Method for Measuring Degree of Wire Segregation

Abstract

The present invention provides a method for measuring the segregation degree of a wire rod, comprising the steps of: taking a cross-sectional sample of the wire rod and processing it into a test sample; obtaining a surface image of the test sample, selecting the segregation spot with the most severe segregation situation in the surface image as the target segregation spot, selecting a first analysis area within the target segregation spot area, and controlling the minimum distance between any point within the first analysis area and the edge contour of the target segregation spot to be not less than a first preset distance; performing surface scanning composition analysis on the first analysis area to obtain the average composition M1 of the segregation elements within the first analysis area; selecting a plurality of comparative analysis areas within the non-segregation area on the same surface of the test sample, respectively performing surface scanning composition analysis on the plurality of comparative analysis areas to obtain the average composition of the segregation elements within the comparative analysis areas and calculating the average value M0 thereof; calculating the ratio of M1 to M0 to obtain the segregation ratio of the segregation elements. The segregation situation detected by this method is more accurate and typical, and the calculated segregation value can more accurately quantitatively reflect the segregation degree of the center of the wire rod.

Description

Technical Field

[0001] The present invention relates to the technical field of alloy detection, and particularly relates to a method for determining the segregation degree of wire rods. Background Art

[0002] Segregation is a solidification phenomenon that cannot be avoided in the conventional production process of alloys such as steel. Due to the difference in the equilibrium concentration of solutes in the solid-liquid two-phase, the solute content in the last solidified part of the steel billet is relatively high, resulting in macrosegregation. The segregation position is rich in solute elements. The existence of segregation deteriorates the performance of the alloy, and cracks and damages are likely to occur during processing and use. Therefore, it is necessary to control and inspect the segregation in the alloy.

[0003] In the analysis of segregation, chip sampling is usually adopted, and the drill bit diameter is usually 3 to 5 mm. For alloy processed structural parts such as wire rods, the segregation range is in the millimeter order of magnitude, and the chips cannot meet the detection requirements. Therefore, at present, only micro-area composition analysis means can be used, and the most commonly used one is the electron probe. However, due to the large composition fluctuation in the segregation area, the data obtained by methods such as line scan analysis, dot analysis, and regional analysis by delimiting a large segregation zone in the existing technical solutions also fluctuate greatly, and the determined segregation degree is limited by the selection of the measurement area, and the measurement result has a certain randomness, making it difficult to fully reflect the actual segregation degree of the segregation area. Summary of the Invention

[0004] The purpose of the present invention is to provide a method for determining the segregation degree of wire rods.

[0005] The present invention provides a method for determining the segregation degree of wire rods, which includes the steps of:

[0006] Taking a cross-sectional sample of the wire rod and processing it into a test sample;

[0007] Obtaining a surface image of the test sample, selecting the segregation spot with the most serious segregation situation in the surface image as the target segregation spot, selecting a first analysis area within the target segregation spot area, and controlling the minimum distance between any point within the first analysis area and the edge contour of the target segregation spot to be not less than a first preset distance;

[0008] Performing surface scan composition analysis on the first analysis area to obtain the average composition of the segregation element M within the first analysis area;

[0009] Selecting a plurality of comparative analysis areas within the non-segregation area on the same surface of the test sample, respectively performing surface scan composition analysis on the plurality of comparative analysis areas to obtain the average composition of the segregation element M within the comparative analysis areas, and obtaining the average value M0 of the average compositions of the plurality of comparative analysis areas;

[0010] Calculate the ratio of M1 to M0 to obtain the segregation ratio of the segregation element.

[0011] As a further improvement of the present invention, selecting the segregation spot with the most severe segregation situation in the surface image as the target segregation spot specifically includes:

[0012] In the surface image, select the segregation spot with the most severe segregation situation as the target segregation spot by combining the distribution area and morphological size of the segregation spots.

[0013] As a further improvement of the present invention, selecting the first analysis area within the target segregation spot area specifically includes:

[0014] Select a square area within the target segregation spot area as the first analysis area, and control the minimum distance between any point within the first analysis area and the edge contour of the target segregation spot to be equal to the first preset distance.

[0015] As a further improvement of the present invention, the first preset distance is 20 μm.

[0016] As a further improvement of the present invention, selecting multiple comparative analysis areas within the non-segregation area on the surface of the same test sample specifically includes:

[0017] Select multiple square comparative analysis areas with the same area as the first analysis area within the non-segregation area on the surface of the same test sample.

[0018] As a further improvement of the present invention, selecting multiple comparative analysis areas within the non-segregation area on the surface of the same test sample further includes:

[0019] Select four areas within the non-segregation area as the comparative analysis areas.

[0020] As a further improvement of the present invention, selecting four areas within the non-segregation area as the comparative analysis areas specifically includes:

[0021] Select four uniformly spaced areas on the circular ring area spaced 1 / 4D from the edge of the test sample as the comparative analysis areas, where D is the wire diameter.

[0022] As a further improvement of the present invention, it further includes:

[0023] Select at least 5 wires of the same batch, and process cross-sectional samples of each into the test samples respectively;

[0024] Measure and calculate the segregation ratio for each of the test samples respectively, and average the 5 segregation ratios to obtain the segregation ratio of the segregation element M.

[0025] As a further improvement of the present invention, processing the cross-sectional sample of the wire rod into a test sample specifically includes:

[0026] Taking a cross-sectional sample of the wire rod, after successively grinding and polishing the cross-section, corroding the cross-section until segregation spots can be distinguished on the cross-section.

[0027] As a further improvement of the present invention, the corrosion of the cross-section specifically includes:

[0028] Corroding the cross-section of the wire rod with a 2% nitric acid alcohol solution.

[0029] The beneficial effect of the present invention is that: for the method for measuring the segregation degree of the wire rod provided by the present invention, directly selecting the segregation spot with the most severe segregation as the detection object, selecting a suitable area therein and then measuring the average composition of the segregation area, and comparing it with the composition of the wire rod matrix area. Compared with the methods of line scan analysis, dot analysis, and delimiting a large segregation zone for regional analysis in the prior art solutions, the segregation situation detected by this method is more accurate and typical, and the calculated segregation value can more accurately quantitatively reflect the segregation degree at the center of the wire rod. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 It is a schematic flowchart of the method for measuring the segregation degree of the wire rod in an embodiment of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0031] To make the objectives, technical solutions, and advantages of the present invention clearer, the technical solutions of the present invention will be clearly and completely described below in conjunction with the specific embodiments of the present invention and the corresponding drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. 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.

[0032] The embodiments of the present invention will be described in detail below. The examples of the embodiments are shown in the drawings, where the same or similar reference numerals denote the same or similar elements or elements with the same or similar functions throughout. The embodiments described below by referring to the drawings are exemplary only for explaining the present invention and should not be construed as limiting the present invention.

[0033] This embodiment provides a method for measuring the segregation degree of a wire rod, which is particularly suitable for detecting the segregation situation at the center of a steel wire rod coil. This method has a small detection error, can quantitatively represent the segregation degree more accurately, and is convenient for comparative analysis of the segregation situation of the steel wire rod.

[0034] In this embodiment, the method is specifically described by detecting the segregation degree of spring steel wire rods. The diameter of the spring steel wire rods is 8 - 18 mm, and the main segregation elements in the spring steel wire rods include C, Cr, Mn, etc.

[0035] As Figure 1 shown, the method for measuring the segregation degree of wire rods includes the steps:

[0036] S1: Take a cross-sectional sample of the wire rod and process it into a test sample.

[0037] S2: Obtain the surface image of the test sample, select the segregation spot with the most serious segregation situation in the surface image as the target segregation spot, select the first analysis area A1 within the target segregation spot area, and control the minimum distance between any point within the first analysis area A1 and the edge contour of the target segregation spot to be not less than the first preset distance L.

[0038] S3: Perform surface scanning composition analysis on the first analysis area A1 to obtain the average composition M1 of the segregation element M within the first analysis area A1.

[0039] S4: Select multiple comparative analysis areas A01, A02... A0N within the non-segregation area on the surface of the same test sample, perform surface scanning composition analysis on the multiple comparative analysis areas respectively to obtain the average compositions M01, M02... M0N of the segregation element M within the comparative analysis areas, and calculate the average value M0 of M01 - M0N.

[0040] S5: Calculate the ratio of M1 to M0 to obtain the segregation ratio of the segregation element.

[0041] In step S1, it specifically includes:

[0042] Take a cross-sectional sample of the wire rod, after grinding and polishing the cross-section in sequence, corrode the cross-section until the segregation spots can be distinguished.

[0043] Specifically, the surface of the cross-sectional sample of the spring steel wire rod can be ground in sequence with sandpapers of different mesh numbers at different angles until the surface of the sample is flat and has no obvious scratches, then polished until the surface is bright, and then the surface of the sample is lightly corroded with a 2% nitric acid alcohol solution until the segregation spot area and the non-segregated area of the steel matrix can be clearly distinguished.

