CN106041008A - Initial solidification simulating device and method for molten steel near corner portion of continuous casting crystallizer - Google Patents

Abstract

The invention provides a device and method for simulating the initial solidification of molten steel near the corner of a continuous casting crystallizer, belonging to the technical field of continuous casting of iron and steel; a simulation device equipped with a right-angle mold is used to simulate the vicinity of the inner corner of the crystallizer in the actual continuous casting process The formation process of the initial solidification billet shell, while using the high-speed temperature-measuring thermocouple buried in the crystallizer to obtain the temperature data during the casting process; the two copper plate surfaces of the crystallizer form a right angle, and buried in the copper plate surface and the right angle position There are thermocouples; through the processing and analysis of temperature data and the initial solidification slab shell obtained by the experiment, the initial solidification behavior of molten steel near the corner of the mold is studied, and the mechanism of surface defects at the corner of the slab is accurately understood. It is of great significance to guide the actual production to take corresponding measures to eliminate or reduce the surface defects of the billet at the corner.

Description

Device and method for simulating initial solidification of molten steel near corners of continuous casting crystallizer

technical field

The invention relates to a device and method for simulating the initial solidification of molten steel near the corner of a continuous casting crystallizer, and belongs to the technical field of continuous casting of iron and steel.

Background technique

The quality defects of continuous casting slabs include internal quality defects and surface quality defects. On the one hand, slab defects will affect the production efficiency, yield and final product performance of the continuous casting machine, thereby reducing the economic benefits of production; on the other hand, with the continuous casting With the development of continuous rolling and thin strip slab continuous casting technology, the quality requirements of continuous casting slabs are also getting higher and higher. Therefore, it is an important task for metallurgists to produce defect-free slabs or tolerable slabs that do not affect the performance of the end product. According to statistics, slab cracks account for about 50% of all kinds of defects. The surface quality defects of slabs include surface cracks, deep vibration marks, subcutaneous pinholes and macroscopic inclusions, but mainly surface cracks, and surface transverse cracks are one of the most common and most harmful surface defects of slabs. Surface transverse cracks usually occur near the corners of the slab, more than in the center of the wide face. Many measures have been taken in actual production to reduce the occurrence of corner transverse cracks, but they cannot be eradicated. Judging from the production situation of other iron and steel enterprises at home and abroad, the incidence of transverse cracks at the corners of continuous casting slabs in enterprises with better conditions is controlled at 4% to 5%, while the incidence of transverse cracks at the corners of right-angle continuous casting slabs is often not Stable and easy to repeat. The research shows that the surface quality defects of the slab originate from the initial solidification process of the slab shell in the meniscus region and expand in the secondary cooling zone. Therefore, by studying the initial solidification behavior of molten steel near the corner of the mold, we can accurately understand the mechanism of surface defects at the corner of the slab, and then take corresponding measures to eliminate or reduce the surface defects of the slab at the corner.

Many people have done a lot of research on the initial solidification behavior of molten steel in the mold, which are mainly divided into four categories: industrial field experimental research, small pilot continuous caster experimental research, mathematical simulation research and laboratory thermal simulation research. Industrial field experiments and small-scale pilot-scale continuous casting machine experiments are the most ideal methods to study the initial solidification behavior of molten steel, but there are several disadvantages: the experiment is dangerous, it is difficult to accurately control the experimental conditions we need and obtain real-time data ; The consumption of raw materials is large, the energy consumption is high, and the normal production process is affected, resulting in high experimental costs. Someone obtained an analytical expression by establishing a mathematical model to predict the solidification growth of the initial shell, the formation of vibration marks and the infiltration of mold slag. In addition, numerical methods are used to solve the mathematical model to simulate the initial solidification behavior and possible surface defects during the initial solidification process. The mathematical model is based on certain assumptions, and requires comprehensive and accurate boundary conditions and physical parameters. However, the acquisition of these data is relatively limited. These factors will affect the accuracy of the simulation results. It is difficult for the simulation results to fully and accurately reflect the molten steel. The initial solidification behavior in the crystallizer includes complex, high-temperature, multi-phase and transient "three-pass and one-reverse" phenomena. Laboratory thermal simulation mainly includes low melting point metal continuous casting simulation and steel high temperature continuous casting simulation. Low melting point metal continuous casting simulation can conveniently and effectively study the influence of continuous casting conditions on the initial solidification behavior of metals, but it cannot truly reflect molten steel The initial solidification process of molten steel cannot be studied, and the influence of mold powder on the initial solidification behavior of molten steel cannot be studied. Badri et al. and Sohn et al. used a mold thermal simulation device to simulate the initial solidification of high-temperature molten steel in the mold, which is more realistic than mathematical simulation and low-melting point metal continuous casting simulation, but the crystallizer of the device mold With only one cooling surface, the initial solidification behavior of molten steel in the vicinity of the corners of the mold cannot be studied.

Contents of the invention

Aiming at the deficiencies of the prior art, the present invention provides a device and method for simulating the initial solidification of molten steel near the corner of a continuous casting mold; using a simulation device equipped with a right-angle mold to simulate the vicinity of the corner of the mold in the actual continuous casting process The formation process of the initial solidification shell, while using the high-speed thermocouple buried in the crystallizer to obtain real-time temperature data; through the processing and analysis of the temperature data and the initial solidification shell obtained by the experiment, to study the crystallizer angle The initial solidification behavior of molten steel in the vicinity of the center, the accurate understanding of the generation mechanism of the corner surface defects of the slab, and the corresponding measures to eliminate or reduce the surface defects of the corner slab are of great significance to guide the actual production.

