Method for quickly replacing tundish with high-carbon steel in slab continuous casting

Abstract

The invention relates to the technical field of slab continuous steel casting in the metallurgical industry, and discloses a method for rapidly replacing a high-carbon steel tundish in slab continuous casting. The method comprises the steps that when the tonnage of an old tundish is 45-50 t, the pulling speed is reduced to 0.8-0.9 m / min; when the tonnage of the old tundish is 22-25 t, the pulling speed is reduced to 0.35-0.45 m / min; when 16-18 t of old tundish molten steel is left, the pulling speed is reduced to 0.1-0.2 m / min; the casting speed is increased to 0.35-0.45 m / min when the liquid level of the crystallizer reaches a set value, and the casting speed is increased to 0.35-0.45 m / min when the casting speed is increased to 0.35-0.45 m / min when the casting speed is increased to 0.35-0.45 m / min; and when the new tundish molten steel reaches 45-50 t, the pulling speed is increased to 0.8-0.9 m / min. According to the method, the problem of tail blank chipping in the normal casting stopping process of the slab continuous casting high-carbon steel can be completely eradicated, and the problem that a joint blank is bumped or a casting blank cannot move in the slab continuous casting high-carbon steel tundish quick changing process is solved.

Description

Technical Field

[0001] The present invention relates to the technical field of slab continuous steel casting in the metallurgical industry, and in particular to a method for quickly changing a tundish for slab continuous casting of high-carbon steel. Background Art

[0002] In order to improve the operating rate of the casting machine and increase production, modern slab continuous casting machines generally adopt the ladle quick change technology. The process is that after the casting of the already poured ladle (hereinafter referred to as the "old ladle") is completed, a new ladle (hereinafter referred to as the "new ladle") is quickly moved to the pouring position to maintain the process control of continuous casting of the casting machine.

[0003] High-carbon steel, due to its high strength, hardness, and excellent wear and heat resistance, is widely used in tools such as knives, saw blades, and molds, as well as structural parts such as wheels. However, due to its poor thermal conductivity, high-carbon steel experiences a large temperature gradient during solidification, which can easily lead to cracks caused by internal stress. Especially below 600°C, the toughness drops sharply. Furthermore, the presence of a large amount of cementite in the microstructure causes the last piece of high-carbon steel to fracture brittlely at the end of a normal casting. The broken pieces of steel remain in the continuous casting machine's fan-shaped section, causing the tail piece to fall off. This problem requires a significant amount of time to inspect and remove, seriously affecting the caster's operating rate. Therefore, there is an urgent need to provide a new method to solve the problem of tail piece falling off during the normal casting and stop of high-carbon steel slab continuous casting. Summary of the Invention

[0004] The purpose of the present invention is to overcome the problem of tail billet falling off during the normal casting and stop pouring process of slab continuous casting high carbon steel in the prior art, and provide a method for quick-changing the middle package of slab continuous casting high carbon steel. The method ensures uniform cooling of the surface of the high carbon steel casting billet by controlling the process of quick-changing the middle package of slab continuous casting high carbon steel. It can not only solve the problem of tail billet falling off during the stop pouring process, but also solve the problem of steel stripping in the joint billet during the quick-changing process of the middle package of slab continuous casting high carbon steel, thereby achieving stable and reliable quick-changing the middle package process of slab continuous casting high carbon steel, further improving the operation rate of the casting machine and releasing production capacity, and creating very considerable economic benefits in terms of centralized production grouping, planning scheduling and stable composition control of high carbon steel.

[0005] In order to achieve the above object, the present invention provides a method for quickly changing a tundish for slab continuous casting of high carbon steel, the method comprising the following steps:

[0006] (1) When the old tundish molten steel tonnage is 45-50t, reduce the pouring speed from the working speed to 0.8-0.9m / min and maintain it for 4-5min;

[0007] (2) When the old tundish molten steel tonnage is 22-25t, reduce the casting speed to 0.35-0.45m / min and maintain it for 1-1.5min. At the same time, reduce the cooling water flow rate on the wide side of the crystallizer to 70-80% of the normal flow rate, and reduce the cooling water flow rate on the narrow side of the crystallizer to 65-75% of the normal flow rate;

[0008] (3) When the remaining molten steel in the old tundish is 16-18t, reduce the pouring speed to 0.1-0.2m / min and keep it for ≤3.5 minutes;

[0009] (4) Stop pouring the old tundish and move it away. Move the new tundish to the pouring position, open the new tundish stopper, and start pouring. When the liquid level in the crystallizer reaches the set value, increase the pouring speed to 0.35-0.45 m / min and maintain it for 1-1.5 minutes. At the same time, increase the cooling water flow rate on the wide side and the narrow side of the crystallizer to normal flow rates.

