of aluminum oxide in the slag is higher than that in Example 1, so the recovery rate of magnesium in the electroslag ingot of Comparative Example 5 is significantly lower than that in Example 1. Stabilizing the calcium fluoride content in the quaternary slag at 45% to 55%, the magnesium oxide content at 10% to 14%, and controlling the mass ratio of calcium oxide to aluminum oxide at 1.0 to 1.3 can effectively increase the activity of magnesium oxide in the slag and reduce the activity of aluminum oxide, inhibit the formation of magnesium oxide at the slag-gold interface and the mass transfer of the generated magnesium oxide to the slag, thereby reducing the oxidation and burning of magnesium, and improving the recovery rate of magnesium in the electroslag remelting process to about 20%. In addition, compared with the traditional ternary slag containing calcium fluoride, aluminum oxide and magnesium oxide, the physical properties of the quaternary slag provided by the present invention, such as melting temperature, viscosity, and electrical conductivity, are significantly improved, which is not only conducive to stabilizing the electroslag remelting operation and reducing energy consumption, but also can obtain electroslag ingots with good surface quality.

[0125] Through Table 2 and Figures 1 to 3 It can be seen that the magnesium content in the electroslag ingot of Comparative Example 6 is close to that in the electroslag ingots of Examples 1 and 3, but the average diameter of the primary carbides in the electroslag ingot is significantly larger, indicating that a smaller cooling water flow rate of the crystallizer is not conducive to the heat dissipation of the crystallizer and cannot effectively inhibit the precipitation and growth of primary carbides in the alloy, resulting in serious segregation and larger size of primary carbides in the alloy. When the cooling water flow rate exceeds 4m 3 / h, the improvement effect of crystallizer heat dissipation is not significant, and it is necessary to install a cooling water pipe with stronger pressure bearing capacity, which is not conducive to cost reduction and efficiency improvement. It can be seen that for the electroslag furnace used in the present invention, the crystallizer cooling water flow rate is controlled at 2m 3 / h~4m 3 / h, which can significantly reduce the size of primary carbides in GH3128 nickel-based high-temperature alloy. Formula (1) is applicable to any specification of electroslag furnace, and the optimal cooling water flow rate Q of the crystallizer can be obtained by calculation.

[0126] In summary, in the vacuum induction melting process, the molten pool temperature when adding nickel-magnesium alloy is controlled at 1400℃~1450℃, the vacuum chamber pressure is controlled at 40kPa~60kPa, and the addition amount of nickel-magnesium alloy is controlled at 6kg / ton steel~8kg / ton steel, which can ensure that the vacuum induction ingot has a suitable magnesium content and a high magnesium yield. In the electroslag remelting process, the use of a suitable quaternary slag containing 45%~55% calcium fluoride, 18%~22% calcium oxide, 17%~21% aluminum oxide and 10%~14% magnesium oxide can not only reduce the oxidation and burning of magnesium, but also improve the magnesium yield, and give full play to the role of magnesium in refining and dispersing primary carbides. At the same time, the physical properties of the quaternary slag meet the requirements of electroslag remelting, stabilize the electroslag remelting operation and obtain electroslag ingots with good surface quality. On this basis, the appropriate range of cooling water flow rate Q of the crystallizer is calculated by formula (1), and then the cooling water flow rate Q of the crystallizer is adjusted to appropriately improve the heat dissipation efficiency of the crystallizer during the solidification process, which can inhibit the precipitation and growth of primary carbides. Finally, the primary carbides in the GH3128 nickel-based high-temperature alloy are made finer and evenly dispersed by magnesium treatment and controlling the cooling efficiency during the solidification process.

[0127] In the present invention, the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" etc. mean that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the described specific features, structures, materials or characteristics may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification and the features of the different embodiments or examples, without contradiction.

[0128] Although the embodiments of the present invention have been shown and described above, it is to be understood that the above embodiments are exemplary and are not to be construed as limitations of the present invention. A person skilled in the art may change, modify, replace and vary the above embodiments within the scope of the present invention.

