A method for analyzing and locating the causes of crack defects in automobile outer panel steel

Abstract

The present invention particularly relates to a method for analyzing and locating the cause of cracking defects of steel for automobile outer panels, belonging to the technical field of defect analysis, and the method comprises: measuring defects of a defective plate to be analyzed to obtain defect information; preparing a sample of the defective plate to be analyzed according to the defect information, so that the ratio of the size of the prepared sample to the area of ​​the defect meets a set ratio to obtain a sample; pre-treating the sample to obtain a sample body; performing defect surface analysis on the sample body to obtain a surface analysis result; inlaying the sample body, and then performing cross-section analysis to obtain a cross-section analysis result; performing metallographic analysis on the defects of the sample body at a set multiple to obtain a metallographic analysis result; determining the cause of the cracking defect according to the surface analysis result, the cross-section analysis result and the metallographic analysis result; by combining defect surface analysis, cross-section analysis and metallographic analysis, the source of the defect can be accurately judged, thereby solving the problem that the source of the defect cannot be traced at present.

Description

Technical Field

[0001] The invention belongs to the technical field of defect analysis, and in particular relates to a method for analyzing and locating the cause of crack defects in steel used for automobile outer panels. Background Art

[0002] As the automobile industry develops towards lightweight, higher requirements are placed on the quality of automobile outer panels. On the one hand, the thickness of automobile panels is getting thinner and thinner, and on the other hand, the thinning rate of automobile panels is getting larger and larger, which leads to frequent cracking defects during the stamping process. As we all know, defects may occur in any link of the production process, from slabs to hot rolling, acid rolling to cold rolling. The formation of defects and the process they go through are many, the process is long, the cycle is long, and there are many factors. The defects caused by the previous and subsequent processes are intertwined, making it difficult to identify and determine the defects, and it is impossible to trace the source of the defects. Summary of the invention

[0003] The purpose of the present application is to provide a method for analyzing and locating the cause of crack defects in automobile outer panel steel, so as to solve the problem that the source of the defects cannot be traced at present.

[0004] The embodiment of the present invention provides a method for analyzing and locating the cause of crack defects in steel for automobile outer panels, the method comprising:

[0005] Measure the defects of the defective board to be analyzed and obtain defect information;

[0006] Prepare samples of the defective plate to be analyzed according to the defect information, so that the ratio of the sample size to the defect area meets the set ratio, and obtain the sample;

[0007] Pre-treating the sample to obtain the sample body;

[0008] Performing defect surface analysis on the sample body to obtain a surface analysis result;

[0009] Mounting the sample body, and then performing cross-sectional analysis to obtain cross-sectional analysis results;

[0010] Performing metallographic analysis on the defects of the sample body at a set magnification to obtain metallographic analysis results;

[0011] The cause of the cracking defect is determined based on the surface analysis results, cross-section analysis results and metallographic analysis results.

[0012] Optionally, the preset ratio is 1:15-20.

[0013] Optionally, the pretreatment includes: cleaning the sample to remove dirt. It should be noted that ultrasonic treatment cannot be used in the cleaning process.

[0014] Optionally, the pretreatment further includes: stripping the sample.

[0015] Optionally, when the sample body is a galvanized sheet, performing defect surface analysis on the sample body to obtain a surface analysis result specifically includes:

[0016] Performing a first defect surface analysis on the sample body to obtain a first analysis result;

[0017] Removing the zinc layer from the sample body to obtain a sample without the zinc layer;

[0018] Performing a second defect surface analysis on the zinc-free layer sample to obtain a second analysis result;

[0019] A surface analysis result is obtained according to the first analysis result and the second analysis result.

[0020] Optionally, the first defect surface analysis adopts a method including energy spectrum point analysis and / or energy spectrum surface analysis; and the second defect surface analysis adopts a method including energy spectrum point analysis and / or energy spectrum surface analysis.

[0021] Optionally, in the energy spectrum point analysis, the number of analysis points at the defect is ≥10.

[0022] Optionally, the inlaid inlay is bakelite powder.

[0023] Optionally, the cross-section analysis includes energy spectrum point analysis and / or energy spectrum surface analysis.