[0010] (5) When the new tundish molten steel reaches 45-50t, increase the pouring speed to 0.8-0.9m / min and maintain it for 1-1.2min;

[0011] (6) The pouring speed is then increased to the target speed, and the quick change of the tundish is completed.

[0012] Preferably, in step (1), the working pulling speed is 0.95-1.25 m / min.

[0013] Preferably, in step (1), the 2 The casting speed is reduced from the working speed to 0.8-0.9m / min.

[0014] Preferably, in step (2), the flow rate is 0.05-0.15 m / min. 2 The casting speed is reduced from 0.8-0.9m / min to 0.35-0.45m / min.

[0015] Preferably, in step (2), the normal flow rate of cooling water on the wide surface of the crystallizer is 4200-4800 L / min.

[0016] Preferably, the normal flow rate of cooling water on the narrow side of the crystallizer is 420-480 L / min.

[0017] Preferably, in step (3), the 2 The casting speed is reduced from 0.35-0.45m / min to 0.1-0.2m / min.

[0018] Preferably, in step (4), the crystallizer liquid level is set to a value 100 mm from the upper edge of the crystallizer.

[0019] Preferably, in step (4), the flow rate is 0.05-0.15 m / min. 2 The casting speed is increased from 0.1-0.2m / min to 0.35-0.45m / min.

[0020] Preferably, in step (5), the flow rate is 0.05-0.15 m / min. 2 The casting speed is increased from 0.35-0.45m / min to 0.8-0.9m / min.

[0021] Preferably, in step (6), the target pulling speed is 1-1.2 m / min.

[0022] Preferably, in step (6), the flow rate is 0.05-0.15 m / min. 2 The casting speed is increased from 0.8-0.9m / min to the target casting speed.

[0023] Compared with the prior art, the present invention has at least the following beneficial effects:

[0024] The method of the present invention innovates the process control of the quick-change tundish for high-carbon steel in slab continuous casting, and constructs a system matching the tonnage of the tundish with the pouring speed, including the timing, amplitude and holding time of slowing down the casting speed, and the timing and amplitude of adjusting the cooling water volume on the wide and narrow surfaces of the crystallizer, so as to ensure that the surface of the high-carbon steel ingot is cooled evenly, and solves the problem of tail ingot falling off during the casting stoppage process. At the same time, the surface of the high-carbon steel ingot is cooled evenly, avoiding local cooling transition and bulging, and avoiding the phenomenon of steel barring in the joint ingot or the ingot not moving caused by excessive cooling of the ingot shell and excessive shrinkage in the low casting speed stage. It not only realizes the stability and reliability of the quick-change tundish for high-carbon steel in slab continuous casting, further improves the operating rate of the casting machine and releases production capacity, but also creates very considerable economic benefits for the centralized production grouping, planning and scheduling, and stable composition control of high-carbon steel. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 It is a schematic diagram of the implementation method of the quick-change tundish process control for slab continuous casting of high carbon steel. DETAILED DESCRIPTION

[0026] The following describes the specific embodiments of the present invention in detail with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are only used to illustrate and explain the present invention and are not intended to limit the present invention.

[0027] The endpoints of the ranges and any values disclosed herein are not limited to the precise ranges or values, and these ranges or values should be understood to include values close to these ranges or values. For numerical ranges, the endpoints of each range, the endpoints of each range and individual point values, and the individual point values can be combined with each other to obtain one or more new numerical ranges, which should be considered to be specifically disclosed herein.

[0028] In order to solve the problem of tail billet falling off during normal pouring and stopping of slab continuous casting of high-carbon steel, the inventors have discovered a method for controlling the quick-change tundish process of slab continuous casting of high-carbon steel through research. The method constructs a system for matching the tonnage of the tundish with the pouring speed, which ensures uniform cooling of the surface of the high-carbon steel ingot, and effectively solves the problem of tail billet falling off during the stopping process. In the process of studying the problem of tail billet falling off during normal pouring and stopping, the inventors found that due to uneven cooling during the pouring process of the quick-change tundish process, the joint billet may have steel sticking out or the ingot may not move. The process control process of the present invention can solve the problem of tail billet falling off while also solving the problem of steel sticking out or the ingot may not move.