The present invention is a simulation device for initial solidification of molten steel near the corner of a continuous casting crystallizer,

Including crystallizer vibration motor (1), casting motor (2), first lifting motor (3), second lifting motor (4), casting device (5), crystallizer (6), cooling water channel, inertia protection Gas hood (12), positioning electrode (15), melting furnace (16), base (17), temperature acquisition system (18), furnace control system (19), motor control system (20), first lifting bracket (21), the second lifting bracket (22);

The first lifting motor (3), the second lifting motor (4) are housed on the described base (17), the first lifting motor (3) controls the first lifting bracket (21) to move up and down, the second lifting motor ( 4) controlling the second lifting bracket (22) to move up and down;

The smelting furnace (16) is arranged on the base (17) and between the first lifting motor (3) and the second lifting motor (4); the crystallizer vibration motor (1) and the drawing motor (2) are all arranged on the first lifting bracket (21); the temperature acquisition system (18) is connected with a thermocouple buried in the crystallizer (6);

The crystallizer (6) is wrapped by the puller (5), and only the first copper plate surface (23) and the second copper plate surface (24) are exposed to contact with molten steel; the crystallizer (6) passes through the The crystallizer vibrating motor (1) is driven to vibrate up and down; the second lifting bracket (22) is connected to the positioning electrode (15); the drawing motor (2) controls the drawing device (5) to Pull down; the outer wall opposite to the first copper plate surface (23) is the first outer wall (27) of the crystallizer, and the side wall of the crystallizer directly connected to the first copper plate surface (23) is the first side wall of the crystallizer (25), the first group of thermocouples (29), the second group of Thermocouple (30) and No. 1 cooling channel (10); The outer wall opposite to the second copper plate surface (24) in the crystallizer is the crystallizer second outer wall (28), and the second copper plate surface (24) The directly connected crystallizer side wall is the crystallizer second side wall (26); in the space formed by the second copper plate surface (24), the crystallizer second side wall (26) and the crystallizer second outer wall (28) No. 2 cooling channel (11), a third set of thermocouples (31), and a fourth set of thermocouples (32) are arranged;

In the crystallizer (6), there is also a No. 3 cooling water channel (9) between the No. 1 cooling water channel (10) and the No. 2 cooling water channel (11).

The invention relates to a simulation device for initial solidification of molten steel near the corner of a continuous casting crystallizer. The second lifting motor (4) controls the vertical movement of the second lifting bracket (22), and further controls the operation of the positioning electrode (15).

The present invention is an initial solidification simulation device for molten steel near the corner of a continuous casting crystallizer. The width of the first copper plate surface (23) is 20-50 mm, preferably 25-35 mm, more preferably 30 mm;

The width of the second copper plate surface (24) is 20-50mm, preferably 25-35mm, more preferably 30mm;

The thickness of the first side wall (25) of the crystallizer is 10-30mm, preferably 15-25mm, more preferably 20mm;

The thickness of the crystallizer second side wall (26) is 10-30mm, preferably 15-25mm, more preferably 20mm;

The width of the first outer wall (27) of the crystallizer is 30-80mm, preferably 40-60mm, more preferably 50mm;

The width of the second outer wall (28) of the crystallizer is 30-80mm, preferably 40-60mm, more preferably 50mm.

The invention relates to a device for simulating the initial solidification of molten steel near the corner of a continuous casting crystallizer. The included angle formed by the first copper plate surface (23) and the second copper plate surface (24) is 90°.

The present invention is a device for simulating the initial solidification of molten steel near the corner of a continuous casting crystallizer. The first set of thermocouples (29) and the second set of thermocouples (30) are on the same plane, and the plane is perpendicular to the surface of the first copper plate. (23) and parallel to the drawing direction;

All thermocouples in the first group of thermocouples (29) can be on different vertical lines;

All thermocouples in the second group of thermocouples (30) are on the same vertical line, and the vertical line is along the casting direction;

The third group of thermocouples (31) and the fourth group of thermocouples (32) are in the same plane, and the plane forms an angle of 45 degrees with the first copper plate surface (23), and also forms a 45 degree angle with the second copper plate surface (24). degree angle;

All thermocouples in the third group of thermocouples (31) can be on different vertical lines;

All thermocouples in the fourth group of thermocouples (32) are on the same vertical line, said vertical line is along the drawing direction.

A kind of molten steel initial solidification simulation device near the corner of continuous casting crystallizer of the present invention, the vertical distance from the first group of thermocouples (29) to the first copper plate surface (23) is 1-5mm, preferably 1-3mm, further Preferably 2mm; the vertical distance from the first group of thermocouples (29) to the crystallizer first side wall (25) is 10-20mm, preferably 12-18mm, more preferably 15mm;

The vertical distance from the second group of thermocouples (30) to the first copper plate surface (23) is 5-12mm, preferably 6-10mm, more preferably 7mm; the second group of thermocouples (30) to the crystallizer first side The vertical distance of the wall (25) is 10-20mm, preferably 12-18mm, more preferably 15mm;

The vertical distance between the first group of thermocouples (29) and the second group of thermocouples (30) is 1-8mm, preferably 3-6mm, more preferably 5mm;

The vertical distance of the third group of thermocouples (31) to the plane B is 1-5mm, preferably 1-3mm, more preferably 2mm; definition: intersect with the first copper plate surface (23) and the second copper plate surface (24) Line is A side, is B side with the intersecting line of the first outer wall (27) of crystallizer, the second outer wall of crystallizer, and a plane passes A, B two sides simultaneously, then defines this plane as plane A, perpendicular to plane A And the plane passing side A is plane B; said side A is the crystallizer corner (33).

The vertical distance from the fourth group of thermocouples (32) to the plane B is 5-12mm, preferably 6-10mm, more preferably 7mm;

The vertical distance from the third group of thermocouples (31) to the fourth group of thermocouples (32) is 1-8mm, preferably 3-6mm, more preferably 5mm.

The present invention is an initial solidification simulation device for molten steel near the corner of a continuous casting crystallizer. The diameter of the No. 1 cooling channel (10) is 5-13mm, preferably 7-11mm, and more preferably 8mm; the cooling channel (10) The vertical distance between the central axis and the first copper plate surface (23) is 9-18mm, preferably 10-14mm, more preferably 12mm; the vertical distance between the cooling channel (10) and the crystallizer first side wall (25) 6-15mm, preferably 8-12mm, more preferably 10mm;

The diameter of the No. 2 cooling channel (11) is 5-13mm, preferably 7-11mm, more preferably 8mm; the vertical distance between the central axis of the cooling channel (11) and the second copper plate surface (24) is 9-18mm , preferably 10-14mm, more preferably 12mm; the vertical distance between the cooling channel (11) and the crystallizer second side wall (26) is 6-15mm, preferably 8-12mm, more preferably 10mm;

The diameter of No. 3 cooling channels (9) is 5-13mm, preferably 7-11mm, more preferably 8mm; the central axis of the cooling channels (9) is between the third group of thermocouples (31) and the fourth group of thermocouples (32) The plane formed, the vertical distance from the central axis of the cooling channel (9) to the plane B is greater than the vertical distance from the third and fourth sets of thermocouples to the plane B, and the vertical distance from the cooling channel (9) to the plane B is 9-18mm, preferably 10-14mm, more preferably 12mm. That is, the vertical distance from the cooling channel (9) to the corner of the crystallizer (33) is 9-18mm, preferably 10-14mm, more preferably 12mm.