[0044] In other embodiments of the present invention, the composition of the corrosion solution can also be adjusted according to the category of the detection object, as long as the clear morphology of the segregation spots can be corroded.

[0045] In step S2, selecting the segregation spot with the most serious segregation situation as the target segregation spot specifically includes:

[0046] Obtain the surface image of the test sample through an optical microscope. In the surface image, select the segregation spot with the most severe segregation as the target segregation spot by combining the distribution area and morphological size of the segregation spots.

[0047] The appearance and morphology of the segregation spots in the image present as dark spots with slightly concave or no obvious concave shapes and different sizes. Specifically in terms of shape, the segregation spots are mostly irregularly shaped ellipses, circles or oval-shaped like melon seeds. The spot distribution can be intermittent square-shaped, concentric circular or irregularly distributed. The size of the segregation spots varies due to many factors such as the alloy composition of the test object, smelting method, processing method, etc. When selecting the segregation spot with the most severe segregation, considering the above factors comprehensively, manually select the segregation spot with the most severe segregation in the central area of the cross-section. Since the morphology of the segregation spots is relatively easy to analyze and distinguish, the accuracy of the selected segregation spot with the most severe segregation is also relatively high.

[0048] In step S2, select the first analysis area A1 within the target segregation spot area, specifically including:

[0049] Select a square area within the target segregation spot area as the first analysis area A1, and control the minimum distance between any point within the first analysis area A1 and the edge contour of the target segregation spot to be not less than the first preset distance L.

[0050] Here, limit the area position of the first analysis area A1 within the target segregation spot to ensure that the distance between it and the edge contour of the target segregation spot is not less than the first preset distance L, that is, select the first analysis area A1 within the range of indenting the first preset distance L along the edge contour of the target segregation spot, so as to ensure that the first analysis area A1 avoids the area with large composition deviation in the edge area of the segregation spot, thereby improving the accuracy of subsequent detection and making the reliability of the detected data higher.

[0051] Furthermore, under the condition of meeting the above conditions, control the minimum distance between any point within the first analysis area A1 and the edge contour of the target segregation spot to be equal to the first preset distance L, so as to select the area with the largest possible area within the segregation spot area to improve the accuracy of component analysis.

[0052] Furthermore, selecting a square area as the first analysis area A1 can facilitate surface scanning analysis of it and accurate calculation of its area, thereby facilitating the subsequent selection of the comparative analysis area based on the area of the first analysis area A1.

[0053] Specifically, in this embodiment, considering factors such as segregation elements in spring steel, the degree of element segregation, steel processing method, corrosion degree of the etching solution, etc., set the first preset distance L to 20 μm. In other embodiments of the present invention, the length of the first preset distance can also be adjusted according to the above factors.

[0054] In step S3, it specifically includes:

[0055] Perform area scanning analysis on the first analysis area A1 with an electronic probe to obtain the average composition M1 of the segregation element M in the first analysis area A1.

[0056] In this embodiment, area scanning analysis is performed on the average compositions of C, Mn, and Cr. In other embodiments of the present invention, area scanning analysis can also be performed on other elements as needed.

[0057] In step S4, select a plurality of comparative analysis areas A01, A02... A0N on the non-segregation area of the same test sample surface, which specifically includes:

[0058] Select a plurality of square comparative analysis areas A01, A02... A0N with the same area as the first analysis area A1 on the non-segregation area of the same test sample surface.

[0059] Select a comparative analysis area with the same shape and area as the first analysis area to ensure that the conditions for component analysis in the comparative analysis area are the same as those in the first analysis area, thereby further improving the reliability of the data.

[0060] Furthermore, select four areas in the non-segregation area as comparative analysis areas, namely comparative areas A01, A02, A03, and A04.

[0061] Specifically, select four uniformly spaced areas on the circular ring area spaced 1 / 4D from the edge of the test sample as comparative analysis areas A01, A02, A03, and A04, where D is the wire diameter.

[0062] Here, when selecting the comparative analysis area, select the relatively uniform middle area, avoid the area with segregation at the center and the area with relatively uneven composition at the edge, and select four uniformly spaced areas. After measuring the composition, calculate the average value, so that the average value M0 can better represent the overall composition of the wire and ensure that the steel matrix composition for comparative analysis is more representative.

[0063] In other embodiments of the present invention, more comparative analysis areas can also be selected to further make the average value M0 closer to the average composition of the wire matrix.