[0029] Specifically, the method for quickly changing a tundish for slab continuous casting of high carbon steel provided by the present invention comprises the following steps:

[0030] (1) When the molten steel tonnage of the old tundish is 45-50t, reduce the pouring speed from the working speed to 0.8-0.9m / min, preferably 0.85m / min, and maintain it for 4-5min;

[0031] (2) When the tonnage of molten steel in the old tundish is 22-25t, reduce the casting speed from 0.8-0.9m / min to 0.35-0.45m / min, preferably 0.4m / min, and maintain it for 1-1.5min. At the same time, reduce the cooling water flow rate on the wide side of the crystallizer to 70-80% of the normal flow rate, and reduce the cooling water flow rate on the narrow side of the crystallizer to 65-75% of the normal flow rate;

[0032] (3) When the remaining molten steel in the old tundish is 16-18t, reduce the pouring speed from 0.35-0.45m / min to 0.1-0.2m / min, preferably 0.15m / min, and keep it for ≤3.5 minutes;

[0033] (4) The old tundish stops pouring and moves away, the new tundish moves to the pouring position, the new tundish stopper is opened, and pouring begins. When the liquid level in the crystallizer reaches the set value, the pouring speed is increased from 0.1-0.2 m / min to 0.35-0.45 m / min, preferably 0.4 m / min, and maintained for 1-1.5 min. At the same time, when the pouring speed is 0.35-0.45 m / min (preferably 0.4 m / min), the cooling water flow rate on the wide side and the cooling water flow rate on the narrow side of the crystallizer are both increased to normal flow rates;

[0034] (5) When the new tundish molten steel reaches 45-50t, increase the pouring speed from 0.35-0.45m / min to 0.8-0.9m / min, preferably 0.85m / min, and maintain it for 1-1.2min;

[0035] (6) Then the casting speed is increased from 0.8-0.9 m / min to the target casting speed, and the quick change of the tundish is completed.

[0036] In a preferred embodiment, Figure 1 As shown, the method for quickly changing a tundish for slab continuous casting of high carbon steel provided by the present invention comprises the following steps:

[0037] (1) When the tonnage of molten steel in the old tundish is 45-50t, reduce the pouring speed from the working speed to 0.85m / min and maintain it for 4-5min;

[0038] (2) When the tonnage of molten steel in the old tundish is 22-25t, reduce the casting speed from 0.85m / min to 0.4m / min and maintain it for 1-1.5min. At the same time, reduce the cooling water flow rate on the wide side of the crystallizer to 70-80% of the normal flow rate, and reduce the cooling water flow rate on the narrow side of the crystallizer to 65-75% of the normal flow rate;

[0039] (3) When the remaining molten steel in the old tundish is 16-18 tons, reduce the pouring speed from 0.4m / min to 0.15m / min and keep it for ≤3.5 minutes;

[0040] (4) Stop pouring the old tundish and move it away. Move the new tundish to the pouring position, open the new tundish stopper, and start pouring. When the liquid level in the crystallizer reaches the set value, increase the pouring speed from 0.15m / min to 0.4m / min and maintain it for 1-1.5min. At the same time, when the pouring speed is 0.4m / min, increase the cooling water flow rate on the wide side and the narrow side of the crystallizer to normal flow rate.

[0041] (5) When the new tundish molten steel reaches 45-50t, increase the pouring speed from 0.4m / min to 0.85m / min and maintain it for 1-1.2min;

[0042] (6) Then the casting speed is increased from 0.85 m / min to the target casting speed, and the quick change of the tundish is completed.

[0043] The method of the present invention is particularly suitable for high carbon steel with a casting thickness of 210-250 mm and a carbon content of 0.50-0.90%.

[0044] In the method of the present invention, before step (1), when the molten steel tonnage in the old tundish is greater than 50t, the casting speed is the working casting speed. In some embodiments, the working casting speed can be 0.95-1.25m / min, preferably 1m / min.

[0045] In the present invention, in order to ensure uniform cooling of the surface of the ingot, the pouring speed should be slowly increased and decreased.

[0046] In some embodiments, in step (1), the flow rate is 0.05-0.15 m / min. 2 (For example 0.05m / min 2 , 0.1m / min 2 or 0.15m / min 2 ) rate to reduce the casting speed from the working speed to 0.8-0.9m / min.

