Method for casting production of large-specification high-end automobile steel continuous casting billet

Abstract

The invention relates to a method for casting production of a large-specification high-end automobile steel continuous casting billet, and belongs to the technical field of ferrous metallurgy methods. According to the technical scheme, stopper rod adjustment and zero calibration before tundish casting are carried out, a tundish adjustment liquid level is arranged below a starting liquid level, and the starting time program is increased. The method has the beneficial effects that the success rate of automatic casting is increased, meanwhile, the stability of the liquid level of the crystallizer is greatly improved, the internal quality of a casting blank is improved, the cutting amount of a casting head blank is greatly reduced, the labor cost and the process cost are reduced, and the stability of the quality of a continuous casting blank is also improved; and the increasingly high-end and rapid development requirements of the automobile steel are met.

Description

Technical Field

[0001] The invention relates to a method for producing large-size high-end automobile steel continuous casting billets by open pouring, and belongs to the technical field of steel metallurgy methods. Background Art

[0002] Automotive materials are the foundation of the development of the automotive industry. As the basic structural and functional materials of the automotive industry, steel materials have obvious advantages and good prospects. The usage accounts for 60%-80% of the vehicle's own weight. With the rapid development of the automotive industry, more stringent requirements are also put forward for the high quality of steel materials. Continuous casting is a key process for the production quality of steel enterprises. At present, most of the continuous casting machines in China still use the traditional manual pouring method, which has problems such as large differences in personnel operation, unstable crystallizer liquid level increase, declining continuous casting billet quality, and high production accident rate. Non-standard operation is not conducive to the stability of continuous casting billet quality, and also has an adverse effect on the success rate of pouring. Summary of the invention

[0003] The purpose of the present invention is to provide a method for producing large-size high-end automobile steel continuous casting billets by pouring. The method improves the success rate of automatic pouring by precise adjustment of the stopper rod, zeroing of the tundish before pouring, setting the tundish to adjust the liquid level below the starting liquid level, adding a starting time program, etc. At the same time, the liquid level stability of the crystallizer is also greatly improved, the internal quality of the billet is improved, the cutting amount of the pouring head billet is greatly reduced, the labor cost and process cost are reduced, and the stability of the quality of the continuous casting billet is improved, which meets the requirements of the increasingly high-end and rapid development of automobile steel and effectively solves the above-mentioned problems existing in the background technology.

[0004] The technical solution of the present invention is: a method for producing large-size high-end automobile steel continuous casting billets by pouring, comprising the following steps: a tundish preparation process, a crystallizer preparation process and a tundish pouring process,

[0005] The intermediate package preparation process comprises the following steps:

[0006] (1) Adjust the spacing of the water inlet of the tundish; adjust the stopper mechanism to zero position and make it consistent with the display on the operation panel to control its adjustment range; control the deviation between the electric lifting and actual stopper movement position of the electric cylinder during the cold test;

[0007] (2) Control the baking time of the tundish, the baking time of the nozzle, and the baking temperature;

[0008] The preparation process in the crystallizer includes the following steps:

[0009] (3) The dummy rod is sent into the crystallizer, and the upper part of the dummy head is sent into the lower mouth of the crystallizer to a specified length, and the gap is sealed with asbestos, and the cold material is placed;

[0010] (4) Calibrate the crystallizer liquid level and set the program to set the adjustment liquid level, standard flow time, starting liquid level and emergence time;

[0011] The tundish pouring process includes the following steps:

[0012] (5) The tundish is opened to the casting position, the water inlet of the tundish is lowered to the specified distance into the crystallizer, and the ladle slide is opened to allow the molten steel to flow into the tundish;

[0013] (6) When the weight of the molten steel in the tundish is 10-15 tons, add the covering agent. When the weight of the molten steel in the tundish is 25-28 tons, press the stopper rod downward;

[0014] (7) When the weight of molten steel in the tundish reaches 30 tons, the automatic pouring program starts, and the first stopper opening and the second stopper opening are set. When the molten steel reaches the adjusted liquid level, the stopper opening is adjusted according to the flow time;

[0015] (8) When the molten steel reaches the starting level and the flow time meets the emergence time, the straightening machine starts automatically, the stopper rod controls the flow into the crystallizer liquid level automatic control model, and the pulling speed increase executes the automobile steel process model.

[0016] In the tundish preparation process, in step (1), the tundish water nozzle flow spacing is ≤10mm, the stopper rod mechanism adjustment range is within -0.5 to 0.5mm, and the deviation between the electric cylinder cold test electric lifting and the actual stopper rod movement position is ≤0.2mm; in step (2), the tundish baking time is 3-4h, the water nozzle baking time is 1.5-2.0h, and the baking temperature is controlled at 1100-1300℃.

[0017] In the preparation process in the crystallizer, in step (3), the cross-section of the crystallizer is 400×500 mm, the length is 900 mm, the upper part of the ingot head is fed into the lower mouth of the crystallizer to a prescribed length of 50-100 mm, the length of the cold material placed in is 200-300 mm, and the number is 60-90; in step (4), the liquid level is adjusted to be 450 mm from the upper mouth of the crystallizer, the standard flow time is in the range of 90-120 s, that is, the lower limit of the standard flow time is 90 s, the upper limit of the standard flow time is 120 s, the starting liquid level is 200 mm from the upper mouth of the crystallizer, and the emergence time is 200-250 seconds.

