Method for high-manganese steel tails without damaging casting machine equipment

Abstract

The invention relates to the technical field of high-manganese steel casting, and particularly discloses a method for preventing casting machine equipment from being damaged by high-manganese steel tails, which comprises the following specific steps of: compiling a casting plan, arranging high-manganese steel and a steel grade capable of being cast in a mixed way in the same casting, and arranging the high-manganese steel in front of the steel grade capable of being cast in back of the steel grade capable of being cast in a mixed way; high-manganese steel is smelted and poured till the last furnace of steel, when the balance of the high-manganese steel in a tundish is 15-20 t, the mixed pouring steel grade is opened, the tonnage of the tundish is kept in a half-tundish state after the mixed pouring steel grade is opened, and after pouring is conducted for 60-80 t, the tundish is lifted to be full; then measuring the temperature of the tundish, and organizing slag change in the crystallizer when the temperature is higher than the liquid phase temperature of the mixed casting steel grade; the thickness of liquid slag is measured after slag replacement is finished, and when the thickness is 10-30 mm, the speed is increased to the target pulling speed of the mixed casting steel grade; pouring of the mixed pouring steel grade is finished, top sealing and tail discharging are conducted, and a mixed pouring blank is cut off according to requirements. The method can prevent the high manganese steel tails from damaging a casting machine, increase the casting time length and save the cost, and the mixed casting blank can be used for process research and material variety expansion.

Description

Technical Field

[0001] The invention relates to the technical field of high manganese steel casting, in particular to a method for high manganese steel tail discharge without damaging casting machine equipment. Background Art

[0002] High manganese steel refers to high-strength alloy steel with a manganese content of more than 10%. Due to the difference in manganese content, it has different material properties from traditional low-carbon steel, such as work hardening, wear resistance, high toughness, low temperature resistance, etc., which can meet the design and construction needs of structural materials in different fields. However, high manganese steel also has very significant technical difficulties. First of all, with the increase of manganese content, the molten steel will have poor fluidity, low thermal conductivity, large linear shrinkage, and small temperature difference between the solidus and liquidus. This greatly increases the difficulty of pouring and tailing of high manganese steel ingots, and it is very easy to produce internal and external defects of the ingots such as segregation and cracks. In view of this, in the continuous casting process, many factories adopt the direct tailing method.

[0003] Due to the above characteristics of high manganese steel, its castability is poor during the continuous casting production process. Due to the large linear shrinkage at the tail, it is often difficult to do a good job of capping the tail. If the direct tail method is adopted, it is easy to cause swelling. In addition, due to the low pulling speed at the tail, the slab stays in the fan-shaped segment for a long time, the slab cools down quickly, and the surface temperature drops rapidly (the tail has a lower characteristic temperature), the strength of the slab increases, and the fan-shaped segment needs to bear a greater force to resist the deformation of the slab, resulting in a sharp increase in the torque of the fan-shaped segment, and the slab cannot be pulled. In severe cases, the fan-shaped segment may even be damaged, causing the casting machine accuracy to deviate and increasing the casting machine maintenance time.

[0004] Therefore, in order to solve the problem of damage to casting machine equipment during the tail discharge of the ingot, a method of mixing high manganese steel with other steel grades is proposed, in which the tail discharge of the mixed steel grade replaces the direct tail discharge of high manganese steel, thereby avoiding damage to the casting machine equipment. Summary of the invention

[0005] The purpose of the present invention is to provide a method for discharging high manganese steel tail without damaging casting machine equipment, so as to solve the problem of swelling and damage to casting machine equipment in the process of discharging high manganese steel slab tail.

[0006] In order to solve the above technical problems, the present invention provides the following technical solutions:

[0007] A method for tail discharge of high manganese steel without damaging casting machine equipment, wherein high manganese steel and mixable steel are arranged in the same pouring, and when the high manganese steel is poured into the last furnace and the remaining steel in the tundish is pulled, the high manganese steel and the mixable steel are mixed and cast through the tundish.

[0008] When the high manganese steel liquid is poured to the last remaining batch of molten steel, and the tonnage of the tundish is controlled to a low level (15-20t), the pouring position is opened to mix the molten steel, and the molten steel of the high manganese steel is mixed with the molten steel of the mixable steel grade in the tundish to obtain the molten steel of the mixed steel grade. After opening, the tonnage of the tundish is kept in a half-filled state, and it is increased to a full fill after pouring 60-80t; then the temperature of the tundish is measured, and when it is higher than the liquidus temperature of the mixed steel grade, the slag is replaced in the crystallizer; after the slag replacement is completed, the liquid slag thickness is measured, and when it is 10-30mm, the speed is increased to the target pulling speed of the mixed steel grade; the pouring of the mixed steel grade is completed and the top and tail are capped, and the mixed billet is cut off as required.

