阅读说明：本技术 一种热轧钢带边裂缺陷的检测分析方法 (Method for detecting and analyzing edge crack defect of hot-rolled steel strip ) 是由 赵琼 于 2018-12-26 设计创作，主要内容包括：本发明适用于热轧钢带生产技术领域,提供了一种热轧钢带边裂缺陷的检测分析方法,方法步骤包括；边裂现场调研、切制样坯、制样与检测试验、边裂原因分析和分析结果；本发明克服了以往检测的局限性,将生产实际状况与科学实验及理论相结合,通过对边裂现场的实际调研、标准取制样及各相关项的检测及综合分析,全面地再现生产过程各工序存在的问题点,促使各工序对问题点的快速控制,解决边裂问题,使生产得以恢复,其实质是透过表观缺陷,结合实际调研与科学的数据佐证,最后使边裂缺陷得到控制的落地,切实地解决生产中的实际问题的一种可行的方法。(The invention is suitable for the technical field of hot rolled steel strip production, and provides a method for detecting and analyzing edge crack defects of a hot rolled steel strip, which comprises the following steps of; carrying out on-site investigation on edge cracks, cutting sample blanks, preparing samples, testing, analyzing edge crack causes and analyzing results; the invention overcomes the limitation of the previous detection, combines the actual production condition with scientific experiments and theories, comprehensively reproduces the problem points of each procedure in the production process through the actual investigation and research of the crack site, the standard sampling and sample preparation and the detection and comprehensive analysis of each relevant item, prompts each procedure to rapidly control the problem points, solves the problem of edge crack, recovers the production, and finally makes the edge crack defect controlled to fall to the ground by combining the actual investigation and scientific data evidence through the apparent defect, thereby practically solving the actual problem in the production.)

1. A method for detecting and analyzing edge crack defects of a hot rolled steel strip is characterized by comprising the following steps:

(1) and (3) investigating the edge crack field: checking the basic information of the edge crack, checking the parameters of the steel rolling process and checking the parameters of the steel-making process;

(2) cutting a sample blank:

a, selecting an edge crack metallographic sample blank, cutting a sample blank with the longitudinal length of 300mm and the width of 30mm along the edge crack, and cutting 2 longitudinal metallographic samples and transverse metallographic samples with edge cracks from the sample blank respectively;

b, cutting a chemical component sample from 1/4-3/4 in the width direction of the edge crack roll, and polishing off an iron oxide skin layer on the surface of a rectangular sample with the longitudinal length of 20mm and the transverse length of 150-200 mm;

c, cutting an oxygen-nitrogen sample, avoiding edge cracking, cutting the oxygen-nitrogen sample, and then preparing a standard oxygen-nitrogen spherical sample;

d, cutting a lateral crack sample with the metal at the most edge part in the width direction, and performing electron microscope and x-ray energy spectrum analysis;

(3) sample preparation and detection test:

a, metallographic phase sample preparation and detection; observing cracks, inclusion and slag inclusion of the metallographic sample blank, carrying out microscopic structure observation, and observing oxidation decarburization and crystal grain change conditions on two sides of the cracks by using the longitudinal metallographic sample; observing the abnormal conditions of the depth, the propagation direction and the crack position of the crack, the oxidation decarburization condition, the oxidation decarburization depth and the grain size of the transverse metallographic specimen;

b, analyzing oxygen and nitrogen and spectral components; detecting the contents of oxygen and nitrogen in the oxygen and nitrogen sample by an oxygen and nitrogen analyzer; detecting the component contents of carbon, silicon, aluminum, phosphorus and sulfur in the chemical component sample by a spectrometer;

c, analyzing by an electron microscope; checking abnormal conditions on two sides of the crack of the transverse edge crack sample through an electron microscope, wherein the abnormal conditions comprise air holes, high-temperature oxidation points and slag inclusion, and performing X-ray energy spectrum micro-area component determination on abnormal substances observed by the electron microscope through an energy spectrometer to judge the properties and the sources of the substances;

d, analyzing hypo-tissues; checking the internal quality and the external quality of the casting blank for the same furnace casting blank with edge crack, checking whether bubbles exist, the casting blank is deformed on a narrow surface, and checking whether cracks are caused by deformation; for the cross-section blank of the current-period casting blank, whether the edge part of the casting blank has an appearance defect causing edge crack or not is judged;

(4) analyzing the reason of edge cracking; comprehensively analyzing the detection results, constructing data chains causing edge cracks, and mutually verifying to obtain accurate and operable analysis results;

(5) analyzing the result; and sending the detection data and the analysis result to related management personnel and technical personnel in time.