[0018] The tundish pouring process,

[0019] In step (5), the water outlet of the tundish is inserted into the crystallizer to a prescribed distance of 350-400 mm from the upper opening of the crystallizer;

[0020] In step (6), when the weight of the molten steel in the tundish is 10-15 tons, 20-40 bags of covering agent are added, and when the weight of the molten steel in the tundish is 25-28 tons, the program stopper rod is set to press downward by 0.5-1.0 mm;

[0021] In step (7), the first stopper rod opening is 18-25mm, the flow is maintained for 5-8s, and the stopper rod is closed for 2-3s; the second stable stopper rod opening is 10-16mm; when the molten steel reaches the adjusted liquid level, the stopper rod opening is adjusted according to the flow time. If the flow time is less than the lower limit of the standard flow time, the stopper rod opening is reduced by S = (X1-X) × 0.1mm. If the flow time X1≤X≤X2, the stopper rod opening remains unchanged. If the flow time X>X2, the stopper rod opening is increased by S = (X-X2) × 0.1mm, wherein X1 is the lower limit of the standard flow time, X2 is the upper limit of the standard flow time, X is the flow time, and S is the stopper rod opening adjustment amount.

[0022] The chemical composition of the steel and its weight percentage are: C: 0.90-1.10%, Si: 0.10-0.30%, Mn: ≤0.75%, Cr: 1.10-1.50%, P: ≤0.015%, S: ≤0.015%, Al: ≤0.035%, Ti: ≤0.020%, N: ≤0.004% and O: ≤0.001%, and the rest are Fe and unavoidable impurity elements.

[0023] The beneficial effects of the present invention are as follows: the success rate of automatic pouring is improved by precise adjustment of the stopper rod, zeroing of the tundish before pouring, setting the tundish to adjust the liquid level below the starting liquid level, adding a starting time program, etc. At the same time, the liquid level stability of the crystallizer is also greatly improved, the internal quality of the ingot is improved, the cutting amount of the ingot at the start of pouring is greatly reduced, the labor cost and process cost are reduced, and the stability of the quality of the continuous casting ingot is improved, meeting the requirements of the increasingly high-end and rapid development of automobile steel. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 is a low-magnification image of the continuous casting slab of Example 2 of the present invention;

[0025] Figure 2 is a low-magnification image of the continuous casting slab of Example 7 of the present invention;

[0026] Figure 3 This is a low-magnification image of the continuous casting slab of Comparative Example 1 of the present invention;

[0027] Figure 4 is a high-magnification image of inclusions in Example 2 of the present invention;

[0028] Figure 5 is a high-magnification image of inclusions in Example 7 of the present invention;

[0029] Figure 6 This is a high-magnification image of inclusions in Comparative Example 1 of the present invention. DETAILED DESCRIPTION

[0030] In order to make the purpose, technical solutions and advantages of the invention implementation cases clearer, the technical solutions in the implementation cases of the present invention will be clearly and completely described below in conjunction with the drawings in the implementation cases. Obviously, the implementation cases described are only a small part of the implementation cases of the present invention, rather than all the implementation cases. Based on the implementation cases in the present invention, all other implementation cases obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0031] A method for producing large-size high-end automobile steel continuous casting billets by pouring, comprising the following steps: a tundish preparation process, a crystallizer preparation process and a tundish pouring process.

[0032] The intermediate package preparation process comprises the following steps:

[0033] (1) Adjust the spacing of the water inlet of the tundish; adjust the stopper mechanism to zero position and make it consistent with the display on the operation panel to control its adjustment range; control the deviation between the electric lifting and actual stopper movement position of the electric cylinder during the cold test;

[0034] (2) Control the baking time of the tundish, the baking time of the nozzle, and the baking temperature;

[0035] The preparation process in the crystallizer includes the following steps:

[0036] (3) The dummy rod is sent into the crystallizer, and the upper part of the dummy head is sent into the lower mouth of the crystallizer to a specified length, and the gap is sealed with asbestos, and the cold material is placed;

[0037] (4) Calibrate the crystallizer liquid level and set the program to set the adjustment liquid level, standard flow time, starting liquid level and emergence time;

[0038] The tundish pouring process includes the following steps:

[0039] (5) The tundish is opened to the casting position, the water inlet of the tundish is lowered to the specified distance into the crystallizer, and the ladle slide is opened to allow the molten steel to flow into the tundish;

[0040] (6) When the weight of the molten steel in the tundish is 10-15 tons, add the covering agent. When the weight of the molten steel in the tundish is 25-28 tons, press the stopper rod downward;

[0041] (7) When the weight of molten steel in the tundish reaches 30 tons, the automatic pouring program starts, and the first stopper opening and the second stopper opening are set. When the molten steel reaches the adjusted liquid level, the stopper opening is adjusted according to the flow time;

[0042] (8) When the molten steel reaches the starting level and the flow time meets the emergence time, the straightening machine starts automatically, the stopper rod controls the flow into the crystallizer liquid level automatic control model, and the pulling speed increase executes the automobile steel process model.

[0043] In the tundish preparation process, in step (1), the tundish water nozzle flow spacing is ≤10mm, the stopper rod mechanism adjustment range is within -0.5 to 0.5mm, and the deviation between the electric cylinder cold test electric lifting and the actual stopper rod movement position is ≤0.2mm; in step (2), the tundish baking time is 3-4h, the water nozzle baking time is 1.5-2.0h, and the baking temperature is controlled at 1100-1300℃.

[0044] In the preparation process in the crystallizer, in step (3), the cross-section of the crystallizer is 400×500 mm, the length is 900 mm, the upper part of the ingot head is fed into the lower mouth of the crystallizer to a prescribed length of 50-100 mm, the length of the cold material placed in is 200-300 mm, and the number is 60-90; in step (4), the liquid level is adjusted to be 450 mm from the upper mouth of the crystallizer, the standard flow time is in the range of 90-120 s, that is, the lower limit of the standard flow time is 90 s, the upper limit of the standard flow time is 120 s, the starting liquid level is 200 mm from the upper mouth of the crystallizer, and the emergence time is 200-250 seconds.

[0045] The tundish pouring process,

[0046] In step (5), the water outlet of the tundish is inserted into the crystallizer to a prescribed distance of 350-400 mm from the upper opening of the crystallizer;

[0047] In step (6), when the weight of the molten steel in the tundish is 10-15 tons, 20-40 bags of covering agent are added, and when the weight of the molten steel in the tundish is 25-28 tons, the program stopper rod is set to press downward by 0.5-1.0 mm;

[0048] In step (7), the first stopper rod opening is 18-25mm, the flow is maintained for 5-8s, and the stopper rod is closed for 2-3s; the second stable stopper rod opening is 10-16mm; when the molten steel reaches the adjusted liquid level, the stopper rod opening is adjusted according to the flow time. If the flow time is less than the lower limit of the standard flow time, the stopper rod opening is reduced by S = (X1-X) × 0.1mm. If the flow time X1≤X≤X2, the stopper rod opening remains unchanged. If the flow time X>X2, the stopper rod opening is increased by S = (X-X2) × 0.1mm, wherein X1 is the lower limit of the standard flow time, X2 is the upper limit of the standard flow time, X is the flow time, and S is the stopper rod opening adjustment amount.

[0049] The chemical composition of the steel and its weight percentage are: C: 0.90-1.10%, Si: 0.10-0.30%, Mn: ≤0.75%, Cr: 1.10-1.50%, P: ≤0.015%, S: ≤0.015%, Al: ≤0.035%, Ti: ≤0.020%, N: ≤0.004% and O: ≤0.001%, and the rest are Fe and unavoidable impurity elements.

[0050] Example 1

[0051] In this embodiment, the present invention includes the process of preparing the tundish, preparing inside the crystallizer, and pouring the tundish.

[0052] Tundish preparation includes the following steps:

[0053] (1) The actual spacing of the water outlet of the tundish was adjusted to 6 mm; the stopper mechanism was adjusted to zero position, and the operation panel displayed -0.12 mm; the deviation between the electric lifting of the electric cylinder and the actual stopper movement position during the cold test was 0.08 mm.

[0054] (2) The baking time of the tundish is 3.5 hours, the baking time of the nozzle is 1.5 hours, and the actual baking temperature is 1208℃.

[0055] Preparation in the crystallizer includes the following steps:

[0056] (1) The cross section of the crystallizer is 400×500 mm and the length is 900 mm. The dummy rod is inserted into the crystallizer, and the upper part of the dummy head is inserted into the lower mouth of the crystallizer by 80 mm. The gap is sealed with asbestos, and 80 cold materials with a length of 200 mm are placed.

[0057] (2) Calibrate the crystallizer liquid level and set the program. The adjustment liquid level is 450 mm from the top of the crystallizer. The standard flow time for this liquid level is in the range of 90-120 s (the lower limit is 90 s for X1 and the upper limit is 120 s for X2). The starting liquid level is 200 mm from the top of the crystallizer. In addition, the automatic start can only be achieved when the emergence time is 200-250 seconds.

[0058] The tundish pouring process includes the following steps:

[0059] (1) The tundish is opened to the casting position, the water inlet of the tundish is lowered and inserted into the crystallizer 380 mm from the upper opening of the crystallizer, and the ladle slide is opened to allow the molten steel to flow into the tundish.

[0060] (2) When the weight of the molten steel in the tundish is 12 tons, 25 bags of covering agent are added. When the weight of the molten steel in the tundish is 26 tons, the program stopper rod is set to be pressed down by 0.6 mm to prevent the stopper rod from moving upward due to the buoyancy of the molten steel, which may affect the accuracy of automatic pouring and even cause premature pouring and production accidents.

[0061] (3) When the weight of molten steel in the tundish is 30 tons, the automatic pouring program is started. The first flow plug opening is 22 mm, the flow is maintained for 7 seconds, and the stopper is closed for 2 seconds. The second stable flow plug opening is 14 mm. When the molten steel is 450 mm away from the top of the crystallizer, the flow time is 81 seconds, and the stopper opening is reduced by S = (X1-X) × 0.1 = 0.9 mm.

[0062] (4) When the molten steel is 200 mm away from the top of the crystallizer and the flow time is 223 s, the straightening machine starts automatically, the stopper rod controls the flow into the crystallizer liquid level automatic control model, and the pulling speed increase executes the automobile steel process model.

[0063] Example 2

[0064] In this embodiment, the present invention includes the process of preparing the tundish, preparing inside the crystallizer, and pouring the tundish.

[0065] Tundish preparation includes the following steps:

[0066] (1) The actual spacing of the water outlet of the tundish was adjusted to 4 mm; the stopper mechanism was adjusted to zero position, and the operation panel displayed 0.09 mm; the deviation between the electric lifting of the electric cylinder and the actual stopper movement position during the cold test was 0.14 mm.

[0067] (2) The baking time of the tundish is 3.2 hours, the baking time of the nozzle is 1.6 hours, and the actual baking temperature is 1187°C.

[0068] Preparation in the crystallizer includes the following steps:

[0069] (1) The cross section of the crystallizer is 400×500 mm and the length is 900 mm. The dummy rod is inserted into the crystallizer, and the upper part of the dummy head is inserted 60 mm into the lower mouth of the crystallizer. The gap is sealed with asbestos, and 75 cold materials with a length of 250 mm are placed.

[0070] (2) Calibrate the crystallizer liquid level and set the program. The adjustment liquid level is 450 mm from the top of the crystallizer. The standard flow time for this liquid level is in the range of 90-120 s (the lower limit is 90 s for X1 and the upper limit is 120 s for X2). The starting liquid level is 200 mm from the top of the crystallizer. In addition, the automatic start can only be achieved when the emergence time is 200-250 seconds.

[0071] The tundish pouring process includes the following steps:

[0072] (1) The tundish is opened to the casting position, the water inlet of the tundish is lowered and inserted into the crystallizer to a distance of 365 mm from the upper opening of the crystallizer, and the ladle slide is opened to allow the molten steel to flow into the tundish.

[0073] (2) When the weight of the molten steel in the tundish is 14 tons, 32 bags of covering agent are added. When the weight of the molten steel in the tundish is 27 tons, the program stopper rod is set to press down 0.7 mm to prevent the stopper rod from moving upward due to the buoyancy of the molten steel, which may affect the accuracy of automatic pouring and even cause premature pouring and production accidents.

[0074] (3) When the weight of molten steel in the tundish reaches 30 tons, the automatic pouring procedure is started. The first time the flow plug opening is 24 mm, the flow is maintained for 6 seconds, and the stopper is closed for 3 seconds. The second time the flow plug opening is stable, it is 12 mm. When the molten steel is 450 mm away from the top of the crystallizer, the flow time is 98 seconds, and the stopper opening remains unchanged.

[0075] (4) When the molten steel is 200 mm away from the top of the crystallizer and the flow time is 212 s, the straightening machine starts automatically, the stopper rod controls the flow into the crystallizer liquid level automatic control model, and the pulling speed increase executes the automobile steel process model.

[0076] Example 3

[0077] In this embodiment, the present invention includes the process of preparing the tundish, preparing inside the crystallizer, and pouring the tundish.

[0078] Tundish preparation includes the following steps:

[0079] (1) The actual spacing of the water outlet of the tundish was adjusted to 7 mm; the stopper mechanism was adjusted to zero position, and the operation panel displayed 0.06 mm; the deviation between the electric lifting of the electric cylinder and the actual stopper movement position during the cold test was 0.09 mm.

[0080] (2) The baking time of the tundish is 3.7 hours, the baking time of the nozzle is 1.8 hours, and the actual baking temperature is 1267℃.

[0081] Preparation in the crystallizer includes the following steps:

[0082] (1) The cross section of the crystallizer is 400×500 mm and the length is 900 mm. The dummy rod is inserted into the crystallizer, and the upper part of the dummy head is inserted into the lower mouth of the crystallizer by 72 mm. The gap is sealed with asbestos, and 65 cold materials with a length of 300 mm are placed.

[0083] (2) Calibrate the crystallizer liquid level and set the program. The adjustment liquid level is 450 mm from the top of the crystallizer. The standard flow time for this liquid level is in the range of 90-120 s (the lower limit is 90 s for X1 and the upper limit is 120 s for X2). The starting liquid level is 200 mm from the top of the crystallizer. In addition, the automatic start can only be achieved when the emergence time is 200-250 seconds.

[0084] The tundish pouring process includes the following steps:

[0085] (1) The tundish is opened to the casting position, the water inlet of the tundish is lowered and inserted into the crystallizer to a distance of 382 mm from the upper opening of the crystallizer, and the ladle slide is opened to allow the molten steel to flow into the tundish.

[0086] (2) When the weight of the molten steel in the tundish is 13 tons, 35 bags of covering agent are added. When the weight of the molten steel in the tundish is 26 tons, the program stopper rod is set to press down 0.5 mm to prevent the stopper rod from moving upward due to the buoyancy of the molten steel, which may affect the accuracy of automatic pouring and even cause premature pouring and production accidents.

[0087] (3) When the weight of molten steel in the tundish is 30 tons, the automatic pouring program is started. The first flow plug opening is 22 mm, the flow is maintained for 5 seconds, and the stopper is closed for 2 seconds. The second stable flow plug opening is 15 mm. When the molten steel is 450 mm away from the top of the crystallizer, the flow time is 136 seconds, and the stopper opening increases by S = (X-X2) × 0.1 = 1.6 mm.

[0088] (4) When the molten steel is 200 mm away from the top of the crystallizer and the flow time is 234 s, the straightening machine starts automatically, the stopper rod controls the flow into the crystallizer liquid level automatic control model, and the pulling speed increase executes the automobile steel process model.

[0089] Example 4

[0090] In this embodiment, the present invention includes the process of preparing the tundish, preparing inside the crystallizer, and pouring the tundish.

[0091] Tundish preparation includes the following steps:

[0092] (1) The actual spacing of the water outlet of the tundish was adjusted to 4 mm; the stopper mechanism was adjusted to zero position, and the operation panel displayed 0.16 mm; the deviation between the electric lifting of the electric cylinder and the actual stopper movement position during the cold test was 0.05 mm.

[0093] (2) The baking time of the tundish is 3.6 hours, the baking time of the nozzle is 1.6 hours, and the actual baking temperature is 1213°C.

[0094] Preparation in the crystallizer includes the following steps:

[0095] (1) The cross section of the crystallizer is 400×500 mm and the length is 900 mm. The dummy rod is inserted into the crystallizer, and the upper part of the dummy head is inserted into the lower mouth of the crystallizer by 58 mm. The gap is sealed with asbestos, and 75 cold materials with a length of 250 mm are placed.

[0096] (2) Calibrate the crystallizer liquid level and set the program. The adjustment liquid level is 450 mm from the top of the crystallizer. The standard flow time for this liquid level is in the range of 90-120 s (the lower limit is 90 s for X1 and the upper limit is 120 s for X2). The starting liquid level is 200 mm from the top of the crystallizer. In addition, the automatic start can only be achieved when the emergence time is 200-250 seconds.

[0097] The tundish pouring process includes the following steps:

[0098] (1) The tundish is opened to the casting position, the water inlet of the tundish is lowered and inserted into the crystallizer 370 mm from the upper opening of the crystallizer, and the ladle slide is opened to allow the molten steel to flow into the tundish.

