• 专利附录
  • 专利说明
  • 权利要求
  • 类似技术
  • 同族专利
  • 引用文献
  • 法律状态
  • 优先权
    • 专利摘要:
    PURPOSE: An apparatus for directly observing hot crack in a zone where a solid state and a liquid state coexist, and a method thereof are provided to conveniently observe the generation of the hot crack. CONSTITUTION: A heating coil(104) heats one side of a test piece(103) fixed by a tension tester(100). A cooling gas nozzle(105) sprays cooling gas cooling the other side of the test piece. A camera(106) takes a photograph of a zone where a solid state and a liquid state of the test piece coexist in tensioning the test piece. An image processor(107) processes the photographed image by using an image processing program capable of tracing a position to derivate the transformed quantity and the transforming rate of the test piece.
    公开号:KR20030034943A
    申请号:KR1020010066769
    申请日:2001-10-29
    公开日:2003-05-09
    发明作者:이주동；전기홍
    申请人:주식회사 포스코；
    IPC主号:
    专利说明:

    Direct Observation Apparatus and method of Hot Crack in Coexistence Zone of Solid phase and Liquid phase}
    [11] The present invention direct hot crack in the solid phase and liquid phase coexistence zone configured to directly observe the generation process of the hot crack occurs in the zone where the solid phase and liquid phase coexist during continuous casting through the specimen of the tensile tester An observation device and a method thereof are provided.
    [12] Generally, in the case of alloys, the area where the solid phase and the liquid phase coexist during solidification (hereinafter referred to as the 'liquid coexistence area') is very fragile and prone to cracking. It has a big impact on product quality. Therefore, in order to cast without the occurrence of such cracks, it is necessary to measure the degree of solidification crack sensitivity of the alloy. This sensitivity can be largely evaluated through the critical strain amount of crack initiation and the length of crack propagation. In general, a method of repeating a method of measuring the occurrence and length of cracks by cutting and grinding the specimen after applying a certain deformation by a punch test or a bending test is used. This method has the disadvantage that the number of experiments, the number of specimens, time is consumed and the accuracy is not very high.
    [13] Accordingly, the present invention has been made to solve the problems of the prior art as described above, through the high-speed camera and the image processing apparatus can directly observe the process of the generation of hot cracks occurring in the region where the solid and liquid phase coexists It is an object of the present invention to provide a hot crack direct observation apparatus and a method in a coexistence zone between a solid phase and a liquid phase.
    [1] 1 is a schematic diagram schematically showing the components of a hot crack direct observation apparatus in a solid and liquid coexistence zone according to an embodiment of the present invention,
    [2] FIG. 2A is a photograph taken with a high speed camera of a crack generated in an area where a solid and liquid phase near a melting point coexist using the apparatus shown in FIG. 1;
    [3] FIG. 2B is a graph showing the crack generation process of FIG.
    [4] 3 is a photograph showing a crack generation process over time through the apparatus shown in FIG.
    [5] FIG. 4 is a graph measuring critical deformation of hot cracks according to the surface temperature of the specimen through the apparatus shown in FIG. 1.
    [6] ♠ Explanation of symbols on the main parts of the drawing ♠
    [7] 100: high temperature tensile tester 101: upper jig
    [8] 102: lower jig 103: specimen
    [9] 104: heating coil 105: cooling gas nozzle
    [10] 106: high speed camera 107: image processing device
    [14] Hot crack direct observation apparatus of the present invention for achieving the above object, the heating coil for heating one side of the specimen fixed by the tensile tester, and the cooling gas for cooling the other side of the specimen An image taken using a cooling gas nozzle, a camera for capturing an image of an area where the solid phase and liquid phase of the specimen coexist when the specimen is tensioned, and an image processing program capable of tracking the position over time through the captured image It characterized in that it comprises an image processing apparatus for deriving the deformation amount and the deformation rate of the specimen by processing.
    [15] In addition, the hot crack direct observation method of the present invention is to directly observe the hot crack in the area where the solid phase and the liquid phase of the specimen coexists through the hot crack direct observation apparatus configured as described above, the one surface of the specimen A first step of heating with a heating coil to maintain a molten state and cooling the other side with a cooling gas sprayed through the cooling gas nozzle to form the coexistence zone in the specimen; Applying a tensile load to the specimen and photographing an image of the coexistence zone with a camera; And a third step of observing the deformation amount and the deformation rate of the specimen by analyzing the specific position of the captured image with time through the image processing apparatus.
    [16] In the following, with reference to the accompanying drawings, a preferred embodiment of a hot crack direct observation apparatus in the coexistence zone of a solid phase and a liquid phase according to the present invention will be described in detail.
    [17] 1 is a schematic diagram showing components of a hot crack direct observation apparatus in a solid phase and a liquid phase coexistence zone according to an embodiment of the present invention.