2. The method for detecting and analyzing the edge crack defect of the hot-rolled steel strip as claimed in claim 1, wherein the method comprises the following steps: the basic information of the edge cracks comprises the shape, the color, the number, the furnace coil number and the radial position information of the edge cracks in the coil; the steel rolling process parameters comprise the heating temperature and the in-furnace time of the casting blank; the steelmaking process parameters comprise the recorded data of the casting blank quality, the addition of deoxidized alloy and aluminum wires, the times of furnace turning and the end point carbon.

3. The method for detecting and analyzing the edge crack defect of the hot-rolled steel strip as claimed in claim 2, wherein the method comprises the following steps: the longitudinal sample size is 20mm in longitudinal direction and 15-20mm in width direction, and the transverse sample size is 20mm in width direction and 15-20mm in longitudinal direction.

4. The method for detecting and analyzing the edge crack defect of the hot-rolled steel strip as claimed in claim 3, wherein the method comprises the following steps: the oxygen and nitrogen sample weight is obtained according to the sample size requirement of the oxygen and nitrogen instrument.

5. The method for detecting and analyzing the edge crack defect of the hot-rolled steel strip as claimed in claim 4, wherein the method comprises the following steps: and the size of the edge crack transverse sample is consistent with that of the transverse metallographic sample.

6. The method for detecting and analyzing the edge crack defect of the hot-rolled steel strip as claimed in claim 5, wherein the method comprises the following steps: and the metallographic sample blank is subjected to inlaying, coarse grinding, fine grinding and polishing, cracks, inclusion and slag inclusion are observed, and then microstructure observation is carried out after the metallographic sample blank is corroded by 4% nitric acid alcohol solution.

7. The method for detecting and analyzing the edge crack defect of the hot-rolled steel strip as claimed in claim 6, wherein the method comprises the following steps: the oxygen and nitrogen samples need to be cleaned of surface scale.

8. The method for detecting and analyzing the edge crack defect of the hot-rolled steel strip as claimed in claim 7, wherein the method comprises the following steps: the thickness of the longitudinal hot cutting size of the cross-section billet of the casting blank is 50 +/-5 mm.

9. The method for detecting and analyzing the edge crack defect of the hot-rolled steel strip as claimed in claim 8, wherein the method comprises the following steps: the original analysis of the edge crack comprises the on-site investigation result, various detection structures and the edge crack map contrast.

Technical Field

The invention belongs to the technical field of hot rolled steel strip production, and particularly relates to a method for detecting and analyzing edge crack defects of a hot rolled steel strip.

Background

The technique comprehensively provides a method for detecting and analyzing the edge crack defect of the hot rolled steel strip, is suitable for detecting and analyzing the edge crack defect of the hot rolled steel strip production enterprise, provides accurate detection and analysis results for quality improvement and process control, and can determine the problem of which process point is detected according to the detection and analysis results, thereby guiding the corresponding process point to quickly control the defect problem, reducing quality loss and quickly recovering the normal production.

Generally, users of hot rolling wide belts and narrow belts determine the specification of an order contract according to the width of a manufactured workpiece and a hot rolling enterprise, the width is generally not changeable, but when edge cracks occur in production, the problem that the users cannot use the hot rolling wide belts and the hot rolling narrow belts due to the defect of edges is caused, and the contract delivery period is prolonged; meanwhile, once edge cracks appear in a production enterprise, the production enterprise often has batch quality loss, finds out edge crack problem points quickly and controls the problem, and the problem is solved quickly, so that the main problem points of the edge cracks need to be determined from numerous influence factors, and the control can be performed pertinently.

