Preparation method of electroslag remelting consumable electrode bar

Abstract

The invention relates to a preparation method of an electroslag remelting consumable electrode bar. The preparation method comprises the following steps: 1) mixing alumina powder, vinyl alkyl ketone and vinyl alkyl acid ester into alumina powder suspension; (2) thermal spraying is conducted, specifically, one end of the consumable electrode bar is sprayed with the aluminum oxide powder suspension liquid through a thermal spraying machine, the aluminum oxide solution at the temperature of 150-200 DEG C is sprayed to the end of the consumable electrode bar to form a heat-resistant coating, the spraying pressure is 1.5-2.5 MPa, and the thickness of the heat-resistant coating is controlled to be 10-20 microns; 3) cooling: cooling the sprayed consumable electrode bar to room temperature; and 4) drying: drying the cooled self-consuming striking rod to remove moisture. According to the consumable electrode bar, the high-temperature-resistant coating is sprayed to the end of the consumable electrode bar, and the phenomenon that the consumable electrode wraps slag at the bottom of an electroslag ingot is effectively avoided.

Description

Technical Field

[0001] The invention relates to an electroslag remelting consumable electrode, in particular to a method for preparing an electroslag remelting consumable electrode rod. Background Art

[0002] When starting the arc in the prior art electroslag remelting, power is first supplied and the power is gradually increased to start the arcing and slag melting, and all the pre-melted slag is added in a short time. The increase in the slag melting power easily causes the pre-melted slag and the consumable electrode to melt at the same time. Because the slag temperature is not superheated enough in the initial stage, after the electrode ingot is melted, 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 leads to uneven composition of the electrode ingot and affects the chemical composition and performance of the final alloy. This will affect the mechanical properties of the product, such as strength, hardness, corrosion resistance, etc.

[0003] Patent application CN202311209877.7 discloses a protective atmosphere nickel alloy electroslag remelting arc starting process. This patent improves the slag wrapping phenomenon at the bottom of the electroslag ingot by controlling the current and voltage during arc starting to reduce the melting of the consumable electrode during arc starting. However, in actual production, the sizes and materials of electrode rods are diverse, resulting in different currents and voltages required for arc starting. Therefore, a single method of controlling the arc starting power cannot be applicable to all consumable electrodes. Summary of the invention

[0004] The technical problem to be solved by the present invention is to provide a method for preparing an electroslag remelting consumable electrode rod, which can effectively avoid the phenomenon of the consumable electrode being wrapped with slag at the bottom of an electroslag ingot.

[0005] To achieve the above object, the present invention adopts the following technical solutions:

[0006] A method for preparing an electroslag remelting consumable electrode rod, spraying a high temperature resistant coating on the end of the consumable electrode, specifically comprising:

[0007] 1) mixing alumina powder, vinyl alkyl ketone and vinyl alkyl ester to form an alumina powder suspension;

[0008] 2) Thermal spraying: spraying alumina powder suspension on one end of the consumable electrode rod with a thermal sprayer, spraying 150-200°C alumina solution on the end of the consumable electrode rod to form a heat-resistant coating, spraying pressure 1.5-2.5MPa, controlling the thickness of the heat-resistant coating to be 10-20μm;

[0009] 3) Cooling: The consumable electrode rod after spraying is cooled to room temperature;

[0010] 4) Drying: Dry the cooled consumable electric prod to remove moisture.

[0011] The mass ratio of the aluminum oxide powder: vinyl alkyl ketone: vinyl alkyl ester in step 1) is 7-10:2-3:1;

[0012] Step 1) Alumina powder, vinyl alkyl ketone and vinyl alkyl ester are uniformly mixed in a solution by a high-speed rotary mixer until the alumina powder is completely suspended.

[0013] Step 2) The length of the heat-resistant coating is 1 / 3 to 2 / 3 of the consumable electrode rod.

[0014] The drying temperature in step 4) is 70-85°C.

[0015] Compared with the prior art, the present invention has the following beneficial effects:

[0016] 1) Reduce the adhesion between slag and electrode: The melting point of alumina is 2054℃, while the melting point of the electrode rod used for electroslag remelting is generally 1300℃-1500℃. The coating has a higher melting point. In addition, the molecular structure of alumina remains stable at high temperatures and will not easily decompose or change phases due to temperature changes. This stability enables the heat-resistant coating 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.

[0017] 2) Improve the wear resistance of the electrode: Alumina is a material with high hardness. Coating it on the electrode surface can increase the wear resistance of the electrode and reduce the electrode wear caused by the scouring effect of the slag during the arc starting process. The surface of the heat-resistant coating is relatively smooth and the molecules are arranged tightly, which reduces the chance of the slag molecules adhering to the surface. The slag moves and slides more easily on a smooth surface, which helps the slag fall off the electrode surface instead of forming a slag coating.

[0018] 3) Optimize heat conduction: The electrical conductivity of the heat-resistant coating during the electroslag remelting process is lower than that of the molten metal, which means that the heat-resistant coating can effectively reduce the current density on the electrode surface and avoid overheating and damage to the electrode surface. The design of the heat-resistant coating can optimize the conduction of heat, so that the heat is transferred to the slag pool more evenly, which helps to improve the control accuracy of the smelting process.

[0019] 4) Improve the high temperature stability of the electrode: At high temperatures, alumina and polyvinyl alkyl ketone / vinyl alkyl esters will react chemically to form stable compounds. This reaction can maintain the stability of the coating through the formation of chemical bonds. For example, alumina can react chemically with the hydroxyl or carboxyl groups of vinyl alkyl ketone / vinyl alkyl esters to form stable aluminum alkyl compounds. These aluminum alkyl compounds can exist stably at high temperatures and protect the alumina layer during the electrode melting process. In addition, polymers of vinyl alkyl ketones and vinyl alkyl esters also have good stability at high temperatures. These polymers generally have high thermal stability and do not decompose or denature at high temperatures. Therefore, during the electroslag remelting process, these polymers can maintain the integrity of the coating and provide good protection at the electrode ends. DETAILED DESCRIPTION

[0020] It should be noted that, unless otherwise defined, all technical and scientific terms used herein have the same meaning as those generally understood by technicians in the technical field of this application; the terms used in the specification of the application herein are only for the purpose of describing specific embodiments and are not intended to limit the present application. The reference to "embodiment" in this article means that the specific features, structures or characteristics described in conjunction with the embodiment may be included in at least one embodiment of the present application. The appearance of this phrase in various places in the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment that is mutually exclusive with other embodiments. It is explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments. Based on the embodiments in the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0021] Example 1

[0022] A method for preparing an electroslag remelting consumable electrode rod, spraying a high temperature resistant coating on the end of the consumable electrode, comprising the following steps:

[0023] 1) mixing alumina powder with vinyl alkyl ketone and vinyl alkyl ester solution in a mass ratio of 7:2:1, wherein the particle size of the alumina powder is 5-50 μm, and uniformly mixing by a high-speed rotating mixer to form an alumina powder suspension;

[0024] 2) Thermal spraying: Clamp the consumable electrode rod on the rotating table of the thermal spraying machine, with the nozzle 10 cm away from the consumable electrode rod. Thermally spray the end of the consumable electrode rod with alumina powder suspension to evenly form an alumina powder coating on the outer surface of the consumable electrode rod. The spraying liquid temperature is 170°C, the spraying pressure is 2.0MPa, and the thickness of the spraying layer is controlled within 15μm. The length of the heat-resistant coating is 1 / 3 of the consumable electrode rod;

[0025] 3) After spraying, the consumable electrode rod is left to cool to room temperature;

[0026] 4) The cooled consumable electric prod is dried at 80°C to remove moisture.

[0027] Example 2

[0028] A method for preparing an electroslag remelting consumable electrode rod, spraying a high temperature resistant coating on the end of the consumable electrode, comprising the following steps:

[0029] 1) mixing alumina powder with vinyl alkyl ketone and vinyl alkyl ester solution in a mass ratio of 8:2:1, wherein the particle size of the alumina powder is 5-50 μm, and uniformly mixing by a high-speed rotating mixer to form an alumina powder suspension;

[0030] 2) Thermal spraying: Clamp the consumable electrode rod on the rotating table of the thermal spraying machine, with the nozzle 10 cm away from the consumable electrode rod. Thermally spray the end of the consumable electrode rod with alumina powder suspension to evenly form an alumina powder coating on the outer surface of the consumable electrode rod. The spraying liquid temperature is 170°C, the spraying pressure is 2.0MPa, and the thickness of the spraying layer is controlled within 15μm. The length of the heat-resistant coating is 2 / 3 of the consumable electrode rod;

[0031] 3) After spraying, the consumable electrode rod is left to cool to room temperature;

[0032] 4) The cooled consumable electric prod is dried at 85°C to remove moisture.

[0033] Application Example 1:

[0034] Electroslag furnace smelting Φ600mmD2 mold steel:

[0035] 1) The consumable electrode rod manufactured in Example 1 is clamped in an electroslag furnace, and the size of the consumable electrode rod satisfies that the ratio of the cross-sectional area of ​​the consumable electrode rod to the cross-sectional area of ​​the crystallizer used is 0.52.

[0036] 2) Use D2 steel to make the 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.

[0037] 3) Place arc starter on top of the bottom plate and spread 0.5 kg ANF-6 pre-slag around the arc starter.

[0038] 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 lowered, 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 7-9s, 3kg of ANF-6 steel slag is added through the feed port for conventional smelting.

[0039] The electroslag smelting process is normal, the surface quality is good after smelting, and the bottom of the electroslag ingot is clean without slag inclusion. The composition of D2 steel is qualified.

[0040] Application Example 2:

[0041] Electroslag furnace smelting Φ800mm 42CrMo mold steel:

[0042] 1) The consumable electrode rod manufactured in Example 1 is clamped in an electroslag furnace, and the size of the consumable electrode rod satisfies that the ratio of the cross-sectional area of ​​the consumable electrode rod to the cross-sectional area of ​​the crystallizer used is 0.6.

[0043] 2) Use 42CrMo steel to make the bottom plate, and carefully polish the oxide layer on the surface of the bottom plate. The diameter of the bottom plate is 7 / 8 of the diameter of the electroslag furnace. Place the bottom plate securely in the center of the electroslag furnace base in the crystallizer.

[0044] 3) Place an arc starter on the bottom plate and evenly spread 0.8 kg of ANF-6 pre-slag around the arc starter.

[0045] 4) Introduce argon gas into the electroslag furnace to create a protective atmosphere; the arc-starting voltage in the electroslag furnace is set to 70V±5V, and the current is 3500A±50A. Slowly lower the consumable electrode, and when the consumable electrode contacts the arc-starting agent, start the electroslag furnace to start arcing and slag making. After the arc is generated for 8-10s, add 4kg of ANF-6 steel slag through the feed port, and then carry out conventional smelting.

[0046] It was observed that the heat-resistant coating on the end of the consumable electrode rod significantly reduced the occurrence of slag inclusion, which effectively improved the purity of the molten steel. The final steel ingot has a smooth surface without obvious defects such as slag inclusion and pores. The internal structure is uniform and dense, and the chemical composition is evenly distributed, which effectively improves the internal quality of the steel ingot and provides a good foundation for subsequent processing and use.

[0047] Application Example 3:

[0048] Electroslag furnace smelting Φ1000mm 3Cr2W8V mold steel:

[0049] 1) The consumable electrode rod manufactured in Example 2 is clamped in an electroslag furnace. The size of the consumable electrode rod must ensure that the ratio of the cross-sectional area of ​​the consumable electrode rod to the cross-sectional area of ​​the crystallizer used is 0.7.

[0050] 2) Use 3Cr2W8V steel to make the bottom plate, carefully polish the oxide layer on the surface of the bottom plate, and the diameter of the bottom plate is 5 / 6 of the diameter of the electroslag furnace. Place the bottom plate in the center of the electroslag furnace base in the crystallizer.

[0051] 3) Place an arc starter on top of the bottom plate and spread 1 kg of ANF-6 pre-slag around the arc starter.

[0052] 4) Argon gas is introduced into the electroslag furnace as a protective gas; the arc-starting voltage in the electroslag furnace is set to 80V±5V, and the current is 4000A±50A. The consumable electrode is lowered at a uniform speed, 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 9-11 seconds, 5kg of ANF-6 steel slag is added through the feed port, followed by conventional smelting.

[0053] Thanks to the heat-resistant coating on the end of the consumable electrode rod, the slag wrapping phenomenon is greatly reduced during the smelting process, effectively ensuring the stability and consistency of the molten steel quality. The resulting steel ingot has excellent surface quality, presents a uniform and delicate texture, and has no visible flaws and defects. At the same time, the internal quality is excellent, the microstructure is uniform and fine, and all performance indicators have reached an ideal level, providing a reliable material guarantee for the manufacture of high-quality molds.

[0054] 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 an electroslag remelting consumable electrode rod, characterized in that: Spraying a high temperature resistant coating on the end of the consumable electrode includes: 1) mixing alumina powder, vinyl alkyl ketone and vinyl alkyl ester to form an alumina powder suspension; 2) Thermal spraying: spraying alumina powder suspension on one end of the consumable electrode rod with a thermal sprayer, spraying 150-200°C alumina solution on the end of the consumable electrode rod to form a heat-resistant coating, spraying pressure 1.5-2.5MPa, controlling the thickness of the heat-resistant coating to be 10-20μm; 3) Cooling: The consumable electrode rod after spraying is cooled to room temperature; 4) Drying: Dry the cooled consumable electric prod to remove moisture.

2. The method for preparing an electroslag remelting consumable electrode rod according to claim 1, characterized in that: The mass ratio of the aluminum oxide powder: vinyl alkyl ketone: vinyl alkyl ester in step 1) is 7-10:2-3:

1.

3. The method for preparing an electroslag remelting consumable electrode rod according to claim 1, characterized in that: Step 1) The alumina powder, vinyl alkyl ketone and vinyl alkyl ester are uniformly mixed in a solution by a high-speed rotating mixer until the alumina powder is completely suspended.

4. The method for preparing an electroslag remelting consumable electrode rod according to claim 1, characterized in that: Step 2) The length of the heat-resistant coating is 1 / 3 to 2 / 3 of the consumable electrode rod.

5. The method for preparing an electroslag remelting consumable electrode rod according to claim 1, characterized in that: The drying temperature in step 4) is 70-85°C.