[0047] In some embodiments, in step (2), the flow rate is 0.05-0.15 m / min. 2 (For example 0.05m / min 2 , 0.1m / min 2 or 0.15m / min 2 ) rate to reduce the casting speed from 0.8-0.9m / min to 0.35-0.45m / min.

[0048] In the method described in the present invention, in step (2), the normal flow rate of cooling water on the wide side of the crystallizer can be 4200-4800 L / min, preferably 4500 L / min; the normal flow rate of cooling water on the narrow side of the crystallizer can be 420-480 L / min, preferably 450 L / min.

[0049] In some embodiments, in step (3), the flow rate is 0.05-0.15 m / min. 2 (For example 0.05m / min 2 , 0.1m / min 2 or 0.15m / min 2 ) rate to reduce the casting speed from 0.35-0.45m / min to 0.1-0.2m / min.

[0050] In the present invention, the setting value of the crystallizer liquid level in step (4) is 100 mm from the upper edge of the crystallizer, that is, the vertical distance 100 mm from the upper edge of the crystallizer to the liquid surface is the setting value of the crystallizer liquid level.

[0051] In some embodiments, in step (4), the flow rate is 0.05-0.15 m / min. 2 (For example 0.05m / min2 , 0.1m / min 2 or 0.15m / min 2 ) rate to increase the casting speed from 0.1-0.2m / min to 0.35-0.45m / min.

[0052] In some embodiments, in step (5), the flow rate is 0.05-0.15 m / min. 2 (For example 0.05m / min 2 , 0.1m / min 2 or 0.15m / min 2 ) rate to increase the casting speed from 0.35-0.45m / min to 0.8-0.9m / min.

[0053] In some embodiments, in step (6), the flow rate is 0.05-0.15 m / min. 2 (For example 0.05m / min 2 , 0.1m / min 2 or 0.15m / min 2 ) rate to increase the casting speed from 0.8-0.9m / min to the target casting speed.

[0054] In the present invention, the target pulling speed is determined according to actual needs. When producing high carbon steel with a thickness of 210-250 mm and a carbon content of 0.50-0.90%, the target pulling speed in step (6) is preferably 1-1.2 m / min.

[0055] By adopting the method for quickly changing the tundish during slab continuous casting of high-carbon steel of the present invention, the surface of the high-carbon steel slab is cooled evenly, and there is no phenomenon of steel barring in the joint slab or the slab not moving due to local overcooling and excessive shrinkage of the slab. Therefore, the quick changing of the tundish during slab continuous casting of high-carbon steel can be stably realized, which significantly improves the operation rate of the casting machine and solves the problem of the tail slab falling off during the casting stop process.

[0056] The present invention will be described in detail below through examples, but the protection scope of the present invention is not limited thereto.

[0057] Example 1

[0058] This embodiment provides a method for quickly changing a tundish during slab continuous casting of high-carbon steel, which is used to produce high-carbon steel with a thickness of 230 mm and a carbon content of 0.70%. The specific process is as follows:

[0059] a) When the old tundish molten steel tonnage is 45t, the flow rate is 0.1m / min 2 The pouring speed was slowly reduced from 1 m / min (working speed) to 0.85 m / min and maintained for 4 min.

[0060] b) When the old tundish molten steel tonnage is 22t, the flow rate is 0.1m / min 2 The pouring speed was reduced from 0.85 m / min to 0.4 m / min and maintained for 1 min.

[0061] c) When the casting speed drops to 0.4 m / min, the cooling water volume on the wide side of the crystallizer is reduced from 4500 L / min (normal flow) to 3150 L / min, and the cooling water volume on the narrow side of the crystallizer is reduced from 450 L / min (normal flow) to 292.5 L / min.

[0062] d) When the remaining molten steel in the old tundish is 16t, the flow rate is 0.1m / min. 2 The pouring speed was reduced from 0.4 m / min to 0.15 m / min, and the pouring speed of 0.15 m / min was maintained for 3 minutes.

[0063] e) The old tundish stops pouring and moves away, the new tundish moves to the pouring position, and the quick-change tundish casting connector is placed in the crystallizer.

[0064] f) Open the tundish stopper and start pouring. When the liquid level in the crystallizer reaches the set value (100 mm from the upper edge of the crystallizer), start pouring at a speed of 0.1 m / min. 2 The pouring speed was increased from 0.15 m / min to 0.4 m / min and maintained for 1 min.

