阅读说明：本技术 一种防止重熔合金偏析的电渣重熔装置及其方法 (Electroslag remelting device and method for preventing remelting alloy segregation ) 是由 施晓芳 常立忠 于 2021-08-24 设计创作，主要内容包括：本发明公开了一种防止重熔合金偏析的电渣重熔装置及其方法,属于电渣重熔技术领域。它包括结晶器、电源和磁场单元；所述结晶器从上往下依次包括第一结晶器、过渡结晶器和第二结晶器；所述第一结晶器和过渡结晶器绝缘相连,所述过渡结晶器和第二结晶器绝缘相连；在所述渣池中,与第一结晶器的底部对应位置处为第一渣池层,与第二结晶器的顶部对应位置处为第二渣池层,底层为第三渣池层；所述电源包括第一电源和第二电源；所述第一电源将自耗电极与第一渣池层连接；所述第二电源将第二渣池层与第三渣池层连接。本发明能有效避免熔融金属与结晶器的粘接问题,同时提升重熔效率并改善电渣锭的凝固质量。(The invention discloses an electroslag remelting device and method for preventing remelting alloy segregation, and belongs to the technical field of electroslag remelting. The device comprises a crystallizer, a power supply and a magnetic field unit; the crystallizer sequentially comprises a first crystallizer, a transition crystallizer and a second crystallizer from top to bottom; the first crystallizer is connected with the transition crystallizer in an insulating way, and the transition crystallizer is connected with the second crystallizer in an insulating way; in the slag pool, a first slag pool layer is arranged at the position corresponding to the bottom of the first crystallizer, a second slag pool layer is arranged at the position corresponding to the top of the second crystallizer, and a third slag pool layer is arranged at the bottom layer; the power supply comprises a first power supply and a second power supply; the first power supply connects the consumable electrode with the first slag bath layer; and the second power supply is used for connecting the second slag pool layer with the third slag pool layer. The invention can effectively avoid the problem of bonding between molten metal and the crystallizer, and simultaneously improve the remelting efficiency and the solidification quality of the electroslag ingot.)

1. An electroslag remelting device for preventing remelting alloy segregation is characterized by comprising a crystallizer, a power supply and a magnetic field unit;

the crystallizer can be used for containing a slag pool (120), and comprises a first crystallizer (200), a transition crystallizer (400) and a second crystallizer (600) from top to bottom in sequence; the first crystallizer (200) can be inserted with a consumable electrode (100) and submerged into a slag bath (120); the first crystallizer (200) is in insulated connection with the transition crystallizer (400), and the transition crystallizer (400) is in insulated connection with the second crystallizer (600);

in the slag pool (120), a first slag pool layer (121) is arranged at the position corresponding to the bottom of the first crystallizer (200), a second slag pool layer (122) is arranged at the position corresponding to the top of the second crystallizer (600), and a third slag pool layer (123) is arranged at the bottom;

the power supply comprises a first power supply (910) and a second power supply (920); the first power supply (910) is used for connecting the consumable electrode (100) with the first slag bath layer (121) and supplying direct current to the consumable electrode (100) and the slag bath (120) between the consumable electrode (100) and the first slag bath layer (121); the second power supply (920) connects the second slag pool layer (122) with the third slag pool layer (123) and is used for providing pulse current for the part between the second slag pool layer (122) and the third slag pool layer (123);

the magnetic field unit comprises a first magnetic field unit and a second magnetic field unit; the first magnetic field unit is arranged outside the first crystallizer (200) and used for providing a longitudinal magnetic field into the first crystallizer (200); the second magnetic field unit is arranged outside the second crystallizer (600) and used for providing a transverse magnetic field into the second crystallizer (600).

2. The electroslag remelting device for preventing the segregation of remelted alloy according to claim 1, wherein the diameter of the first crystallizer (200) is D1, the diameter of the second crystallizer (600) is D2, and the diameters of D1/D2 are (3-4): 1; the diameter of the transition crystallizer (400) is gradually reduced from top to bottom, the diameter of the top end of the transition crystallizer is D1, and the diameter of the bottom end of the transition crystallizer is D2.

3. An electroslag remelting apparatus according to claim 2, wherein a first conductive ring (300) is arranged between the first crystallizer (200) and the transition crystallizer (400), and the diameter of the first conductive ring (300) is D1; the first conducting ring (300) is respectively arranged corresponding to the bottom end of the first crystallizer (200) and the top end of the transition crystallizer (400), and is respectively connected with the first crystallizer (200) and the transition crystallizer (400) through an insulating ring (800); the first power supply (910) is connected with the first slag bath layer (121) through a first conductive ring (300).

4. An electroslag remelting apparatus according to claim 2, wherein a second conductive ring (500) is arranged between the second crystallizer (600) and the transition crystallizer (400), the diameter of the second conductive ring (500) is D2; the second conducting ring (500) is respectively arranged corresponding to the top end of the second crystallizer (600) and the bottom end of the transition crystallizer (400), and is respectively connected with the second crystallizer (600) and the transition crystallizer (400) through an insulating ring (800); the second power supply (920) is connected with the second slag bath layer (122) through a second conductive ring (500).