The present invention is a molten steel initial solidification simulation device near the corner of a continuous casting crystallizer, No. 1 cooling water channel (10) and No. 3 cooling water channel (9) are both outlet channels; No. 3 cooling water channel (9) is a water inlet channel, and Connect with water flow meter (7) and cooling water valve (8) in turn.

The present invention is a device for simulating the initial solidification of molten steel near the corners of a continuous casting crystallizer. The first group of thermocouples (29) has m thermocouples in total, and the first group of thermocouples (29) is inserted into the top of the mold (6). The thermocouple with the shortest distance is counted as 1 _, and _the thermocouple with the shortest distance _to the crystallizer (6) bottom in the first group of thermocouples (29) is counted as 1; The ratio of the vertical distance to the height _of the crystallizer (6) is 0.6-0.9:1, preferably 0.7-0.8:1, more preferably 0.75:1; The height ratio of the device (6) is 1:4-8, preferably 1:6-8, more preferably 1:7; said m is greater than or equal to 4;

The second group of thermocouples (30) has n thermocouples in total, and the thermocouple with the shortest distance to the crystallizer (6) top in the second group of thermocouples (30) is counted as 2 _, and the second group of thermocouples (30 ) to the thermocouple with the shortest distance to the bottom of the crystallizer (6) is counted as 2 _; the ratio of the vertical distance from the top of the thermocouple 2 _to the top of the crystallizer (6) and the height of the crystallizer (6) is 0.6-0.9:1 , preferably 0.7-0.8:1, more preferably 0.75:1; the ratio of the vertical distance from thermocouple 2 to the _bottom of crystallizer (6) and the height of crystallizer (6) is 1:4-8, preferably 1 :6-8, further preferably 1:7; said n is greater than or equal to 4;

The third group of thermocouples (31) has p thermocouples in total, and the thermocouple with the shortest distance to the crystallizer (6) top in the third group of thermocouples (31) is counted as 3 _, and the third group of thermocouples (31 ) to the thermocouple with the shortest distance to the bottom of the crystallizer (6) is counted as 3 _; the ratio of the vertical distance from the top of the thermocouple 3 _to the top of the crystallizer (6) and the height of the crystallizer (6) is 0.6-0.9:1 , preferably 0.7-0.8:1, more preferably 0.75:1; the ratio of the vertical distance from thermocouple 3 to the _bottom of crystallizer (6) and the height of crystallizer (6) is 1:4-8, preferably 1 :6-8, further preferably 1:7; the p is greater than or equal to 4;

The fourth group of thermocouples (32) has q thermocouples in total, and the thermocouple with the shortest distance to the crystallizer (6) top in the fourth group of thermocouples (32) is counted as 4 _, and the fourth group of thermocouples (32 ) to the thermocouple with the shortest distance to the bottom of the crystallizer (6) is counted as 4 _; the ratio of the vertical distance from the top of the thermocouple 4 _to the top of the crystallizer (6) and the height of the crystallizer (6) is 0.6-0.9:1 , preferably 0.7-0.8:1, more preferably 0.75:1; the ratio of the vertical distance from thermocouple 4 to the _bottom of crystallizer (6) and the height of crystallizer (6) is 1:4-8, preferably 1 :6-8, more preferably 1:7; said q is greater than or equal to 4.

The invention relates to a device for simulating the initial solidification of molten steel near the corners of a continuous casting crystallizer. The material of the continuous casting crystallizer (6) is copper, preferably red copper.

The present invention also provides a method for simulating the initial solidification of molten steel near the corner of the continuous casting crystallizer by using the above-mentioned device, the method is as follows:

step one

Prepare the experimental steel grade and the corresponding experimental mold slag; put the experimental steel grade into the melting furnace (16) to heat up to melting, and keep the molten steel temperature at 20-50°C above the liquidus temperature of the experimental steel grade; use inert protection during the heating process The gas shield (12) prevents the molten steel from being oxidized; then adding mold slag, the thickness of the liquid mold slag layer (13) formed after the mold slag is melted is 5-10mm;

step two

Turn on the lifting motor (4) to control the movement of the positioning electrode (15). When the positioning electrode (15) contacts the high-temperature conductive liquid surface, the low-voltage circuit is connected, and the positioning electrode (15) stops moving; the computer records the positioning electrode (15) at this time. 15), the computer sends an operating command to the lifting motor (3) according to the position information of the positioning electrode (15), so that the puller (5) and the crystallizer (6) move downward together and enter the molten pool (14) At this time, the thermocouple 1 _is at the same height as the bottom end of the positioning electrode (15); when the crystallizer (6) enters the molten pool (14), its amplitude and vibration are controlled by the crystallizer vibration motor (1). frequency; the crystallizer (6) opens the cooling water valve (8) when entering the molten pool (14);

step three

After the crystallizer (6) stays in the molten pool (14) for 3-8s, start the casting motor (2) to drive the puller (5) to pull down, and the solidified billet on the crystallizer (6) follows the puller (5) Running downwards, new molten steel continuously contacts the first copper plate surface (23) and the second copper plate surface (24) of the mold, so as to simulate the drawing process of the factory and pull out the initially solidified shell of a set length ; At the same time, the temperature acquisition system (18) collects the temperature change in the crystallizer (6) during the casting process with frequency f, and stores the temperature data in the computer;

step four

After the billet drawing process is finished, the lifting bracket (21) moves upwards, so that the initially solidified billet shell is separated from the molten pool, and cooled in the air, and finally the billet shell is cut off;

step five

According to the measured values of the first group of thermocouples (29) and the second group of thermocouples (30) in the drawing process, calculate the heat flux density of the first copper plate surface (23) in the drawing process;

According to the measured values of the third group of thermocouples (31) and the third group of thermocouples (32) during the casting process, the heat flux density at the corner of the crystallizer (33) during the casting process is calculated;

step six

Measure the thickness of the shell face position near the first group of thermocouples (29) and the corner position near the third group of thermocouples (32) and adopt the solidification square root law to the thickness and time of the shell face position and corner position Fitting the relation to get the relationship between the solidification thickness and time of the billet shell, and obtain the average solidification coefficient of the face position and corner position of the billet shell;

step seven

Measure the vibration mark spacing and the vibration mark depth on the surface of the blank shell face position near the first group of thermocouples (29);