The existing common detection and analysis technology only reflects the characteristics of some aspects of edge crack from a certain aspect, lacks of a corroborative scientific data chain and often leads to one-sided analysis conclusion.

The following are the characteristics and limitations of each test:

(1) analyzing macro topography; from the appearance characteristics of edge cracks, the color, the number and the defect positions of the edge cracks can be preliminarily analyzed, but convincing scientific data cannot be taken out, and the opinions of different process managers and technicians cannot be unified;

(2) carrying out metallographic detection; whether oxidation decarburization exists at an edge crack or not can be generally observed through metallographic detection so as to judge whether the casting blank problem or the steel rolling problem exists, but the detection result has the limitation that firstly, the real reason causing the casting blank crack cannot be determined; secondly, when the sampling is not standard and the defect information of the original metal at the widest-direction edge part is not obtained, the phenomenon of oxidation and decarburization can not be observed, and the problem that the steel rolling is determined to be constant because the oxidation and decarburization can not be observed in the situation.

(3) Detecting hypoploid tissues; the macroscopic structure analysis can only see the quality defect inside a casting blank in the smelting or continuous casting process, but can lack the quality information of a steel rolling process;

(4) detecting components; the detection of chemical composition and oxygen and nitrogen analysis can analyze and judge the problems existing in the steel-making process, and the influence on the steel rolling process cannot be detected.

(5) An electron microscope; the method can be used for carrying out amplification observation on information which cannot be observed by the metallographic microstructure, and can be used for carrying out micro-area qualitative and quantitative analysis on EDS components, thereby further supplementing the metallographic microstructure.

(6) Carrying out on-site investigation; the actual operation, the process execution condition and the product quality condition of different procedures in the production process can be considered in the field.

Disclosure of Invention

The invention provides a method for detecting and analyzing edge crack defects of a hot rolled steel strip, aiming at solving the problem that steel rolling production enterprises can only visually observe by appearance and judge by experience when no metallographic detection is carried out; the method comprises the following steps of (1) observing whether oxidation decarburization exists at an edge crack by using a metallographic phase detected by a metallographic phase so as to judge whether a casting blank has a problem or not; because electron microscope equipment cost is higher, some enterprises use less. The single detection methods are relatively single-sided, have large limitations, cannot accurately give an analysis result, and cannot pointedly judge and quickly control the process with production problems, so that the quality problems can be sustained, and the problem of larger quality loss is caused.

The invention is realized in such a way that a detection and analysis method for the edge crack defect of the hot rolled steel strip;

(1) and (3) investigating the edge crack field: checking the basic information of the edge crack, checking the parameters of the steel rolling process and checking the parameters of the steel-making process;

(2) cutting a sample blank:

a, selecting an edge crack metallographic sample blank, cutting a sample blank with the longitudinal length of 300mm and the width of 30mm along the edge crack, and cutting 2 longitudinal metallographic samples and transverse metallographic samples with edge cracks from the sample blank respectively;

b, cutting a chemical component sample from 1/4-3/4 in the width direction of the edge crack roll, and polishing off an iron oxide skin layer on the surface of a rectangular sample with the longitudinal length of 20mm and the transverse length of 150-200 mm;

c, cutting an oxygen-nitrogen sample, avoiding edge cracking, cutting the oxygen-nitrogen sample, and then preparing a standard oxygen-nitrogen spherical sample;

d, cutting a lateral crack sample with the metal at the most edge part in the width direction, and performing electron microscope and x-ray energy spectrum analysis;