5. The electroslag remelting device for preventing the segregation of remelted alloy according to claim 4, wherein the bottom of the second crystallizer (600) is further provided with a bottom water tank (700), and the top of the bottom water tank (700) is provided with a conductive layer (710); and the second power supply (920) is connected with the third slag pool layer (123) through the conducting layer (710).

6. The electroslag remelting device for preventing remelted alloy segregation according to claim 1, wherein the first magnetic field unit comprises a first magnetic field generating coil (210), and the first magnetic field generating coil (210) can generate a stable longitudinal magnetic field after being electrified, and the magnetic field strength of the first magnetic field generating coil is 0.05T-0.1T; the second magnetic field unit comprises a second magnetic field generating coil (610), and the second magnetic field generating coil (610) can generate a stable transverse magnetic field after being electrified, and the magnetic field intensity of the second magnetic field generating coil is 0.01T-0.05T.

7. The electroslag remelting apparatus for preventing remelted alloy segregation according to claim 1, wherein the first power supply (910) is a dc power supply, and a positive electrode of the dc power supply is connected to the consumable electrode (100) and a negative electrode thereof is connected to the first slag bath layer (121); the second power supply (920) is a pulse power supply, the anode of the pulse power supply is connected with the second slag pool layer (122), the cathode of the pulse power supply is connected with the third slag pool layer (123), the waveform of the pulse power supply is square wave, the frequency of the pulse power supply is 10 kHz-20 kHz, and the current density of the pulse power supply is 50A/cm-100A/cm.

8. An electroslag remelting method for preventing remelted alloy segregation, which is based on the electroslag remelting device for preventing remelted alloy segregation in any one of claims 1 to 7, and comprises the following steps:

(1) placing a crystallizer on a conducting layer (710) at the top of a bottom water tank (700), starting a first power supply (910) to deliver direct current, pouring molten slag into the crystallizer to form a slag pool (120), immersing a consumable electrode (100) into the slag pool (120), starting a first magnetic field unit to provide a magnetic field for a first crystallizer (200), and beginning remelting;

(2) after remelting starts, a second power supply (920) is started to transmit pulse current, a second magnetic field unit is started to provide a magnetic field for a second crystallizer (600), and a bottom water tank (700) is downwards drawn to ensure that the liquid level of a slag pool (120) is kept still;

(3) when the formed electroslag ingot (140) reaches a specified height, the bottom water tank (700) stops drawing, and the power supply and the magnetic field are turned off to stop remelting.

9. The electroslag remelting method for preventing the segregation of remelted alloy according to claim 8, wherein in the step (1), after the crystallizer is placed on the bottom water tank (700), the consumable electrode (100) is lowered to a position 20-30 mm away from the insulating ring (800) between the first crystallizer (200) and the first conductive ring (300), and then the first power supply (910) is turned on; the distance between the liquid level of the slag pool (120) and the bottom of the consumable electrode (100) is 20-30 mm.

10. The electroslag remelting method for preventing the segregation of remelted alloy according to claim 8, wherein in the step (2), when the liquid level of the metal in the second mold (600) reaches 20-30 cm from the insulating ring (800) between the second mold (600) and the second conductive ring (500), the second power supply (920) and the second magnetic field unit are turned on;

in the step (3), the first power supply (910) and the first magnetic field unit are turned off simultaneously when the bottom water tank (700) stops twitching, the second power supply (920) and the second magnetic field unit are turned off after 20-60 min, and remelting is finished.

Technical Field

The invention belongs to the technical field of electroslag remelting, and particularly relates to an electroslag remelting device and method for preventing remelting alloy segregation.

Background

Many high-quality materials such as high-temperature alloy, high-speed steel, stainless steel and the like are produced by adopting an electroslag remelting technology. However, the electroslag remelting technology has many advantages, such as low remelting efficiency and high production cost, which reduce the competitiveness of the product to some extent. Therefore, a rapid electroslag remelting technology is developed, the rule that the ratio of the melting speed to the diameter of an electroslag ingot is not more than 1 is broken through, and the remelting speed is greatly increased. The core of the rapid remelting is that the diameter of the slag pool is larger than that of the electroslag ingot. However, this technique has two problems: 1) because the diameter of the slag bath is larger, metal molten drops do not drop into the electroslag ingot crystallizer in the consumable electrode melting process, but drop into the transition position of the slag bath crystallizer and the electroslag ingot crystallizer, and then flow to the electroslag ingot crystallizer. Because the transition part of the slag bath crystallizer and the electroslag ingot crystallizer adopts a strong water-cooling copper material, liquid drops on the liquid drops can be adhered on the transition part, so that the service life of the copper material is influenced, and remelting interruption can be possibly caused. Therefore, how to make the metal molten drop from the center of the electrode instead of dropping on the whole section is the key for solving the problem; 2) although the remelting rate is greatly increased, the cost is that the molten metal pool becomes deeper and the solidification quality becomes worse. Although the solidification quality is better than that of die casting or continuous casting, the method cannot be compared with the traditional electroslag ingot.