[0024] Optionally, the set multiples include 50 times, 100 times, 150 times, 200 times, 250 times and 300 times.

[0025] One or more technical solutions in the embodiments of the present invention have at least the following technical effects or advantages:

[0026] The method for analyzing and locating the cause of crack defects in automobile outer panel steel provided in an embodiment of the present invention can accurately determine the source of the defects by combining defect surface analysis, cross-section analysis and metallographic analysis, thereby solving the current problem of being unable to trace the source of the defects.

[0027] The above description is only an overview of the technical solution of the present invention. In order to more clearly understand the technical means of the present invention, it can be implemented according to the contents of the specification. In order to make the above and other purposes, features and advantages of the present invention more obvious and easy to understand, the specific implementation methods of the present invention are listed below. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0029] Figure 1 It is a flow chart of the method provided by the embodiment of the present invention. DETAILED DESCRIPTION

[0030] The present invention will be described in detail below in conjunction with specific implementations and examples, and the advantages and various effects of the present invention will be more clearly presented. It should be understood by those skilled in the art that these specific implementations and examples are used to illustrate the present invention, rather than to limit the present invention.

[0031] Throughout the specification, unless otherwise specifically stated, the terms used herein should be understood as meanings commonly used in the art. Therefore, unless otherwise defined, all technical and scientific terms used herein have the same meanings as those generally understood by those skilled in the art to which the present invention belongs. In the event of a conflict, the present specification takes precedence.

[0032] Unless otherwise specified, various raw materials, reagents, instruments and equipment used in the present invention can be purchased from the market or prepared by existing methods.

[0033] The technical solution of the embodiment of the present application is to solve the above technical problems, and the overall idea is as follows:

[0034] According to a typical embodiment of the present invention, a method for analyzing and locating the cause of cracking defects in steel for automobile outer panels is provided, the method comprising:

[0035] S1. Measure the defects of the defective board to be analyzed and obtain defect information;

[0036] Specifically, after the defective plate is retrieved, first determine the relative position of the crack in the steel plate, whether there are any fallen foreign objects, observe the crack surface, perform macroscopic measurements of the defect, including length, width and other information, and take photos with a ruler to obtain defect information.

[0037] S2. Prepare the defective plate to be analyzed according to the defect information so that the sample size and the area ratio of the defect meet the set ratio to obtain the sample;

[0038] In some embodiments, the preset ratio is 1:15-20.

[0039] If the control area is too large, it will occupy the analysis space and affect the analysis efficiency; if the control area is too small, part of the defects will be embedded in the matrix, which may destroy the integrity of the defects and affect the accuracy of the analysis.

[0040] Specifically, the size of the sample produced should be proportional to the defect, with an area ratio of 15≤S≤20.

[0041] S3. Pre-treating the sample to obtain the sample body;

[0042] In some embodiments, pre-processing includes: performing a dirty wash on the sample.

[0043] It should be noted that ultrasonic treatment cannot be used during the cleaning process, as it is easy to shake off the defects embedded in the substrate, making it impossible to determine the true cause of the defects.

[0044] In some embodiments, the pretreatment further comprises: performing paint stripping treatment on the sample.

[0045] When the sample is a painted sample, it is necessary to strip the paint on the painted sample. The paint stripper is a mixture of chlorinated hydrocarbons, ketones, esters, alcohols, benzene series and other solvents. The solvent's penetration and swelling effect on the covering is used to effectively remove the surface paint. Keep it for 1 minute after each application and then wash it until the surface paint is completely removed.

[0046] S4. Perform defect surface analysis on the sample body to obtain surface analysis results;

[0047] In some embodiments, when the sample body is a galvanized sheet, performing defect surface analysis on the sample body to obtain a surface analysis result specifically includes:

[0048] S4.1. Perform a first defect surface analysis on the sample body to obtain a first analysis result;

[0049] The first defect surface analysis specifically includes: taking photos of the surface, taking photos of the defect morphology at magnifications of 50 times, 100 times, 200 times, and 500 times under the backscattering field of view of the electron microscope, and saving them; conducting energy spectrum point analysis on the surface: in the backscattering mode, comparing and analyzing the components of the defect and the normal part, the number of analysis points at the defect must not be less than 10, and there is a surface scanning component analysis for the area with dense abnormal particles; conducting a surface scanning analysis of the surface: magnifying the defect to an appropriate multiple (ranging from 200 to 1000 times), and conducting an energy spectrum surface scanning analysis.

[0050] S4.2. removing the zinc layer from the sample body to obtain a zinc-free sample;

[0051] Specifically, the dezincification reagent used for zinc layer removal includes hydrochloric acid solution and corrosion inhibitor hexamethylenetetramine, wherein the ratio of concentrated hydrochloric acid to water is 1:1, and 3.5 g of hexamethylenetetramine is added to each liter of diluted hydrochloric acid solution.

[0052] S4.3. Perform a second defect surface analysis on the zinc-free layer sample to obtain a second analysis result;

[0053] The second defect surface analysis specifically includes: taking photos of the surface, taking photos of the defect morphology at magnifications of 50 times, 100 times, 200 times, and 500 times under the backscattering field of view of the electron microscope, and saving them; conducting energy spectrum point analysis on the surface: in the backscattering mode, comparing and analyzing the components of the defect and the normal part, the number of analysis points at the defect must not be less than 10, and there is a surface scanning component analysis for the area with dense abnormal particles; conducting a surface scanning analysis of the surface: magnifying the defect to an appropriate multiple (ranging from 200 to 1000 times), and conducting an energy spectrum surface scanning analysis.

[0054] S4.4. Obtain a surface analysis result based on the first analysis result and the second analysis result.

[0055] S5. The sample body is mounted, and then a cross-sectional analysis is performed to obtain a cross-sectional analysis result;

[0056] Specifically, the cross-section inlay used in the inlay is bakelite powder, which is kept warm at 130-160°C for 8-15 minutes.

[0057] The cross-sectional analysis specifically includes: cutting the steel matrix along the rolling direction at the position near the defect to ensure parallel cutting and parallel grinding and polishing, and using inlay powder for inlay; gradually grinding away the steel matrix to expose the defect, placing it under an electron microscope for observation, and using energy spectrum point analysis and surface scanning to detect the defect; grinding away the steel matrix layer by layer until the defect completely disappears. During the process, energy spectrum point analysis and surface scanning are used to detect the defect as needed.

[0058] S6. Performing metallographic analysis on the defects of the sample body at a set magnification to obtain metallographic analysis results;

[0059] The metallographic analysis specifically includes: observing the sample's structure, grain size, and distribution of the zinc layer near the defect at 50 times, 100 times, 150 times, 200 times, 250 times, and 300 times respectively.

[0060] S7. Determine the cause of the cracking defect based on the surface analysis results, cross-section analysis results and metallographic analysis results.

[0061] The method for analyzing and locating the cause of crack defects in the automobile outer panel steel of the present application will be described in detail below in combination with the embodiments, comparative examples and experimental data.

[0062] Example 1

[0063] A method for analyzing and locating the cause of crack defects in automobile outer panel steel, the method comprising:

[0064] S1. Measure the defects of the defective board to be analyzed and obtain defect information;

[0065] The defective sample of the defective plate to be analyzed has been painted and is a galvanized plate. The defect is a cracked long strip with no foreign matter falling off. The length and width of the defect are about 1.5mm and 1mm respectively.

[0066] S2. Prepare the defective plate to be analyzed according to the defect information so that the sample size and the area ratio of the defect meet the set ratio to obtain the sample;

[0067] The length and width of the defect are about 1.5mm and 1mm respectively, and the sheared specimen is 30mm 2 .

[0068] S3. Pre-treating the sample to obtain the sample body;

[0069] The dirt around the sample was cleaned and the sample was cleaned 10 times with a paint stripper.

