CN113084102B - Crystallizer protection slag liquid slag layer thickness testing device and method based on wettability - Google Patents

Abstract

The invention relates to a wettability-based testing device and method for the thickness of mold slag liquid slag layer, mainly comprising a measuring device and a wettability-based measuring wire, the measuring wire is inserted into a continuous casting mold through the measuring device Molding slag layer, the measuring wire is a first metal wire and a second metal wire arranged side by side, and the entire length or a section of the first metal wire is provided with a surface coating, and the surface coating has good wettability to liquid slag The thickness of the liquid slag layer is obtained by reflecting the sintered layer/liquid slag layer/steel liquid interface on the second metal wire according to the difference in wettability between the steel and the slag of the measuring wire. Using the device and method for measuring the thickness of the mold slag liquid slag layer of the present invention has the advantages of simple operation, small error and high test efficiency, and can simultaneously obtain the information of the total thickness of the mold slag liquid slag layer and the mold slag slag layer.

Description

Device and method for measuring the thickness of mold slag liquid slag layer based on wettability

technical field

The invention relates to the technical field of iron and steel smelting processes, and relates to a device and a method for testing the thickness of a mold mold slag liquid slag layer, in particular to a mold mold mold slag liquid slag layer thickness testing device and testing method based on wettability.

Background technique

In the field of steel production, continuous casting, as the main forming process of molten steel, has an important impact on the output and quality of steel. In order to ensure the smooth running of the continuous casting process and improve the surface quality of the slab, mold powder is used in the production. After the mold slag is added to the mold, it is sintered and melted under the action of longitudinal heat transfer of the molten steel, forming a powder slag layer-sintering layer-liquid slag layer from top to bottom, which mainly plays the role of heat insulation, preventing secondary oxidation of molten steel and absorbing steel. The role of inclusions in the liquid; the liquid slag flows between the billet shell and the mold wall through the meniscus, and forms a liquid slag film-solid slag film from the inside to the outside under the cooling effect of the copper wall, which controls the slab lubrication and lateral heat transfer. Among them, the thickness of the liquid slag layer has an important influence on the realization of the function of the mold slag. If the liquid slag layer is too thin, a slag film of sufficient thickness cannot be formed between the slab and the mold wall, which will easily lead to the occurrence of a bond breakout accident; in addition, as the molten steel level fluctuates, the liquid slag layer cannot effectively isolate the molten steel to avoid coiling. Slag, causing defects such as slag inclusion on the surface of the slab. If the liquid slag layer is too thick, a large slag circle is easily formed on the wall of the mold, which blocks the liquid slag flow channel on the meniscus, and cannot form a uniform and stable slag film, and cracks or even cracks break out under the action of stress. In summary, it is very important to control a reasonable slag layer structure in the continuous casting process, especially to maintain a liquid slag layer with a suitable thickness, so the accurate detection and control of the thickness of the liquid slag layer is also particularly critical.

At present, the measurement methods of the thickness of the liquid slag layer can be divided into four types according to the measurement principle. (1) Temperature difference method: The temperature difference between the mold slag sintering layer, the liquid slag layer and the molten steel is used to measure the metal wire, copper wire and aluminum wire. Due to the difference in melting point between the metal wires, the respective melting states are different, so the thickness of the slag layer can be calculated according to their length difference. The most critical problem of this method is that the temperature between the layers of the mold slag does not remain unchanged, but there is a certain temperature gradient, and the melting position of the metal wire cannot truly reflect the position of the interface between the layers. Therefore, in the actual measurement process of this method The error is large. (2) Electrode method: Insert two MoSi ₂ rod electrodes into the mold slag layer at a certain rate, and calculate the thickness of the liquid slag layer according to the time interval between two resistance changes. This method can quickly respond to the structural changes of mold slag, but the test results are affected by factors such as MoSi ₂ rod sticking slag sticking to steel, electricity and noise. (3) Carbon concentration detection method: insert a carbon concentration sensor into the mold slag layer, and transmit the carbon concentration information in the mold to the computer in real time, according to the position of the maximum carbon concentration and the first occurrence of the carbon concentration in the molten steel. The distance calculates the thickness of the liquid slag layer. This method reduces artificial errors to a certain extent, but the results are affected by factors such as the thickness of the carbon-rich layer, the insertion speed of the sensor, and the response frequency. (4) Heat flux density calculation method: According to the heat flux density fluctuation of the sintered layer/liquid slag layer/liquid steel interface when the crystallizer vibrates, the frequency-power spectrum of the heat flux density and the thickness of the liquid slag layer are calculated by the AR model. This method has a high degree of automation and can obtain the thickness information of the liquid slag layer in real time. However, it is necessary to install a large number of thermocouples on the crystallizer and modify the existing equipment, which is not conducive to large-scale promotion. In view of the defects of inaccurate interface, large measurement error and low efficiency in the above-mentioned method, it is urgent to develop a new device and method for testing the thickness of mold slag liquid slag layer thickness.