Claims

1. A method for controlling the precipitation of primary carbides during the solidification process of GH3128 nickel-based high-temperature alloy, characterized in that: The method comprises a vacuum induction melting process and an electroslag remelting process, wherein in the vacuum induction melting process, when the temperature of the molten steel reaches 1400° C. to 1450° C. and the pressure of the vacuum chamber reaches 40 kPa to 60 kPa, a nickel-magnesium alloy is added to the molten steel, and the amount of the nickel-magnesium alloy added is 6 kg to 8 kg per ton of steel. After being melted, the molten steel is cast into a casting mold to obtain a vacuum induction ingot; In the electroslag remelting process, the cooling water pipe of the crystallizer is connected, and the quaternary slag containing calcium fluoride, calcium oxide, aluminum oxide and magnesium oxide is used as the fixed slag material, and the vacuum induction ingot is used as the consumable electrode for remelting to obtain the electroslag ingot, wherein the mass percentage of the quaternary slag is 45% to 55% of calcium fluoride, 18% to 22% of calcium oxide, 17% to 21% of aluminum oxide, and 10% to 14% of magnesium oxide. The cooling water flow rate of the crystallizer is 2m 3 / h~4m 3 / h, calculate the cooling water flow rate Q of the crystallizer using the following formula 1: （1）； In the above formula H is the heat dissipation coefficient of the crystallizer, kcal / (m 2 ·h·℃); H 1 is the heat dissipation coefficient of the electroslag ingot surface to the crystallizer, kcal / (m 2 ·h·℃); D is the equivalent diameter of the crystallizer, m; Q is the cooling water flow rate of the crystallizer, m 3 / h; r is the radius of the crystallizer cooling water pipe, m.

2. The method for controlling the precipitation of primary carbides during the solidification process of GH3128 nickel-based high-temperature alloy according to claim 1, characterized in that: The vacuum induction melting process comprises: Step 1: Prepare raw materials; According to the chemical composition ratio of GH3128 nickel-based high-temperature alloy, metal nickel, metal chromium, metal molybdenum and metal tungsten are loaded into the crucible of the vacuum induction furnace, and high-purity graphite, industrial silicon, electrolytic manganese, aluminum particles, sponge titanium and nickel-magnesium alloy are loaded into the sealed silo in sequence; Step 2: Melting; Heat the crucible electrically and evacuate the crucible until the raw materials are completely melted; Step 3: alloying; Add high-purity graphite, industrial silicon and electrolytic manganese to the completely melted molten steel in step 2 in sequence, and then add aluminum particles and sponge titanium in sequence after the molten steel is completely melted; Step 4: Adding nickel-magnesium alloy and casting; Adjusting the temperature of the molten steel in step 3 and filling the vacuum chamber of the vacuum induction furnace with argon gas; When the temperature of the molten steel reaches 1400°C to 1450°C and the pressure of the vacuum chamber reaches 40kPa to 60kPa, nickel-magnesium alloy is added to the molten steel, and after being melted, it is cast into a mold to obtain a vacuum induction ingot.

3. The method for controlling the precipitation of primary carbides during the solidification process of GH3128 nickel-based high-temperature alloy according to claim 1 or 2, characterized in that: The electroslag remelting process comprises: Step 5: Remelting material preparation; Preparation of quaternary slag: pre-melting and drying the quaternary slag containing calcium fluoride, calcium oxide, aluminum oxide and magnesium oxide; Preparation of consumable electrode: removing the oxide layer of the vacuum induction ingot obtained in step 4 to obtain a consumable electrode; Preparation of arc starter: The arc starter is prepared by mixing the chips obtained by turning a consumable electrode with calcium fluoride powder, wherein the mass ratio of the chips to calcium fluoride is 1:1; Step 6: Assembling the protective atmosphere electroslag furnace; Install the crystallizer, connect the cooling water pipes of the crystallizer and the bottom water tank respectively, and calculate the cooling water flow rate Q of the crystallizer according to formula 1; Place the arc starter in the crystallizer, install the consumable electrode on the electrode holding device, open the gas valve and let in argon gas; Step 7: electroslag remelting; Turn on the power to start the arc, add the quaternary slag that has been pre-melted and dried in step 5 into the crystallizer, start remelting the consumable electrode, and adjust the current and voltage during the remelting process to achieve a relatively stable state; After remelting, the electroslag ingot is demoulded.

4. The method for controlling the precipitation of primary carbides during solidification of GH3128 nickel-based high-temperature alloy according to claim 3, characterized in that: In step 5, the mass ratio of calcium oxide to aluminum oxide is 1 to 1.

3.

5. The method for controlling the precipitation of primary carbides during the solidification process of GH3128 nickel-based high-temperature alloy according to claim 3, characterized in that: In step 6, the cooling water flow rate Q of the crystallizer is controlled according to formula 1 to achieve solidification of the molten steel in the molten pool at a cooling rate of 10°C / min to 30°C / min.

6. The method for controlling the precipitation of primary carbides during solidification of GH3128 nickel-based high-temperature alloy according to claim 3, characterized in that: In step 5, the pre-melting process includes: Step 51: pre-melting the quaternary slag at 1450° C. to 1600° C. for 10 min to 30 min to obtain a pre-melted slag material; The drying process comprises: Step 52: The pre-melted slag obtained in step 51 is baked at 400° C. to 800° C. for 4 h to 10 h to obtain a dried slag material.

7. The method for controlling the precipitation of primary carbides during solidification of GH3128 nickel-based high-temperature alloy according to claim 3, characterized in that: In step 5, the mass ratio of the quaternary slag to the consumable electrode is 1:8 to 1:12.

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