    [18] As shown in FIG. 1, the hot crack direct observation apparatus of the present invention heats one surface of the specimen 103 fixed by the upper jig 101 and the lower jig 102 of the high temperature tensile tester 100. The heating coil 104, the cooling gas nozzle 105 for injecting the cooling gas for cooling the other surface of the specimen 103, and the deformation, cracking, and propagation processes of the specimen 103 during tensioning. A high speed camera 106 and an image processing apparatus 107 for deriving a threshold deformation amount, a crack length, etc. by processing the photographed image using an image processing program capable of tracking the position over time through the photographed image. .
    [19] That is, the present invention raises one side of the specimen 103 to the melting point through the heating coil 104 to create a molten state, and the other of the specimen 103 through the cooling gas injected through the cooling gas nozzle 105. By cooling the surface of the side to give a temperature gradient to the specimen 103 to form a solid-liquid coexistence zone, and to directly observe the occurrence of hot cracks in the solid-liquid coexistence zone. At this time, the high temperature tensile tester 100 is a high frequency heating method, the melting temperature of the specimen 103 varies depending on the composition, but in the case of steel is usually 1500 ℃ or more. In addition, the photographing speed of the high speed camera 106 is at least 500 frames per second, and the image processing apparatus 107 analyzing the photographed image has a function of tracking a specific position of the image over time.
    [20] As the high speed camera 106 usable in the present invention, a 'Motion Corder Series SR-C' manufactured by 'Kodak' having a memory capable of storing a photographed image for about 10 seconds may be used. As the image processing apparatus 107, a program dedicated to the high speed camera 106 may be used under a trade name of 'Motion Track'.
    [21] However, the present invention does not need to use a specific high speed camera and a program as described above, and at least 500 frames per second, a recording speed of at least 10 seconds, a memory capacity of 10 seconds or more, and a specific position of a captured image are tracked according to time and amount of deformation. It doesn't matter if you have the ability to predict.
    [22] In FIG. 1, reference numeral 108 denotes a high temperature portion thermocouple, 109 denotes a low temperature portion thermocouple, and 110 denotes a crack.
    [23] In the following, a method for observing a hot crack generation process through the hot crack direct observation apparatus of the present invention configured as described above will be described in detail.
    [24] As shown in FIG. 1, one side of the specimen 103 is heated to the liquidus temperature (melting point) of the specimen 103 to maintain a molten state, and the other side is cooled through the cooling nozzle 105. Cool with the He cooling gas being sprayed to maintain the desired temperature. Then, the specimen 103 has a solid coexistence zone. Thus, when the specimen 103 has a solid-liquid coexistence zone, a tensile load is applied to the specimen 103.
    [25] Then, the high-speed camera 106 continuously photographs the crack generation process of the solid-state coexistence zone at a speed of 500 frames or more per second, and analyzes a specific position of the photographed image according to time through the image processing apparatus 107. The strain amount and strain rate can be observed.
    [26] Since the method of the present invention can directly monitor the deformation process at a specific position, it is possible to more accurately measure the strain at the crack occurrence position. However, since the conventional method of calculating the strain by measuring the change in the distance between the mark marks marked by the measurement position on the average was not possible to measure the exact strain. In addition, even if the conventional method adopts a method of giving a temperature gradient using the heating coil and the cooling nozzle of the present invention, in order to measure the critical deformation amount of crack generation, the specimen is cut and polished after applying a certain strain, and then cracked through a microscope observation. Observe the presence of At this time, if there is no crack, the same experiment should be repeated by increasing the strain. Thus, even when the heating coil and the cooling nozzle of the present invention are used in the conventional method, it takes a lot of time and the number of experiments to predict the time of crack generation, and it is impossible to experiment for all strains, so the accuracy of the experiment is low.
    [27] In conclusion, the present invention captures the crack generation and propagation process in the solid-liquid coexistence zone of the temperature gradient specimen 103 at a speed of at least 500 frames per second using the high-speed camera 106, and captures the photographed digital image. Through the image processing program that tracks a specific position in the photographed image according to time after storing in 107, the critical strain amount and propagation length of the crack are measured in a single experiment much more quickly and conveniently than in the conventional method.
    [28] Performance conditions and equipment that can prevent internal cracks during continuous casting such as secondary cooling, casting speed, etc. based on crack generation sensitivity map or high temperature brittle database produced using the measured values obtained through the above method Conditions can be set.
    [29] Experimental Example
    [30] FIG. 2A is a photograph taken by a high speed camera of a crack generated in a region where a solid phase and a liquid phase coexist near the melting point using the apparatus shown in FIG. 1, and FIG. 2B is a graph illustrating the crack generation process of FIG. 2A.
    [31] In experimenting with the present invention, one side of the specimen maintains the liquidus temperature at about 1520 ° C., while the other side maintains the liquidus temperature at 1100 ° C., with a strain rate of about 20% at an average stroke speed of 2 mm / s. Tensile load was applied until. At this time, the shooting speed of the high speed camera was 500 frames per second and the shooting was performed for about 2 seconds.
    [32] In order to measure the critical strain of crack initiation, it is important to know exactly where the tensile load is applied and the specimen starts to deform. In practice, a tensile tester may receive a signal indicating this starting point, but its accuracy is very low and cannot be applied.