SUMMARY OF THE INVENTION

In view of the shortcomings of the prior art, the main purpose of the present invention is to provide a wettability-based method for measuring the thickness of the mold slag liquid slag layer, so as to solve the problem of large errors and low efficiency in measuring the thickness of the liquid slag layer in the prior art The second purpose is to provide a test device for the thickness of the mold slag liquid slag layer.

In order to solve the technical problem, the device and method for measuring the thickness of mold slag liquid slag layer based on wettability proposed by the present invention mainly include a measuring device and a measuring wire based on wettability, and the measuring wire passes the measurement The device is inserted into the mold slag slag layer of the continuous casting mold, and the sintered layer/liquid slag layer/steel liquid interface is reflected by the difference in the wettability of the measuring wire to the steel and the slag, so as to obtain the thickness of the liquid slag layer.

Preferably, the measuring device includes a handle, a telescopic rod, a measuring rod, a holed slag baffle, and a timer.

Preferably, the measuring wire consists of a wire and a surface-coated wire.

Preferably, the melting point of the metal wire is higher than the temperature of the molten steel in the mold.

Preferably, the surface coating has better wettability to the liquid slag than the metal wire, and is a metal oxide, such as oxides such as aluminum oxide, ferric oxide, and a mixture of the two.

Preferably, the measuring wire is inserted vertically into the crystallizer, the sintered layer/liquid slag layer interface is reflected by the surface coating viscous slag, and the metal wire sticks to the steel reflects the liquid slag layer/liquid steel interface.

The wettability-based method for testing the thickness of mold mold slag liquid slag layer is characterized by comprising the following steps:

1) According to the process requirements, prepare the aforementioned wettability-based crystallizer mold slag liquid slag layer thickness test device;

2) Insert the first metal wire and the second metal wire at the front end of the measuring handle 1 into the mold slag layer of the continuous casting mold. A sintered layer/liquid slag layer interface is formed on the surface coating of one metal wire, and a liquid slag layer/liquid steel interface is formed on the second metal wire, thereby obtaining the thickness of the liquid slag layer.

further:

Between steps 1) and 2), it also includes: A adjusting the angle of the measuring rod and the measuring handle to meet the needs of the on-site operating environment;

B. Insert the measuring wire vertically into the mold slag layer through the measuring handle until the bottom end of the slag baffle is flush with the mold slag surface, or the upper end of the measuring wire is flush with the mold slag surface;

The thickness of the liquid slag layer is obtained by finding the sintered layer/liquid slag layer interface on the surface coating of the first metal wire, and finding the liquid slag layer/liquid steel interface on the second metal wire; using measurement Ruler, or the scale on the measuring rod, measure the distance from the interface of the sintering layer/liquid slag layer to the liquid slag layer/liquid steel interface to be the thickness of the liquid slag layer, and the distance from the top of the surface coating to the liquid slag layer/liquid steel interface is the mold slag The total thickness of the slag layer.

Compared with the prior art, adopting the mold slag liquid slag layer thickness testing device and method of the present invention has the following beneficial effects:

1. According to the difference in wettability between substances, the present invention obtains a clear interface of sintered layer/liquid slag layer/liquid steel by means of oxide coating sticking to slag and metal wire sticking to molten steel, which solves the problem of interface inconsistency in existing measurement methods. The error problem caused by the accuracy is accurate, and the test results are accurate.

2. The present invention utilizes the difference in wettability of oxide coating and metal wire to liquid slag and molten steel, and measures the thickness of mold slag and liquid slag layer according to the interface of sintering layer/liquid slag layer/liquid steel. The principle is reliable, and the structure is simple and easy to operate. , and can measure the total thickness of mold slag liquid slag layer and slag layer at the same time.