(3) sample preparation and detection test:

a, metallographic phase sample preparation and detection; observing cracks, inclusion and slag inclusion of the metallographic sample blank, carrying out microscopic structure observation, and observing oxidation decarburization and crystal grain change conditions on two sides of the cracks by using the longitudinal metallographic sample; observing the abnormal conditions of the depth, the propagation direction and the crack position of the crack, the oxidation decarburization condition, the oxidation decarburization depth and the grain size of the transverse metallographic specimen;

b, analyzing oxygen and nitrogen and spectral components; detecting the contents of oxygen and nitrogen in the oxygen and nitrogen sample by an oxygen and nitrogen analyzer; detecting the component contents of carbon, silicon, aluminum, phosphorus and sulfur in the chemical component sample by a spectrometer;

c, analyzing by an electron microscope; checking abnormal conditions on two sides of the crack of the transverse edge crack sample through an electron microscope, wherein the abnormal conditions comprise air holes, high-temperature oxidation points and slag inclusion, and performing X-ray energy spectrum micro-area component determination on abnormal substances observed by the electron microscope through an energy spectrometer to judge the properties and the sources of the substances;

d, analyzing hypo-tissues; checking the internal quality and the external quality of the casting blank for the same furnace casting blank with edge crack, checking whether bubbles exist, the casting blank is deformed on a narrow surface, and checking whether cracks are caused by deformation; for the cross-section blank of the current-period casting blank, whether the edge part of the casting blank has an appearance defect causing edge crack or not is judged;

(4) analyzing the reason of edge cracking; comprehensively analyzing the detection results, constructing data chains causing edge cracks, and mutually verifying to obtain accurate and operable analysis results;

(5) analyzing the result; and sending the detection data and the analysis result to related management personnel and technical personnel in time.

The invention also provides the optimization that the basic information of the edge cracks comprises the information of the appearance, the color, the quantity, the furnace coil number and the radial position of the edge cracks in the coil; the steel rolling process parameters comprise the heating temperature and the in-furnace time of the casting blank; the steelmaking process parameters comprise the recorded data of the casting blank quality, the addition of deoxidized alloy and aluminum wires, the times of furnace turning and the end point carbon.

The invention also provides that preferably, the longitudinal sample dimension is 20mm in longitudinal direction and 15-20mm in width direction, and the transverse sample dimension is 20mm in width direction and 15-20mm in longitudinal direction.

The invention also provides a preferable mode, and the size of the edge crack transverse sample is consistent with that of the transverse metallographic sample.

Preferably, the metallographic sample blank is subjected to inlaying, coarse grinding, fine grinding and polishing, cracks, inclusion and slag inclusion are observed, and then microstructure observation is carried out after the metallographic sample blank is corroded by 4% nitric acid alcohol solution.

The invention also provides that the oxygen-nitrogen sample needs to be cleaned of surface iron oxide scale.

The invention also provides a preferable mode, and the thickness of the transverse billet of the casting billet in the longitudinal hot cutting dimension is 50 +/-5 mm.

The invention also provides the optimization that the original analysis of the edge crack comprises the on-site investigation result, various detection structures and the edge crack map contrast.

Compared with the prior art, the invention has the beneficial effects that: the invention relates to a method for detecting and analyzing edge crack defects of a hot rolled steel strip, which overcomes the limitations of the prior detection, combines the actual production condition with scientific experiments and theories, comprehensively reproduces the problem points existing in each process in the production process through the actual investigation and research of the edge crack field, the standard sampling and sample preparation and the detection and comprehensive analysis of each relevant item, prompts each process to rapidly control the problem points, solves the edge crack problem, recovers the production, and finally makes the edge crack defect fall to the ground by combining the actual investigation and scientific data evidence through the apparent defect, thereby practically solving the actual problem in the production.

Drawings

FIG. 1 is a schematic diagram of a detection and analysis timing structure according to the present invention;

FIG. 2 is a schematic diagram of a detailed timing structure of the field investigation of the present invention;

FIG. 3 is a schematic diagram of a detailed timing structure of a blank sample according to the present invention;

FIG. 4 is a schematic diagram of a detailed timing structure of sample preparation and detection tests according to the present invention;

FIG. 5 is a diagram illustrating a detailed timing structure of an original edge crack analysis according to the present invention;

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is described in further detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

Referring to fig. 1-5, the present invention provides a technical solution for detecting and analyzing edge crack defects of a hot rolled steel strip: