CN112964856A - Method for detecting surface crack defects of continuous casting round billet - Google Patents
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Abstract
The invention relates to a method for detecting surface crack defects of continuous casting round billets, which comprises the following steps: (1) preparing a billet sample; (2) preparing a porous sample containing groove; (3) placing a steel billet sample to be detected into the porous sample containing groove, and reserving a gap between the steel billet sample and the side wall of the porous sample containing groove; (4) corrosion by strong acid solution; (5) neutralizing with hot alkali solution; (6) and detecting surface crack defects. The invention utilizes the porous sample containing groove to contain the continuous casting round billet sample, avoids the situations of difficult operation and easy slipping when the sample is directly clamped and is immersed in acid liquor and taken out from the acid liquor, adopts the selective corrosion acid-base neutralization thermal acid corrosion method, and completely and effectively displays the crack defect form distributed along the circumferential surface of the billet sample in original appearance.
Description
Technical Field
The invention relates to the technical field of metal material detection and analysis, in particular to a method for detecting surface crack defects of continuous casting round billets.
Background
The surface crack defect of the continuous casting billet is one of the more common casting billet defects, and the incidence rate of the surface crack defect of the continuous casting billet containing peritectic steel with the carbon content fraction of 0.13-0.17 wt% and simultaneously containing trace Nb and other alloy elements is obviously higher than that of the common casting billet. Cracks are likely to be generated on the surface of a casting blank in the processes of molten steel solidification, casting blank cooling and straightening, larger surface cracks can be removed in a surface flame cleaning mode, and smaller cracks below an iron scale on the surface of the casting blank are difficult to find and are exposed in the subsequent forging and rolling processes; in addition, fine micro-cracks are easily formed on the surface of the round billet during the rolling process of the square billet into the round billet, which can increase the rejection rate of products.
At present, the common method for inspecting the surface crack defects of the continuous casting billet is a low-power hot acid etching method. The method comprises the steps of taking a cross section of a steel billet, grinding and processing the cross section to obtain a certain smooth finish, corroding the cross section by using a 1:1 hydrochloric acid aqueous solution, and macroscopically observing whether the edge of the cross section has an inwardly-extending crack or not. The method is suitable for cross section inspection of square billets, plate billets or round billets with larger sizes. When the round steel billets, steel bars and the like with small sizes need to be inspected to determine whether cracks exist on the whole circumferential surface along the longitudinal direction, the method has certain limitation. Because the round steel billet is easy to roll, especially the rodlike round steel billet with smaller diameter is easy to drop into an acid tank because of unstable clamping when a billet sample is immersed into acid liquor and taken out of the acid tank in an opaque hot acid solution, so that the corrosion time and effect are difficult to control, over-corrosion or insufficient corrosion time is caused, and the appearance of cracks on the surface of the sample cannot be effectively displayed. Based on the situation, how to ensure the defect and crack original appearance display of the round billet with smaller size is the problem to be solved.
Disclosure of Invention
The invention provides a method for detecting surface crack defects of continuous casting round billets, which utilizes a porous sample containing groove to contain a continuous casting round billet sample, avoids the situations of difficult operation and easy slipping when the sample is immersed in acid liquor and taken out from the acid liquor during direct clamping of the sample, adopts an acid-base neutralization thermal etching method of selective corrosion, and completely and effectively displays the crack defect forms distributed along the circumferential surface of the billet sample in original appearance.
In order to achieve the purpose, the invention adopts the following technical scheme:
a method for detecting surface crack defects of continuous casting round billets comprises the following steps:
(1) preparing a billet sample; cutting one or more sections of continuous casting round billets to be used as billet samples, wherein the length of each billet sample is 120-200 mm;
(2) preparing a porous sample containing groove; the multi-hole sample containing groove is made of a stainless steel plate, a plurality of through holes are formed in the bottom and the four walls of the multi-hole sample containing groove respectively, the length of the multi-hole sample containing groove is larger than that of a steel billet sample, and the width of the multi-hole sample containing groove meets the requirement that a plurality of steel billet samples can be placed side by side;
(3) placing a steel billet sample to be detected into the porous sample containing groove, and reserving a gap between the steel billet sample and the side wall of the porous sample containing groove;
(4) corrosion by strong acid solution; heating the acid liquor to 60-70 ℃, integrally immersing the porous sample containing tank containing the steel billet sample into the heated acid liquor, ensuring that the steel billet sample is completely immersed by the acid liquor, keeping for 20-30 minutes after the temperature of the solution is raised to 60-70 ℃, and then taking out the porous sample containing tank from the acid liquor;
(5) neutralizing with hot alkali solution; preparing an alkali liquor in advance, and heating to 50-60 ℃; immediately immersing the porous sample containing groove taken out of the acid solution into the heated alkali liquor, staying for 3-5 minutes, and then taking out the porous sample containing groove; washing the steel billet sample in the porous sample containing groove with water at 15-25 ℃, simultaneously brushing the surface of the steel billet sample, and finally drying with hot air;
(6) detecting surface crack defects; confirming the position of the crack, measuring the length and the depth of the crack, and counting the number of the crack.