Through retrieval, chinese invention patent CN200910010241.3 discloses an electroslag casting device and method with additional electromagnetic stirring, chinese invention patent CN200910050347.6 discloses a method and device for magnetic controlled electroslag remelting and high-efficiency refining of high temperature alloy, chinese utility model patent CN201320838387.9 discloses a composite electroslag casting device using a steady magnetic field to optimize metal solidification structure, chinese invention patent CN201310017421.0 discloses a method for controlling electroslag casting by an additional transient magnetic field and an electroslag casting device, the above patents all apply an alternating magnetic field in the electroslag remelting process, change the solidification structure by stirring, rather than make the liquid film at the end of the electrode migrate to the core of the electrode, the problem solving points are different, and the core problem of rapid remelting cannot be solved; the electromagnetic stirring effect is similar to that of the traditional electromagnetic stirring, and the traditional electromagnetic stirring is easy to cause a white bright band, namely segregation; in addition, the adjustable range of the current change in the remelting process is small and cannot be adjusted at will, so that the influence on the remelting process is limited.

Through retrieval, Chinese invention patent CN201910760149.2 discloses a device and a method for electromagnetically controlling electroslag refining high-end bearing steel, and Chinese invention patent CN201410712573.7 discloses a method and a device for electromagnetically and compositely controlling electroslag remelting and fine grain casting, wherein the above patents apply a variable magnetic field in a crystallizer to improve a solidification structure, the basic principle of the electromagnetic force is the same as that of the traditional continuous casting electromagnetic stirring, namely induction current is generated through an alternating magnetic field, and the electromagnetic force is generated under the interaction of the magnetic field and the current to stir a slag bath and a molten bath. While the slag bath is stirred reversely, the metal molten drops are scattered and dropped, and the electroslag process generally hopes that the solidification process of the metal molten bath is stable and does not hope severe fluctuation. Therefore, the normal remelting process avoids the generation of a disordered magnetic field, and the stirring of the molten metal bath by adopting violent electromagnetic force can generate adverse effects.

Through search, the chinese invention patent CN201510178541.8 discloses a continuous casting method for large alloy ingots with uniform structure and a magnetic controlled electroslag continuous casting device, which combines a conductive crystallizer with a vertical magnetic field, and respectively adjusts the intensity of alternating current flowing through a slag bath and a metal bath to make the horizontal component of alternating current in the remelting process interact with an external vertical steady magnetic field to respectively generate periodic reverse lorentz magnetic force with adjustable intensity, so as to drive the slag bath and the metal bath to respectively obtain proper periodic reverse rotation motion, thereby improving the solidification structure. However, the slag pool generates periodic reverse motion by adopting electromagnetic force, so that the temperature field of the slag pool is uniform, and metal liquid drops at the end part of the electrode cannot be gathered to the core part; in addition, the current flowing through the slag bath and the metal bath in the patent shares one power supply, namely, under the condition that the output voltage of the power supply is constant, the current is adjusted completely by depending on the resistance on the short net, so that the useless energy consumption on the resistance is increased, and the thinking of reducing the energy consumption by the quick remelting technology is contrary to the thinking of reducing the energy consumption by the quick remelting technology. For another example, chinese patent CN201610871586.8 discloses a method for controlling the direction of solidification structure of ingot by electroslag remelting in a conductive crystallizer, which uses a conductive crystallizer in the electroslag remelting process, sets a current path by closing a switch, controls the distribution ratio of currents passing through the crystallizer and a bottom water tank, changes the shape and depth of a metal molten pool, and controls the direction of the solidification structure, but does not have the effect of heterogeneous nucleation. The method for refining and homogenizing the solidification structure of the continuous casting billet disclosed by the Chinese invention patent CN201610606343.1 and the method for improving the solidification quality of the electroslag remelting steel ingot disclosed by the Chinese invention patent CN201810294788.X both directly apply pulse current to the molten steel to refine the solidification structure, which directly generates disturbance to the slag and metal of the remelting part at the same time, and although the generated disturbance can improve the solidification quality of the electroslag ingot to a certain extent, the remelting efficiency is greatly influenced, and the disturbance has a general effect on the solidification quality improvement of the electroslag ingot.

In summary, although some systems in the prior art have utilized magnetic fields or pulse currents to improve the solidification quality of an electroslag ingot instead of conventional magnetic stirring, such stirring effects are general, and the remelting efficiency and the solidification quality of the electroslag ingot cannot be simultaneously obtained, and metal droplets in the remelting process are easy to drop and adhere to a crystallizer. Therefore, in the field of rapid electroslag remelting at present, a new electroslag remelting device or method needs to be invented to improve remelting efficiency and electroslag ingot quality, which has important significance for development of rapid electroslag technology.

Disclosure of Invention

1. Problems to be solved

Aiming at the problems of low remelting efficiency and poor solidification quality of an electroslag ingot of an electroslag remelting device or method in the prior art, the invention provides an electroslag remelting device and an electroslag remelting method for preventing remelting alloy segregation; the magnetic field action is respectively arranged in the slag bath of the remelting part and the metal bath forming the electroslag ingot, and the power supply for heating slag and melting electrodes and the power supply for refining the solidification structure are mutually and independently arranged, so that the problems of low electroslag remelting efficiency and poor solidification quality of the electroslag ingot in the prior art are effectively solved.

2. Technical scheme

In order to solve the problems, the technical scheme adopted by the invention is as follows:

the invention relates to an electroslag remelting device for preventing remelting alloy segregation, which comprises a crystallizer, a power supply and a magnetic field unit;

the crystallizer can be internally provided with a slag tank and sequentially comprises a first crystallizer, a transition crystallizer and a second crystallizer from top to bottom; a consumable electrode can be inserted into the first crystallizer and is immersed into the slag bath; the first crystallizer is connected with the transition crystallizer in an insulating way, and the transition crystallizer is connected with the second crystallizer in an insulating way; the first crystallizer and the transition crystallizer are in insulation connection, namely the first crystallizer and the transition crystallizer are connected through an insulating material, and the first crystallizer is communicated with the transition crystallizer; likewise, the same applies between the transition crystallizer and the second crystallizer;

in the slag pool, a first slag pool layer is arranged at the position corresponding to the bottom of the first crystallizer, a second slag pool layer is arranged at the position corresponding to the top of the second crystallizer, and a third slag pool layer is arranged at the bottom layer; the power supply comprises a first power supply and a second power supply; the first power supply is used for connecting the consumable electrode with the first slag bath layer and supplying direct current to the consumable electrode and a slag bath between the consumable electrode and the first slag bath layer; the second power supply is used for connecting the second slag pool layer with the third slag pool layer and providing pulse current for the part between the second slag pool layer and the third slag pool layer; the magnetic field unit comprises a first magnetic field unit and a second magnetic field unit; the first magnetic field unit is arranged outside the first crystallizer and used for providing a longitudinal magnetic field into the first crystallizer; the second magnetic field unit is arranged outside the second crystallizer and used for providing a transverse magnetic field into the second crystallizer.

The slag pool is a molten slag material, so that a first slag pool layer, a second slag pool layer and a third slag pool layer in the slag pool are all conductive layers and are electrically connected with a power supply through leads to form a power-on loop; in addition, in a subsequent more preferable scheme, the conducting rings are respectively arranged around the first slag pool layer and the second slag pool layer and are connected with the power supply through the conducting rings, and the conducting layer is arranged at the bottom of the third slag pool layer and is connected with the power supply through the conducting layer, so that the first power supply or the second power supply can be conveniently connected with the first slag pool layer, the second slag pool layer or the third slag pool layer.

Preferably, the first crystallizer and the second crystallizer are both cylindrical, and the transition crystallizer is in a circular truncated cone shape.

Preferably, the diameter of the first crystallizer is D1, the diameter of the second crystallizer is D2, and the ratio D1/D2 is (3-4): 1; the diameter of the transition crystallizer is gradually reduced from top to bottom, the diameter of the top end of the transition crystallizer is D1, and the diameter of the bottom end of the transition crystallizer is D2.

Preferably, a first conductive ring is arranged between the first crystallizer and the transition crystallizer, and the diameter of the first conductive ring is D1; the first conducting ring is respectively arranged corresponding to the bottom end of the first crystallizer and the top end of the transition crystallizer and is respectively connected with the first crystallizer and the transition crystallizer through insulating rings; and the first power supply is connected with the first slag pool layer through the first conducting ring.

Preferably, a second conductive ring is arranged between the second crystallizer and the transition crystallizer, and the diameter of the second conductive ring is D2; the second conducting ring is respectively arranged corresponding to the top end of the second crystallizer and the bottom end of the transition crystallizer and is respectively connected with the second crystallizer and the transition crystallizer through insulating rings; and the second power supply is connected with the second slag pool layer through a second conducting ring.

Preferably, the bottom of the second crystallizer is also provided with a bottom water tank, and the top of the bottom water tank is provided with a conducting layer; and the second power supply is connected with the third slag pool layer through the conducting layer.

Preferably, the first conductive ring, the second conductive ring and the conductive layer can adopt high-purity conductive graphite or metal such as copper, platinum and the like.

Preferably, the first magnetic field unit comprises a first magnetic field generating coil, the first magnetic field generating coil can generate a stable longitudinal magnetic field after being electrified, and the magnetic field intensity of the first magnetic field generating coil is 0.05T-0.1T; the second magnetic field unit comprises a second magnetic field generating coil, the second magnetic field generating coil can generate a stable transverse magnetic field after being electrified, and the magnetic field intensity of the second magnetic field generating coil is 0.01T-0.05T; the first magnetic field generating coil and the second magnetic field generating coil can control the direction of the generated magnetic field by designing the winding mode of the first magnetic field generating coil and the second magnetic field generating coil; for example, a first magnetic field generating coil is spirally wound along the length direction of the first crystallizer, and a longitudinal magnetic field inside the first crystallizer can be generated by electrifying the first magnetic field generating coil; if a second magnetic field generating coil wound in a direction perpendicular to the length direction of the second crystallizer is arranged around the second crystallizer, the second magnetic field generating coil is electrified to generate a transverse magnetic field in the second crystallizer; the above is merely an example of the coils that can generate the longitudinal magnetic field and the transverse magnetic field, and the specific form of the first magnetic field generating coil and the second magnetic field generating coil is not limited as long as both can generate the magnetic field direction defined in the present invention.

Preferably, the first power supply is a direct current power supply, the positive electrode of the direct current power supply is connected with the consumable electrode, and the negative electrode of the direct current power supply is connected with the first slag pool layer; the second power supply is a pulse power supply, the anode of the pulse power supply is connected with the second slag pool layer, the cathode of the pulse power supply is connected with the third slag pool layer, the waveform of the pulse power supply is square wave, the frequency of the pulse power supply is 10-20 kHz, and the current density of the pulse power supply is 50-100A/cm; the current density is the ratio of the effective value of the current generated by the second power source divided by the diameter D2 of the second crystallizer.

The invention relates to an electroslag remelting method for preventing remelted alloy segregation, which is based on an electroslag remelting device for preventing remelted alloy segregation and comprises the following specific remelting steps:

(1) placing a crystallizer on a bottom water tank, starting a first power supply to deliver direct current, pouring molten slag into the crystallizer to form a slag pool, immersing a consumable electrode into the slag pool, starting a first magnetic field unit to provide a magnetic field for a first crystallizer, and remelting;

(2) after remelting starts, a second power supply is started to deliver pulse current, a second magnetic field unit is started to provide a magnetic field for a second crystallizer, and a bottom water tank is downwards drawn to ensure that the liquid level of the slag pool is kept still;

(3) when the formed electroslag ingot reaches the specified height, the bottom water tank stops drawing, and the power supply and the magnetic field are turned off to stop remelting.

Preferably, in the step (1), after the crystallizer is placed on the bottom water tank, the self-consuming electrode is lowered to a position 20 mm-30 mm away from the insulating ring between the first crystallizer and the first conducting ring, and then the first power supply is turned on; the distance between the liquid level of the slag pool and the bottom of the consumable electrode is 20 mm-30 mm.

Preferably, in the step (2), when the liquid level of the metal in the second crystallizer reaches a distance of 20cm to 30cm from the insulating ring between the second crystallizer and the second conductive ring, the second power supply and the second magnetic field unit are turned on.

Preferably, in the step (3), the first power supply and the first magnetic field unit are turned off simultaneously when the pumping of the bottom water tank is stopped, and the second power supply and the second magnetic field unit are turned off after 20-60 min, so that the remelting is finished.

3. Advantageous effects

Compared with the prior art, the invention has the beneficial effects that:

(1) the invention relates to an electroslag remelting device for preventing remelting alloy segregation, which comprises a crystallizer, a power supply and a magnetic field unit; the crystallizer can be internally provided with a slag tank and sequentially comprises a first crystallizer, a transition crystallizer and a second crystallizer from top to bottom; a consumable electrode can be inserted into the first crystallizer and is immersed into the slag bath; the first crystallizer is connected with the transition crystallizer in an insulating way, and the transition crystallizer is connected with the second crystallizer in an insulating way; in the slag pool, a first slag pool layer is arranged at the position corresponding to the bottom of the first crystallizer, a second slag pool layer is arranged at the position corresponding to the top of the second crystallizer, and a third slag pool layer is arranged at the bottom layer; the power supply comprises a first power supply and a second power supply; the first power supply is used for connecting the consumable electrode with the first slag bath layer and supplying direct current to the consumable electrode and a slag bath between the consumable electrode and the first slag bath layer; the second power supply is used for connecting the second slag pool layer with the third slag pool layer and providing pulse current for the part between the second slag pool layer and the third slag pool layer; the magnetic field unit comprises a first magnetic field unit and a second magnetic field unit; the first magnetic field unit is arranged outside the first crystallizer and used for providing a longitudinal magnetic field into the first crystallizer; the second magnetic field unit is arranged outside the second crystallizer and used for providing a transverse magnetic field into the second crystallizer; through the arrangement, under the action of the magnetic field of the first magnetic field unit and the direct current, the metal droplets formed by melting the consumable electrode in the first crystallizer are subjected to stable force towards the inner core of the consumable electrode instead of conventional stirring force, so that the metal droplets can be gathered towards the core part of the consumable electrode and can be dripped downwards to the center of the crystallizer, the metal droplets are prevented from dripping on the side wall of the crystallizer, the damage to the crystallizer is reduced, and the stable operation of the remelting process is ensured; under the action of current applied by a second magnetic field unit and a second power supply, the alloy solute in the two-phase region is subjected to pulse micro-vibration power to replace the traditional electromagnetic stirring force, so that the diffusion of the alloy solute in the two-phase region is promoted, the segregation is inhibited, and the solidification quality of an electroslag ingot is improved; therefore, the remelting process is stably and efficiently carried out in the first crystallizer, and the metal molten drops dropping from the center of the crystallizer generate effective micro-vibration power in the second crystallizer, so that the remelting efficiency is improved, and the solidification quality of the electroslag ingot is improved.

(2) The invention relates to an electroslag remelting method for preventing remelted alloy segregation, which is based on an electroslag remelting device for preventing remelted alloy segregation and comprises the following specific remelting steps: placing a crystallizer on a bottom water tank, starting a first power supply to deliver direct current, pouring molten slag into the crystallizer to form a slag pool, immersing a consumable electrode into the slag pool, starting a first magnetic field unit to provide a magnetic field for a first crystallizer, and remelting; after remelting starts, a second power supply is started to deliver pulse current, a second magnetic field unit is started to provide a magnetic field for a second crystallizer, and a bottom water tank is downwards drawn to ensure that the liquid level of the slag pool is kept still; when the formed electroslag ingot reaches the specified height, stopping the drawing of the bottom water tank, and closing the power supply and the magnetic field to stop remelting; by the method, the electroslag remelting can be quickly and efficiently realized, and an electroslag ingot with small segregation degree and high solidification quality is formed.

Drawings

FIG. 1 is a schematic view showing the start of remelting in an electroslag remelting apparatus for preventing segregation of a remelted alloy according to the present invention;

FIG. 2 is a schematic view showing a normal remelting process in an electroslag remelting apparatus for preventing segregation of a remelted alloy according to the present invention;

FIG. 3 is a schematic view of a conventional electroslag remelting apparatus according to comparative example 1;

FIG. 4 is a schematic view of the solidification structure of an electroslag ingot produced in example 1 of the present invention;

FIG. 5 is a schematic view of the solidification structure of an electroslag ingot produced in comparative example 1.

In the figure:

100. a consumable electrode; 110. a metal droplet; 120. a slag pool; 121. a first slag bath layer; 122. a second slag pool layer; 123. a third slag bath layer; 130. a molten metal bath; 140. electroslag ingot;

200. a first crystallizer; 210. a first magnetic field generating coil;

300. a first conductive ring;

400. a transition crystallizer;

500. a second conductive ring;

600. a second crystallizer; 610. a second magnetic field generating coil;

700. a bottom water tank; 710. a conductive layer;

800. an insulating ring;

910. a first power supply; 920. a second power supply; 930. an alternating current power supply.

Detailed Description

The following detailed description of exemplary embodiments of the invention refers to the accompanying drawings, which form a part hereof, and in which are shown by way of illustration exemplary embodiments in which the invention may be practiced, and in which features of the invention are identified by reference numerals. The following more detailed description of the embodiments of the invention is not intended to limit the scope of the invention, as claimed, but is presented for purposes of illustration only and not limitation to describe the features and characteristics of the invention, to set forth the best mode of carrying out the invention, and to sufficiently enable one skilled in the art to practice the invention. It will, however, be understood that various modifications and changes may be made without departing from the scope of the invention as defined in the appended claims. The detailed description and drawings are to be regarded as illustrative rather than restrictive, and any such modifications and variations are intended to be included within the scope of the present invention as described herein. Furthermore, the background is intended to be illustrative of the state of the art as developed and the meaning of the present technology and is not intended to limit the scope of the invention or the application and field of application of the invention.

Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs; the terminology used herein in the description of the invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention; as used herein, the term "and/or" includes any and all combinations of one or more of the associated listed items.

It will be understood that when an element is referred to as being "on" another element, it can be directly on the other element or intervening elements may also be present; when an element is referred to as being "connected" to another element, it can be directly connected to the other element or intervening elements may also be present; the terms "transverse," "longitudinal," "top," "bottom," and the like as used herein are for descriptive purposes only.

The invention is further described with reference to specific examples.

Example 1

The present embodiment provides an electroslag remelting apparatus for preventing segregation of remelted alloy, as shown in fig. 1 and 2, which includes a crystallizer, a power supply, a magnetic field unit, and a bottom water tank 700. The crystallizer is arranged on the bottom water tank 700, and the bottom water tank 700 is used for providing cold energy for the crystallizer to solidify metal to form an electroslag ingot; the bottom water tank 700 is provided with a conductive layer 710 on top.

