CN111830131A - Quantitative method for central looseness or shrinkage cavity of casting blank - Google Patents
Quantitative method for central looseness or shrinkage cavity of casting blank Download PDFInfo
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- CN111830131A CN111830131A CN202010617822.XA CN202010617822A CN111830131A CN 111830131 A CN111830131 A CN 111830131A CN 202010617822 A CN202010617822 A CN 202010617822A CN 111830131 A CN111830131 A CN 111830131A
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- 238000005266 casting Methods 0.000 title claims abstract description 45
- 238000004445 quantitative analysis Methods 0.000 title claims abstract description 7
- 238000000034 method Methods 0.000 claims abstract description 37
- 238000007654 immersion Methods 0.000 claims abstract description 9
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims abstract description 9
- 238000009659 non-destructive testing Methods 0.000 claims description 6
- 238000002360 preparation method Methods 0.000 claims description 4
- 238000005498 polishing Methods 0.000 claims description 2
- 238000012360 testing method Methods 0.000 claims description 2
- 238000009749 continuous casting Methods 0.000 abstract description 18
- 238000001514 detection method Methods 0.000 abstract description 10
- 238000012545 processing Methods 0.000 abstract description 8
- 238000005070 sampling Methods 0.000 abstract description 7
- 230000007547 defect Effects 0.000 abstract description 6
- 238000011002 quantification Methods 0.000 abstract 1
- 229910000831 Steel Inorganic materials 0.000 description 5
- 238000005554 pickling Methods 0.000 description 5
- 239000010959 steel Substances 0.000 description 5
- 239000002253 acid Substances 0.000 description 4
- 238000007689 inspection Methods 0.000 description 4
- 238000004519 manufacturing process Methods 0.000 description 4
- 238000005406 washing Methods 0.000 description 4
- VEXZGXHMUGYJMC-UHFFFAOYSA-N Hydrochloric acid Chemical compound Cl VEXZGXHMUGYJMC-UHFFFAOYSA-N 0.000 description 2
- 230000007797 corrosion Effects 0.000 description 2
- 238000005260 corrosion Methods 0.000 description 2
- 238000011161 development Methods 0.000 description 2
- 238000010586 diagram Methods 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 238000005516 engineering process Methods 0.000 description 2
- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical compound CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 description 1
- NINIDFKCEFEMDL-UHFFFAOYSA-N Sulfur Chemical compound [S] NINIDFKCEFEMDL-UHFFFAOYSA-N 0.000 description 1
- 238000004458 analytical method Methods 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 238000004364 calculation method Methods 0.000 description 1
- 239000013078 crystal Substances 0.000 description 1
- 238000011156 evaluation Methods 0.000 description 1
- 238000002474 experimental method Methods 0.000 description 1
- 238000010438 heat treatment Methods 0.000 description 1
- 238000010191 image analysis Methods 0.000 description 1
- 238000005272 metallurgy Methods 0.000 description 1
- 238000012821 model calculation Methods 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 239000011148 porous material Substances 0.000 description 1
- 238000007639 printing Methods 0.000 description 1
- 238000011158 quantitative evaluation Methods 0.000 description 1
- 238000011160 research Methods 0.000 description 1
- 229910052717 sulfur Inorganic materials 0.000 description 1
- 239000011593 sulfur Substances 0.000 description 1
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- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N29/00—Investigating or analysing materials by the use of ultrasonic, sonic or infrasonic waves; Visualisation of the interior of objects by transmitting ultrasonic or sonic waves through the object
- G01N29/04—Analysing solids
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N29/00—Investigating or analysing materials by the use of ultrasonic, sonic or infrasonic waves; Visualisation of the interior of objects by transmitting ultrasonic or sonic waves through the object
- G01N29/44—Processing the detected response signal, e.g. electronic circuits specially adapted therefor
- G01N29/4409—Processing the detected response signal, e.g. electronic circuits specially adapted therefor by comparison
- G01N29/4427—Processing the detected response signal, e.g. electronic circuits specially adapted therefor by comparison with stored values, e.g. threshold values
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Abstract
The application discloses a quantitative method for central porosity or shrinkage of a casting blank, and provides a rapid and accurate detection method for the central porosity or shrinkage of the casting blank, so that an accurate and effective theoretical basis is provided for a continuous casting process. The method comprises the following steps: (1) sampling and preparing a sample; (2) ultrasonic water immersion nondestructive flaw detection; (3) calculating data; (4) and (5) grading the defects. The method has the advantage of simple operation in the sample processing process, and meanwhile, the defect quantification of the method is converted from two-dimensional to three-dimensional in the prior art, so that the defect degree of center porosity or shrinkage cavity can be more accurately judged, the error caused by conventional artificial subjective judgment is avoided, and the objectivity of defect grading is improved.