The acid solution is prepared by mixing hydrochloric acid and water in a volume ratio of 1: (0.8-1.2) aqueous hydrochloric acid solution.
The alkali liquor is sodium hydroxide aqueous solution with the concentration of 2-3%.
The diameter of the through hole in the stainless steel groove is 10-30 mm.
Handles are arranged on two sides of the top of the stainless steel groove.
The diameter of the continuous casting round billet is less than or equal to 200 mm.
Compared with the prior art, the invention has the beneficial effects that:
1) the crack defect existing on the circumferential surface of the small-diameter continuous casting round billet can be clearly and comprehensively displayed, and the distribution state, the size and the size of the crack can be accurately detected.
2) The multi-hole sample containing groove is used for containing the steel billet sample, so that the corrosion operation time of the continuous casting round steel billet sample with small diameter and easy rolling can be accurately controlled, and the situations of difficult operation and easy slipping when the sample is directly clamped and immersed in acid liquor and taken out from the acid liquor are avoided.
3) The method has the characteristics of small pollution, energy conservation and simple and convenient operation, can detect a plurality of continuous casting round billets at the same time, and has high detection efficiency.
Drawings
Fig. 1 is a schematic perspective view of a stainless steel tank according to the present invention.
Detailed Description
The following further describes embodiments of the present invention with reference to the accompanying drawings:
the invention relates to a method for detecting surface crack defects of continuous casting round billets, which comprises the following steps:
(1) preparing a billet sample; cutting one or more sections of continuous casting round billets to be used as billet samples, wherein the length of each billet sample is 120-200 mm;
(2) preparing a porous sample containing groove; as shown in fig. 1, the porous sample containing groove is made of a stainless steel plate, a plurality of through holes are respectively formed in the bottom and the four walls of the porous sample containing groove, the length of the porous sample containing groove is greater than that of a billet sample, and the width of the porous sample containing groove meets the requirement that a plurality of billet samples can be placed side by side;
(3) placing a steel billet sample to be detected into the porous sample containing groove, and reserving a gap between the steel billet sample and the side wall of the porous sample containing groove;
(4) corrosion by strong acid solution; heating the acid liquor to 60-70 ℃, integrally immersing the porous sample containing tank containing the steel billet sample into the heated acid liquor, ensuring that the steel billet sample is completely immersed by the acid liquor, keeping for 20-30 minutes after the temperature of the solution is raised to 60-70 ℃, and then taking out the porous sample containing tank from the acid liquor;
(5) neutralizing with hot alkali solution; preparing an alkali liquor in advance, and heating to 50-60 ℃; immediately immersing the porous sample containing groove taken out of the acid solution into the heated alkali liquor, staying for 3-5 minutes, and then taking out the porous sample containing groove; washing the steel billet sample in the porous sample containing groove with water at 15-25 ℃, simultaneously brushing the surface of the steel billet sample, and finally drying with hot air;
(6) detecting surface crack defects; confirming the position of the crack, measuring the length and the depth of the crack, and counting the number of the crack.
The acid solution is prepared by mixing hydrochloric acid and water in a volume ratio of 1: (0.8-1.2) aqueous hydrochloric acid solution.
The alkali liquor is sodium hydroxide aqueous solution with the concentration of 2-3%.
The diameter of the through hole in the stainless steel groove is 10-30 mm.
Handles are arranged on two sides of the top of the stainless steel groove.
The diameter of the continuous casting round billet is less than or equal to 200 mm.
Compared with the conventional detection method, the detection method for the surface crack defects of the continuous casting round billet has the following characteristics:
(1) the multi-hole sample containing groove is adopted, a plurality of steel billet samples can be uniformly arranged in the multi-hole sample containing groove, and in the corrosion operation process, acid liquor or alkali liquor entering the groove from the bottom of the stainless steel groove and the through holes on the 4 side walls can ensure that the surfaces of the steel billet samples are uniformly corroded.
(2) Because the steel billet sample is wholly immersed or taken out by the porous sample containing groove, the corrosion time and temperature of the surface of the steel billet sample can be accurately controlled, the local over-corrosion or under-corrosion is avoided, and a good corrosion effect is obtained.