[0099] (2) When the weight of the molten steel in the tundish is 11 tons, 32 bags of covering agent are added. When the weight of the molten steel in the tundish is 28 tons, the program stopper rod is set to press down 0.8 mm to prevent the stopper rod from moving upward due to the buoyancy of the molten steel, which may affect the accuracy of automatic pouring and even cause premature pouring and production accidents.

[0100] (3) When the weight of molten steel in the tundish is 30 tons, the automatic pouring program is started. The first flow plug opening is 24 mm, the flow is maintained for 7 seconds, and the stopper is closed for 3 seconds. The second stable flow plug opening is 14 mm. When the molten steel is 450 mm away from the top of the crystallizer, the flow time is 141 seconds, and the stopper opening increases by S = (X-X2) × 0.1 = 2.1 mm.

[0101] (4) When the molten steel is 200 mm away from the top of the crystallizer and the flow time is 227 s, the straightening machine starts automatically, the stopper rod controls the flow into the crystallizer liquid level automatic control model, and the pulling speed increase executes the automobile steel process model.

[0102] Example 5

[0103] In this embodiment, the present invention includes the process of preparing the tundish, preparing inside the crystallizer, and pouring the tundish.

[0104] Tundish preparation includes the following steps:

[0105] (1) The actual spacing of the water outlet of the tundish was adjusted to 8 mm; the stopper mechanism was adjusted to zero position, and the operation panel displayed 0.11 mm; the deviation between the electric lifting of the electric cylinder and the actual stopper movement position during the cold test was 0.07 mm.

[0106] (2) The baking time of the tundish is 3.2 hours, the baking time of the nozzle is 1.5 hours, and the actual baking temperature is 1186°C.

[0107] Preparation in the crystallizer includes the following steps:

[0108] (1) The cross section of the crystallizer is 400×500 mm and the length is 900 mm. The dummy rod is inserted into the crystallizer, and the upper part of the dummy head is inserted into the lower mouth of the crystallizer by 68 mm. The gap is sealed with asbestos, and 82 cold materials with a length of 200 mm are placed.

[0109] (2) Calibrate the crystallizer liquid level and set the program. The adjustment liquid level is 450 mm from the top of the crystallizer. The standard flow time for this liquid level is in the range of 90-120 s (the lower limit is 90 s for X1 and the upper limit is 120 s for X2). The starting liquid level is 200 mm from the top of the crystallizer. In addition, the automatic start can only be achieved when the emergence time is 200-250 seconds.

[0110] The tundish pouring process includes the following steps:

[0111] (1) The tundish is opened to the casting position, the water inlet of the tundish is lowered and inserted into the crystallizer to a distance of 388 mm from the upper opening of the crystallizer, and the ladle slide is opened to allow the molten steel to flow into the tundish.

[0112] (2) When the weight of the molten steel in the tundish is 14 tons, 36 bags of covering agent are added. When the weight of the molten steel in the tundish is 27 tons, the program stopper rod is set to press down 0.6 mm to prevent the stopper rod from moving upward due to the buoyancy of the molten steel, which may affect the accuracy of automatic pouring and even cause premature pouring and production accidents.

[0113] (3) When the weight of molten steel in the tundish is 30 tons, the automatic pouring program is started. The first flow plug opening is 19 mm, the flow is maintained for 6 seconds, and the stopper is closed for 2 seconds. The second stable flow plug opening is 16 mm. When the molten steel is 450 mm away from the top of the crystallizer, the flow time is 79 seconds, and the stopper opening is reduced by S = (X1-X) × 0.1 = 1.1 mm.

[0114] (4) When the molten steel is 200 mm away from the top of the crystallizer and the flow time is 242 s, the straightening machine starts automatically, the stopper rod controls the flow into the crystallizer liquid level automatic control model, and the pulling speed increase executes the automobile steel process model.

[0115] Example 6

[0116] In this embodiment, the present invention includes the process of preparing the tundish, preparing inside the crystallizer, and pouring the tundish.

[0117] Tundish preparation includes the following steps:

[0118] (1) The actual spacing of the water outlet of the tundish was adjusted to 6 mm; the stopper mechanism was adjusted to zero position, and the operation panel displayed -0.22 mm; the deviation between the electric lifting of the electric cylinder and the actual stopper movement position during the cold test was 0.14 mm.

[0119] (2) The baking time of the tundish is 3.8 hours, the baking time of the nozzle is 1.8 hours, and the actual baking temperature is 1258°C.

[0120] Preparation in the crystallizer includes the following steps:

[0121] (1) The cross section of the crystallizer is 400×500 mm and the length is 900 mm. The dummy rod is inserted into the crystallizer, and the upper part of the dummy head is inserted into the lower mouth of the crystallizer by 84 mm. The gap is sealed with asbestos, and 70 cold materials with a length of 300 mm are placed.

[0122] (2) Calibrate the crystallizer liquid level and set the program. The adjustment liquid level is 450 mm from the top of the crystallizer. The standard flow time for this liquid level is in the range of 90-120 s (the lower limit is 90 s for X1 and the upper limit is 120 s for X2). The starting liquid level is 200 mm from the top of the crystallizer. In addition, the automatic start can only be achieved when the emergence time is 200-250 seconds.

[0123] The tundish pouring process includes the following steps:

[0124] (1) The tundish is opened to the casting position, the water inlet of the tundish is lowered and inserted into the crystallizer to a distance of 354 mm from the upper opening of the crystallizer, and the ladle slide is opened to allow the molten steel to flow into the tundish.

[0125] (2) When the weight of the molten steel in the tundish is 12 tons, 32 bags of covering agent are added. When the weight of the molten steel in the tundish is 28 tons, the program stopper rod is set to press down 0.7 mm to prevent the stopper rod from moving upward due to the buoyancy of the molten steel, which may affect the accuracy of automatic pouring and even cause premature pouring and production accidents.

[0126] (3) When the weight of molten steel in the tundish reaches 30 tons, the automatic pouring procedure is started. The first time the flow plug opening is 24 mm, the flow is maintained for 7 seconds, and the stopper is closed for 3 seconds. The second time the flow plug opening is stable, it is 14 mm. When the molten steel is 450 mm away from the top of the crystallizer, the flow time is 106 seconds, and the stopper opening remains unchanged.

[0127] (4) When the molten steel is 200 mm away from the top of the crystallizer and the flow time is 235 s, the straightening machine starts automatically, the stopper rod controls the flow into the crystallizer liquid level automatic control model, and the pulling speed increase executes the automobile steel process model.

[0128] Example 7

[0129] In this embodiment, the present invention includes the process of preparing the tundish, preparing inside the crystallizer, and pouring the tundish.

[0130] Tundish preparation includes the following steps:

[0131] (1) The actual spacing of the water outlet of the tundish was adjusted to 8 mm; the stopper mechanism was adjusted to zero position, and the operation panel displayed 0.31 mm; the deviation between the electric lifting of the electric cylinder and the actual stopper movement position during the cold test was 0.08 mm.

[0132] (2) The baking time of the tundish is 3.2 h, the baking time of the nozzle is 1.6 h, and the actual baking temperature is 1206 °C.

[0133] Preparation in the crystallizer includes the following steps:

[0134] (1) The cross section of the crystallizer is 400×500 mm and the length is 900 mm. The dummy rod is inserted into the crystallizer, and the upper part of the dummy head is inserted into the lower mouth of the crystallizer by 63 mm. The gap is sealed with asbestos, and 78 cold materials with a length of 250 mm are placed.

[0135] (2) Calibrate the crystallizer liquid level and set the program. The adjustment liquid level is 450 mm from the top of the crystallizer. The standard flow time for this liquid level is in the range of 90-120 s (the lower limit is 90 s for X1 and the upper limit is 120 s for X2). The starting liquid level is 200 mm from the top of the crystallizer. In addition, the automatic start can only be achieved when the emergence time is 200-250 seconds.

[0136] The tundish pouring process includes the following steps:

[0137] (1) The tundish is opened to the casting position, the water inlet of the tundish is lowered and inserted into the crystallizer to a distance of 367 mm from the upper opening of the crystallizer, and the ladle slide is opened to allow the molten steel to flow into the tundish.

[0138] (2) When the weight of the molten steel in the tundish is 10 tons, 24 bags of covering agent are added. When the weight of the molten steel in the tundish is 26 tons, the program stopper rod is set to press down 0.6 mm to prevent the stopper rod from moving upward due to the buoyancy of the molten steel, which may affect the accuracy of automatic pouring and even cause premature pouring and production accidents.

[0139] (3) When the weight of molten steel in the tundish is 30 tons, the automatic pouring program is started. The first flow plug opening is 20 mm, the flow is maintained for 8 seconds, and the stopper is closed for 2 seconds. The second stable flow plug opening is 13 mm. When the molten steel is 450 mm away from the top of the crystallizer, the flow time is 126 seconds, and the stopper opening increases by S = (X-X2) × 0.1 = 0.6 mm.

[0140] (4) When the molten steel is 200 mm away from the top of the crystallizer and the flow time is 211 s, the straightening machine starts automatically, the stopper rod controls the flow into the crystallizer liquid level automatic control model, and the pulling speed increase executes the automobile steel process model.

[0141] Example 8

[0142] In this embodiment, the present invention includes the process of preparing the tundish, preparing inside the crystallizer, and pouring the tundish.

[0143] Tundish preparation includes the following steps:

[0144] (1) The actual spacing of the water outlet of the tundish was adjusted to 5 mm; the stopper mechanism was adjusted to zero position, and the operation panel displayed -0.18 mm; the deviation between the electric lifting of the electric cylinder and the actual stopper movement position during the cold test was 0.17 mm.

[0145] (2) The baking time of the tundish is 3.8 hours, the baking time of the nozzle is 1.7 hours, and the actual baking temperature is 1252℃.

[0146] Preparation in the crystallizer includes the following steps:

[0147] (1) The cross section of the crystallizer is 400×500 mm and the length is 900 mm. The dummy rod is inserted into the crystallizer, and the upper part of the dummy head is inserted into the lower mouth of the crystallizer 89 mm. The gap is sealed with asbestos, and 86 cold materials with a length of 200 mm are placed.

[0148] (2) Calibrate the crystallizer liquid level and set the program. The adjustment liquid level is 450 mm from the top of the crystallizer. The standard flow time for this liquid level is in the range of 90-120 s (the lower limit is 90 s for X1 and the upper limit is 120 s for X2). The starting liquid level is 200 mm from the top of the crystallizer. In addition, the automatic start can only be achieved when the emergence time is 200-250 seconds.

[0149] The tundish pouring process includes the following steps:

[0150] (1) The tundish is opened to the casting position, the water inlet of the tundish is lowered and inserted into the crystallizer to a distance of 381 mm from the upper opening of the crystallizer, and the ladle slide is opened to allow the molten steel to flow into the tundish.

[0151] (2) When the weight of the molten steel in the tundish is 14 tons, 34 bags of covering agent are added. When the weight of the molten steel in the tundish is 28 tons, the program stopper rod is set to press down 0.8 mm to prevent the stopper rod from moving upward due to the buoyancy of the molten steel, which may affect the accuracy of automatic pouring and even cause premature pouring and production accidents.

[0152] (3) When the weight of molten steel in the tundish is 30 tons, the automatic pouring program is started. The first flow plug opening is 19 mm, the flow is maintained for 6 seconds, and the stopper is closed for 3 seconds. The second stable flow plug opening is 15 mm. When the molten steel is 450 mm away from the top of the crystallizer, the flow time is 82 seconds, and the stopper opening is reduced by S = (X1-X) × 0.1 = 0.8 mm.