[0009] Compared with the prior art, the beneficial effects achieved by the present invention are:

[0010] The present invention arranges a mixable steel grade in the last furnace of the high manganese steel pouring, and when the high manganese steel liquid in the tundish is poured to a low tonnage, opens the mixed pouring furnace for mixed pouring, and pours according to the requirements of the steel grade until the tail is discharged. This solution not only solves the problem of bulging and damage to casting machine equipment during the tail discharge of high manganese steel slabs, but also has the advantages of convenient operation and convenient production organization, avoids damage to the casting machine by the tail discharge of high manganese steel, increases the pouring length, saves production costs, and at the same time, the slabs produced by mixed pouring can be used for process research, expanding the types of materials;

[0011] By rationally arranging the pouring plan, high manganese steel and mixed steel grades are arranged in the same pouring to ensure the continuity of the pouring and extend the pouring length, and controlling the temperature of the molten steel in the tundish. By controlling the temperature of the molten steel on the platform, the preheating of the tundish, the insulation design, the pouring speed and other measures, ensure that the temperature of the molten steel in the tundish is higher than the liquid phase temperature of the mixed steel grade. Then, the slag replacement operation is carried out in the crystallizer. When the temperature in the tundish is higher than the liquid phase temperature of the mixed steel grade, the slag replacement operation in the crystallizer is organized to prevent the two types of steel from being incompatible with the protective slag and causing production quality accidents. Further measure the thickness of the liquid slag in the crystallizer. After completing the slag replacement operation, measure the thickness of the liquid slag in the crystallizer to ensure that the slag thickness is within the appropriate range to provide good lubrication.

[0012] And protective function, finally at the end of the pouring of the mixed steel, the mixed billet is cut off as required to prevent steel mixing and facilitate distinction. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 It is a flow chart of the operation mode of the present invention. DETAILED DESCRIPTION

[0014] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0015] Embodiment 1:

[0016] See also Figure 1 , the present invention provides a technical solution:

[0017] A method for preventing the tail discharge of high manganese steel from damaging casting machine equipment is to arrange a mixable steel grade in the last furnace of a high manganese steel pouring cycle, open the mixed pouring furnace molten steel for mixed pouring when the pouring of the high manganese steel furnace is completed and the tonnage of the middle ladle is low, and then pour according to the requirements of the steel grade until the tail discharge. This method can avoid damage to the casting machine caused by the tail discharge of high manganese steel, increase the pouring cycle length, save production costs, and the slabs produced by the mixed pouring can be used for process research to expand the variety of materials.

[0018] The type of steel that can be mixed and cast is Q235B carbon structural steel.

[0019] The specific plan is: first prepare a pouring plan for molten steel, arrange the casting of high manganese steel and mixed steel in the same pouring, ensure the continuity of the pouring and extend the length of the pouring, high manganese steel should be poured in the front and mixed steel in the back.

[0020] High manganese steel is smelted and poured. When the last batch of molten steel of high manganese steel is poured, the mixed-cast steel is arranged to be poured and smelted and waited. When the pouring of the last batch of high manganese steel is completed and the molten high manganese steel in the tundish reaches a low tonnage, the molten steel of the mixed-casting batch is opened, and the molten steel of the mixed-casting steel can be mixed with the remaining molten high manganese steel in the tundish for pouring. By controlling the inflow speed of the molten steel and the tonnage of the tundish, the mixing of the two molten steels in the tundish can be achieved. The purpose of this method is to avoid damage to the casting machine equipment caused by direct tail discharge of high manganese steel, and at the same time, it can also increase the length of the pouring.

[0021] When the high manganese steel in the tundish has been poured to the remaining 15-20t, open the mixed casting furnace molten steel, control the molten steel level in the tundish to maintain a half-filled state, and continue to pour 60-80t of molten steel of mixed casting steel grades into the tundish to raise the molten steel level in the tundish to a full-filled state, in order to reduce the production of mixed-cast billets; during the mixed casting process, if the molten steel level in the tundish is too high, the molten steel will stay in the tundish for too long, thereby increasing the production of mixed-cast billets.

[0022] In order to reduce the risk of molten steel solidification and improve the stability of the pouring process and the quality of the ingot, it is necessary to ensure that the temperature of the molten steel in the tundish is higher than the liquidus temperature of the mixed steel grade, and take the following measures: ensure that the molten steel supplied to the tundish has a sufficiently high temperature, and the temperature of the molten steel out of the furnace can be increased by controlling the smelting process and heating equipment; before pouring, preheat the tundish to a certain temperature, which can reduce the heat loss of the molten steel in the tundish and help maintain the temperature of the molten steel;

[0023] Insulation design of the tundish can improve its insulation performance, reduce heat loss, maintain the temperature of molten steel, and properly control the pouring speed of molten steel to reduce the residence time of molten steel in the tundish and reduce heat loss. Maintain continuous pouring as much as possible to avoid long-term residence of molten steel in the tundish to reduce temperature drop.

