Vacuum consumable melting electrode inversion preparation of homogenized ingot smelting method

Abstract

The application relates to the technical field of special steel smelting, and discloses a smelting method for preparing homogeneous ingots through vacuum consumable melting electrode overturning, wherein the electrode overturning coefficient is determined by using a smelting speed, a cooling water flow, an electrode overturning frequency and a filling ratio; whether the smelted ingot needs to be overturned and remelted again to reduce segregation can be accurately determined according to the electrode overturning coefficient, and finally, a homogeneous high-quality ingot is obtained.

Description

Technical Field

[0001] This invention relates to the field of special steel smelting technology, specifically to a smelting method for preparing homogeneous ingots by vacuum consumable melting electrode flipping. Background Technology

[0002] Vacuum arc remelting is a technique that uses electric arc energy to melt metals in a vacuum environment. In this process, the material to be melted acts as one electrode, and a water-cooled copper crucible acts as the other. An arc is ignited between the two electrodes, and the material is melted by the high temperature of the arc and dripped into the crucible, gradually solidifying into an ingot. Vacuum arc remelting is widely used in the preparation of titanium alloys, high-temperature alloys, and special steels due to its significant effects in removing hydrogen and some volatile impurities, reducing inclusion content, and improving the uniformity of alloy composition. Macroscopic segregation of solute during solidification is a common defect in ingots and is difficult to eliminate through subsequent heat treatment, severely affecting the uniformity of the microstructure and deteriorating material properties.

[0003] Therefore, how to obtain homogeneous, high-quality ingots has become a technical problem that urgently needs to be solved by those skilled in the art. Summary of the Invention

[0004] This application provides a smelting method for preparing homogeneous ingots by vacuum consumable melting electrode flipping. In this method, the electrode flipping coefficient is determined by the melting rate, cooling water flow rate, number of electrode flipping times and filling ratio. Based on the electrode flipping coefficient, it is possible to accurately determine whether the smelted ingot needs to be flipped and remelted again to reduce segregation, and finally obtain a homogeneous high-quality ingot.

[0005] This application provides a smelting method for preparing homogeneous ingots by vacuum consumable melting electrode flipping, including:

[0006] Fabrication of consumable electrodes;

[0007] The consumable electrode is welded to the auxiliary electrode of the vacuum consumable remelting furnace in a positive mounting manner to perform a vacuum consumable melting process and obtain an ingot.

[0008] The electrode reversal coefficient is determined based on the melting rate of the consumable electrode, the cooling water flow rate, the number of electrode reversals, and the filling ratio during the vacuum consumable melting process.

[0009] Determine whether the electrode reversal coefficient is greater than 1; if the electrode reversal coefficient is greater than 1, then the ingot forging machine polishes and grinds it, and uses the polished ingot as a consumable electrode. The consumable electrode is then welded to the auxiliary electrode of the vacuum consumable remelting furnace in a reverse manner, and the vacuum consumable melting process is repeated to obtain the ingot, until the electrode reversal coefficient is not greater than 1; wherein the filling ratio of the polished ingot to the crystallizer is a preset filling ratio.

[0010] In some embodiments, the method further includes:

[0011] If the electrode flipping coefficient is not greater than 1, the segregation ratio at multiple locations on the ingot is measured; if the segregation ratio at multiple locations on the ingot is within a preset range, the ingot is determined to be qualified.

[0012] In some embodiments, the multiple locations on the ingot include a 1 / 2 radius point 40 mm from the top of the ingot, a 1 / 2 radius point on the horizontal plane where the center of the ingot is located, and a 1 / 2 radius point 40 mm from the bottom of the ingot.

[0013] In some embodiments, the consumable electrode has the following chemical composition by weight percentage: C: ≤0.4%, Cr: 1%~22%, Mo: 0~6%, Ni: 0~12%, Co: 0~8%, Si: 0~2%, V: 0~1%, Mn: 0~2%, N: 0~1.2%, with the remainder being Fe.

[0014] In some embodiments, the consumable electrode has the following chemical composition by weight percentage: C: 0.25%~0.35%, Cr: 1%~1.2%, Mo: 1.8%~2.2%, Ni: 10%~10.4%, Co: 7%~7.5%, V: 0.08%~0.12%, with the remainder being Fe.