[0070] S4. Perform defect surface analysis on the sample body to obtain surface analysis results;

[0071] S5. The sample body is mounted, and then a cross-sectional analysis is performed to obtain a cross-sectional analysis result;

[0072] S6. Performing metallographic analysis on the defects of the sample body at a set magnification to obtain metallographic analysis results;

[0073] The defects were observed under a scanning electron microscope at a magnification of 1000 times, and energy spectrum analysis was performed on the defects, revealing that they were calcium aluminate components.

[0074] S7. Determine the cause of the cracking defect based on the surface analysis results, cross-section analysis results and metallographic analysis results.

[0075] Based on the calcium aluminate composition, it can be determined that the defect comes from the ladle slag, and the judgment result is verified to be accurate.

[0076] Example 2

[0077] A method for analyzing and locating the cause of crack defects in automobile outer panel steel, the method comprising:

[0078] S1. Measure the defects of the defective board to be analyzed and obtain defect information;

[0079] The defective sample to be analyzed is a galvanized sheet without paint. The defect is an elliptical crack with no foreign matter falling off. The long axis and wide axis of the elliptical defect are about 1mm and 0.8mm respectively.

[0080] S2. Prepare the defective plate to be analyzed according to the defect information so that the sample size and the area ratio of the defect meet the set ratio to obtain the sample;

[0081] The length and width of the defect are about 1mm and 0.8mm respectively, and the sheared specimen is 12mm 2 .

[0082] S3. Pre-treating the sample to obtain the sample body;

[0083] The dirt around the sample was cleaned.

[0084] S4. Perform defect surface analysis on the sample body to obtain surface analysis results;

[0085] S5. The sample body is mounted, and then a cross-sectional analysis is performed to obtain a cross-sectional analysis result;

[0086] S6. Performing metallographic analysis on the defects of the sample body at a set magnification to obtain metallographic analysis results;

[0087] The defects were observed under a scanning electron microscope at a magnification of 900 times, and an energy spectrum analysis was performed on the defects, which revealed that they were composed of aluminum oxide.

[0088] S7. Determine the cause of the cracking defect based on the surface analysis results, cross-section analysis results and metallographic analysis results.

[0089] Based on the composition of alumina, it can be determined that the defect comes from the falling off of the nozzle blockage, and the judgment result is verified to be accurate.

[0090] Example 3

[0091] A method for analyzing and locating the cause of crack defects in automobile outer panel steel, the method comprising:

[0092] S1. Measure the defects of the defective board to be analyzed and obtain defect information;

[0093] The defective sample to be analyzed is a galvanized sheet without paint. The defect is a cracked circular pit, which has fallen off. The length and width of the circular defect are about 1mm and 1mm respectively.

[0094] S2. Prepare the defective plate to be analyzed according to the defect information so that the sample size and the area ratio of the defect meet the set ratio to obtain the sample;

[0095] The length and width of the defect are about 1mm and 1mm respectively, and the sheared specimen is 18mm2 .

[0096] S3. Pre-treating the sample to obtain the sample body;

[0097] The dirt around the sample was cleaned.

[0098] S4. Perform defect surface analysis on the sample body to obtain surface analysis results;

[0099] S5. The sample body is mounted, and then a cross-sectional analysis is performed to obtain a cross-sectional analysis result;

[0100] S6. Performing metallographic analysis on the defects of the sample body at a set magnification to obtain metallographic analysis results;

[0101] The defects were observed under a scanning electron microscope at a magnification of 800 times, and an energy spectrum analysis was performed on the defects, revealing that they were composed of Fe and had no inclusions.

[0102] S7. Determine the cause of the cracking defect based on the surface analysis results, cross-section analysis results and metallographic analysis results.

[0103] There is only Fe in the cross section, without iron oxide; metallographic analysis shows that there is obvious grain deformation at the edge of the defect, which is significantly different from the uniform grains of the matrix.

[0104] According to the results of cross section and metallographic structure, it can be judged that the defect comes from the intrusion of foreign matter after cold rolling and galvanizing, and the judgment result is verified to be accurate.

[0105] Comparative Example 1

[0106] A method for analyzing and locating the cause of crack defects in automobile outer panel steel, the method comprising:

[0107] S1. Measure the defects of the defective board to be analyzed and obtain defect information;

[0108] The defective sample of the defective plate to be analyzed has been painted and is a galvanized plate. The defect is a cracked long strip with no foreign matter falling off. The length and width of the defect are about 1.5mm and 1mm respectively.