Measuring the vibration mark spacing and the vibration mark depth on the surface of the shell corner position near the third group of thermocouples (32);

step eight

The continuous casting parameters were changed, and the experiment was repeated to study the influence of continuous casting process parameters on the initial solidification behavior of molten steel near the corner of the mold. When the adjusted parameters in step 8 make the temperature fluctuation of the crystallizer less than 3°C and the heat flux fluctuation less than 0.2MW/ ^m2 ; the temperature difference at different positions of the same level of the crystallizer is less than 5°C and the heat flux difference is less than 0.3MW /m ² ; the difference between the average solidification coefficient at the face and corner of the billet shell is less than 0.2mm/s ^1/2 ; the difference between each vibration mark spacing is less than 1mm, and the vibration mark depth is less than 0.4mm, the corresponding continuous casting The parameters are the optimization parameters. The better the shell surface quality is obtained.

The present invention is an initial solidification simulation device for molten steel near the corner of a continuous casting crystallizer. In step six, the qualitative relationship between the average solidification coefficient of different parts of the billet shell and the heat flux density of the first copper plate surface (23) can also be obtained; The qualitative relationship between the average solidification coefficient of different parts of the billet shell and the heat flux density at the corner of the crystallizer (33); in order to provide directions for adjusting related parameters.

The present invention is a device for simulating the initial solidification of molten steel near the corner of a continuous casting crystallizer. The depth at which the crystallizer enters the molten pool (14) is 70-90 mm, preferably 80 mm;

The invention discloses a method for simulating the initial solidification of molten steel near the corners of a continuous casting crystallizer. The mold stays in the molten pool for 5 seconds; the puller (5) pulls down to form a new thickness of the initially solidified shell 0-6mm; the length of the new initial solidified shell is 40-60mm, preferably 50mm;

The present invention is a method for simulating the initial solidification of molten steel near the corner of a continuous casting crystallizer. The casting speed is 8-12mm/s, preferably 10mm/s;

The invention discloses a method for simulating the initial solidification of molten steel near the corner of a continuous casting crystallizer. The amplitude of the crystallizer (6) is 2-7 mm, preferably 4.5 mm; the vibration frequency is 80-150 cpm, preferably 100 cpm.

The invention discloses a method for simulating the initial solidification of molten steel near the corner of a continuous casting crystallizer, wherein the value of f is 30-80 Hz.

The invention discloses a method for simulating the initial solidification of molten steel near the corner of a continuous casting crystallizer. The temperature of the cooling water is 20-30°C, preferably 25°C; the flow rate of the cooling water is 3-6L/min, preferably 4L/min.

As a preference, in step five

During the casting process, the temperature in the copper plate surface (23) of the mold and the temperature in the corner (33) of the mold are compared and analyzed in terms of the size and change trend; based on the measured temperature in the mold, two-dimensional transmission The thermal mathematical model 2DIHCP for mold heat flux software (registration number 2016SR067373) calculates the size of the heat flux on the hot surface of the mold copper plate surface (23) and the mold corner (33), and the small difference and change trend of the two The differences are compared and analyzed.

The present invention is a method for simulating the initial solidification of molten steel near the corner of the continuous casting crystallizer. The expression of the solidification square root law is E is the shell thickness, mm; k is the average solidification coefficient, mm/s ^1/2 ; t is the solidification time, s.

Advantages of the present invention:

1) The two copper plate surfaces 23, 24 of the crystallizer of the present invention form a right angle, which is equivalent to a right angle of the tubular billet or combined slab crystallizer in actual production, and is more universal than the chamfering crystallizer simulation device and practicality;

2) The two copper plate surfaces 23, 24 of the crystallizer of the present invention form a right angle, which can be used to study the initial solidification behavior of molten steel near the corner 33 of the mold, including heat transfer, mass transfer, momentum transfer, steel slag reaction and protection Slag behavior, etc.;

3) Carry out simulation experiments with steel and mold slag as raw materials, the experimental conditions are closer to the actual production process, and the experimental results have guiding significance for actual production;

4) The experimental process is simple and convenient to operate, and it is convenient to adjust various continuous casting parameters to understand the influence of continuous casting parameters on the initial solidification behavior of molten steel near the corner of the mold. At the same time, the experiment is low in risk and low in cost.

Description of drawings

Fig. 1 is the simulation device for the initial solidification of molten steel near the corner of the continuous casting crystallizer;

Fig. 2 is the schematic diagram of continuous casting right-angle crystallizer structure;

Fig. 3 is the left view of continuous casting right-angle crystallizer;

Fig. 4 is the top view of continuous casting right-angle crystallizer;

Fig. 5 is the temperature measured by thermocouples on the face of the crystallizer in the casting process in Example 1;

Fig. 6 is the temperature measured by the thermocouple at the corner of the crystallizer in the casting process in Example 1;

Fig. 7 is the heat flux figure of the first copper plate surface thermocouple area of crystallizer in embodiment 1;

Fig. 8 is the heat flux figure of crystallizer corner thermocouple area in embodiment 1;

Fig. 9 is the actual billet shell obtained from the billet drawing experiment in Example 1.

Figure 1, 2, 3, 4, 1 is the crystallizer vibration motor, 2 is the casting motor, 3 is the first lifting motor, 4 is the second lifting motor, 5 is the casting device, 6 is the crystallizer, 7 is the water flow Flow meter, 8 is the cooling water valve, 9 is the No. 3 cooling water channel, 10 is the No. 1 cooling water channel, 11 is the No. 2 cooling water channel, 12 is the inert protective gas cover, 13 is the liquid mold slag layer, 14 is the molten pool, 15 is the positioning electrode, 16 is the melting furnace, 17 is the base, 18 is the temperature acquisition system, 19 is the furnace control system, 20 is the motor control system, 21 is the first lifting bracket, 22 is the second lifting bracket, 23 is The first copper plate surface, 24 is the second copper plate surface, 25 is the first side wall of the crystallizer, 26 is the second side wall of the crystallizer, 27 is the first outer wall of the crystallizer, 28 is the second outer wall of the crystallizer, and 29 is the first A group of thermocouples, 30 is the second group of thermocouples, 31 is the third group of thermocouples, 32 is the fourth group of thermocouples, and 33 is the corner of the crystallizer.