[0024] The temperature of the molten steel in the tundish can be monitored in real time using temperature monitoring equipment and adjusted as needed. The temperature of the molten steel in the tundish can also be maintained by adjusting the molten steel supply temperature or taking other measures.

[0025] When the temperature in the tundish is higher than the liquidus temperature of the mixed steel, the slag change operation in the crystallizer is organized to prevent production quality accidents caused by the incompatibility of the protective slags of the two steel grades.

[0026] The crystallizer is an important component of the continuous casting machine. Its main function is to solidify the molten steel into a billet with a certain shape and size. In the crystallizer, the molten steel is in contact with the protective slag, which plays the role of lubrication, heat insulation and preventing the molten steel from oxidation. During the continuous casting process, the protective slag will gradually be consumed and deteriorated, and needs to be replaced regularly. When the temperature in the tundish is higher than the liquidus temperature of the mixed steel grade, it means that the temperature of the molten steel is high. At this time, replacing the protective slag can avoid excessive consumption and deterioration of the protective slag at high temperature, thereby ensuring the quality of the billet.

[0027] The crystallizer consists of an outer shell, a copper plate, a cooling system and a vibration device. The outer shell is used to support and fix other parts of the crystallizer. The copper plate is the part that is in direct contact with the molten steel. The cooling system is used to cool the copper plate to control the solidification rate of the molten steel. The vibration device is used to make the crystallizer produce tiny vibrations to promote the solidification and demolding of the molten steel.

[0028] The replacement of protective slag is completed through special equipment and operation. The specific operation method is to add new protective slag into the crystallizer and discharge the old protective slag at the same time. In the process of replacing the protective slag, it is necessary to pay attention to controlling the amount of protective slag added and the discharge speed to avoid adverse effects on the quality of the casting.

[0029] Mold slag is a slag material added to the crystallizer during the steelmaking process. It is composed of various components, such as oxides, fluorides, carbonates, etc. When molten steel is injected into the crystallizer, the mold slag will quickly melt on the surface of the molten steel and form a layer of liquid slag film, namely liquid slag. The mold slag usually melts rapidly above 1300℃ to form liquid slag. Under the action of gravity and the flow of molten steel, the liquid slag flows in the crystallizer and covers the surface of the molten steel. The formation of liquid slag plays a role in heat insulation, air isolation, lubrication of the ingot, absorption of inclusions, etc. in the steelmaking process, thereby improving the quality of the molten steel and the surface quality of the ingot.

[0030] After completing the slag replacement operation (i.e. completing the operation of replacing the protective slag in the crystallizer), it is necessary to measure the thickness of the liquid slag in the crystallizer: when the thickness of the liquid slag is between 10-30mm, the pulling speed is increased to the target pulling speed of the mixed cast steel grade. The purpose of measuring the thickness of the liquid slag is to ensure that the thickness of the slag film is within the appropriate range to provide good lubrication and protection: the appropriate liquid slag thickness helps to reduce surface defects of the ingot, such as cracks and inclusions, and can maintain the thermal balance and lubrication conditions in the crystallizer, which helps to stabilize the production process.

[0031] At the end of the pouring of the mixed steel grades, the top is capped and the tail is discharged, that is, when the mixed steel grades are poured, the molten steel in the crystallizer is capped.

[0032] The method used for capping treatment is to clean the protective slag in the crystallizer after the pouring is completed, and then add cooling parts and iron filings into the crystallizer to achieve the effect of quickly cooling and solidifying the tail end of the ingot, preventing the molten steel from overflowing when pulling the tail ingot and damaging the casting machine equipment.

[0033] Finally, the mixed cast billet is cut off as required. Because the composition of this section of slab is different from the two types of steel before and after the mixing, it belongs to a new type of steel. Cutting off the mixed cast billet can prevent steel mixing and facilitate distinction.

[0034] The operation method is that after the pouring of the mixed steel grade is completed, the mixed billet is cut from the slab using a cutting device, and the cutting position is usually determined according to the length and requirements of the mixed billet.