[0065] g) When the casting speed is increased to 0.4m / min, the cooling water flow rates on the wide and narrow sides of the crystallizer are increased to the normal flow rates of 4500L / min and 450L / min respectively.

[0066] h) When the new tundish molten steel reaches 47t, the flow rate is 0.1m / min 2 The pouring speed was increased from 0.4 m / min to 0.85 m / min and maintained for 1 min.

[0067] i) Then at 0.1m / min 2 The casting speed is increased from 0.85m / min to the process target casting speed of 1.2m / min, and the quick change of the tundish is completed.

[0068] In this embodiment, no tail billet falling off occurs, no billet failure or seam billet steel breaking occurs during the quick-change tundish, and the high-carbon steel quick-change tundish is successfully completed.

[0069] Example 2

[0070] This embodiment provides a method for quickly changing a tundish during slab continuous casting of high-carbon steel, which is used to produce high-carbon steel with a thickness of 230 mm and a carbon content of 0.80%. The specific process is as follows:

[0071] a) When the old tundish molten steel tonnage is 50t, the flow rate is 0.1m / min 2 The pouring speed was slowly reduced from 1 m / min (working speed) to 0.85 m / min and maintained for 5 min.

[0072] b) When the old tundish molten steel tonnage is 25t, the flow rate is 0.1m / min 2 The pouring speed was reduced from 0.85 m / min to 0.4 m / min and maintained for 1.5 min.

[0073] c) When the casting speed drops to 0.4 m / min, the cooling water volume on the wide side of the crystallizer is reduced from 4500 L / min (normal flow) to 3600 L / min, and the cooling water volume on the narrow side of the crystallizer is reduced from 450 L / min (normal flow) to 337.5 L / min.

[0074] d) When the remaining molten steel in the old tundish is 18t, the flow rate is 0.1m / min. 2 The pouring speed was reduced from 0.4 m / min to 0.15 m / min, and the pouring speed of 0.15 m / min was maintained for 3.5 minutes.

[0075] e) The old tundish stops pouring and moves away, the new tundish moves to the pouring position, and the quick-change tundish casting connector is placed in the crystallizer.

[0076] f) Open the tundish stopper and start pouring. When the liquid level in the crystallizer reaches the set value (100 mm from the upper edge of the crystallizer), start pouring at a speed of 0.1 m / min. 2 The pouring speed was increased from 0.15 m / min to 0.4 m / min and maintained for 1.5 min.

[0077] g) When the casting speed is increased to 0.4m / min, the cooling water flow rates on the wide and narrow sides of the crystallizer are increased to the normal flow rates of 4500L / min and 450L / min respectively.

[0078] h) When the new tundish molten steel reaches 48t, the flow rate is 0.1m / min 2 The pouring speed was increased from 0.4 m / min to 0.85 m / min and maintained for 1.2 min.

[0079] i) Then at 0.1m / min 2 The casting speed is increased from 0.85m / min to the process target casting speed of 1.1m / min, and the quick change of the tundish is completed.

[0080] In this embodiment, no tail billet falling off occurs, no billet failure or seam billet steel breaking occurs during the quick-change tundish, and the high-carbon steel quick-change tundish is successfully completed.

[0081] Example 3

[0082] This embodiment provides a method for quickly changing a tundish during slab continuous casting of high-carbon steel, which is used to produce high-carbon steel with a thickness of 230 mm and a carbon content of 0.75%. The specific process is as follows:

[0083] a) When the old tundish molten steel tonnage is 48t, the flow rate is 0.1m / min 2 The pouring speed was slowly reduced from 1 m / min (working speed) to 0.85 m / min and maintained for 4.5 min.

[0084] b) When the old tundish molten steel tonnage is 23t, the flow rate is 0.1m / min 2 The pouring speed was reduced from 0.85 m / min to 0.4 m / min and maintained for 1.2 min.

[0085] c) When the casting speed drops to 0.4m / min, the cooling water volume on the wide side of the crystallizer is reduced from 4500L / min (normal flow) to 3375L / min, and the cooling water volume on the narrow side of the crystallizer is reduced from 450L / min (normal flow) to 315L / min.

[0086] d) When the remaining molten steel in the old tundish is 17t, the flow rate is 0.1m / min. 2 The pouring speed was reduced from 0.4 m / min to 0.15 m / min, and the pouring speed of 0.15 m / min was maintained for 3 minutes.