[0064] After calculating the segregation ratio, the wire segregation degree measurement method further includes:

[0065] Select at least 5 wires of the same batch, and respectively process cross-sectional samples into test samples;

[0066] The segregation ratio is measured and calculated for the test samples respectively, and the average value of the 5 segregation ratios is obtained to get the segregation ratio of the segregation element M.

[0067] Here, by measuring multiple wires, the accuracy of the segregation ratio measurement is further improved, and different positions of the same wire can also be measured and calculated. In other embodiments of the present invention, the number of test samples can also be selected according to the number of wires.

[0068] In summary, for the method for measuring the segregation degree of the wire provided in this embodiment, the segregation spot with the most serious segregation is directly selected as the detection object. After selecting a suitable area therein, the average composition of the segregation area is measured and compared with the composition of the wire matrix area. Compared with the methods of line scan analysis, dot analysis, and delimiting a large segregation zone for regional analysis in the prior art solutions, the segregation situation detected by this method is more accurate and typical, and the calculated segregation value can more accurately quantitatively reflect the segregation degree at the center of the wire.

[0069] It should be understood that although this specification is described according to embodiments, not every embodiment only contains an independent technical solution. This narrative way of the specification is only for clarity. Those skilled in the art should regard the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

[0070] The series of detailed descriptions listed above are only specific descriptions of the feasible embodiments of the present invention, and are not used to limit the protection scope of the present invention. Any equivalent embodiments or changes made without departing from the technical spirit of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for measuring the degree of wire segregation, characterized in that, Including the steps of: Taking a cross-sectional sample of the wire rod and processing it into a test sample; Obtaining a surface image of the test sample, selecting the segregation spot with the most severe segregation in the surface image as the target segregation spot, selecting a square area within the target segregation spot area as the first analysis area, and controlling the minimum distance between any point within the first analysis area and the edge contour of the target segregation spot to be equal to a first preset distance, where the first preset distance is 20 μm; Performing a surface scanning composition analysis on the first analysis area to obtain the average composition M1 of the segregation element M within the first analysis area; Selecting a plurality of comparative analysis areas within the non-segregation area on the same surface of the test sample, respectively performing a surface scanning composition analysis on the plurality of comparative analysis areas to obtain the average compositions of the segregation element M within the plurality of comparative analysis areas, and calculating the average value M0 of the average compositions of the plurality of comparative analysis areas; Calculating the ratio of M1 to M0 to obtain the segregation ratio of the segregation element.

2. The method for measuring the degree of wire segregation according to claim 1, characterized in that The step of selecting the segregation spot with the most severe segregation in the surface image as the target segregation spot specifically includes: In the surface image, selecting the segregation spot with the most severe segregation as the target segregation spot by combining the distribution area and morphological size of the segregation spot.

3. The method for measuring the degree of wire segregation according to claim 1, wherein, The step of selecting a plurality of comparative analysis areas within the non-segregation area on the same surface of the test sample specifically includes: Selecting a plurality of square comparative analysis areas with the same area as the first analysis area within the non-segregation area on the same surface of the test sample.

4. The method for measuring the degree of wire segregation according to claim 3, wherein The step of selecting a plurality of comparative analysis areas within the non-segregation area on the same surface of the test sample further includes: Selecting four areas within the non-segregation area as the comparative analysis areas.

5. The method for measuring the degree of wire segregation according to claim 4, characterized in that, The step of selecting four areas within the non-segregation area as the comparative analysis areas specifically includes: Selecting four uniformly spaced areas on a circular ring area spaced 1 / 4D from the edge of the test sample as the comparative analysis areas, where D is the diameter of the wire rod.

6. The method for measuring the degree of wire segregation according to claim 1, wherein Further including: Selecting at least 5 wire rods of the same batch, respectively taking cross-sectional samples and processing them into the test samples; Measuring and calculating the segregation ratios for the test samples respectively, and calculating the average value of the 5 segregation ratios to obtain the segregation ratio of the segregation element M.

7. The method for measuring the degree of wire segregation according to claim 1, wherein The step of taking a cross-sectional sample of the wire rod and processing it into a test sample specifically includes: Taking a cross-sectional sample of the wire rod, successively grinding and polishing the cross-section, and then corroding the cross-section until the segregation spots can be distinguished.

8. The method for measuring the degree of wire segregation according to claim 7, wherein, The step of corroding the cross-section specifically includes: Corroding the cross-section of the wire rod with a 2% nitric acid alcohol solution.

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