The crystallizer sequentially comprises a first crystallizer 200, a transition crystallizer 400 and a second crystallizer 600 from top to bottom, wherein the first crystallizer 200 in the embodiment is cylindrical, the diameter of the first crystallizer 200 is D1 ═ 600mm, the diameter of the second crystallizer 200 is D2 ═ 200mm, and the diameters of the first crystallizer 200 and the second crystallizer are D1/D2 ═ 3.5: 1; as other embodiments of the present invention, the D1/D2 may adopt 3: 1 or 4: 1; because the diameter of the first crystallizer 200 is larger, the diameter of the consumable electrode 100 can be synchronously increased, so that the remelting efficiency of the consumable electrode 100 in the first crystallizer 200 is effectively improved, and when the molten metal falls into the second crystallizer 600 with a smaller diameter, efficient vibration is generated under the action of the pulse micro-vibration power of the embodiment, so that the problem of segregation is effectively avoided. The transitional crystallizer 400 is in a shape of a circular truncated cone, the diameter of the transitional crystallizer is gradually reduced from top to bottom, the diameter of the top end of the transitional crystallizer is D1, and the diameter of the bottom end of the transitional crystallizer is D2; the consumable electrode 100 can be inserted into the first crystallizer 200 and submerged into the slag bath 120, and the diameter of the consumable electrode 100 is 400 mm. The first crystallizer 200 is connected with the transition crystallizer 400 in an insulating way, the transition crystallizer 400 is connected with the second crystallizer 600 in an insulating way, and the specific insulating connection mode is as follows: a first conducting ring 300 is arranged between the first crystallizer 200 and the transition crystallizer 400, the diameter of the first conducting ring 300 is D1, the first conducting ring 300 is respectively arranged corresponding to the bottom end of the first crystallizer 200 and the top end of the transition crystallizer 400, and is respectively connected with the first crystallizer 200 and the transition crystallizer 400 through an insulating ring 800; a second conductive ring 500 is arranged between the second crystallizer 600 and the transition crystallizer 400, the diameter of the second conductive ring 500 is D2, the second conductive ring 500 is respectively arranged corresponding to the top end of the second crystallizer 600 and the bottom end of the transition crystallizer 400, and is respectively connected with the second crystallizer 600 and the transition crystallizer 400 through an insulating ring 800.

It should be noted that in the present embodiment, the first conductive ring 300, the second conductive ring 500, and the conductive layer 710 are made of high-purity conductive graphite. As other embodiments of the present invention, the first conductive ring 300, the second conductive ring 500, and the conductive layer 710 may also be made of copper, or an inert metal such as platinum, which does not participate in the reflow and crystallization process.

In this embodiment, the crystallizer may contain a slag bath 120, in the slag bath 120, a first slag bath layer 121 is located at a position corresponding to the bottom of the first crystallizer 200, a second slag bath layer 122 is located at a position corresponding to the top of the second crystallizer 600, and a third slag bath layer 123 is located at the bottom.

The power supplies include a first power supply 910 and a second power supply 920. The first power supply 910 is a dc power supply, the positive pole of the dc power supply is connected to the consumable electrode 100, and the negative pole of the dc power supply is connected to the first slag bath layer 121 through the first conductive ring 300, and is configured to provide dc current to the consumable electrode 100 and the slag bath 120 between the consumable electrode 100 and the first slag bath layer 121. The second power source 920 is a pulse power source, the positive electrode of the pulse power source is connected with the second slag pool layer 122 through the second conductive ring 500, the negative electrode of the pulse power source is connected with the third slag pool layer 123 through the conductive layer 710, the waveform of the pulse power source is square wave, the frequency of the pulse power source is 10kHz, the current of the pulse power source is 1000A, the current density obtained through calculation is 50A/cm, and the pulse power source is used for providing pulse current for the part between the second slag pool layer 122 and the third slag pool layer 123.

The magnetic field unit comprises a first magnetic field unit and a second magnetic field unit; the first magnetic field unit comprises a first magnetic field generating coil 210, the first magnetic field generating coil 210 is arranged outside the first crystallizer 200, and after the first magnetic field generating coil 210 is electrified, a stable longitudinal magnetic field can be provided for the inside of the first crystallizer 200, and the magnetic field intensity of the stable longitudinal magnetic field is 0.07T; the second magnetic field unit includes a second magnetic field generating coil 610, the second magnetic field generating coil 610 is disposed outside the second mold 600, the second magnetic field generating coil 610 can provide a stable transverse magnetic field with a magnetic field strength of 0.02T into the second mold 600 after being energized.

The embodiment also provides an electroslag remelting method for preventing remelted alloy segregation, and based on the electroslag remelting device for preventing remelted alloy segregation, the remelted steel of the embodiment is 9Cr18Mo stainless bearing steel. The consumable electrode 100 leads the direct current to the slag bath 120, and then returns to the negative electrode of the direct current power transformer through the first conductive ring 300, the longitudinal stable magnetic field applied by the first magnetic field generating coil 210 acts with the direct current power to generate a centripetal force on the metal droplet 110 generated by melting the consumable electrode 100, so that the melting layer at the end part of the consumable electrode 100 moves towards the core part and peels off, and the metal droplet 110 is prevented from dropping and being adhered to the transition crystallizer 400. The second conductive ring 500 introduces a pulsed power supply current into the solidifying molten metal pool 130 and returns from the bottom tank 700, the pulsed current acting with the steady transverse magnetic field produces high frequency pulsed micro-vibrations that promote the movement of the two-phase region solute, thereby reducing segregation. The remelting method comprises the following specific steps:

(1) as shown in fig. 1, before remelting starts, the bottom water tank 700 is first closely contacted with the bottom of the second crystallizer 600, and then the consumable electrode 100 is lowered until the consumable electrode 100 is 20mm away from the insulating ring 800 between the first crystallizer 200 and the first conductive ring 300; then, the first power supply 910 is started, molten slag melted outside the furnace is poured into the crystallizer to form a slag pool 120, and the consumable electrode 100 is immersed in the slag pool 120 for 30 mm; when the remelting is started, the first magnetic field generating coil 210 outside the first crystallizer 200 is energized, and the magnetic field strength is set to 0.07T.