[0087] e) The old tundish stops pouring and moves away, the new tundish moves to the pouring position, and the quick-change tundish casting connector is placed in the crystallizer.

[0088] f) Open the tundish stopper and start pouring. When the liquid level in the crystallizer reaches the set value (100 mm from the upper edge of the crystallizer), start pouring at a speed of 0.1 m / min. 2 The pouring speed was increased from 0.15 m / min to 0.4 m / min and maintained for 1.2 min.

[0089] g) When the casting speed is increased to 0.4m / min, the cooling water flow rates on the wide and narrow sides of the crystallizer are increased to the normal flow rates of 4500L / min and 450L / min respectively.

[0090] h) When the new tundish molten steel reaches 49t, the flow rate is 0.1m / min 2 The pouring speed was increased from 0.4 m / min to 0.85 m / min and maintained for 1.1 min.

[0091] i) Then at 0.1m / min 2The casting speed is increased from 0.85m / min to the process target casting speed of 1.1m / min, and the quick change of the tundish is completed.

[0092] In this embodiment, no tail billet falling off occurs, no billet failure or seam billet steel breaking occurs during the quick-change tundish, and the high-carbon steel quick-change tundish is successfully completed.

[0093] Comparative Example 1

[0094] The method of Example 1 was followed, except that in step c), when the casting speed dropped to 0.4 m / min, the amount of cooling water on the wide side of the crystallizer was not adjusted, and the amount of cooling water on the narrow side of the crystallizer was not adjusted, that is, the amount of cooling water on the wide side of the crystallizer and the amount of cooling water on the narrow side of the crystallizer were both at normal flow rates during the entire process.

[0095] In this comparative example, during the quick-change tundish process, there were accidents such as the ingot not moving or the steel stripping of the seam in the ingot.

[0096] Comparative Example 2

[0097] The method of Example 1 was followed, except that in step d), the casting speed was reduced from 0.4 m / min to 0 m / min.

[0098] This comparative example provides a method for quickly changing a tundish during slab continuous casting of high-carbon steel, which is used to produce high-carbon steel with a thickness of 230 mm and a carbon content of 0.70%. The specific process is as follows:

[0099] a) When the old tundish molten steel tonnage is 45t, the flow rate is 0.1m / min 2 The pouring speed was slowly reduced from 1 m / min (working speed) to 0.85 m / min and maintained for 4 min.

[0100] b) When the old tundish molten steel tonnage is 22t, the flow rate is 0.1m / min 2 The pouring speed was reduced from 0.85 m / min to 0.4 m / min and maintained for 1 min.

[0101] c) When the casting speed drops to 0.4 m / min, the cooling water volume on the wide side of the crystallizer is reduced from 4500 L / min (normal flow) to 3150 L / min, and the cooling water volume on the narrow side of the crystallizer is reduced from 450 L / min (normal flow) to 292.5 L / min.

[0102] d) When the remaining molten steel in the old tundish is 16t, the flow rate is 0.1m / min. 2 The pouring speed was reduced from 0.4 m / min to 0 m / min, and the pouring speed of 0 m / min was maintained for 3 minutes.

[0103] e) The old tundish stops pouring and moves away, the new tundish moves to the pouring position, and the quick-change tundish casting connector is placed in the crystallizer.

[0104] f) Open the tundish stopper and start pouring. When the liquid level in the crystallizer reaches the set value (100 mm from the upper edge of the crystallizer), start pouring at a speed of 0.1 m / min. 2 The casting speed was increased from 0 m / min to 0.4 m / min and maintained for 1 min.

[0105] g) When the casting speed is increased to 0.4m / min, the cooling water flow rates on the wide and narrow sides of the crystallizer are increased to the normal flow rates of 4500L / min and 450L / min respectively.

[0106] h) When the new tundish molten steel reaches 47t, the flow rate is 0.1m / min 2 The pouring speed was increased from 0.4 m / min to 0.85 m / min and maintained for 1 min.

[0107] i) Then at 0.1m / min 2 The casting speed is increased from 0.85m / min to the process target casting speed of 1.2m / min, and the quick change of the tundish is completed.

[0108] In this comparative example, no tail billet falling off occurred, and no billet failure or seam billet steel stripping accidents occurred during the quick-change tundish process. The high-carbon steel quick-change tundish was successfully completed.

[0109] In this comparative example, during the quick-change tundish process, there were accidents such as the ingot not moving or the steel stripping of the seam in the ingot.