[0035] Embodiment 2:

[0036] A method for tail discharge of high manganese steel without damaging casting machine equipment comprises the following steps: preparing a pouring plan, arranging high manganese steel and a castable steel type in the same pouring, ensuring the continuity of the pouring and extending the pouring length, with the high manganese steel in front and the castable steel type in the back; smelting and pouring high manganese steel to the last batch of steel, the castable steel type waiting at the pouring position, opening the tundish when the high manganese steel in the tundish is poured to a residual amount of 20 tons, and keeping the tonnage of the tundish in a half-tundish state, and raising the tonnage to a full state after pouring 80 tons; measuring the temperature of the tundish, and organizing slag replacement in a crystallizer when the temperature in the tundish is 1550°C; measuring the thickness of the liquid slag after the slag replacement is completed, and raising the speed to the target pulling speed of the castable steel type when the thickness of the liquid slag is 20 mm; finishing the pouring of the castable steel type and capping the tail discharge, and cutting the castable billet as required.

[0037] Working principle of the present invention:

[0038] By reasonably arranging the pouring plan, high manganese steel and mixed cast steel are arranged in the same pouring to ensure the continuity of the pouring and extend the pouring length. When the high manganese steel is poured to the last furnace, the mixed cast steel is allowed to wait at the pouring position. When the high manganese steel in the tundish is poured to a surplus of 15-20t, it is opened, and the tonnage of the tundish is kept in a half-pack state. After pouring 60-80t, it is raised to a full pack. Then the temperature of the tundish is measured. When the temperature in the tundish is higher than the liquidus temperature of the mixed cast steel, the slag in the crystallizer is replaced. After the slag replacement is completed, the thickness of the liquid slag is measured. When the thickness of the liquid slag is 10-30mm, the speed is increased to the target pulling speed of the mixed cast steel. Finally, the casting of the mixed cast steel is completed and the tail is capped, and the mixed cast billet is cut off as required. This can avoid the damage of the high manganese steel tail to the casting machine, increase the pouring length, save production costs, and the slabs produced by mixed casting can be used for process research and expand the variety of materials.

[0039] Although specific 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 specific embodiments without departing from the principles and spirit thereof, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A method for tailing high manganese steel without damaging casting machine equipment, characterized in that: The high manganese steel and the mixable steel are arranged in the same pouring. When the high manganese steel is cast to the last furnace and the remaining steel in the tundish is pulled, the high manganese steel and the mixable steel are mixed and cast through the tundish.

2. The method for discharging high manganese steel tail without damaging casting machine equipment according to claim 1, characterized in that: When the molten steel of high manganese steel is poured to the remaining last batch of molten steel, the molten steel of the mixable steel grade is waiting at the pouring position, and the tonnage of the tundish is controlled to a low level (15-20t), the pouring position is opened to mix the molten steel, and the molten high manganese steel is mixed with the molten steel of the mixable steel grade to obtain the molten steel of the mixed steel grade.

3. The method for discharging high manganese steel tail without damaging casting machine equipment according to claim 2, characterized in that: The temperature inside the tundish is higher than the liquidus temperature of the mixed steel.

4. The method for discharging high manganese steel tail without damaging casting machine equipment according to claim 3, characterized in that: The liquidus temperature of the mixed cast steel is 1510-1550℃.

5. The method for discharging high manganese steel tail without damaging casting machine equipment according to claim 4, characterized in that: During the pouring process of high manganese steel, when the molten steel level in the tundish drops to a low tonnage, the mixed pouring furnace is opened to allow the molten steel of the mixable steel grades to enter the tundish and mix with the high manganese steel. After opening, the molten steel level in the tundish is maintained at a half-filled state.

6. The method for discharging high manganese steel tail without damaging casting machine equipment according to claim 5, characterized in that: While keeping the tundish half-full, continue pouring 60-80t of mixed steel molten steel and raise the steel level in the tundish to full.

7. The method for discharging high manganese steel tail without damaging casting machine equipment according to claim 5, characterized in that: The minimum tonnage standard for high manganese steel liquid in the tundish is 15-20t.

8. The method for discharging high manganese steel tail without damaging casting machine equipment according to claim 4, characterized in that: Measure the temperature of the tundish. When the temperature inside the tundish is higher than the liquidus temperature of the mixed steel, replace the protective slag in the crystallizer.

9. The method for discharging high manganese steel tail without damaging casting machine equipment according to claim 8, characterized in that: After completing the protective slag replacement operation, the molten steel of the mixed cast steel grade flows into the crystallizer from the tundish. The protective slag will form a layer of liquid slag on the surface of the molten steel. The thickness of the liquid slag in the crystallizer is then measured. When the liquid slag thickness meets the requirements, the pulling speed is increased to the target pulling speed of the mixed cast steel grade.

10. The method for discharging high manganese steel tail without damaging casting machine equipment according to claim 5, characterized in that: The standard thickness of liquid slag is 10-30mm.

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