Description
Technical Field
The invention belongs to the technical field of metallurgy detection, relates to a method for evaluating the internal quality of a continuous casting billet, and particularly relates to a method for quantifying the central porosity or shrinkage of the casting billet.
Background
In recent decades, with the progress of continuous casting technology in China, the whole steel industry has a rapid development trend. Continuous casting technology is not only one of the indexes for measuring the level of the steel industry, but also has become a main technical power for the development of steel production. With the improvement of the production capacity of steel enterprises and various market demands, the quality inspection of casting blanks becomes one of the key means for ensuring the production quality of continuous casting.
The central porosity and the central shrinkage cavity of the casting blank are important defects influencing the quality of the casting blank, the central porosity and the central shrinkage cavity degree of the casting blank are accurately described, and the method has great significance for optimizing the subsequent continuous casting process. In the continuous casting production, three low-power detection methods, namely a sulfur printing method, a hot acid washing method and a cold acid washing method, are often adopted to detect the quality of a casting blank. The hot acid washing method and the cold acid washing method can detect the central looseness and the central shrinkage cavity degree of the casting blank.
The hot pickling process includes heating the processed sample in dilute hydrochloric acid for some time, and the dilute hydrochloric acid corrodes the steel in different degrees to form segregant, inclusion, crystal boundary, etc. around the crack. The cold pickling method and the hot pickling method have basically the same effect, and do not need a pickling tank and an additional device. The two methods have the defects that the pickling degree cannot be controlled manually, the corrosion degree is not enough or excessive corrosion easily occurs, and the evaluation result is inaccurate by adopting manual observation and judgment.
The invention with the publication number of CN105548207B, and a quantitative determination method for central porosity or shrinkage cavity of continuous casting slab, discloses a quantitative determination method for central porosity or shrinkage cavity of continuous casting slab, which comprises the following steps: taking a casting blank sheet at the transverse center of a casting blank, and processing the surface of the casting blank sheet to ensure that the cross section roughness Ra of the casting blank sheet is 1.2-1.3 mu m; b. making a pattern: b, shooting or scanning the cross section of the casting blank sheet processed in the step a to prepare a high-definition picture; c. image processing: processing the high-definition picture obtained in the step b into a black-white image; d. image analysis: setting the central porosity or shrinkage cavity of the casting blank as a single hole, counting blackWhitening the area of a single-hole pixel of a hole on the image; e. and (3) correlation calculation: calculating to obtain the actual area Sn/mm of the nth single hole of the casting blank sheet2: the calculated value represents the central porosity or central shrinkage degree K. The method has certain requirements on the roughness of the sample, the operation is complex, human errors exist in high-definition picture processing, and the accuracy of the result needs to be considered.
The invention with the publication number of CN103278424A discloses a quantitative evaluation method for center porosity or center shrinkage cavity of a continuous casting billet, which is characterized in that samples with the same size are respectively cut at one fourth of the thickness of the continuous casting billet and the center of the continuous casting billet, the surface of each sample is processed to reach certain smoothness, and the surface of each sample is cleaned by absolute ethyl alcohol. According to the measuring method of QB/T2855-2007 standard, the densities of two samples at the same position of the casting blank are respectively measured. The density of a sample at one fourth of the thickness of the continuous casting billet is rho0The density rho of the sample at the center of the continuous casting slab,
[(ρ0-ρ)/ρ0]the value of x 100% characterizes the degree of central porosity or central shrinkage. The invention adopts quarter sampling, and the sampling mode has the problems that the sample at the quarter of the casting blank is lack of representativeness and the sampling density is small; the accuracy of the detection result needs to be considered.
Therefore, the quantitative assessment method for the central porosity or the central shrinkage of the continuous casting slab related to the prior art has limitations, and intensive research in the aspect is needed.
Disclosure of Invention
The invention aims to solve the technical problem of providing a method for quickly and accurately detecting the central porosity or shrinkage cavity of a continuous casting billet, and providing an accurate and effective theoretical basis for a continuous casting process.
In order to achieve the aim, the quantitative method for the central porosity or shrinkage cavity of the casting blank comprises the following steps:
(1) pretreating a sample, namely polishing the surface of the sample to be detected to be flat and smooth, measuring the size of the sample, recording the length of the sample to be detected as a, the width of the sample to be detected as b and the thickness of the sample to be detected as c;
(2) nondestructive testing, namely putting the polished and flat and smooth sample into ultrasonic water immersion nondestructive testing equipment for nondestructive testing to obtain testing data, and deriving the diameter z, position data (x, y) and the number n of the central loose or shrinkage cavity;
(3) calculating data, namely setting the center porosity or shrinkage cavity of the casting blank as a single sphere, counting the size and the number of the spheres, and calculating the volume V of the sphere according to a formula a);
calculating the casting blank volume V according to a formula b);
abC when v is cast
Calculating to obtain a central porosity or shrinkage cavity index W according to a formula c);
W-V ball/V casting
(5) And determining the level of central porosity or shrinkage according to the w value. When W is 0, the grade of central porosity or shrinkage cavity is judged as 0 grade; when w is more than or equal to 0.050 and less than 0.07, the grade of central loosening or shrinkage cavity is judged as grade 1; when w is more than or equal to 0.07 and less than 0.09, the grade of central loosening or shrinkage cavity is judged as grade 2; when w is more than or equal to 0.09 and less than 0.11, the grade of central loosening or shrinkage cavity is judged as grade 3; when w is more than or equal to 0.11 and less than or equal to 0.13, the level of central porosity or shrinkage cavity is judged to be 4, the numerical value of the rating dividing point is confirmed by the inventor through a large amount of experiments and creative labor, the rating result of the standard YB/T4002-2013 is compatible by corresponding the w value to the rating standard, and the uncertainty caused by artificial subjective judgment is reduced.
Further, the upper surface and the lower surface of the sample to be detected in the step (1) are flat and parallel;
furthermore, the upper limit and the lower limit of W are formulated according to YB/T4002-2013, and the range of W is more than or equal to 0 and less than or equal to 0.13.
Advantageous effects
Compared with the prior art, the beneficial effect of this application includes:
1. the method for quantitatively analyzing the central loosening or shrinkage is adopted, so that the method has the advantage of simple operation in the sample treatment process;
2. the degree of central looseness or shrinkage is judged quantitatively, so that errors caused by judgment of a conventional artificial subjective comparison map are reduced;
3. the method is based on three-dimensional model calculation, and compared with the two-dimensional picture analysis in the prior art, the method can more accurately judge the central porosity or shrinkage cavity degree;
4. the method disclosed by the invention is convenient for detecting the internal quality of the casting blank through implementation and application, can quickly and accurately reflect the quality of the casting blank, provides an accurate and effective theoretical basis for a continuous casting process, and has a wide application prospect and a wide popularization value.
Drawings
FIG. 1 is a low magnification diagram of 3623-287si of example 1
FIG. 2 is a low-power diagram of 1835 and 592si of example 2
FIG. 3 is a 1931-
FIG. 4 is a flaw detection chart of 3623-287si in example 1
FIG. 5 is a schematic view of the 1835 and 592si flaw detection of example 2
FIG. 6 is a 1931-
Detailed Description
Technical solutions in the embodiments of the present invention will be described in detail below, and it is apparent that the described embodiments are only a part of the embodiments of the present invention, and not all embodiments. All other embodiments, which can be obtained by a person skilled in the art without any inventive step based on the embodiments of the present invention, are within the scope of the present invention.
Example 1
The method of the invention determines the central looseness and shrinkage degree of the furnace with the furnace number of 3623-287 si.
(1) Sampling and sample preparation: taking an 87si square billet sample with the cross section of 398mm by 284mm and the height of 130mm, and processing the surface of a casting blank to ensure that the surface of the square billet sample is flat and the upper surface and the lower surface are parallel;
(2) ultrasonic water immersion nondestructive flaw detection: carrying out ultrasonic water immersion nondestructive inspection on the 87si square billet sample;
(3) calculating data; the central porosity or shrinkage cavity of the casting blank is set as a singleCounting the size and number of spheres, wherein 28 holes with the radius of 15 mu m and 3 holes with the radius of 25 mu m are counted according to the formula a)
The volume of the pores V is calculated to be 0.00055m3The casting volume V of the cast slab is calculated to be 0.014m according to the formula b) V3According to the formula c), W is V ball/V casting, the central porosity or shrinkage index is calculated to be 0.039, and the corresponding grade is between 0 grade and 1 grade, so that the central porosity or shrinkage index is 0.5 grade. As can be seen from FIGS. 1 and 4, the rating standard center hole shrinkage of YB/T-4002 and 2013 is also 0.5 grade.
Example 2
The method of the invention determines the degree of central looseness and shrinkage cavity of the furnace with the furnace number of 1835 and 592 si.
(1) Sampling and sample preparation: taking a 92si square billet sample with 398mm by 284mm cross section and 130mm height, and processing the surface of a casting blank to ensure that the surface of the square billet sample is flat and the upper surface and the lower surface are parallel;
(2) ultrasonic water immersion nondestructive flaw detection: carrying out ultrasonic water immersion nondestructive inspection on the 92si square billet sample;
(3) calculating data; setting the central porosity or shrinkage cavity of the casting blank as a single sphere, counting the size and the number of the spheres, and counting that 20 holes with the radius of 15 mu m and 6 holes with the radius of 25 mu m exist according to a formula a)
The volume V of the hole was calculated to be 0.000686m3The casting volume V of the cast slab is calculated to be 0.014m according to the formula b) V3According to the formula c), W is V ball/V casting, the center porosity or shrinkage cavity index W is calculated to be 0.049, and the corresponding grade is between 0 grade and 1 grade, so that the grade is 0.5 grade. As can be seen from FIGS. 2 and 5, the YB/T-4002 and 2013 rating standard also has a central porosity and shrinkage of 0.5 grade.
Although the grades of the example 1 and the example 2 are judged to be 0.5 grade, the conditions of center porosity and center shrinkage of the casting blank of the example 1 are better than those of the casting blank of the example 2 according to the W value.
Example 3
The method of the invention determines the central looseness and shrinkage degree of the furnace with the furnace number of 1931 and 592 si.
(1) Sampling and sample preparation: taking a 92si square billet sample with 398mm by 284mm cross section and 130mm height, and processing the surface of a casting blank to ensure that the surface of the square billet sample is flat and the upper surface and the lower surface are parallel;
(2) ultrasonic water immersion nondestructive flaw detection: carrying out ultrasonic water immersion nondestructive inspection on the 92si square billet sample;
(3) calculating data; setting the central porosity or shrinkage cavity of the casting blank as a single sphere, counting the size and the number of the spheres, and counting that 25 holes with the radius of 15 mu m and 6 holes with the radius of 25 mu m exist according to a formula a)
The volume V of the hole was calculated to be 0.000728m3The casting volume V of the cast slab is calculated to be 0.014m according to the formula b) V3According to the formula c), W is V ball/V casting, the center porosity or shrinkage cavity index W is calculated to be 0.052, and the corresponding grade is 1 grade. As can be seen from the low-magnification images in FIGS. 3 and 6, the rating standard of YB/T-4002 and 2013 is also class 1. From the examples 1, 2 and 3, the rating obtained by the technical scheme of the invention has better consistency and representativeness with the rating of the YB/T-4002-.
The foregoing is merely a detailed description of the present application, and it should be noted that modifications and embellishments could be made by those skilled in the art without departing from the principle of the present application, and these should also be considered as the protection scope of the present application.
Claims (3)
1. A quantitative method for central loosening or shrinkage cavity of a casting blank is characterized by comprising the following steps: the method comprises the following steps: the preparation method comprises the following steps:
(1) sample pretreatment, namely polishing the surface of a sample to be detected to be flat, measuring the size of the sample, recording the length of the sample to be detected as a, the width of the sample to be detected as b and the thickness of the sample to be detected as c;
(2) nondestructive testing, namely putting the polished and flat and smooth sample into ultrasonic water immersion nondestructive testing equipment for nondestructive testing to obtain testing data, and deriving the diameter z, position data (x, y) and the number n of the central loose or shrinkage cavity;
(3) calculating data, namely setting the center porosity or shrinkage cavity of the casting blank as a single sphere, counting the size and the number of the spheres, and calculating a sphere volume V sphere according to a formula a);
calculating the casting blank volume V according to a formula b);
v. cast as abc
Calculating to obtain a central porosity or shrinkage cavity index W according to a formula c);
W-V ball/V casting
(4) Determining the level of central porosity or shrinkage cavity of the casting blank according to the w value; the larger the w value, the more severe the degree of central porosity or shrinkage; when W is 0, the grade of central porosity or shrinkage cavity is judged as 0 grade; when w is more than or equal to 0.050 and less than 0.07, the grade of central loosening or shrinkage cavity is judged as grade 1; when w is more than or equal to 0.07 and less than 0.09, the grade of central loosening or shrinkage cavity is judged as grade 2; when w is more than or equal to 0.09 and less than 0.11, the grade of central loosening or shrinkage cavity is judged as grade 3; when w is more than or equal to 0.11 and less than or equal to 0.13, the grade of central looseness or shrinkage cavity is judged as 4 grade.
2. The method for quantifying the center porosity or shrinkage of an ingot blank according to claim 1, wherein in the step (1), the upper surface and the lower surface of the sample to be detected are flat and parallel.
3. The method of claim 1, wherein the upper and lower limits of W are set according to YB/T4002-2013.
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN115308000A (en) * | 2022-08-29 | 2022-11-08 | 华中科技大学 | Sample for quantitative characterization of evolution of casting hole defects and preparation method thereof |
Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1788872A (en) * | 2005-12-28 | 2006-06-21 | 西北有色金属研究院 | Method for extruding pig metal to steel bar |
| CN105333843A (en) * | 2015-10-20 | 2016-02-17 | 北京北冶功能材料有限公司 | Method for quantitative evaluation of the size of central pipe for a high temperature mother alloy rod |
| CN105548207A (en) * | 2016-02-02 | 2016-05-04 | 攀钢集团攀枝花钢铁研究院有限公司 | Quantitative determination method of central porosity or shrinkage of continuously cast slab |
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- 2020-07-01 CN CN202010617822.XA patent/CN111830131A/en active Pending
Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1788872A (en) * | 2005-12-28 | 2006-06-21 | 西北有色金属研究院 | Method for extruding pig metal to steel bar |
| CN105333843A (en) * | 2015-10-20 | 2016-02-17 | 北京北冶功能材料有限公司 | Method for quantitative evaluation of the size of central pipe for a high temperature mother alloy rod |
| CN105548207A (en) * | 2016-02-02 | 2016-05-04 | 攀钢集团攀枝花钢铁研究院有限公司 | Quantitative determination method of central porosity or shrinkage of continuously cast slab |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN115308000A (en) * | 2022-08-29 | 2022-11-08 | 华中科技大学 | Sample for quantitative characterization of evolution of casting hole defects and preparation method thereof |
| CN115308000B (en) * | 2022-08-29 | 2024-05-17 | 华中科技大学 | Sample for quantitative characterization of casting hole defect evolution and preparation method thereof |
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