[0110] Generally, because the casting speed must be reduced during a quick tundish change, the casting speed for common steel grades is typically reduced to zero during a quick tundish change. However, the inventors have discovered that for high-carbon steel, the casting speed cannot be reduced to zero during the quick tundish change in step d). Otherwise, the joint billet may sag or the cast billet may become stuck. Consequently, in Comparative Example 2, these issues occurred. In Example 1, the casting speed was reduced to 0.15 m / min in step d), rather than to zero, thus avoiding these issues.

[0111] It can be seen from the examples and comparative examples that the method for quick-changing the tundish for slab continuous casting of high-carbon steel described in the present invention not only solves the problem of tail slab falling off during normal stoppage of slab continuous casting of high-carbon steel, but also solves the problem of steel sticking out of the joint slab or the cast slab not moving during the quick-changing process of the tundish for slab continuous casting of high-carbon steel.

[0112] It should be understood that parts not elaborated in detail in this specification belong to the prior art.

[0113] The preferred embodiments of the present invention have been described in detail above, but the present invention is not limited thereto. Within the technical concept of the present invention, various simple variations of the technical solution of the present invention may be made, including combining the various technical features in any other appropriate manner. These simple variations and combinations should also be regarded as disclosed in the present invention and fall within the scope of protection of the present invention.

Claims

1. A method for quickly changing a tundish during slab continuous casting of high carbon steel, characterized in that: The method comprises the following steps: (1) When the old tundish molten steel tonnage is 45-50t, reduce the pouring speed from the working speed to 0.8-0.9m / min and maintain it for 4-5min; (2) When the old tundish molten steel tonnage is 22-25t, reduce the casting speed to 0.35-0.45m / min and maintain it for 1-1.5min. At the same time, reduce the cooling water flow rate on the wide side of the crystallizer to 70-80% of the normal flow rate, and reduce the cooling water flow rate on the narrow side of the crystallizer to 65-75% of the normal flow rate; (3) When the remaining molten steel in the old tundish is 16-18t, reduce the pouring speed to 0.1-0.2m / min and keep it for ≤3.5 minutes; (4) Stop pouring the old tundish and move it away. Move the new tundish to the pouring position, open the new tundish stopper, and start pouring. When the liquid level in the crystallizer reaches the set value, increase the pouring speed to 0.35-0.45 m / min and maintain it for 1-1.5 minutes. At the same time, increase the cooling water flow rate on the wide side and the narrow side of the crystallizer to normal flow rates. (5) When the new tundish molten steel reaches 45-50t, increase the pouring speed to 0.8-0.9m / min and maintain it for 1-1.2min; (6) The pouring speed is then increased to the target speed, and the quick change of the tundish is completed.

2. The method according to claim 1, characterized in that In step (1), the working pulling speed is 0.95-1.25 m / min.

3. The method according to claim 1 or 2, characterized in that In step (1), the speed is 0.05-0.15 m / min. 2 The casting speed is reduced from the working speed to 0.8-0.9m / min.

4. The method according to claim 1, wherein In step (2), the speed is 0.05-0.15 m / min. 2 The casting speed is reduced from 0.8-0.9m / min to 0.35-0.45m / min.

5. The method according to claim 1 or 4, characterized in that In step (2), the normal flow rate of cooling water on the wide surface of the crystallizer is 4200-4800 L / min; And / or, in step (2), the normal flow rate of cooling water on the narrow side of the crystallizer is 420-480 L / min.

6. The method according to claim 1, characterized in that In step (3), the speed is 0.05-0.15 m / min. 2 The casting speed is reduced from 0.35-0.45m / min to 0.1-0.2m / min.

7. The method according to claim 1, characterized in that In step (4), the crystallizer liquid level is set to a value of 100 mm from the upper edge of the crystallizer.

8. The method according to claim 1 or 7, characterized in that In step (4), the speed is 0.05-0.15 m / min. 2 The casting speed is increased from 0.1-0.2m / min to 0.35-0.45m / min.

9. The method according to claim 1, characterized in that In step (5), the speed is 0.05-0.15 m / min. 2 The casting speed is increased from 0.35-0.45m / min to 0.8-0.9m / min.

10. The method according to claim 1, characterized in that In step (6), the target pulling speed is 1-1.2 m / min; and / or, in step (6), at 0.05-0.15 m / min 2 The casting speed is increased from 0.8-0.9m / min to the target casting speed.

Images