[0109] S2. Prepare the defective plate to be analyzed according to the defect information so that the sample size and the area ratio of the defect meet the set ratio to obtain the sample;

[0110] The length and width of the defect are about 1.5mm and 1mm respectively, and the sheared specimen is 10mm 2 .

[0111] S3. Pre-treating the sample to obtain the sample body;

[0112] The dirt around the sample was cleaned and the sample was cleaned 10 times with a paint stripper.

[0113] S4. Perform defect surface analysis on the sample body to obtain surface analysis results;

[0114] S5. The sample body is mounted, and then a cross-sectional analysis is performed to obtain a cross-sectional analysis result;

[0115] S6. Performing metallographic analysis on the defects of the sample body at a set magnification to obtain metallographic analysis results;

[0116] The defects were observed under a scanning electron microscope at a magnification of 1000 times, and an energy spectrum analysis was performed on the defects. The defects were Fe and had no inclusions.

[0117] S7. Determine the cause of the cracking defect based on the surface analysis results, cross-section analysis results and metallographic analysis results.

[0118] There is only Fe in the cross section, without iron oxide; metallographic analysis shows no decarburization layer and grain deformation.

[0119] Based on the above analysis, it is impossible to determine the source of the defect.

[0120] Re-analyze the corresponding samples other than the intercepted samples:

[0121] S1. Measure the defects of the defective board to be analyzed and obtain defect information;

[0122] The defective sample of the defective plate to be analyzed has been painted and is a galvanized plate. The defect is a cracked long strip with no foreign matter falling off. The length and width of the defect are about 1.5mm and 1mm respectively.

[0123] S2. Prepare the defective plate to be analyzed according to the defect information so that the sample size and the area ratio of the defect meet the set ratio to obtain the sample;

[0124] The length and width of the defect are about 1.5mm and 1mm respectively, and the sheared specimen is 25mm 2 .

[0125] S3. Pre-treating the sample to obtain the sample body;

[0126] The dirt around the sample was cleaned and the sample was cleaned 10 times with a paint stripper.

[0127] S4. Perform defect surface analysis on the sample body to obtain surface analysis results;

[0128] S5. The sample body is mounted, and then a cross-sectional analysis is performed to obtain a cross-sectional analysis result;

[0129] S6. Performing metallographic analysis on the defects of the sample body at a set magnification to obtain metallographic analysis results;

[0130] The defects were observed under a scanning electron microscope at a magnification of 1000 times, and an energy spectrum analysis was performed on the defects, revealing that they were composed of aluminum oxide.

[0131] S7. Determine the cause of the cracking defect based on the surface analysis results, cross-section analysis results and metallographic analysis results.

[0132] Based on the composition of alumina, it can be determined that the defect is caused by the falling off of the nozzle plug. It was verified that the first analysis process was wrong, which resulted in the inability to clearly analyze the cause of the defect.

[0133] Comparative Example 2

[0134] A method for analyzing and locating the cause of crack defects in automobile outer panel steel, the method comprising:

[0135] S1. Measure the defects of the defective board to be analyzed and obtain defect information;

[0136] The defective sample to be analyzed is a galvanized sheet without paint coating. The defect is an elliptical crack with no foreign matter falling off. The long axis and wide axis of the elliptical defect are about 1mm and 0.6mm respectively.

[0137] S2. Prepare the defective plate to be analyzed according to the defect information so that the sample size and the area ratio of the defect meet the set ratio to obtain the sample;

[0138] The length and width of the defect are about 1mm and 0.6mm respectively, and the sheared specimen is 12mm 2 .

[0139] S3. Pre-treating the sample to obtain the sample body;

[0140] The dirt around the sample was cleaned, and ultrasonic vibration cleaning was not applicable.

[0141] S4. Perform defect surface analysis on the sample body to obtain surface analysis results;

[0142] The defect is aluminum oxide.