    [33] However, as shown in Fig. 2, in the case of using the apparatus of the present invention, since the movement of any point on the image can be accurately measured, the starting point of the crack generation can be clearly known and the deformation amount according to time can be determined based on this value. It can measure accurately, and it is possible to measure the critical strain amount at the time of crack generation. In FIG. 2, reference numeral 200 denotes a deformation start point, and 201 denotes a crack occurrence point.
    [34] 3 is a photograph showing a crack generation process over time through the device shown in FIG. (A) of FIG. 3 shows a process of completely molten liquid phase in the surface portion of the crack by capillary phenomenon, before (c) at the start of cracking, (c) at the beginning of cracking, ( d) shows the result that the liquid phase has completely penetrated into the crack and stopped. As can be seen in the picture shown in Figure 3, when using the device of the present invention it is possible to accurately observe the cracking process.
    [35] FIG. 4 is a graph measuring critical deformation of hot cracks according to the surface temperature of the specimen through the apparatus shown in FIG. 1. As can be seen in Figure 4, it can be seen that the lower the surface temperature of the specimen, the more the critical deformation increases, making it difficult to crack. In addition, steel grades (steel grade A, steel grade B) having different materials may have different critical deformation amounts depending on their surface temperatures.
    [36] And, through the data obtained through the device of the present invention can be configured a simple crack generation sensitivity map as shown in Figure 4 or a separate high temperature brittle database. By using such crack generation sensitivity map or high temperature brittle database, it is possible to derive the optimum casting speed, mold cooling, and secondary cooling conditions for casting of defects during continuous casting according to the development of new steel grades.
    [37] As described in detail above, the hot crack direct observation apparatus and method in the solid phase and liquid phase coexistence zone of the present invention facilitate the generation of hot cracks occurring in the solid phase and liquid phase coexistence region through a high speed camera and an image processing apparatus. You can observe it directly.
    [38] In addition, by configuring the simple crack generation sensitivity map or by configuring a separate high temperature brittle database through the data obtained through the direct observation device of the present invention, it is possible to derive the optimum casting speed, mold cooling, secondary cooling operation conditions.
    [39] In the above description of the hot crack direct observation apparatus and the method for the method in the coexistence zone of the solid phase and the liquid phase of the present invention together with the accompanying drawings, which describes the best embodiment of the present invention by way of example and limits the present invention. It is not.
    [40] In addition, it is obvious that any person skilled in the art can make various modifications and imitations without departing from the scope of the technical idea of the present invention.
    权利要求:
    Claims (4)
    [1" claim-type="Currently amended] In the apparatus for directly observing the process of hot cracks occurring in the region where the solid phase and liquid phase coexist through the specimen of the tensile tester,
    A heating coil for heating one side of the specimen fixed by the tensile tester, a cooling gas nozzle for injecting a cooling gas for cooling the other side of the specimen, and a solid phase of the specimen during tensioning of the specimen. Image processing which derives the deformation amount and the deformation speed of the specimen by processing the photographed image by using the camera which captures the image of the zone where liquid and liquid coexist, and the image processing program which can track the position over time through the captured image. Hot crack direct observation apparatus comprising a device.
    [2" claim-type="Currently amended] The hot crack direct observation apparatus according to claim 1, wherein the camera has a shooting speed of at least 500 frames per second and a storage capacity of a captured image of at least 10 seconds.
    [3" claim-type="Currently amended] A heating coil for heating one side of the specimen fixed by the tensile tester, a cooling gas nozzle for injecting a cooling gas for cooling the other side of the specimen, and a region in which the solid phase and the liquid phase of the specimen coexist Directly observing hot cracks in the coexistence zone through a hot crack direct observation device including a camera for photographing an image and an image processing device for deriving the amount and strain of the specimen by processing the photographed image. In the method,
    A first step of heating one side of the specimen with the heating coil to maintain a molten state and cooling the other side with cooling gas sprayed through the cooling gas nozzle to form the coexistence zone in the specimen; ;
    Applying a tensile load to the specimen and photographing an image of the coexistence zone with a camera;
    And a third step of observing a deformation amount and a deformation rate of the specimen by analyzing a specific position of the photographed image with time through the image processing apparatus.
    [4" claim-type="Currently amended] 4. The method of claim 3, wherein the camera photographs the camera at a shooting speed of at least 500 frames per second.
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    同族专利:
    公开号 | 公开日
    KR100848649B1|2008-07-28|
    引用文献:
    公开号 | 申请日 | 公开日 | 申请人 | 专利标题
    法律状态:
    2001-10-29|Application filed by 주식회사 포스코
    2001-10-29|Priority to KR1020010066769A
    2003-05-09|Publication of KR20030034943A
    2008-07-28|Application granted
    2008-07-28|Publication of KR100848649B1
    优先权:
    申请号 | 申请日 | 专利标题
    KR1020010066769A|KR100848649B1|2001-10-29|2001-10-29|Direct Observation Apparatus and method of Hot Crack in Coexistence Zone of Solid phase and Liquid phase|
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