(2) As the remelting process proceeds, the consumable electrode 100 is gradually melted, the liquid level of the slag pool 120 gradually rises, and when the liquid level of the metal in the second mold 600 rises to a position 20cm away from the insulating ring 800 between the second mold 600 and the second conductive ring 500, the second power supply 920 is turned on to supply power with a frequency of 10kHz and a current of 1000A; energizing a second magnetic field generating coil 610, the magnetic field strength being 0.02T; then the bottom water tank 700 is drawn downwards at a certain speed, so that the liquid level of the slag pool 120 is kept unchanged all the time. It should be noted that, as shown in fig. 2, the direction of the arrow in the figure is the drawing direction of the bottom water tank 700, when the bottom water tank 700 is drawn downwards at a certain speed, a molten metal bath 130 appears inside the second mold 600, and an electroslag ingot 140 is gradually formed at the bottom of the mold, so that the power circuit of the second power supply 920 becomes: the positive pole of the pulse power source is connected with molten metal bath 130 through second conductive ring 500, and the negative pole is connected with electroslag ingot 140 through conductive layer 710, so that a closed conductive path is formed among second conductive ring 500, molten metal bath 130, electroslag ingot 140 and conductive layer 710.

(3) When the formed electroslag ingot 140 reaches a specified height, the bottom water tank 700 stops drawing, the first power supply 910 is turned off and the first magnetic field generating coil 210 is powered off, and after 20min, the second power supply 920 and the second magnetic field generating coil 610 are turned off, and remelting is finished.

After the electroslag remelting operation, no metal bonding can be seen on the crystallizer copper plate and the high-purity conductive graphite, so that the electroslag remelting device and the method for preventing remelting alloy segregation can effectively avoid the bonding problem of the remelting metal; in addition, the solidified structure of the finally formed electroslag ingot is dense, and as shown in FIG. 4, the secondary dendrite spacing is 60 μm to 80 μm, so that the degree of segregation is small and the solidification quality is high.

Comparative example 1

The comparative example provides a conventional electroslag remelting device and method, the general structure of which is shown in fig. 3, the remelting steel is 9Cr18Mo stainless bearing steel, the geometric dimensions of the crystallizer and the electrode adopted by the comparative example are basically the same as those of the example 1, and the main difference from the example 1 is that: the alternating current power supply 930 is directly adopted to electrify the whole slag bath 120 without adopting the action of a pulse power supply and a magnetic field, and the operation method comprises the following steps:

(1) as shown in fig. 3, before remelting starts, the bottom water tank 700 is in close contact with the bottom of the crystallizer, and then when the consumable electrode 100 is descended to 100mm below the liquid level of the predetermined slag pool 120, liquid slag is poured into the crystallizer, power is supplied, remelting starts;

(2) along with the melting of the consumable electrode 100, the liquid level of the slag pool 120 gradually rises, and when the liquid level rises to a specified height, the bottom water tank 700 is downwards drawn at a certain speed;

(3) when the formed electroslag ingot 140 reaches a predetermined height, the drawing of the bottom water tank 700 is stopped, the alternating current power supply 930 is turned off, and the remelting is finished.

After the electroslag remelting operation, obvious metal bonding can be seen on a crystallizer copper plate with naked eyes, and the dendrite spacing is 90-120 μm, as shown in figure 5, the solidification quality is general.

Comparing embodiment 1 with comparative example 1, it can be seen that the electroslag remelting apparatus and method for preventing remelting alloy segregation of the present invention can not only effectively avoid the problem of adhesion of the remelted metal, but also improve the electroslag remelting efficiency and the solidification quality of the formed electroslag ingot.

More specifically, although exemplary embodiments of the invention have been described herein, the invention is not limited to these embodiments, but includes any and all embodiments modified, omitted, combined, e.g., between various embodiments, adapted and/or substituted, as would be recognized by those skilled in the art from the foregoing detailed description. The limitations in the claims are to be interpreted broadly based the language employed in the claims and not limited to examples described in the foregoing detailed description or during the prosecution of the application, which examples are to be construed as non-exclusive. Any steps recited in any method or process claims may be executed in any order and are not limited to the order presented in the claims. The scope of the invention should, therefore, be determined only by the appended claims and their legal equivalents, rather than by the descriptions and examples given above.

Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. In case of conflict, the present specification, including definitions, will control. When "diameter, magnetic field strength, frequency, time, current density, distance, or other value or parameter is expressed as a range, preferred range, or a range defined by a list of upper preferable values and lower preferable values, this is to be understood as specifically disclosing all ranges formed from any pair of any upper range limit or preferred value and any lower range limit or preferred value, regardless of whether ranges are separately disclosed. For example, a range of 1 to 50 should be understood to include any number, combination of numbers, or subrange selected from 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, or 50, and all fractional values between the above integers, e.g., 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, and 1.9. With respect to sub-ranges, specifically consider "nested sub-ranges" that extend from any endpoint within the range. For example, nested sub-ranges of exemplary ranges 1-50 may include 1-10, 1-20, 1-30, and 1-40 in one direction, or 50-40, 50-30, 50-20, and 50-10 "in another direction.