1 _is the thermocouple with the shortest distance to the crystallizer 6 top in the first group of thermocouples 29,

1 _below is the thermocouple with the shortest distance to the crystallizer (6) bottom in the first group of thermocouples (29),

2 _is the thermocouple with the shortest distance to the crystallizer (6) top in the second group of thermocouples (30),

2 is the thermocouple with the shortest distance to the crystallizer (6) _bottom in the second group of thermocouples (30),

3 _is the thermocouple with the shortest distance to the crystallizer (6) top in the third group of thermocouples (31),

3 is the thermocouple with the shortest distance to the crystallizer (6) _bottom in the third group of thermocouples (31),

4 _is the thermocouple with the shortest distance to the crystallizer (6) top in the fourth group of thermocouples (32),

_{The bottom} 4 is the thermocouple with the shortest distance to the crystallizer (6) bottom in the fourth group of thermocouples (32);

1, 2, 3, 4 can see the connection relationship of the various parts of the simulation device designed by the present invention and the structure of the continuous casting right-angle crystallizer.

In Figure 5, curve No. 1 represents the temperature measured by thermocouple No. 1, curve No. 2 represents the temperature measured by thermocouple No. 2, curve No. 3 represents the temperature measured by thermocouple No. 3, and curve No. 4 represents the temperature measured by thermocouple No. 4. Temperature, curve No. 5 represents the temperature measured by thermocouple No. 5, curve No. 6 represents the temperature measured by thermocouple No. 6, curve No. 7 represents the temperature measured by thermocouple No. 7, and curve No. 8 represents the temperature measured by thermocouple No. 8; It can be seen from Fig. 5 that the temperature change in the first copper plate surface (23) of the crystallizer during the casting process is based on the temperature measured by the thermocouple, and the first copper plate surface (23) of the mold can be calculated by using a two-dimensional inverse mathematical model. ) heat flux.

In Figure 6, curve No. 8 represents the temperature measured by thermocouple No. 8, curve No. 10 represents the temperature measured by thermocouple No. 10, curve No. 11 represents the temperature measured by thermocouple No. 11, and curve No. 12 represents the temperature measured by thermocouple No. 12. Temperature, curve No. 13 represents the temperature measured by thermocouple No. 13, curve No. 14 represents the temperature measured by thermocouple No. 14, curve No. 15 represents the temperature measured by thermocouple No. 15, and curve No. 16 represents the temperature measured by thermocouple No. 16; It can be seen from Fig. 6 that the temperature change in the corner of the mold (33) during the casting process, based on the temperature measured by the thermocouple, the heat flux of the corner of the mold (33) can be calculated by using a two-dimensional inverse mathematical model .

It can be seen from Figure 7 that the heat flux in _the thermocouple area of the first copper plate surface (23) of the mold changes with time during the casting process. The ordinate is the position of the hot surface of the mold. 1 _{on the} thermocouple.

It can be seen from Fig. 8 that the heat flux in the thermocouple area at the corner (33) of the mold changes with time during the casting process, 0mm corresponds to 3 _lower thermocouples, and 30mm corresponds to 3 _upper thermocouples.

From Figure 9, we can see the distribution of the surface vibration marks, the depth of the vibration marks and the phenomenon of surface slag entrainment at the corners and faces of the billet shell.

detailed description

Example 1

In the embodiment, the used thermocouple is produced by Omega Company, the model is K-type armored thermocouple, and its diameter is 0.5mm.

In this embodiment, the components are connected according to Fig. 1 to form a simulation device for the initial solidification of molten steel near the corner of the continuous casting mold, and the mold is designed according to Fig. 2, Fig. 3 and Fig. 4 .

Wherein the width of the first copper plate surface (23) is 30mm;

The width of the second copper plate surface (24) is 30mm;

The thickness of the crystallizer first side wall (25) is 20mm;

The thickness of crystallizer second side wall (26) is 20mm;

The width of crystallizer first outer wall (27) is 50mm;

The width of the second outer wall (28) of the crystallizer is 50 mm.

The first group of thermocouples (29) and the second group of thermocouples (30) are in the same plane, and the plane is perpendicular to the first copper plate surface (23) and parallel to the drawing direction;

All thermocouples in the first group of thermocouples (29) can be on different vertical lines;

All thermocouples in the second group of thermocouples (30) are on the same vertical line, and the vertical line is along the casting direction;

The third group of thermocouples (31) and the fourth group of thermocouples (32) are in the same plane, and the plane forms an angle of 45 degrees with the first copper plate surface (23), and also forms a 45 degree angle with the second copper plate surface (24). degree angle;

All thermocouples in the third group of thermocouples (31) can be on different vertical lines;

All thermocouples in the fourth group of thermocouples (32) are on the same vertical line, said vertical line is along the drawing direction.

The vertical distance from the first group of thermocouples (29) to the first copper plate surface (23) is 2mm; the vertical distance from the first group of thermocouples (29) to the crystallizer first side wall (25) is 15mm;

The vertical distance of the second group of thermocouples (30) to the first copper plate surface (23) is 7mm; the vertical distance of the second group of thermocouples (30) to the crystallizer first side wall (25) is 15mm;

The vertical distance between the first group of thermocouples (29) and the second group of thermocouples (30) is 5mm;

The vertical distance from the third group of thermocouples (31) to the crystallizer corner (33) is 2mm;

The vertical distance from the fourth group of thermocouples (32) to the mold corner (33) is 7mm;

The vertical distance from the third group of thermocouples (31) to the fourth group of thermocouples (32) is 5mm.

The diameter of No. 1 cooling water channel (10) is 8mm; The vertical distance between the central axis of described cooling water channel (10) and the first copper plate surface (23) is 12mm; Described cooling water channel (10) and crystallizer first side wall (25) The vertical distance is 10mm;

The diameter of No. 2 cooling water channel (11) is 8mm; The vertical distance between the central axis of described cooling water channel (11) and the second copper plate surface (24) is 12mm; Described cooling water channel (11) and crystallizer second side wall (26) The vertical distance is 10mm;

The diameter of No. 3 cooling water passage (9) is 8mm; The central axis of described cooling water passage (9) is in the plane that the third group thermocouple (31) and the fourth group thermocouple (32) constitute, and crystallizer corner The vertical distance of (33) is 12mm.