Description of drawings

Fig. 1 is the structural representation of the device for testing the thickness of mold slag liquid slag layer in the embodiment of the present invention;

2 is a schematic diagram of a layered structure of mold slag in an embodiment of the present invention;

3 is a schematic diagram of a sintered layer/liquid slag layer/liquid steel interface on the measuring wire in the embodiment of the present invention;

FIG. 4 is a flow chart of a method for measuring the thickness of a mold slag liquid slag layer in an embodiment of the present invention.

Among them: handle 1, measuring rod 2, bolt 3, telescopic rod 4, measuring wire 5, first wire 6, second wire 7, surface coating 8, fixing bolt 9, slag baffle 10, timer 11, Scale 12.

Detailed ways

The technical solutions in the embodiments of the present invention will be described below with reference to the accompanying drawings in the embodiments of the present invention. It should be understood that the embodiments described herein are only some of the embodiments of the invention. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

The purpose of the present invention is mainly to provide a wettability-based method for measuring the thickness of the mold slag liquid slag layer, so as to solve the technical problems of large errors and low efficiency in the liquid slag layer thickness measurement in the prior art.

Please refer to FIG. 1 , the wettability-based mold slag liquid slag layer thickness test device provided by the embodiment of the present invention includes a handle 1, and a measuring wire 5 is provided at the front end of the handle 1, and the measuring wire 5 is a first metal arranged side by side. The wire 6 and the second wire 7 are provided with a surface coating 8 on the entire length or a section of the first wire 6 , and the surface coating 8 has better wettability to liquid slag than the second wire 7 . The first metal wire 6 and the second metal wire 7 have melting points that conform to the test molten metal, and are generally greater than the melting point of the molten metal.

In the figure, the front end of the handle 1 is rotatably connected with a measuring rod 2, and the front end of the handle 1 and the measuring rod 2 are rotatably connected by an angle adjustment bolt 3. As shown in the figure, the bolt 3 is used to adjust the distance between it and the handle 1. The length of the handle 1 is retractable. Specifically, a stretchable telescopic rod 4 is set on the handle 1, and its length is adjusted through the telescopic telescopic rod 4 to meet the measurement needs of various spatial position distances; The front end of the measuring rod 2 is inclined downward, which is convenient for going deep into the mold slag layer to be measured during measurement; at the front end of the measuring rod 2, a slag blocking plate 10 is arranged to facilitate the positioning of the test position; the measuring wire 5 passes through the slag blocking plate The through hole of the plate hole 10 is fixed or connected to the measuring rod 2 or the slag baffle plate 10 , and is installed on the measuring rod 2 or the slag baffle plate 10 through the fixing bolts 9 in the figure.

In this embodiment, the first and second metal wires are both Q195 metal wires. The surface of the first metal wire 6 is provided with a surface coating 8, and the surface coating 8 has a length of 80 mm and a thickness of 0.3-0.5 mm. The two Q195 wires are national standard No. 17 wires with a length of 150mm. The surface coating 8 is a metal oxide, such as aluminum oxide, or ferric oxide, or a mixture of the two.

When making the surface coating 8, the oxide powder and water glass are mixed in a ratio of 1:2, and after stirring, evenly spread on the metal wire with a brush, the above-mentioned metal wire is placed in a 300 ℃ dryer to dry for 2 hours and then cooled naturally. , the oxide coating is prepared.

There is a timer 11 on the handle 1, and the timer 11 is set to a time, such as 3s, when the time is reached, an alarm sound is issued to remind the measurer to end the measurement and take the measurement wire 5 out of the mold.

A scale 12 is provided on the measuring rod 2 to facilitate measuring the distance between the liquid slag layer/liquid steel interface on the second metal wire 7 and the sintered layer/liquid slag layer interface on the surface coating 8 .

As shown in Figure 2, after the mold slag is added to the mold, due to the longitudinal heat transfer of the molten steel, a powder slag layer - a sintered layer - a liquid slag layer is formed in sequence from top to bottom. In the device of this embodiment, the interface between the layers is distinguished according to the different wettability of the surface and the Q195 metal wire to each layer. As shown in Figure 3, the second metal wire has a good wetting effect with the molten steel, so the top of the molten steel to which it adheres can be determined as the molten steel level. The surface coating of the first metal wire has no wetting effect between the solid slag and the sintered layer, and has strong wettability with the liquid slag, so the top of the liquid slag that it adheres to can be judged as the slag liquid level. The distance between the two interfaces is the thickness of the liquid slag layer, and the distance between the top of the surface coating and the molten steel surface is the total thickness of the mold slag layer.

Fig. 4 is the flow chart of the measurement method of the present invention; the present invention takes the measurement of the thickness of the mold slag layer of the slab continuous casting 200 series stainless steel mold as an example (production conditions: pulling speed 1m/min, slab section 200×1240mm ² , middle The molten steel temperature in the package is 1485°C), and the general operation steps are as follows:

1) according to the technological requirements, prepare the wettability-based mold slag liquid slag layer thickness test device of the present invention;

2) Insert the first metal wire 6 and the second metal wire 7 at the front end of the measuring handle 1 into the mold slag layer of the continuous casting mold, according to the difference in the wettability of the first metal wire 6 and the second metal wire 7 to steel and slag The sintered layer/liquid slag layer/liquid steel interface is reflected to obtain the thickness of the liquid slag layer.

More specific steps are as follows:

S1, according to the process requirements, prepare the wettability-based mold slag liquid slag layer thickness test device of the present invention; install the measuring wire 5 on the measuring rod 2 through the slag blocking plate 10, and keep the first metal wire The top of the surface coating 8 of 6 is flush with the bottom of the slag baffle;

S2. Adjust the angle between the measuring rod 2 and the handle 1 and the length of the telescopic rod 4 to adapt to the on-site operating environment;

S3, vertically insert the measuring wire 5 into the mold slag layer through the handle 1, until the bottom end of the slag blocking plate 10 is flush with the mold slag surface and is in the same plane;

S4, keep the test position, and immediately take the measuring wire 5 out of the crystallizer after the timing device 11 sends a stop test signal;

S5. Find the liquid slag layer/liquid steel interface on the second metal wire 7, and find the sintered layer/liquid slag layer interface on the surface coating 8 of the first metal wire 6. Usually, it is necessary to remove the measuring wire 5 from Remove it from the measuring device, which is convenient and accurate to determine the aforementioned interface;

S6. Use a measuring ruler or the scale 12 on the measuring rod 2 to measure the distance from the interface of the sintered layer/liquid slag layer to the liquid slag layer/liquid steel interface, which is the thickness of the liquid slag layer, and the top of the surface coating to the liquid slag layer/liquid steel The interface spacing is the total thickness of the mold slag layer.

Using the above steps, three repeated tests were carried out on the thickness of the mold slag layer at the narrow side, 1/4 position and 1/2 position of the width in the mold, and the results are shown in Table 1.

Table 1 Slab continuous casting 200 series stainless steel mold mold slag layer thickness test results (mm)

Embodiment 2

In this example, the thickness of mold slag slag layer of slab continuous casting 300 series stainless steel mold is tested. The on-site process conditions are: pulling speed 1.1m/min, slab section 200×1530mm ² , molten steel temperature in tundish 1496℃. Using the method described in Example 1, according to the steps S1 to S6, the thickness of the mold slag layer in the narrow side of the mold, the 1/4 position and the 1/2 position in the width direction was repeated three times, and the results are shown in Table 2. .

Table 2 Slab continuous casting 300 series stainless steel mold mold slag layer thickness test results (mm)

Embodiment 3

In this example, the thickness of the mold slag layer of slab continuous casting peritectic steel mold is tested. The on-site process conditions are: pulling speed 1.2m/min, slab section 230×1530mm ² , and molten steel temperature in tundish 1547°C. In this embodiment, the preset test duration of the timer 11 is 2s. Using the method described in Example 1, according to steps S1 to S6, three repeated tests were carried out on the mold slag layer thickness on the narrow side of the mold, 1/4 position and 1/2 position in the width direction, and the results are shown in Table 3.

Table 3 Slab continuous casting peritectic steel mold mold slag layer thickness test results (mm)

Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit the technical solutions. Although the applicant has described the present invention in detail with reference to the preferred embodiments, those of ordinary skill in the art should The technical solution of the invention is modified or equivalently replaced without departing from the spirit and scope of the technical solution, and should be included in the scope of the claims of the present invention.

Claims (9)

1. The method for testing the thickness of the liquid slag layer of the crystallizer casting slag based on wettability is characterized by comprising the following steps of:

1) preparing a crystallizer protection slag liquid slag layer thickness testing device based on wettability according to process requirements;

the crystallizer casting slag liquid slag layer thickness testing device based on wettability comprises a measuring handle (1), wherein a measuring wire (5) is arranged at the front end of the measuring handle (1), the measuring wire (5) is a first metal wire (6) and a second metal wire (7) which are arranged side by side, a surface coating (8) is arranged on the whole length or a section of length of the first metal wire (6), and the wettability of the surface coating (8) to liquid slag is better than that of the second metal wire (7); the melting points of the first metal wire (6) and the second metal wire (7) are larger than that of the molten steel;

the front end of the measuring handle (1) is rotatably connected with a measuring rod (2); the measuring wire (5) is arranged at the front end of the measuring rod (2);

2) inserting a first metal wire (6) and a second metal wire (7) at the front end of a measuring handle (1) into a slag layer of a continuous casting crystallizer protection slag, reflecting a sintering layer/liquid slag layer/molten steel interface according to the wettability difference of the first metal wire (6) and the second metal wire (7) to steel and slag, forming the sintering layer/liquid slag layer interface on a surface coating (8) of the first metal wire (6), and forming a liquid slag layer/liquid steel interface on the second metal wire (7), thereby obtaining the thickness of the liquid slag layer.

2. The wettability-based crystallizer protection slag liquid slag layer thickness test method as claimed in claim 1, wherein: the front end of the measuring rod (2) is provided with a slag trap (10), the slag trap (10) is provided with a through hole, and the first metal wire (6) and the second metal wire (7) respectively penetrate through the through hole and are fixed on the measuring rod (2) or the slag trap (10).

3. The method for testing the thickness of the slag layer of the crystallizer protection slag liquid based on wettability according to claim 1, wherein the lengths of the first metal wire (6) and the second metal wire (7) are equal.

4. The method for testing the thickness of the slag layer of the crystallizer casting slag liquid based on the wettability according to any one of claims 1 to 3, wherein the surface coating (8) is aluminum oxide, ferric oxide or a mixture of the aluminum oxide and the ferric oxide.

5. The method for testing the thickness of the slag layer of the crystallizer casting slag liquid based on wettability according to any one of claims 1 to 3, wherein a timing device (11) is arranged on the measuring handle (1).

6. The wettability-based thickness test method for the slag layer of the crystallizer protection slag liquid according to claim 4, wherein a graduated scale (12) is arranged on the measuring rod (2).

7. The method for testing the thickness of the slag layer of the crystallizer casting slag liquid based on the wettability according to any one of claims 2 or 3, wherein the front end of the measuring handle (1) is rotatably connected with the measuring rod (2) through a bolt (3).

8. The method for testing the thickness of the slag layer of the crystallizer casting slag liquid based on wettability according to any one of claims 1 to 3, wherein the method comprises the following steps:

between step 1), 2), still include: a, adjusting the angle between the measuring rod (2) and the measuring handle (1) to meet the requirement of a field operation environment;

and B, vertically inserting the measuring wire (5) into the covering slag layer through the measuring handle (1) until the bottom end of the slag trap (10) is flush with the surface of the covering slag, or the upper end of the measuring wire (5) is flush with the surface of the covering slag.

9. The method for testing the thickness of the slag layer of the crystallizer casting slag liquid based on wettability according to any one of claims 1 to 3, wherein the method comprises the following steps: the thickness of the obtained liquid slag layer is obtained by finding a sintering layer/liquid slag layer interface on the surface coating (8) of the first metal wire (6) and finding a liquid slag layer/molten steel interface on the second metal wire (7); and measuring the distance from the interface of the sintered layer/the liquid slag layer to the interface of the liquid slag layer/the molten steel by using a measuring scale or a graduated scale (12) on the measuring rod (2), wherein the distance is the thickness of the liquid slag layer, and the distance from the top end of the surface coating to the interface of the liquid slag layer/the molten steel is the total thickness of the covering slag layer.

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