[0153] (4) When the molten steel is 200 mm away from the top of the crystallizer and the flow time is 236 s, the straightening machine starts automatically, the stopper rod controls the flow into the crystallizer liquid level automatic control model, and the pulling speed increase executes the automobile steel process model.

[0154] Comparative Example 1

[0155] In this comparative example, a method for manually pouring and producing large-size high-end automobile steel continuous casting billets includes the process of tundish preparation, preparation inside the crystallizer, and tundish pouring.

[0156] Tundish preparation includes the following steps:

[0157] (1) The actual spacing of the water outlet of the tundish was adjusted to 8 mm; the stopper mechanism was adjusted to zero position, and the operation panel displayed 0.31 mm; the deviation between the electric lifting of the electric cylinder and the actual stopper movement position during the cold test was 0.07 mm.

[0158] (2) The baking time of the tundish is 3.4 hours, the baking time of the nozzle is 1.5 hours, and the actual baking temperature is 1204℃.

[0159] Preparation in the crystallizer includes the following steps:

[0160] (1) The cross section of the crystallizer is 400×500 mm and the length is 900 mm. The dummy rod is inserted into the crystallizer, and the upper part of the dummy head is inserted into the lower mouth of the crystallizer by 71 mm. The gap is sealed with asbestos, and 72 cold materials with a length of 250 mm are placed.

[0161] (2) Manual pouring is adopted. When the molten steel level is 200 mm away from the top of the crystallizer, the straightening machine is manually started. At the same time, the emergence time is kept within 200-250 seconds as much as possible.

[0162] The tundish pouring process includes the following steps:

[0163] (1) The tundish is opened to the casting position, the water inlet of the tundish is lowered and inserted into the crystallizer to a distance of 364 mm from the upper opening of the crystallizer, and the ladle slide is opened to allow the molten steel to flow into the tundish.

[0164] (2) When the weight of molten steel in the tundish is 15 tons, 38 bags of covering agent are added, and no stopper rod is set to press down before pouring.

[0165] (3) When the weight of molten steel in the tundish is 30 tons, pouring is started manually, the stopper is opened manually to fully open the opening, the flow is maintained for 5 seconds, and the stopper is closed to maintain for 2 seconds; the stopper is opened manually and stably to an appropriate opening for flow and is adjusted in real time.

[0166] (4) When the molten steel is 200 mm away from the top of the crystallizer and the flow time is 187 s, the stopper rod is manually closed and the waiting time is 8 to 195 s. Since the waiting time is too long, it will inevitably increase the production risk. That is, the straightening machine is manually started. When the liquid level rises to the set level, the stopper rod control flow enters the crystallizer liquid level automatic control model, and the pulling speed is manually controlled to the pulling speed set by the automobile steel process.

[0167] Comparative Example 2

[0168] In this comparative example, a method for manually pouring and producing large-size high-end automobile steel continuous casting billets includes the process of tundish preparation, preparation inside the crystallizer, and tundish pouring.

[0169] Tundish preparation includes the following steps:

[0170] (1) The actual spacing of the water outlet of the tundish was adjusted to 6 mm; the stopper mechanism was adjusted to zero position, and the operation panel displayed -0.24 mm; the deviation between the electric lifting of the electric cylinder and the actual stopper movement position during the cold test was 0.11 mm.

[0171] (2) The baking time of the tundish is 3.2 hours, the baking time of the nozzle is 1.6 hours, and the actual baking temperature is 1186°C.

[0172] Preparation in the crystallizer includes the following steps:

[0173] (1) The cross section of the crystallizer is 400×500 mm and the length is 900 mm. The dummy rod is inserted into the crystallizer, and the upper part of the dummy head is inserted into the lower mouth of the crystallizer by 81 mm. The gap is sealed with asbestos, and 65 cold materials with a length of 300 mm are placed.

[0174] (2) Manual pouring is adopted. When the molten steel level is 200 mm away from the top of the crystallizer, the straightening machine is manually started. At the same time, the emergence time is kept within 200-250 seconds as much as possible.

[0175] The tundish pouring process includes the following steps:

[0176] (1) The tundish is opened to the casting position, the water inlet of the tundish is lowered and inserted into the crystallizer to a distance of 378 mm from the upper opening of the crystallizer, and the ladle slide is opened to allow the molten steel to flow into the tundish.

[0177] (2) When the weight of molten steel in the tundish is 12 tons, 32 bags of covering agent are added, and no stopper rod is set to press down before pouring.

[0178] (3) When the weight of molten steel in the tundish is 30 tons, pouring is started manually, the stopper is opened manually to fully open the opening, the flow is maintained for 6 seconds, and the stopper is closed to maintain for 3 seconds; the stopper is opened manually and stably to an appropriate opening for flow and is adjusted in real time.

[0179] (4) When the molten steel is 280 mm away from the top of the crystallizer, the flow time has reached the upper limit of 250 s. At this time, the stopper opening is fully opened and the flow is fed for 2 s. The time should not be too long, which may cause production safety accidents. That is, the straightening machine is manually started. When the liquid level rises to the set level, the stopper control flow enters the crystallizer liquid level automatic control model, and the pulling speed is manually controlled to the pulling speed set by the automobile steel process.

[0180] The surface and internal quality of the heads of the continuous casting billets were checked for Example 2, Example 7 and Comparative Example 1. It was found through inspection and measurement that the head billets of Example 2 and Example 7 needed to be cut and thrown by 1.6m and 1.4m respectively, and the head billet of Comparative Example 1 needed to be cut and thrown by 2.6m. In addition, the success rate of pouring was increased from 92.4% for manual pouring to 96.7% for automatic pouring.