No. 1 cooling water channel (10) and No. 3 cooling water channel (9) are water outlets; No. 3 cooling water channel (9) is a water inlet, and is connected with water flowmeter (7) and cooling water valve (8) in sequence.

The first group of thermocouples (29) has four thermocouples in total, and the distance between adjacent thermocouples is 10mm. The thermocouples are represented by No. 1, No. 3, No. 5 and No. 7 from top to bottom. The shortest thermocouple to the crystallizer (6) top in the first group of thermocouples (29) is counted as 1 _, the shortest thermocouple to the crystallizer (6) bottom in the first group of thermocouples (29) Couple is counted as 1 _; the ratio of the vertical distance from thermocouple 1 _to the top of crystallizer (6) and the height of crystallizer (6) is 0.75:1; the vertical distance from thermocouple 1 to the _bottom of crystallizer (6) and The height ratio of crystallizer (6) is 1:7;

The second group of thermocouples (30) has 4 thermocouples in total, and the distance between adjacent thermocouples is 10mm. The thermocouples are represented by No. 2, No. 4, No. 6 and No. 8 from top to bottom. The shortest thermocouple _to the crystallizer (6) bottom in the second group of thermocouples (30) is counted as 2 _; The ratio is 0.75:1; the ratio of the vertical distance from thermocouple 2 to the _bottom of crystallizer (6) and the height of crystallizer (6) is 1:7;

The first group of thermocouples (29) and the second group of thermocouples (30) are located at the surface of the crystallizer (23);

The third group of thermocouples (31) has 4 thermocouples in total, and the distance between adjacent thermocouples is 10mm. The thermocouples are represented by No. 9, No. 11, No. 13 and No. 15 from top to bottom. The thermocouple with the shortest distance to crystallizer (6) bottom in the third group _of thermocouples (31) is counted as 3 _; The ratio of 0.75:1; the ratio of the vertical distance from thermocouple 3 to the _bottom of crystallizer (6) and the height of crystallizer (6) is 1:7;

The fourth group of thermocouples (32) has 4 thermocouples in total, and the distance between adjacent thermocouples is 10mm. The thermocouples are represented by No. 10, No. 12, No. 14 and No. 16 from top to bottom. The shortest thermocouple _to the crystallizer (6) bottom in the fourth group of thermocouples (32) is counted as 4 _; The ratio is 0.75:1; the ratio of the vertical distance from the thermocouple 4 _to the bottom of the crystallizer (6) and the height of the crystallizer (6) is 1:7.

The third group of thermocouples (31) and the fourth group of thermocouples (32) are located at the corners of the crystallizer (33);

The specific operation is as follows:

1) Prepare 25 kg of the experimental steel grade, and the composition of the experimental steel grade is as shown in Table 1; add the experimental steel grade to the melting furnace (16) and heat up to melt, so that the temperature of the molten steel reaches 1545° C. and is maintained for 5 minutes to make the composition of the molten steel uniform; Use an inert protective gas cover (12) to prevent the molten steel from being oxidized during the heating process;

Table 1. Chemical composition of experimental steel grades (%)

2) Add 300g of mold flux, the composition of which is shown in Table 2; the thickness of the liquid mold flux layer (13) formed after melting the mold flux is about 7mm;

Table 2. Mold flux chemical composition (%)

3) Turn on the lifting motor (4) to control the movement of the positioning electrode (15). When the positioning electrode (15) touches the high-temperature conductive liquid surface, the low-voltage circuit is connected, and the positioning electrode (15) stops moving; the computer records the positioning at this time. The position of the electrode (15), the computer sends an operating command to the lifting motor (3) according to the position information of the positioning electrode (15);

4) The lifting bracket (21) controlled by the lifting motor (3) makes the puller (5) and the crystallizer (6) move downward together, and the depth of the crystallizer (6) entering the molten pool (14) is 80mm, now thermocouple 1 _is at the same height as the bottom of the positioning electrode (15); when the mold (6) enters the molten pool (14), its amplitude is controlled by the mold vibration motor (1) to be 4.5 mm and the vibration frequency are 100cpm; when the crystallizer (6) enters the molten pool (14), the cooling water valve (8) is opened, the cooling water temperature is 25°C, and the cooling water flow rate is 4L/min.

5) After the crystallizer (6) stays in the molten pool (14) for 5 seconds, start the drawing motor (2) to drive the drawing device (5) to pull down, and the solidified billet on the crystallizer will follow the drawing device (5) Running downwards, new molten steel constantly contacts the first copper plate surface (23) and the second copper plate surface (24) of the mold, to simulate the drawing process of the factory, the drawing speed is 10mm/s, and the 50mm long initial Solidify the shell, the thickness of the initially solidified shell is 0-6mm; at the same time, the temperature acquisition system (18) collects the temperature change in the crystallizer (6) during the casting process at a frequency of 60 Hz, and stores the temperature data in the computer; The temperature collected by the thermocouple is shown in Figure 5 and Figure 6;

6) After the billet drawing process is completed, the lifting bracket (21) moves upwards, so that the initially solidified billet shell is separated from the molten pool, and cooled in the air, and finally the billet shell is cut off; the billet shell obtained in the experiment is shown in Figure 7 ;

7) According to the measured values of the first group of thermocouples (29) and the second group of thermocouples (30) in the drawing process, calculate the heat flux density of the first copper plate surface (23) in the drawing process, as shown in Figure 7 According to the measured values of the third group of thermocouples (31) and the third group of thermocouples (32) in the drawing process, calculate the heat flux of the mold corner (33) in the drawing process, as shown in Figure 8 Show;

8) Measure the thickness of the shell face position near the first group of thermocouples (29) and the corner position near the third set of thermocouples (32) and use the solidification square root law to compare the thickness of the shell face position and the corner position with The relationship between time and time is fitted to obtain the relationship between the solidification thickness of the billet shell and time, and the average solidification coefficient of the face position and corner position of the billet shell is obtained;

9) Measure the vibration mark spacing and the vibration mark depth on the surface of the billet shell face position near the first group of thermocouples (29); mark depth;

10) Change the continuous casting parameters and repeat the experiment to study the influence of the continuous casting process parameters on the initial solidification behavior of molten steel near the corner of the mold. And then get the optimal implementation conditions.

Claims (10)

1. A simulation device for initial solidification of molten steel near the corner of a continuous casting mold, comprising a mold vibration motor (1), a casting motor (2), a first lifting motor (3), a second lifting motor (4), Puller (5), crystallizer (6), cooling channel, inert protective gas cover (12), positioning electrode (15), melting furnace (16), base (17), temperature acquisition system (18), melting furnace Control system (19), motor control system (20), first lifting bracket (21), second lifting bracket (22); it is characterized in that: The first lifting motor (3), the second lifting motor (4) are housed on the described base (17), the first lifting motor (3) controls the first lifting bracket (21) to move up and down, the second lifting motor ( 4) controlling the second lifting bracket (22) to move up and down; The smelting furnace (16) is arranged on the base (17) and between the first lifting motor (3) and the second lifting motor (4); the crystallizer vibration motor (1) and the drawing motor (2) are all arranged on the first lifting bracket (21); the temperature acquisition system (18) is connected with a thermocouple buried in the crystallizer (6); The crystallizer (6) is wrapped by the puller (5), and only the first copper plate surface (23) and the second copper plate surface (24) are exposed to contact with molten steel; the crystallizer (6) passes through the The crystallizer vibrating motor (1) is driven to vibrate up and down; the second lifting bracket (22) is connected to the positioning electrode (15); the drawing motor (2) controls the drawing device (5) to Pull down; the outer wall opposite to the first copper plate surface (23) is the first outer wall (27) of the crystallizer, and the side wall of the crystallizer directly connected to the first copper plate surface (23) is the first side wall of the crystallizer (25), the first group of thermocouples (29), the second group of Thermocouple (30) and No. 1 cooling channel (10); The outer wall opposite to the second copper plate surface (24) in the crystallizer is the crystallizer second outer wall (28), and the second copper plate surface (24) The directly connected crystallizer side wall is the crystallizer second side wall (26); in the space formed by the second copper plate surface (24), the crystallizer second side wall (26) and the crystallizer second outer wall (28) No. 2 cooling channel (11), a third set of thermocouples (31), and a fourth set of thermocouples (32) are arranged; The angle formed by the first copper plate surface (23) and the second copper plate surface (24) is 90°; In the crystallizer (6), there is also a No. 3 cooling water channel (9) between the No. 1 cooling water channel (10) and the No. 2 cooling water channel (11). 2. The initial solidification simulation device of molten steel near the corner of a continuous casting mold according to claim 1, characterized in that: The width of the first copper plate surface (23) is 20-50mm; The width of the second copper plate surface (24) is 20-50mm; The thickness of the crystallizer first side wall (25) is 10-30mm; The thickness of crystallizer second side wall (26) is 10-30mm; The width of the crystallizer first outer wall (27) is 30-80mm; The width of the second outer wall (28) of the crystallizer is 30-80mm. 3. The initial solidification simulation device of molten steel near the corner of a continuous casting mold according to claim 1, characterized in that: The first group of thermocouples (29) and the second group of thermocouples (30) are in the same plane, and the plane is perpendicular to the first copper plate surface (23) and parallel to the drawing direction; All thermocouples in the first group of thermocouples (29) can be on different vertical lines; All thermocouples in the second group of thermocouples (30) are on the same vertical line, and the vertical line is along the casting direction; The third group of thermocouples (31) and the fourth group of thermocouples (32) are in the same plane, and the plane forms an angle of 45 degrees with the first copper plate surface (23), and also forms a 45 degree angle with the second copper plate surface (24). degree angle; All thermocouples in the third group of thermocouples (31) can be on different vertical lines; All thermocouples in the fourth group of thermocouples (32) are on the same vertical line, said vertical line is along the drawing direction. 4. A simulation device for initial solidification of molten steel near the corner of a continuous casting mold according to claim 1 or 3, characterized in that: The vertical distance of the first group of thermocouples (29) to the first copper plate surface (23) is 1-5mm, and the vertical distance to the crystallizer first side wall (25) is 10-20mm; The vertical distance of the second group of thermocouples (30) to the first copper plate surface (23) is 5-12mm, and the vertical distance to the crystallizer first side wall (25) is 10-20mm; The vertical distance between the first group of thermocouples (29) and the second group of thermocouples (30) is 1-8mm; The vertical distance from the third group of thermocouples (31) to plane B is 1-5mm; definition: take the intersection line of the first copper plate surface (23) and the second copper plate surface (24) as side A, and take the first outer wall of the crystallizer (27), the intersecting line of the second outer wall of the crystallizer is the B side, and a plane passes through the A and B sides at the same time, then the plane is defined as the plane A, and the plane perpendicular to the plane A and passing the A side is the plane B; The A side is the crystallizer corner (33); The vertical distance of the fourth group of thermocouples (32) to the plane B is 5-12mm; The vertical distance from the third group of thermocouples (31) to the fourth group of thermocouples (32) is 1-8mm. 5. A continuous casting chamfering mold slab simulation device according to claim 1, characterized in that: The diameter of the No. 1 cooling channel (10) is 5-13mm, the vertical distance between the central axis of the cooling channel (10) and the first copper plate surface (23) is 9-18mm, and the first side wall (25) of the crystallizer The vertical distance is 6-15mm; The diameter of No. 2 cooling water channel (11) is 5-13mm, and the vertical distance between the central axis of described cooling water channel (11) and the second copper plate surface (24) is 9-18mm, and the crystallizer second side wall (26) The vertical distance is 6-15mm; The diameter of No. 3 cooling water channel (9) is 5-13mm, and the central axis of described cooling water channel (9) is at the plane place that the third group of thermocouples (31) and the fourth group of thermocouples (32) form, and cooling water channel (9) The vertical distance from the central axis to plane B is greater than the vertical distance from the third and fourth groups of thermocouples to plane B, and the distance is 9-18mm. 6. A device for simulating the initial solidification of molten steel near the corner of a continuous casting mold according to claim 1 or 5, characterized in that: No. 1 cooling water channel (10) and No. 3 cooling water channel (9) are both outlet channels ; No. 3 cooling water channel (9) is the water inlet channel, and is connected with the water flow meter (7) and the cooling water valve (8) in sequence. 7. A device for simulating initial solidification of molten steel near the corner of a continuous casting mold according to claim 1, characterized in that: The first group of thermocouples (29) has m thermocouples in total, and the thermocouple with the shortest distance to the crystallizer (6) top in the first group of thermocouples (29) is counted as 1 _, and the first group of thermocouples (29) ) to the thermocouple with the shortest distance to the bottom of the crystallizer (6) is counted as 1 _; the ratio of the vertical distance from the thermocouple 1 _to the top of the crystallizer (6) to the height of the crystallizer (6) is 0.6-0.9:1 ; The ratio of the vertical distance from thermocouple 1 _to the bottom of the crystallizer (6) and the height of the crystallizer (6) is 1:4-8; the m is greater than or equal to 4; The second group of thermocouples (30) has n thermocouples in total, and the thermocouple with the shortest distance to the crystallizer (6) top in the second group of thermocouples (30) is counted as 2 _, and the second group of thermocouples (30 ) to the thermocouple with the shortest distance to the bottom of the crystallizer (6) is counted as 2 _; the ratio of the vertical distance from the top of the thermocouple 2 _to the top of the crystallizer (6) and the height of the crystallizer (6) is 0.6-0.9:1 ; The ratio of the vertical distance from thermocouple 2 _to the bottom of the crystallizer (6) and the height of the crystallizer (6) is 1:4-8; said n is greater than or equal to 4; The third group of thermocouples (31) has p thermocouples in total, and the thermocouple with the shortest distance to the crystallizer (6) top in the third group of thermocouples (31) is counted as 3 _, and the third group of thermocouples (31 ) to the thermocouple with the shortest distance to the bottom of the crystallizer (6) is counted as 3 _; the ratio of the vertical distance from the top of the thermocouple 3 _to the top of the crystallizer (6) and the height of the crystallizer (6) is 0.6-0.9:1 ; Thermocouple 3 _{is down} to the vertical distance of crystallizer (6) bottom and the high ratio of crystallizer (6) is 1:4-8; Described p is greater than or equal to 4; The fourth group of thermocouples (32) has q thermocouples in total, and the thermocouple with the shortest distance to the crystallizer (6) top in the fourth group of thermocouples (32) is counted as 4 _, and the fourth group of thermocouples (32 ) to the thermocouple with the shortest distance to the bottom of the crystallizer (6) is counted as 4 _; the ratio of the vertical distance from the top of the thermocouple 4 _to the top of the crystallizer (6) and the height of the crystallizer (6) is 0.6-0.9:1 ; The ratio of the vertical distance from the bottom of the thermocouple 4 _to the bottom of the crystallizer (6) and the height of the crystallizer (6) is 1:4-8; the q is greater than or equal to 4. 8. A method utilizing the device according to claim 1 to simulate the initial solidification of molten steel near the corner of the continuous casting crystallizer, is characterized in that comprising the following steps: step one Prepare the experimental steel grade and the corresponding experimental mold slag; put the experimental steel grade into the melting furnace (16) to heat up to melting, and keep the molten steel temperature at 20-50°C above the liquidus temperature of the experimental steel grade; use inert protection during the heating process The gas shield (12) prevents the molten steel from being oxidized; then adding mold slag, the thickness of the liquid mold slag layer (13) formed after the mold slag is melted is 5-10mm; step two Turn on the lifting motor (4) to control the movement of the positioning electrode (15). When the positioning electrode (15) contacts the high-temperature conductive liquid surface, the low-voltage circuit is connected, and the positioning electrode (15) stops moving; the computer records the positioning electrode (15) at this time. 15), the computer sends an operating command to the lifting motor (3) according to the position information of the positioning electrode (15), so that the puller (5) and the crystallizer (6) move downward together and enter the molten pool (14) At this time, the thermocouple 1 _is at the same height as the bottom end of the positioning electrode (15); when the crystallizer (6) enters the molten pool (14), its amplitude and vibration are controlled by the crystallizer vibration motor (1). frequency; the crystallizer (6) opens the cooling water valve (8) when entering the molten pool (14); step three After the crystallizer (6) stays in the molten pool (14) for 3-8s, start the casting motor (2) to drive the puller (5) to pull down, and the solidified billet on the crystallizer (6) follows the puller (5) Running downwards, new molten steel continuously contacts the first copper plate surface (23) and the second copper plate surface (24) of the mold, so as to simulate the drawing process of the factory and pull out the initially solidified shell of a set length ; At the same time, the temperature acquisition system (18) collects the temperature change in the crystallizer (6) during the casting process with frequency f, and stores the temperature data in the computer; step four After the billet drawing process is finished, the lifting bracket (21) moves upwards, so that the initially solidified billet shell is separated from the molten pool, and cooled in the air, and finally the billet shell is cut off; step five According to the measured values of the first group of thermocouples (29) and the second group of thermocouples (30) in the drawing process, calculate the heat flux density of the first copper plate surface (23) in the drawing process; According to the measured values of the third group of thermocouples (31) and the third group of thermocouples (32) during the casting process, the heat flux density at the corner of the crystallizer (33) during the casting process is calculated; step six Measure the thickness of the shell face position near the first group of thermocouples (29) and the corner position near the third group of thermocouples (32) and adopt the solidification square root law to the thickness and time of the shell face position and corner position Fitting the relation to get the relationship between the solidification thickness and time of the billet shell, and obtain the average solidification coefficient of the face position and corner position of the billet shell; step seven Measure the vibration mark spacing and the vibration mark depth on the surface of the blank shell face position near the first group of thermocouples (29); Measuring the vibration mark spacing and the vibration mark depth on the surface of the shell corner position near the third group of thermocouples (32); step eight Change the continuous casting parameters, repeat the experiment, and study the influence of the continuous casting process parameters on the initial solidification behavior of the molten steel near the corner of the mold; when the adjusted parameters in step 8 make the temperature fluctuation of the mold less than 3°C and the heat flux fluctuation less than 0.2 MW/m ² ; the temperature difference at different positions at the same level of the crystallizer is less than 5°C, and the heat flux difference is less than 0.3MW/m ² ; the difference between the average solidification coefficient at the face and corner of the billet shell is less than 0.2mm /s ^1/2 ; the difference between each vibration mark spacing is less than 1mm, and the vibration mark depth is less than 0.4mm, the corresponding continuous casting parameters are optimized parameters. 9. A method for simulating the initial solidification of molten steel near the corner of a continuous casting mold according to claim 8, characterized in that: the amplitude of the mold (6) is 2-7mm, and the vibration frequency is 80-150cpm ; The value of f is 30-80Hz. 10. A method for simulating the initial solidification of molten steel near the corner of the continuous casting mold according to claim 8, characterized in that: the temperature of the cooling water is 20-30°C, and the flow rate of the cooling water is 3-6L/min.