Preparation method of GH4169 alloy consumable electrode for electroslag remelting smelting

Abstract

The invention relates to a preparation method of a GH4169 alloy consumable electrode for electroslag remelting smelting. The preparation method comprises the following steps: carrying out surface treatment on an area which is 20cm below the lower part of the consumable electrode; the treated consumable electrode serves as a cathode to be connected with a direct-current power supply cathode, and a pure nickel plate serves as an anode to be connected with a direct-current power supply anode; immersing the polishing area of the consumable electrode into nickel-tungsten electroplating liquid for electroplating; and heating in an annealing furnace at 300-600 DEG C, and cooling along with the furnace. The self-consuming electrode has the advantage that the conductivity and the arcing characteristic of the self-consuming electrode are enhanced. The method has the advantages that the use of the consumable electrode can optimize the uniformity of components in the slag bath and reduce the adhesion between slag and the electrode; and the consumable electrode is used for electroslag remelting, so that the slag wrapping phenomenon during arcing is effectively prevented, and the purity and the quality stability of remelted metal are greatly improved.

Description

Technical Field

[0001] The invention belongs to the field of electroslag remelting, and in particular relates to a method for preparing a GH4169 alloy consumable electrode for electroslag remelting. Background Art

[0002] As an advanced metal refining process, electroslag remelting technology plays an important role in producing high-quality metal materials. During the electroslag remelting process, the performance and state of the consumable electrode have a key impact on the smooth progress of the entire process and the quality of the final product. At the beginning of electroslag remelting, that is, when the arc is struck, the melting process of the consumable electrode needs to be precisely controlled. However, in actual operation, the consumable electrode often melts prematurely.

[0003] When the electric slag remelting GH4169 of the prior art starts the arc, the power is first supplied and the power is gradually increased to start the arc and slag, and all the pre-melted slag is added in a short time. Because the increase in the slag melting power easily causes the pre-melted slag and the electrode ingot to melt at the same time, the slag temperature is insufficient in the initial stage, and after the electrode ingot melts, a small amount of pre-melted slag is easily wrapped in the solidification process of the molten steel at the bottom of the crystallizer, which causes the electric slag ingot, especially the bottom of the electric slag ingot, to crack and other defects during the subsequent forging process.

[0004] The premature melting of the consumable electrode will bring a series of adverse consequences. First, it will destroy the stability of the electroslag remelting process, causing the melting rate to be out of control, affecting the composition uniformity and temperature distribution of the metal molten pool, thereby reducing the quality of the final product. For example, it may cause defects such as looseness and uneven distribution of inclusions inside the metal material. Second, premature melting will increase energy consumption, reduce production efficiency, and increase production costs. Because the uneven melting process may take longer to complete the remelting, consuming more electricity and other resources.

[0005] At present, in order to solve the problem of premature melting of consumable electrodes during arc initiation, the industry has taken a variety of measures. The existing patent application number is: CN202311209877.7, which discloses a protective atmosphere nickel alloy electroslag remelting arc starting process. By improving the electrical parameters and control system of the electroslag remelting equipment, it attempts to accurately control the input energy, but this method often has high requirements for the equipment and is complex to adjust, and it is difficult to maintain a stable effect under different production conditions. There are also attempts to optimize the initial shape and size of the consumable electrode, but this method has great limitations. For different metal materials and remelting process requirements, the specifications of the consumable electrode need to be frequently changed, which increases production costs and operational complexity.

[0006] In view of the above situation, finding a more effective, simple and adaptable method to prevent the consumable electrode from melting prematurely during arc initiation has become an important issue that needs to be urgently solved in the field of electroslag remelting. Summary of the invention

[0007] In order to overcome the shortcomings of the prior art, the purpose of the present invention is to provide a method for preparing a GH4169 alloy consumable electrode for electroslag remelting, which uses an electroplating method to add a nickel-tungsten electroplating layer on the surface of the consumable electrode to reduce arc jumping and instability, and prevent the consumable electrode from melting in advance during arc initiation. The produced consumable electrode has the advantages of high arc initiation efficiency and is not prone to slag rolling during arc initiation.

[0008] To achieve the above object, the present invention is implemented through the following technical solutions:

[0009] A method for preparing a GH4169 alloy consumable electrode for electroslag remelting, comprising the following steps:

[0010] 1) Surface treatment

[0011] Grind the area below 20 cm below the consumable electrode to remove dirt and oxide layer; pickle the polished area with phosphoric acid solution;

[0012] 2) Preparation of nickel-tungsten electroplating solution

[0013] Slowly add nickel sulfate to deionized water and stir, then slowly add sodium tungstate and continue stirring until completely dissolved; then add sodium citrate and boric acid to the solution and continue stirring until completely dissolved, and finally make up to volume with deionized water;

[0014] 3) Electroplating

[0015] Pour nickel-tungsten electroplating solution into the electroplating tank, connect the consumable electrode pretreated in step 1) as the cathode to the negative electrode of the DC power supply, and connect the pure nickel plate as the anode to the positive electrode of the DC power supply; power supply parameters: current density 2-8A / dm 2 , voltage 6~15V;

[0016] The polished area of ​​the consumable electrode is immersed in the electroplating solution, the pure nickel plate is immersed in the electroplating solution, and the distance between the cathode and the anode is 20 to 30 cm, and electroplating is performed; during electroplating, the temperature in the electroplating tank is maintained at 50 to 60° C., and the electroplating solution is stirred at a stirring speed of 200 to 500 rpm;

[0017] 4) Post-plating treatment

[0018] After the electroplating is completed, the consumable electrode is cleaned to remove the residual electroplating solution, and then sent to the annealing furnace; the temperature is increased to 300-600°C at a heating rate of 5-10°C, kept at this temperature for 1-3 hours, and cooled to room temperature along with the furnace.

[0019] In step 1), the consumable electrode is acid-washed, wiped dry, and wrapped in a plastic film for later use.

[0020] Step 2): 300 L of deionized water;

[0021] Nickel sulfate 81.00kg~83.00kg;

[0022] Sodium tungstate 5.4kg~5.6kg;

[0023] Sodium citrate 36kg~40.00kg;

[0024] Boric acid 9kg~10.00kg.

[0025] The pH value of the nickel-tungsten electroplating solution prepared in step 2) is 8-9, and the concentration parameters are: nickel ion concentration is 60±1g / L, tungsten ion concentration is 10±0.1g / L, sodium citrate concentration is 120±1g / L, and boric acid concentration is 30±0.5g / L.

[0026] The diameter of the consumable electrode is no more than 600 mm.

[0027] The consumable electrode is made of GH4169 alloy.

[0028] Compared with the prior art, the present invention has the following beneficial effects:

[0029] 1) The present invention enhances the conductivity of the consumable electrode:

[0030] Nickel-tungsten has good electrical conductivity. The nickel-tungsten electroplating layer can improve the conductivity of the bottom of the electrode, making the current distribution more uniform, thereby improving the efficiency and quality of electroslag remelting. For example, during the remelting process, the current conduction is smoother, reducing the energy loss and temperature unevenness caused by excessive local resistance.

[0031] 2) The present invention improves the arc starting characteristics of the consumable electrode:

[0032] The nickel-tungsten electroplating layer can make the surface of the bottom of the consumable electrode more uniform and smooth, provide a more stable arc starting point when starting the arc, and reduce the arc jumping and instability. For example, without the electroplating layer, there may be tiny unevenness or impurities at the bottom of the electrode, making it difficult to establish a stable arc when starting the arc, but the electroplating layer can effectively avoid this situation.

[0033] 3) The use of the consumable electrode prepared by the present invention can optimize the uniformity of the slag pool composition:

[0034] In the arcing and slag-melting stage, the presence of the electroplating layer helps the slag pool components to be evenly distributed more quickly. This is because the interaction between the electroplating layer and the slag can promote the diffusion and mixing of elements, making the physical and chemical properties of the slag pool more stable and consistent. For example, in the early stage of slag-melting, due to the influence of the electroplating layer, the various components in the slag can be evenly distributed more quickly, creating good conditions for the subsequent remelting process.

[0035] 4) The consumable electrode prepared by the present invention can reduce the adhesion between slag and electrode:

[0036] The melting point of nickel-tungsten electroplating is 2000℃, while the melting point of GH4169 electrode rod is generally 1300℃. The nickel-tungsten electroplating has a higher melting point. Moreover, the nickel-tungsten electroplating remains stable under high temperature of the arc and will not decompose or change phase due to temperature changes. This stability enables the nickel-tungsten electroplating to effectively isolate the direct contact between the electrode and the slag, reducing the erosion of the electrode by the slag. This prevents the electrode from melting during the arc initiation stage, which can reduce the situation where the electrode is wrapped by the slag during the electroslag remelting process.

[0037] 5) The nickel-tungsten electroplating layer on the surface of the consumable electrode in the method of the present invention can give full play to the excellent properties of the nickel-tungsten alloy through the design of the composition ratio and the control of the coating thickness. During the arc starting process, the coating significantly reduces the surface tension at the bottom of the electrode, making it difficult for the slag to adhere and accumulate. At the same time, the good thermal conductivity of the coating helps to evenly distribute the heat at the bottom of the electrode, avoiding abnormal slag flow caused by excessively high or low local temperatures. The high melting point coating also prevents the consumable electrode from melting prematurely during arc starting and slagging.