[0181] The low-magnification and inclusion samples of the continuous casting slabs were taken for inspection and analysis in Example 2, Example 7 and Comparative Example 1. Figure 1 , Figure 2 , Figure 3 They are respectively Example 2, Example 7, and Comparative Example 1 continuous casting billet low multiple, Figure 4 , Figure 5 , Figure 6 They are respectively the high magnification of inclusions in Example 2, Example 7 and Comparative Example 1. It can be seen from the figure that compared with the comparative example, the quality indicators such as low-magnification central porosity, shrinkage cavity, inclusion size, etc. of the continuous casting billet in the embodiments are greatly improved.

[0182] The above embodiments are only used to illustrate rather than limit the technical solutions of the present invention. Although the present invention is described in detail with reference to the above embodiments, those skilled in the art should understand that the present invention can still be modified or replaced by equivalents. Any modification or partial replacement that does not depart from the spirit and scope of the present invention should be included in the scope of the claims of the present invention.

Claims

1. A method for producing large-size high-end automobile steel continuous casting billets, characterized in that The process includes the following steps: the tundish preparation process, the crystallizer preparation process and the tundish pouring process. The intermediate package preparation process comprises the following steps: (1) Adjust the spacing of the water inlet of the tundish; adjust the stopper mechanism to zero position and make it consistent with the display on the operation panel to control its adjustment range; control the deviation between the electric lifting and actual stopper movement position of the electric cylinder during the cold test; (2) Control the baking time of the tundish, the baking time of the nozzle, and the baking temperature; The preparation process in the crystallizer includes the following steps: (3) The dummy rod is sent into the crystallizer, the upper part of the dummy head is sent into the lower mouth of the crystallizer to a specified length, and the gap is sealed with asbestos, and the cold material is placed; (4) Calibrate the crystallizer liquid level and set the program to set the adjustment liquid level, standard flow time, starting liquid level and emergence time; The tundish pouring process includes the following steps: (5) The tundish is opened to the casting position, and when the water inlet of the tundish is lowered to the specified distance into the crystallizer, the ladle slide is opened to allow the molten steel to flow into the tundish; (6) When the weight of the molten steel in the tundish is 10-15 tons, add the covering agent. When the weight of the molten steel in the tundish is 25-28 tons, press the stopper rod downward; (7) When the weight of the molten steel in the tundish reaches 30 tons, the automatic pouring program starts, and the first stopper opening and the second stopper opening are set. When the molten steel reaches the adjusted liquid level, the stopper opening is adjusted according to the flow time; (8) When the molten steel reaches the starting level and the flow time meets the emergence time, the straightening machine starts automatically, the stopper rod controls the flow into the crystallizer liquid level automatic control model, and the pulling speed increase executes the automobile steel process model.

2. The method for producing large-size high-end automobile steel continuous casting billets according to claim 1, characterized in that: In the tundish preparation process, in step (1), the tundish water nozzle flow spacing is ≤10mm, the stopper rod mechanism adjustment range is within -0.5 to 0.5mm, and the electric cylinder cold test electric lifting and actual stopper rod movement position deviation is ≤0.2mm; in step (2), the tundish baking time is 3-4h, the water nozzle baking time is 1.5-2.0h, and the baking temperature is controlled at 1100-1300℃.

3. The method for producing large-size high-end automobile steel continuous casting billets according to claim 1, characterized in that: In the preparation process in the crystallizer, in step (3), the cross-section of the crystallizer is 400×500 mm, the length is 900 mm, the upper part of the ingot head is fed into the lower mouth of the crystallizer to a prescribed length of 50-100 mm, the length of the cold material placed in is 200-300 mm, and the number is 60-90; in step (4), the liquid level is adjusted to be 450 mm from the upper mouth of the crystallizer, the standard flow time is in the range of 90-120 s, that is, the lower limit of the standard flow time is 90 s, the upper limit of the standard flow time is 120 s, the starting liquid level is 200 mm from the upper mouth of the crystallizer, and the emergence time is 200-250 seconds.

4. The method for producing large-size high-end automobile steel continuous casting billets according to claim 1, characterized in that: The tundish pouring process, In step (5), the water outlet of the tundish is inserted into the crystallizer to a prescribed distance of 350-400 mm from the upper opening of the crystallizer; In step (6), when the weight of the molten steel in the tundish is 10-15 tons, 20-40 bags of covering agent are added, and when the weight of the molten steel in the tundish is 25-28 tons, the program stopper rod is set to press down 0.5-1.0 mm; In step (7), the first stopper rod opening is 18-25 mm, the flow is maintained for 5-8 seconds, and the stopper rod is closed for 2-3 seconds; The second stable stopper rod opening is 10-16mm; when the molten steel reaches the adjusted liquid level, the stopper rod opening is adjusted according to the flow time. If the flow time is less than the lower limit of the standard flow time, the stopper rod opening is reduced by S=(X1-X)×0.1mm. If the flow time is X1≤X≤X2, the stopper rod opening remains unchanged. If the flow time X>X2, the stopper rod opening is increased by S=(X-X2)×0.1mm, where X1 is the lower limit of the standard flow time, X2 is the upper limit of the standard flow time, X is the flow time, and S is the stopper rod opening adjustment amount.

5. The method for producing large-size high-end automobile steel continuous casting billets according to claim 1, characterized in that: The chemical composition of the steel and its weight percentage are: C: 0.90-1.10%, Si: 0.10-0.30%, Mn: ≤0.75%, Cr: 1.10-1.50%, P: ≤0.015%, S: ≤0.015%, Al: ≤0.035%, Ti: ≤0.020%, N: ≤0.004% and O: ≤0.001%, the rest are Fe and unavoidable impurity elements.

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