(3) Through the hot acid-base neutralization corrosion operation, the specific micro surface cracks of the small-size continuous casting round billet can be more completely and clearly exposed, and the crack missing detection phenomenon in the conventional corrosion detection is avoided.
The following examples are carried out on the premise of the technical scheme of the invention, and detailed embodiments and specific operation processes are given, but the scope of the invention is not limited to the following examples. The methods used in the following examples are conventional methods unless otherwise specified.
[ example 1 ]
In this embodiment, the billet sample to be detected is obtained from a low-carbon steel continuous casting round billet, and the main chemical components of the billet sample are as follows: 0.11 wt% of C; si 0.05 wt%; 0.30 wt% of Mn; p0.014 wt%; s0.0031 wt%; the balance being Fe. The diameter of the billet sample is
The surface crack defect detection process is as follows:
1. preparation work before detection;
preparing a bottom and four walls with a plurality of through holes (the diameter of the through hole is
) According to the stainless steel porous sample containing groove, 4 steel billet samples are placed in the porous sample containing groove, gaps are reserved between the steel billet samples and between the outermost steel billet sample and the groove wall, and the surfaces of the steel billet samples can be guaranteed to be evenly corroded by a solution filled from the through holes.
Preparing hydrochloric acid aqueous solution with the volume ratio of 1:1 in a conventional acid tank, wherein the depth of the hydrochloric acid aqueous solution can be completely immersed in the billet sample after the porous sample containing tank is placed.
And preparing a sodium hydroxide aqueous solution with the concentration of 2% in another stainless steel tank, wherein the solution depth is the same as that of the stainless steel tank, and the billet sample can be completely immersed after the stainless steel tank is placed in the porous sample containing tank.
2. Hot acid erosion;
heating the hydrochloric acid aqueous solution in the acid tank to 65 ℃, immersing the porous sample containing tank with the billet sample into the hot acid liquid, slightly reducing the temperature of the acid liquid after immersion, starting timing after the temperature of the acid liquid reaches 65 ℃ again, carrying out immersion corrosion for 30 minutes, and swinging the porous sample containing tank properly during immersion corrosion to enable the billet sample to be corroded uniformly. And after timing is finished, taking out the porous sample containing groove, observing the surface of the billet sample, obtaining a better corrosion effect, and stopping corrosion. Immediately after the porous sample holding tank is taken out from the acid tank, the billet sample is rinsed with hot water for 2 minutes.
3. Neutralizing with alkali solution;
heating a prepared sodium hydroxide aqueous solution to 60 ℃, soaking a billet sample which is taken out from an acid solution and washed by hot water into the hot alkali solution together with a porous sample containing groove, staying for 4 minutes, swinging at proper time, then taking out from the alkali solution, washing the billet sample by 20 ℃ water one by one, brushing the surface of the billet sample by a brush, and drying by hot air.
4. Inspecting surface crack defects;
the surface of the billet sample is observed by naked eyes or a magnifying lens of 10 times, after acid-base corrosion and neutralization treatment, various defects on the circumferential surface of the billet sample are clearly shown, the number, the length and the depth of cracks can be conveniently detected, the billet sample is photographed, and the detection result is recorded in an inspection report.
[ example 2 ]
In this example, the billet sample to be tested was cut from 60Si2Mn continuous casting round billet with billet sample diameter of
The surface crack defect detection process is as follows:
1. preparation work before detection;
preparing a bottom and four walls with a plurality of through holes (the diameter of the through hole is
) According to the stainless steel porous sample containing groove, 3 steel blank samples are placed in the porous sample containing groove, gaps are reserved between the steel blank samples and between the outermost steel blank sample and the groove wall, and the surfaces of the steel blank samples can be guaranteed to be evenly corroded by a solution filled from the through holes.
Preparing hydrochloric acid aqueous solution with the volume ratio of 1:1 in a conventional acid tank, wherein the depth of the hydrochloric acid aqueous solution can be completely immersed in the billet sample after the porous sample containing tank is placed.
And preparing a 3% sodium hydroxide aqueous solution in another stainless steel tank, wherein the solution depth is the same as that of the stainless steel tank, and the billet sample can be completely immersed after the stainless steel tank is placed in the porous sample containing tank.
2. Hot acid erosion;
heating the hydrochloric acid aqueous solution in the acid tank to 70 ℃, immersing the porous sample containing tank with the billet sample into the hot acid liquid, slightly reducing the temperature of the acid liquid after immersion, starting timing after the temperature of the acid liquid reaches 70 ℃ again, carrying out immersion corrosion for 30 minutes, and swinging the porous sample containing tank properly during immersion corrosion to enable the billet sample to be corroded uniformly. And after timing is finished, taking out the porous sample containing groove, observing the surface of the billet sample, obtaining a better corrosion effect, and stopping corrosion. Immediately after the porous sample holding tank is taken out from the acid tank, the billet sample is rinsed with hot water for 2 minutes.