[0038] 6) Using consumable electrodes with electroplated nickel-tungsten coating for electroslag remelting not only effectively prevents slag wrapping during arcing, but also greatly improves the purity and quality stability of the remelted metal. Specifically, it reduces the impurity content in the metal, improves the uniformity of the metal's organizational structure, and significantly reduces the scrap rate. DETAILED DESCRIPTION

[0039] The present invention is described in detail below, but it should be noted that the implementation of the present invention is not limited to the following embodiments.

[0040] A method for preparing a GH4169 alloy consumable electrode for electroslag remelting, comprising the following steps:

[0041] 1) Surface pretreatment:

[0042] Take a GH4169 consumable electrode with a diameter of 500 mm and put it into the clamping frame. Use a grinder to grind the lower 20 cm columnar area and the bottom circular surface of the consumable electrode to remove oil, rust and other contaminants.

[0043] Fill the bucket with phosphoric acid solution and pickle the polished area to further remove the oxide layer and activate the surface. It can also form a phosphate protective film on the steel surface to enhance the adhesion of subsequent coatings. After pickling, wipe it dry, wrap it with plastic film and wait for subsequent use.

[0044] 2) Preparation of nickel-tungsten electroplating solution:

[0045] For a consumable electrode with a diameter of 500 mm, prepare 300L of plating solution and calculate the amount of raw materials added:

[0046] Nickel sulfate (NiSO4·6H2O): 270.2 g / L×300L=81.06 kg;

[0047] Sodium tungstate (Na2WO4·2H2O): 18g / L×300L=5.4kg;

[0048] Sodium citrate (Na3C6H5O4·2H2O): 120g / L×300L=36kg;

[0049] Boric acid (H3BO3): 30g / L×300L=9kg;

[0050] Preparation process

[0051] a) Dissolving nickel sulfate: first add 150±1L of deionized water into an acid- and alkali-resistant container, slowly add 81.06kg of nickel sulfate into the deionized water, and simultaneously start a stirring device (such as an electric stirring rod) to stir until the nickel sulfate is completely dissolved.

[0052] b) Dissolve sodium tungstate: Continue stirring and slowly add 5.4 kg of sodium tungstate, stirring until completely dissolved.

[0053] c) Add sodium citrate: Keep stirring and slowly add 36 kg of sodium citrate, stirring until it is completely dissolved.

[0054] d) Adding Boric Acid: Slowly add 9 kg of boric acid and continue stirring to dissolve it.

[0055] e) Make up the volume: Continue stirring and add deionized water to make the solution up to 300 L, stirring thoroughly.

[0056] f) The pH value of the obtained electroplating solution is 8-9, and the concentration parameters are: nickel ion concentration is 60±1 g / L, tungsten ion concentration is 10±0.1 g / L, sodium citrate concentration is 120±1 g / L, and boric acid concentration is 30±0.5 g / L.

[0057] 3) Electroplating operation

[0058] Pour the prepared plating solution into the electroplating tank, connect the previously pretreated consumable electrode to the negative pole of the DC power supply as the cathode, and connect the pure nickel plate to the positive pole of the DC power supply as the anode. Set the power supply parameters: the current is set to 400A and the voltage is 12V.

[0059] The bottom 20 cm of the connected consumable electrode is immersed in the electroplating solution. The area to be plated is 51 square decimeters, so a nickel plate with a surface area of ​​70 square decimeters is put into the electroplating solution, and the cathode and anode are 25 cm apart. After placement, electroplating begins.

[0060] During electroplating, the temperature in the electroplating bath is maintained at 50-60°C, and the electroplating bath is stirred at a stirring speed of 200-500 rpm. The target coating thickness is 0.01 cm, and the current density is 4 A / dm 2 In this case, the plating time is about 14 minutes.

[0061] 4) Post-plating treatment

[0062] After electroplating, the end of the ingot is cleaned to remove the residual plating solution and then annealed.

[0063] 1) Prepare annealing equipment: Place the consumable electrode after electroplating into an annealing furnace that can accurately control the temperature.

[0064] 2) Setting the annealing temperature: For the nickel-tungsten coating, the annealing temperature is set at 500°C.

[0065] 3) Heating: Place the electrode in an annealing furnace and set the heating rate to 10°C / min to raise the furnace temperature to the set annealing temperature.

[0066] 4) Insulation: After reaching the annealing temperature, keep it for 3 hours (insulation time) to allow the coating and substrate to fully undergo structural transformation and stress elimination.

[0067] 5) Cooling: After the insulation is completed, the annealing operation is completed by cooling with the furnace.

[0068] 6) Taking out of the furnace: After cooling to room temperature, the consumable electrode is taken out of the annealing furnace.

[0069] After the above four steps, a consumable electrode with a heat-resistant nickel-tungsten electroplating layer on the bottom is obtained.

[0070] Consumable electrodes are used in electroslag furnace smelting:

[0071] 1) Take the finished consumable electrode and clamp it in the electroslag furnace.

[0072] 2) Use GH4169 to make a bottom plate, and grind off the oxide layer on the surface of the bottom plate. The diameter of the bottom plate is 3 / 4 of the diameter of the electroslag furnace. Place the bottom plate in the center of the electroslag furnace base in the crystallizer.

[0073] 3) Place arc starter on top of the bottom plate and spread 0.5 kg of ANF-6 pre-slag around the arc starter.

[0074] 4) Argon gas is introduced into the electroslag furnace as a protective atmosphere; the arc-starting voltage in the electroslag furnace is 60V±5V, and the current is 3000A±50A. The consumable electrode is probed downward, and when the consumable electrode contacts the arc-starting agent, the electroslag furnace is started to start arcing and slag making. After the arc is generated for 7 to 9 seconds, 10 kg of ANF-6 steel slag is added through the feed port for conventional smelting. The amount of steel slag added is related to the diameter of the consumable electrode:

[0075] The diameter of the consumable electrode is between 300 and 400 mm, and the slag volume ranges from 5 to 6 kg.

[0076] The diameter of the consumable electrode is between 400 and 500 mm, and the slag volume ranges from 6 to 10 kg.

[0077] The diameter of the consumable electrode is between 500 and 550 mm, and the slag volume ranges from 10 to 13 kg.

[0078] Therefore, 10 kg of ANF-6 steel slag was added in this embodiment.

[0079] Now and Three ingot types are used as examples to illustrate:

[0080] Example 1

[0081] Steel type: GH4169 steel, ingot type: Steel slag: CaO-CaF2-Al2O3 slag system.

[0082] Electroplating: Pour nickel-tungsten electroplating solution into the electroplating tank, connect the pretreated consumable electrode as the cathode to the negative pole of the DC power supply, and connect the pure nickel plate as the anode to the positive pole of the DC power supply. The power supply parameters are set to: current density 2A / dm 2 , voltage 6V. Immerse the polished area of ​​the consumable electrode in the electroplating solution, immerse the pure nickel plate in the electroplating solution, and the distance between the cathode and the anode is 20cm. During electroplating, keep the temperature in the electroplating tank at 50℃, and stir the electroplating solution at a stirring speed of 200rpm.

[0083] Post-treatment: After the electroplating is completed, the consumable electrode is cleaned to remove the residual electroplating solution, and then sent to the annealing furnace. The temperature is raised to 300℃ at a heating rate of 5℃, kept at this temperature for 1 hour, and cooled to room temperature with the furnace.

[0084] After the treatment is completed, the consumable electrode is used to directly arc and slag, the slag removal effect is good, the electroslag smelting process is normal, and the composition of the finished product is qualified, as shown in Table 1.

[0085] The electroslag smelting process of this embodiment is normal, the surface quality is good after the smelting is completed, and the bottom of the electroslag ingot produced by the process of this embodiment is clean without slag inclusion.

[0086] Example 2

[0087] Steel type: GH4169 steel, ingot type: Steel slag: CaF2 based slag system.

[0088] Electroplating: Pour nickel-tungsten electroplating solution into the electroplating tank, connect the pretreated consumable electrode to the negative pole of the DC power supply as the cathode, and connect the pure nickel plate to the positive pole of the DC power supply as the anode. The power supply parameters are set as: current density 5A / dm 2 , voltage 10V. Immerse the polished area of ​​the consumable electrode in the electroplating solution, immerse the pure nickel plate completely, and keep the distance between the cathode and the anode at 25cm. During the electroplating process, maintain the temperature in the electroplating tank at 55℃, and stir the electroplating solution at a stirring speed of 350rpm.

[0089] Post-treatment: After electroplating, the consumable electrode is carefully cleaned to remove the residual electroplating solution, and then sent to the annealing furnace. The temperature is raised to 450℃ at a heating rate of 8℃, kept at this temperature for 2 hours, and cooled to room temperature with the furnace.

[0090] After the treatment is completed, the consumable electrode is used to directly arc and slag. The slag removal effect is good, the electroslag smelting process is normal, and the composition of the finished product is qualified, as shown in Table 1.

[0091] The electroslag smelting process of the embodiment is normal, the surface quality is good after the smelting is completed, and the internal structure of the electroslag ingot produced by the process of this embodiment is uniform and dense, without obvious looseness, pores and inclusions, and has excellent purity and homogeneity.

[0092] Example 3

[0093] Steel type: GH4169 steel, ingot type: Steel slag: ANF-6 slag series.

[0094] Electroplating: Pour nickel-tungsten electroplating solution into the electroplating tank, connect the pre-treated consumable electrode to the negative pole of the DC power supply as the cathode, and connect the pure nickel plate to the positive pole of the DC power supply as the anode. The power supply parameters are set to: current density 8A / dm 2 , voltage 15V. Immerse the polished area of ​​the consumable electrode in the electroplating solution, immerse the pure nickel plate completely, and the distance between the cathode and the anode is 30cm. During electroplating, maintain the temperature in the electroplating tank at 60℃, and stir the electroplating solution at a stirring speed of 500rpm.

[0095] Post-treatment: After electroplating, the consumable electrode is thoroughly cleaned to remove the residual electroplating solution, and then sent to the annealing furnace. The temperature is raised to 600℃ at a heating rate of 10℃, kept at this temperature for 3 hours, and cooled to room temperature with the furnace.

[0096] The consumable electrode is used to directly ignite the arc and slag, the slag removal effect is good, the electroslag smelting process is normal, and the composition of the finished product is qualified, as shown in Table 1.

[0097] The chemical composition of the steel ingot of the embodiment is precisely controlled and the impurity content is extremely low.

[0098] Table 1: Steel ingot composition mass percentage %

[0099]

[0100] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and basic spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A method for preparing a GH4169 alloy consumable electrode for electroslag remelting, characterized in that: The following steps are involved: 1) Surface treatment Grind the area below 20 cm below the consumable electrode to remove dirt and oxide layer; pickle the polished area with phosphoric acid solution; 2) Preparation of nickel-tungsten electroplating solution Slowly add nickel sulfate to deionized water and stir, then slowly add sodium tungstate and continue stirring until completely dissolved; then add sodium citrate and boric acid to the solution and continue stirring until completely dissolved, and finally make up to volume with deionized water; 3) Electroplating Pour nickel-tungsten electroplating solution into the electroplating tank, connect the consumable electrode pretreated in step 1) as the cathode to the negative electrode of the DC power supply, and connect the pure nickel plate as the anode to the positive electrode of the DC power supply; power supply parameters: current density 2-8A / dm 2 , voltage 6~15V; The polished area of ​​the consumable electrode is immersed in the electroplating solution, the pure nickel plate is immersed in the electroplating solution, and the distance between the cathode and the anode is 20 to 30 cm, and electroplating is performed; during electroplating, the temperature in the electroplating tank is maintained at 50 to 60° C., and the electroplating solution is stirred at a stirring speed of 200 to 500 rpm; 4) Post-plating treatment After the electroplating is completed, the consumable electrode is cleaned to remove the residual electroplating solution, and then sent to the annealing furnace; the temperature is increased to 300-600°C at a heating rate of 5-10°C, kept at this temperature for 1-3 hours, and cooled to room temperature along with the furnace.

2. The method for preparing a GH4169 alloy consumable electrode for electroslag remelting according to claim 1, characterized in that: In step 1), the consumable electrode is acid-washed, wiped dry, and wrapped in a plastic film for later use.

3. The method for preparing a GH4169 alloy consumable electrode for electroslag remelting according to claim 1, characterized in that: Step 2): 300 L of deionized water; Nickel sulfate 81.00kg~83.00kg; Sodium tungstate 5.4kg~5.6kg; Sodium citrate 36kg~40.00kg; Boric acid 9kg~10.00kg.

4. The method for preparing a GH4169 alloy consumable electrode for electroslag remelting according to claim 1, characterized in that: The pH value of the nickel-tungsten electroplating solution prepared in step 2) is 8-9, and the concentration parameters are: nickel ion concentration is 60±1g / L, tungsten ion concentration is 10±0.1g / L, sodium citrate concentration is 120±1g / L, and boric acid concentration is 30±0.5g / L.

5. The method for preparing a GH4169 alloy consumable electrode for electroslag remelting according to claim 1, characterized in that: The diameter of the consumable electrode is no more than 600 mm.

6. The method for preparing a GH4169 alloy consumable electrode for electroslag remelting according to claim 1, characterized in that: The consumable electrode is made of GH4169 alloy.

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