[0015] In some embodiments, the consumable electrode has the following chemical composition by weight percentage: C: 0.25%~0.35%, Si: ≤1%, Mn: ≤1%, Ni: ≤0.5%, N: 0.3%-0.5%, Cr: 14%~16%, Mo: 0.85%~1.1%, with the remainder being Fe.

[0016] In some embodiments, the step of preparing the consumable electrode includes:

[0017] Fe, Mo, Ni, Cr, Co and W are placed in a crucible inside a vacuum induction melting furnace;

[0018] Place C and V into the feeding device;

[0019] Start the vacuum pump to reduce the gas pressure inside the vacuum induction melting furnace to 4 Pa;

[0020] High-purity argon gas is introduced into the vacuum induction melting furnace until the gas pressure inside the furnace increases to 0.02 MPa;

[0021] The temperature of the vacuum induction melting furnace is controlled at 1600°C to melt the material in the crucible;

[0022] C is added to the crucible using the feeding device, and the vacuum pump is started 2 minutes later to reduce the gas pressure in the furnace to 4 Pa ​​over a period of 15 minutes.

[0023] High-purity argon gas is introduced into the vacuum induction melting furnace until the gas pressure inside the furnace increases to 0.02 MPa;

[0024] V is added to the crucible using the feeding device. After V is completely melted, the material in the crucible is poured into a cast iron mold at 1620°C to obtain the ingot to be processed. The pouring time is 20-25 seconds.

[0025] The ingot to be processed is forged and polished to obtain a consumable electrode, so that the filling ratio of the consumable electrode to the crystallizer is a preset filling ratio.

[0026] In some embodiments, the preset fill ratio is 0.6 to 0.8.

[0027] In some embodiments, the method further includes determining the melting rate of the consumable electrode; wherein the step of determining the melting rate of the consumable electrode includes:

[0028] The melting rate of the consumable electrode is determined based on the crystallizer diameter, filling ratio, and current of the vacuum consumable melting process.

[0029] In some embodiments, the vacuum degree during the vacuum self-consumable melting process is below 5 Pa, the leakage rate is below 0.13 Pa / min, the inlet temperature of the cooling water is 20~25℃, the melting voltage is 32~45V, the filling ratio is 0.6~0.8, the melting current is 19000A, and the cooling water flow rate is 2000~4000 L / min.

[0030] This invention provides a smelting method for preparing homogeneous ingots by vacuum consumable melting electrode flipping. In this method, the electrode flipping coefficient is determined by using the melting rate, cooling water flow rate, number of electrode flipping times and filling ratio. Based on the electrode flipping coefficient, it is possible to accurately determine whether the smelted ingot needs to be flipped and remelted again to reduce segregation, and finally obtain a homogeneous high-quality ingot. The method includes preparing a consumable electrode; welding the consumable electrode to an auxiliary electrode of a vacuum consumable remelting furnace in a forward-mounted manner, performing a vacuum consumable melting process to obtain an ingot; determining an electrode reversal coefficient based on the melting rate, cooling water flow rate, electrode reversal times, and filling ratio of the consumable electrode during the vacuum consumable melting process; determining whether the electrode reversal coefficient is greater than 1; if the electrode reversal coefficient is greater than 1, then forging and polishing the ingot, using the polished ingot as the consumable electrode, and welding the consumable electrode to the auxiliary electrode of the vacuum consumable remelting furnace in a reverse-mounted manner, repeating the vacuum consumable melting process to obtain an ingot, until the electrode reversal coefficient is not greater than 1; wherein the filling ratio of the polished ingot to the crystallizer is a preset filling ratio. Attached Figure Description

[0031] Figure 1 An exemplary flowchart is shown of a smelting method for preparing homogeneous ingots by vacuum consumable melting electrode flipping according to some embodiments. Detailed Implementation

[0032] To make the objectives and implementation methods of this application clearer, the exemplary implementation methods of this application will be clearly and completely described below with reference to the accompanying drawings of the exemplary embodiments of this application. Obviously, the exemplary embodiments described are only some embodiments of this application, and not all embodiments.

[0033] It should be noted that the brief descriptions of terms in this application are only for the convenience of understanding the embodiments described below, and are not intended to limit the embodiments of this application. Unless otherwise stated, these terms should be understood in their ordinary and common meaning.

[0034] The terms "first," "second," "third," etc., used in the specification, claims, and accompanying drawings of this application are used to distinguish similar or related objects or entities, and do not necessarily imply a specific order or sequence, unless otherwise specified. It should be understood that such terms are interchangeable where appropriate.

[0035] The terms “comprising” and “having”, and any variations thereof, are intended to cover but not exclude inclusion, for example, a product or device that includes a range of components is not necessarily limited to all of the components that are clearly listed, but may include other components that are not clearly listed or that are inherent to such product or device.

[0036] To address the aforementioned problems, this application provides a smelting method for preparing homogeneous ingots by vacuum consumable melting electrode flipping. In this method, the electrode flipping coefficient is determined by utilizing the melting rate, cooling water flow rate, number of electrode flipping cycles, and filling ratio. Based on the electrode flipping coefficient, it is possible to accurately determine whether the smelted ingot needs to be flipped and remelted again to reduce segregation, ultimately obtaining a homogeneous, high-quality ingot.

[0037] Figure 1 An exemplary flowchart is shown of a smelting method for preparing homogeneous ingots by vacuum consumable melting electrode flipping according to some embodiments. The method includes steps S100-S400.

[0038] S100, Prepare consumable electrode.

[0039] In this embodiment, the consumable electrode is the molten material mentioned in the background art.

[0040] In some embodiments, the consumable electrode has the following chemical composition by weight percentage: C: ≤0.4%, Cr: 1%~22%, Mo: 0~6%, Ni: 0~12%, Co: 0~8%, Si: 0~2%, V: 0~1%, Mn: 0~2%, N: 0~1.2%, with the remainder being Fe.

[0041] In some embodiments, the consumable electrode, by weight percentage, has the following chemical composition: C: 0.25%~0.35%, Cr: 1%~1.2%, Mo: 1.8%~2.2%, Ni: 10%~10.4%, Co: 7%~7.5%, V: 0.08%~0.12%, with the remainder being Fe. By using the chemical composition of the consumable electrode in this embodiment and the method described in this application, homogeneous, high-quality M54 steel can ultimately be prepared.

[0042] In some embodiments, the consumable electrode, by weight percentage, has the following chemical composition: C: 0.25%~0.35%, Si: ≤1%, Mn: ≤1%, Ni: ≤0.5%, N: 0.3%-0.5%, Cr: 14%~16%, Mo: 0.85%~1.1%, with the remainder being Fe. Using the chemical composition of the consumable electrode in this embodiment and the method described in this application, homogeneous, high-quality high-nitrogen austenitic stainless steel 30Cr15Mo1N can ultimately be prepared.

[0043] In some embodiments, the step of preparing the consumable electrode includes:

[0044] Fe, Mo, Ni, Cr, Co, and W are placed in a crucible within a vacuum induction melting furnace. In some embodiments, the crucible is made of MgO•Al2O3.

[0045] C and V are placed into the feeding device. In this embodiment, the feeding device can be used to add C, V, and Ce into the vacuum induction melting furnace respectively. In some embodiments, Ce, which is a deoxidizer, can also be placed into the feeding device.

[0046] The vacuum pump is started to reduce the gas pressure inside the vacuum induction melting furnace to 4 Pa. In this embodiment, the vacuum pump can control the gas pressure inside the furnace.

[0047] High-purity argon gas is introduced into the vacuum induction melting furnace until the gas pressure inside the furnace increases to 0.02 MPa. In this embodiment, the purity of the high-purity argon gas is 99.999%.

[0048] The temperature of the vacuum induction melting furnace is controlled at 1600°C (1873K) to melt the material in the crucible.

[0049] C is added to the crucible using the feeding device. After 2 minutes, or approximately 2 minutes later, the vacuum pump is started to reduce the gas pressure inside the furnace to 4 Pa ​​over a period of 15 minutes, or approximately 15 minutes, which is vacuum carbon deoxidation.

[0050] High-purity argon gas is introduced into the vacuum induction melting furnace until the gas pressure inside the furnace increases to 0.02 MPa. In this embodiment, after the gas pressure inside the furnace drops to 4 Pa, it is increased to 0.02 MPa by introducing high-purity argon gas.

[0051] V is added to the crucible using the feeding device. After the V has completely melted, the material in the crucible is poured into a cast iron mold at 1620°C (1893K) to obtain the ingot to be processed; wherein the pouring time is 20-25 seconds. In this embodiment, after adding V to the crucible using the feeding device, it can be waited for 2 minutes to allow the V to completely melt.

[0052] In some embodiments, when Ce is placed into the feeding device, Ce is added to the crucible using the feeding device after V has completely melted; after Ce has completely melted, the material in the crucible is poured into a cast iron mold at 1620°C to obtain the ingot to be processed. In this embodiment, after adding Ce to the crucible using the feeding device, a 5-minute wait can be allowed for Ce to completely melt.

[0053] The ingot to be processed is forged and polished to obtain a consumable electrode (VIM ingot), such that the filling ratio of the consumable electrode to the crystallizer is a preset filling ratio. In some embodiments, the preset filling ratio is 0.6 to 0.8.

[0054] The crystallizer in this embodiment is an important component of the vacuum consumable remelting furnace, specifically the water-cooled copper crucible mentioned in the background section. The consumable electrode needs to be remelted in the vacuum consumable remelting furnace. The consumable electrode is vertically suspended in the center of the water-cooled copper crucible, without contacting the crucible wall, maintaining a uniform annular gap.

[0055] S200. The consumable electrode is welded to the auxiliary electrode of the vacuum consumable remelting furnace in a positive mounting manner to perform the vacuum consumable melting process and obtain an ingot.

[0056] In this embodiment, the auxiliary electrode of the vacuum consumable remelting furnace is used to fix the consumable electrode and is also connected to the power supply system. This allows the power supply system to energize the consumable electrode, thereby generating an electric arc between the consumable electrode and the water-cooled copper crucible.

[0057] In this embodiment, the consumable electrode is welded to the vacuum consumable remelting furnace auxiliary electrode in a positive mounting manner, which can be understood as welding the head of the consumable electrode to the vacuum consumable remelting furnace auxiliary electrode.

[0058] In some embodiments, the vacuum degree during the vacuum self-consumable melting process is below 5 Pa, the leakage rate is below 0.13 Pa / min, the inlet temperature of the cooling water is 20~25℃, the melting voltage is 32~45V, the filling ratio is 0.6~0.8, the melting current is 19000A, and the cooling water flow rate is 2000~4000 L / min.

[0059] S300. Determine the electrode reversal coefficient based on the melting speed of the consumable electrode, the cooling water flow rate, the number of electrode reversals, and the filling ratio during the vacuum consumable melting process.

[0060] In some embodiments, the method further includes determining the melting rate of the consumable electrode; wherein the step of determining the melting rate of the consumable electrode includes: determining the melting rate of the consumable electrode based on the crystallizer diameter, the filling ratio, and the current of the vacuum consumable melting process.

[0061] Specifically, the melting rate of the consumable electrode can be determined using formula (1):

[0062] (1)

[0063] in, denoted as , where is the melting rate of the consumable electrode, in kg / min; is the diameter of the crystallizer, in mm; is the filling ratio, representing the ratio of the consumable electrode diameter to the crystallizer diameter; is the current during the vacuum consumable melting process, in A, i = 0.35 - 0.65 × S, where S is the cross-sectional area of ​​the consumable electrode, in mm². 2 .

[0064] In some embodiments, the vacuum degree during the vacuum self-consumable melting process is below 5 Pa, the leakage rate is below 0.13 Pa / min, the cooling water inlet temperature is 20~25℃, the melting voltage is 32~45V, the filling ratio is 0.6~0.8, the melting current is 19000A, and the cooling water flow rate is 2000~4000 L / min. The calculated melting rate is 1.49~3.55 kg / min.

[0065] In this embodiment, the electrode reversal coefficient is determined based on the melting rate of the consumable electrode, the cooling water flow rate, the number of electrode reversals, and the filling ratio during the vacuum consumable melting process. Specifically, the electrode reversal coefficient can be determined using formula (2):

[0066] (2)

[0067] Where δ is the electrode reversal coefficient; is the melting rate of the consumable electrode, in kg / min; Q is the cooling water flow rate, in L / min; a is the filling ratio, representing the ratio of the consumable electrode diameter to the crystallizer diameter; X is the number of electrode flips.

[0068] It is understandable that, for the first time, the self-consumable electrode is welded to the auxiliary electrode of the vacuum self-consumable remelting furnace in a positive mounting manner to perform the vacuum self-consumable melting process, and the number of electrode flipping times corresponding to the ingot casting is 0.

[0069] S400. Determine whether the electrode reversal coefficient is greater than 1. If the electrode reversal coefficient is greater than 1, then polish the ingot forging machine, use the polished ingot as a consumable electrode, and weld the consumable electrode to the vacuum consumable remelting furnace auxiliary electrode in a reverse manner, and repeat the vacuum consumable melting process to obtain the ingot until the electrode reversal coefficient is not greater than 1. The filling ratio of the polished ingot to the crystallizer is a preset filling ratio.

[0070] In this embodiment of the application, when the electrode reversal coefficient δ>1, it means that the ingot obtained by melting needs to be forged again and the self-consumable electrode is welded to the vacuum self-consumable remelting furnace auxiliary electrode by reverse mounting, that is, the tail of the ingot is welded to the vacuum self-consumable remelting furnace auxiliary electrode, and the vacuum self-consumable melting process is repeated after welding to obtain the ingot, until the electrode reversal coefficient is not greater than 1.

[0071] When welding the consumable electrode and the auxiliary electrode of the vacuum consumable remelting furnace in the reverse installation method and re - executing the vacuum consumable melting process to obtain an ingot, continue to determine the electrode flipping coefficient according to the melting speed, cooling water flow rate, electrode flipping times, and filling ratio of the consumable electrode during the vacuum consumable melting process. At this time, since the consumable electrode has been flipped once from the initial forward installation to the current reverse installation, the electrode flipping times are updated and are 1 time at this moment. If the forward installation is carried out again subsequently, the electrode flipping times are updated again and become 2 times.

[0072] In some embodiments, the method further includes: if the electrode flipping coefficient is not greater than 1, measure the segregation ratios at multiple positions on the ingot; if the segregation ratios at multiple positions on the ingot are all within a preset range, determine that the ingot is qualified. In some embodiments, the preset range is 0.8 - 1.1.

[0073] In some embodiments, the multiple positions on the ingot include the 1 / 2 radius at 40 mm from the top of the ingot, the 1 / 2 radius at the horizontal plane where the center of the ingot is located, and the 1 / 2 radius at 40 mm from the bottom of the ingot. This can comprehensively understand the homogenization situation of the ingot. If the segregation ratios at multiple positions are all within the preset range, determine that the ingot is qualified.

[0074] The embodiment of the present application provides a smelting method for preparing a homogeneous ingot by flipping the electrode in vacuum consumable melting. In this method, the electrode flipping coefficient is determined by using the melting speed, cooling water flow rate, electrode flipping times, and filling ratio; according to the electrode flipping coefficient, it can be accurately determined whether the ingot after smelting needs to be flipped and remelted again to achieve the purpose of reducing segregation, improve the efficiency and cost of solving the segregation problem, and finally obtain a homogeneous high - quality ingot, thereby further promoting the development of the vacuum consumable melting process. The method includes preparing a consumable electrode; welding the consumable electrode and the auxiliary electrode of the vacuum consumable remelting furnace in the forward installation method and executing the vacuum consumable melting process to obtain an ingot; determining the electrode flipping coefficient according to the melting speed, cooling water flow rate, electrode flipping times, and filling ratio of the consumable electrode during the vacuum consumable melting process; judging whether the electrode flipping coefficient is greater than 1; if the electrode flipping coefficient is greater than 1, forge, turn, and polish the ingot, use the polished ingot as a consumable electrode, and weld the consumable electrode and the auxiliary electrode of the vacuum consumable remelting furnace in the reverse installation method, and re - execute the step of the vacuum consumable melting process to obtain an ingot until the electrode flipping coefficient is not greater than 1; where the filling ratio of the polished ingot and the mold is a preset filling ratio.

[0075] The method in the embodiment of the present application is further described below through Example 1 and Example 2.

[0076] Example 1: Vacuum double-stage clean smelting of Φ300mm M54 steel #1

[0077] First, the consumable electrode was prepared using 25 kg of consumable electrode raw materials. The chemical composition of the consumable electrode, by weight percentage, i.e., the raw materials, is: C: 0.3%, Cr: 1.12%, Mo: 2%, Ni: 10%, Co: 7.2%, V: 0.1%, with the remainder being Fe.

[0078] Specifically, pure Fe, Mo, Ni, Cr, Co, and W are placed in a crucible made of MgO•Al2O3, while pure C, V, and Ce are placed in the charging device. The vacuum pump is started to reduce the furnace gas pressure to 4 Pa. Then, 99.999% high-purity argon gas is piped into the furnace until the furnace gas pressure increases to 0.02 MPa. The raw materials are melted at 1873 K (1600℃). Pure C is added to the molten steel, i.e., the crucible material. After approximately 2 minutes, the vacuum pump is started to reduce the furnace gas pressure to 4 Pa ​​(approximately 15 minutes), i.e., vacuum carbon deoxidation. Then, 99.999% high-purity argon gas is piped into the furnace until the furnace gas pressure recovers to 0.02 MPa. V from the charging device is added to the molten steel, i.e., the crucible material, and left for 2 minutes until it is completely melted. Then, Ce is added to the molten steel, i.e., the crucible material, and left for 5 minutes until it is completely melted. Molten steel was poured into a cast iron mold at 1893 K (1620℃) to obtain the ingot to be treated. The pouring time was controlled at about 20~25s. The ingot to be treated was forged and ground to a diameter of 220mm to obtain a consumable electrode. The inner diameter of the vacuum consumable furnace crystallizer was 300mm, i.e., the filling ratio a=0.73.

[0079] The consumable electrode head was welded to the auxiliary electrode of the vacuum consumable remelting furnace using a forward mounting method. The first vacuum consumable remelting process was performed, with the vacuum level controlled below 5 Pa, the leakage rate below 0.13 Pa / min, the melting current set to 19000 A, the melting voltage controlled between 32 and 45 V, the cooling water flow rate Q controlled at 3200 L / min, and the cooling water inlet temperature controlled at 23℃. According to formula (1), the melting speed was 2.14 kg / min, resulting in the ingot corresponding to the first vacuum consumable remelting process. According to formula (2), the electrode flipping coefficient δ = 1.28 was calculated.

[0080] Since the electrode reversal coefficient is greater than 1, the ingot is reforged, machined, and ground to a diameter of 220mm to obtain the ground ingot. The ground ingot is used as a consumable electrode, and the reverse mounting method is adopted, that is, the tail of the consumable electrode is welded to the auxiliary electrode of the vacuum consumable remelting furnace. The second vacuum consumable melting process is performed. The process parameters of the second vacuum consumable melting process are the same as those of the first vacuum melting process. According to formula (1), the melting speed v is calculated again to be 2.14kg / min, and the ingot corresponding to the second vacuum consumable melting process is finally obtained. At this time, the electrode reversal number is 1, and according to formula (2), the electrode reversal coefficient δ=0.91 is calculated.

[0081] Since the electrode flipping coefficient δ is less than 1, subsequent remelting is not required. Segregation ratios were measured and statistically analyzed at three locations: half a radius (40mm from the top of the ingot, i.e., the upper part), half a radius (1 / 2 radius from the horizontal plane where the center of the ingot is located, i.e., the middle part), and half a radius (40mm from the bottom of the ingot, i.e., the bottom). The results are shown in Table 1. It can be observed that the segregation ratio at each location is around 1, indicating uniform composition. This means that a 220mm diameter consumable electrode, after one electrode flipping and vacuum consumable remelting, yielded an ingot with low segregation.

[0082] Table 1 Segregation ratio at different locations on the ingot

[0083]

[0084] Example 2: Vacuum double-stage clean smelting of Φ300mm M54 steel #2

[0085] First, the consumable electrode was prepared using 25 kg of consumable electrode raw materials. The chemical composition of the consumable electrode, by weight percentage, was: C: 0.3%, Cr: 1.12%, Mo: 2%, Ni: 10%, Co: 7.2%, V: 0.1%, with the remainder being Fe.

[0086] Specifically, pure Fe, Mo, Ni, Cr, Co, and W are placed in a crucible made of MgO•Al2O3, while pure C, V, and Ce are placed in the charging device. The vacuum pump is started to reduce the furnace gas pressure to 4 Pa. Then, 99.999% high-purity argon gas is piped into the furnace until the furnace gas pressure increases to 0.02 MPa. The raw materials are melted at 1873 K (1600℃). Pure C is added to the molten steel, i.e., the crucible material. After approximately 2 minutes, the vacuum pump is started to reduce the furnace gas pressure to 4 Pa ​​(approximately 15 minutes), i.e., vacuum carbon deoxidation. Then, 99.999% high-purity argon gas is piped into the furnace until the furnace gas pressure recovers to 0.02 MPa. V from the charging device is added to the molten steel, i.e., the crucible material, and left for 2 minutes until it is completely melted. Then, Ce is added to the molten steel, i.e., the crucible material, and left for 5 minutes until it is completely melted. Molten steel was poured into a cast iron mold at 1893 K (1620℃) to obtain the ingot to be treated. The pouring time was controlled at about 20~25s. The ingot to be treated was forged and ground to a diameter of 200mm to obtain a consumable electrode. The inner diameter of the vacuum consumable furnace crystallizer was 300mm, i.e., the filling ratio a=0.67.

[0087] The consumable electrode head was welded to the auxiliary electrode of the vacuum consumable remelting furnace using a forward mounting method. The first vacuum consumable remelting process was performed, with the vacuum level controlled below 5 Pa, the leakage rate below 0.13 Pa / min, the melting current set to 12500 A, the melting voltage controlled between 32 and 45 V, the cooling water flow rate Q controlled at 3000 L / min, and the cooling water inlet temperature controlled at 23℃. According to formula (1), the melting speed v = 2.19 kg / min was obtained, ultimately yielding the ingot corresponding to the first vacuum consumable remelting process. According to formula (2), the electrode flipping coefficient δ = 1.63 was calculated.

[0088] Since the electrode reversal coefficient is greater than 1, the ingot is reforged, machined, and polished to a diameter of 200mm to obtain the polished ingot. The polished ingot is used as a consumable electrode, and the reverse mounting method is adopted, that is, the tail of the consumable electrode is welded to the auxiliary electrode of the vacuum consumable remelting furnace. The second vacuum consumable melting process is performed. The process parameters of the second vacuum consumable melting process are the same as those of the first vacuum melting process. According to formula (1), the melting speed v is calculated again to be 2.19kg / min, and the ingot corresponding to the second vacuum consumable melting process is finally obtained. At this time, the electrode reversal number is 1, and according to formula (2), the electrode reversal coefficient δ=1.15 is calculated.

[0089] Since the electrode reversal coefficient δ is still greater than 1, the ingot corresponding to the second vacuum consumable melting process is reforged, machined, and polished to a diameter of 200mm to obtain the polished ingot. The polished ingot is used as the consumable electrode and is mounted in the correct orientation, that is, the head of the consumable electrode is welded to the auxiliary electrode of the vacuum consumable remelting furnace. The third vacuum consumable melting process is then performed. The process parameters of the third vacuum consumable melting process are the same as those of the first vacuum melting process. The melting speed v = 2.19kg / min is calculated again according to formula (1) to obtain the ingot corresponding to the third vacuum consumable melting process. At this time, the electrode reversal number is 2, and the electrode reversal coefficient δ = 0.95 is calculated according to formula (2).

[0090] Since the electrode flipping coefficient δ is less than 1, subsequent remelting is not required. Segregation ratios were measured and statistically analyzed at three locations: half a radius (40mm from the top of the ingot, i.e., the upper part), half a radius (1 / 2 radius from the horizontal plane where the center of the ingot is located, i.e., the middle part), and half a radius (40mm from the bottom of the ingot, i.e., the bottom). The results are shown in Table 1. It can be observed that the segregation ratio at each location is around 1, indicating uniform composition. This means that the 200mm diameter consumable electrode, after two electrode flipping vacuum consumable remelting processes, yielded an ingot with low segregation.

[0091] Table 2 Segregation ratio at different locations on the ingot

[0092]

[0093] It will be readily understood by those skilled in the art that the above-described advantageous methods can be freely combined and superimposed without conflict. The above are merely preferred embodiments of this application and are not intended to limit this application. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this application should be included within the protection scope of this application. The above are merely preferred embodiments of this application. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the technical principles of this application, and these improvements and modifications should also be considered within the protection scope of this application.

Claims

1. A smelting method for preparing homogeneous ingots by electrode flipping in vacuum consumable melting, characterized in that, include: Fabrication of consumable electrodes; The consumable electrode is welded to the auxiliary electrode of the vacuum consumable remelting furnace in a positive mounting manner to perform a vacuum consumable melting process and obtain an ingot. The electrode reversal coefficient is determined based on the melting rate of the consumable electrode, the cooling water flow rate, the number of electrode reversals, and the filling ratio during the vacuum consumable melting process. Determine whether the electrode reversal coefficient is greater than 1; if the electrode reversal coefficient is greater than 1, then the ingot forging machine polishes and grinds it, and uses the polished ingot as a consumable electrode. The consumable electrode is then welded to the auxiliary electrode of the vacuum consumable remelting furnace in a reverse manner, and the vacuum consumable melting process is repeated to obtain the ingot, until the electrode reversal coefficient is not greater than 1; wherein the filling ratio of the polished ingot to the crystallizer is a preset filling ratio.

2. The method according to claim 1, characterized in that, Also includes: If the electrode flipping coefficient is not greater than 1, the segregation ratio at multiple locations on the ingot is measured; if the segregation ratio at multiple locations on the ingot is within a preset range, the ingot is determined to be qualified.

3. The method according to claim 2, characterized in that, The ingot has several locations, including a 1 / 2 radius point 40 mm from the top of the ingot, a 1 / 2 radius point on the horizontal plane where the center of the ingot is located, and a 1 / 2 radius point 40 mm from the bottom of the ingot.

4. The method according to claim 1, characterized in that, The self-consuming electrode has the following chemical composition by weight percentage: C: ≤0.4%, Cr: 1%~22%, Mo: 0~6%, Ni: 0~12%, Co: 0~8%, Si: 0~2%, V: 0~1%, Mn: 0~2%, N: 0~1.2%, with the remainder being Fe.

5. The method according to claim 1, characterized in that, The consumable electrode, by weight percentage, has the following chemical composition: C: 0.25%~0.35%, Cr: 1%~1.2%, Mo: 1.8%~2.2%, Ni: 10%~10.4%, Co: 7%~7.5%, V: 0.08%~0.12%, with the remainder being Fe.

6. The method according to claim 1, characterized in that, The consumable electrode has the following chemical composition by weight percentage: C: 0.25%~0.35%, Si: ≤1%, Mn: ≤1%, Ni: ≤0.5%, N: 0.3%-0.5%, Cr: 14%~16%, Mo: 0.85%~1.1%, with the remainder being Fe.

7. The method according to claim 4, characterized in that, The steps for preparing the consumable electrode include: Fe, Mo, Ni, Cr, Co and W are placed in a crucible inside a vacuum induction melting furnace; Place C and V into the feeding device; Start the vacuum pump to reduce the gas pressure inside the vacuum induction melting furnace to 4 Pa; High-purity argon gas is introduced into the vacuum induction melting furnace until the gas pressure inside the furnace increases to 0.02 MPa; The temperature of the vacuum induction melting furnace is controlled at 1600°C to melt the material in the crucible; C is added to the crucible using the feeding device, and the vacuum pump is started 2 minutes later to reduce the gas pressure in the furnace to 4 Pa ​​over a period of 15 minutes. High-purity argon gas is introduced into the vacuum induction melting furnace until the gas pressure inside the furnace increases to 0.02 MPa; V is added to the crucible using the feeding device. After V is completely melted, the material in the crucible is poured into a cast iron mold at 1620°C to obtain the ingot to be processed. The pouring time is 20-25 seconds. The ingot to be processed is forged and polished to obtain a consumable electrode, so that the filling ratio of the consumable electrode to the crystallizer is a preset filling ratio.

8. The method according to claim 1 or 7, characterized in that, The preset filling ratio is 0.6~0.

8.

9. The method according to claim 1, characterized in that, It also includes determining the melting rate of the consumable electrode; wherein the step of determining the melting rate of the consumable electrode includes: The melting rate of the consumable electrode is determined based on the crystallizer diameter, filling ratio, and current of the vacuum consumable melting process.

10. The method according to claim 1, characterized in that, The vacuum degree in the vacuum self-consuming melting process is below 5 Pa, the leakage rate is below 0.13 Pa / min, the inlet temperature of the cooling water is 20~25℃, the melting voltage is 32~45V, the filling ratio is 0.6~0.8, the melting current is 19000A, and the cooling water flow rate is 2000~4000 L / min.

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