3. Neutralizing with alkali solution;
heating a prepared sodium hydroxide aqueous solution to 50 ℃, soaking the billet sample which is taken out from the acid solution and washed by hot water into the hot alkali solution together with the porous sample containing groove, staying for 5 minutes, swinging at proper time, then taking out from the alkali solution, washing the billet sample one by using water at 15 ℃, brushing the surface of the billet sample by using a brush, and drying by using hot air.
4. Inspecting surface crack defects;
the surface of the billet sample is observed by naked eyes or a magnifying lens of 10 times, after acid-base corrosion and neutralization treatment, various defects on the circumferential surface of the billet sample are clearly shown, the number, the length and the depth of cracks can be conveniently detected, the billet sample is photographed, and the detection result is recorded in an inspection report.
The above description is only for the preferred embodiment of the present invention, but the scope of the present invention is not limited thereto, and any person skilled in the art should be considered to be within the technical scope of the present invention, and the technical solutions and the inventive concepts thereof according to the present invention should be equivalent or changed within the scope of the present invention.
Claims (6)
1. A method for detecting surface crack defects of continuous casting round billets is characterized by comprising the following steps:
(1) preparing a billet sample; cutting one or more sections of continuous casting round billets to be used as billet samples, wherein the length of each billet sample is 120-200 mm;
(2) preparing a porous sample containing groove; the multi-hole sample containing groove is made of a stainless steel plate, a plurality of through holes are formed in the bottom and the four walls of the multi-hole sample containing groove respectively, the length of the multi-hole sample containing groove is larger than that of a steel billet sample, and the width of the multi-hole sample containing groove meets the requirement that a plurality of steel billet samples can be placed side by side;
(3) placing a steel billet sample to be detected into the porous sample containing groove, and reserving a gap between the steel billet sample and the side wall of the porous sample containing groove;
(4) corrosion by strong acid solution; heating the acid liquor to 60-70 ℃, integrally immersing the porous sample containing tank containing the steel billet sample into the heated acid liquor, ensuring that the steel billet sample is completely immersed by the acid liquor, keeping for 20-30 minutes after the temperature of the solution is raised to 60-70 ℃, and then taking out the porous sample containing tank from the acid liquor;
(5) neutralizing with hot alkali solution; preparing an alkali liquor in advance, and heating to 50-60 ℃; immediately immersing the porous sample containing groove taken out of the acid solution into the heated alkali liquor, staying for 3-5 minutes, and then taking out the porous sample containing groove; washing the steel billet sample in the porous sample containing groove with water at 15-25 ℃, simultaneously brushing the surface of the steel billet sample, and finally drying with hot air;
(6) detecting surface crack defects; confirming the position of the crack, measuring the length and the depth of the crack, and counting the number of the crack.
2. The method for detecting the surface crack defects of the continuously cast round billet as claimed in claim 1, wherein the acid solution is hydrochloric acid and water at a volume ratio of 1: (0.8-1.2) aqueous hydrochloric acid solution.
3. The method for detecting the surface crack defects of the continuously cast round billet according to claim 1, wherein the alkali solution is a sodium hydroxide aqueous solution with the concentration of 2-3%.
4. The method for detecting the surface crack defects of the continuously cast round steel billet according to claim 1, wherein the diameter of the through hole in the stainless steel groove is 10-30 mm.
5. The method for detecting the surface crack defects of the continuously cast round steel billets as claimed in claim 1, wherein handles are arranged on two sides of the top of the stainless steel groove.
6. The method for detecting the surface crack defects of the continuous casting round billet according to claim 1, wherein the diameter of the continuous casting round billet is less than or equal to 200 mm.
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| CN207396302U (en) * | 2017-11-21 | 2018-05-22 | 山东莱芜金雷风电科技股份有限公司 | A kind of coarse micro-grain sample acid etching verifying attachment |
| CN211036111U (en) * | 2019-10-31 | 2020-07-17 | 广东省韶关市质量计量监督检测所 | Thermal acid etching device |
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2021
- 2021-02-09 CN CN202110176061.3A patent/CN112964856A/en active Pending
Patent Citations (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102297785A (en) * | 2011-04-18 | 2011-12-28 | 首钢水城钢铁（集团）有限责任公司 | Method for exposing profile tiny tissue defects of high-carbon steel continuous casting billet |
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| CN106546596A (en) * | 2015-09-17 | 2017-03-29 | 鞍钢股份有限公司 | A kind of method of inspection for determining continuous casting steel billet subsurface inclusion defective locations |
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