[0143] S5. The sample body is mounted, and then a cross-sectional analysis is performed to obtain a cross-sectional analysis result;

[0144] The cross section is composed of aluminum oxide.

[0145] S6. Performing metallographic analysis on the defects of the sample body at a set magnification to obtain metallographic analysis results;

[0146] The defects were observed under a scanning electron microscope at a magnification of 950 times, and an energy spectrum analysis was performed on the defects. The defects were Fe and had no inclusions.

[0147] S7. Determine the cause of the cracking defect based on the surface analysis results, cross-section analysis results and metallographic analysis results.

[0148] Based on the above analysis, it is impossible to determine the source of the defect.

[0149] Reanalyze another defect:

[0150] A method for analyzing and locating the cause of crack defects in automobile outer panel steel, the method comprising:

[0151] S1. Measure the defects of the defective board to be analyzed and obtain defect information;

[0152] The defective sample to be analyzed is a galvanized sheet without paint. The defect is an elliptical crack with no foreign matter falling off. The long axis and wide axis of the elliptical defect are approximately 1.2 mm and 0.6 mm respectively.

[0153] S2. Prepare the defective plate to be analyzed according to the defect information so that the sample size and the area ratio of the defect meet the set ratio to obtain the sample;

[0154] The length and width of the defect are about 1mm and 0.6mm respectively, and the sheared specimen is 15mm 2 .

[0155] S3. Pre-treating the sample to obtain the sample body;

[0156] The samples were ultrasonically cleaned.

[0157] S4. Perform defect surface analysis on the sample body to obtain surface analysis results;

[0158] The defect is Fe, and there are no inclusions.

[0159] S5. The sample body is mounted, and then a cross-sectional analysis is performed to obtain a cross-sectional analysis result;

[0160] The cross section is Fe with no inclusions.

[0161] S6. Performing metallographic analysis on the defects of the sample body at a set magnification to obtain metallographic analysis results;

[0162] The defects were observed under a scanning electron microscope at a magnification of 300 times, and an energy spectrum analysis was performed on the defects. There was no decarburization and the grains were normal.

[0163] S7. Determine the cause of the cracking defect based on the surface analysis results, cross-section analysis results and metallographic analysis results.

[0164] Based on the composition of alumina, it can be determined that the defect is caused by the falling off of the nozzle plug. It was verified that the first analysis process was wrong, which resulted in the inability to clearly analyze the cause of the defect.

[0165] One or more technical solutions in the embodiments of the present invention have at least the following technical effects or advantages:

[0166] The method provided by the embodiment of the present invention can accurately determine the source of the defect by combining defect surface analysis, cross-section analysis and metallographic analysis, thereby solving the current problem of being unable to trace the source of the defect.

[0167] Finally, it should be noted that the terms "comprises," "includes," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that includes a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements that are inherent to such process, method, article, or apparatus.

[0168] Although the preferred embodiments of the present invention have been described, those skilled in the art may make other changes and modifications to these embodiments once they have learned the basic creative concept. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments and all changes and modifications that fall within the scope of the present invention.

[0169] Obviously, those skilled in the art can make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if these modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention is also intended to include these modifications and variations.

Claims

1. A method for analyzing and locating the cause of crack defects in automobile outer panel steel, characterized in that: The method comprises: Performing macro parameter measurement on the defect of the defective board to be analyzed to obtain defect information, wherein the macro parameters include length and width; Prepare samples of the defective plate to be analyzed according to the defect information, so that the ratio of the sample size to the defect area meets the set ratio, and obtain the sample; Pre-treating the sample to obtain a sample body; Performing defect surface analysis on the sample body to obtain a surface analysis result; Mounting the sample body, and then performing cross-sectional analysis to obtain cross-sectional analysis results; Performing metallographic analysis on the defects of the sample body at a set magnification to obtain metallographic analysis results; Determine the cause of the cracking defect according to the surface analysis results, cross-section analysis results and metallographic analysis results; The set ratio is 1:15-20, and the pretreatment includes: cleaning the sample from dirt except ultrasonic treatment; When the sample body is a galvanized sheet, the defect surface analysis of the sample body is performed to obtain the surface analysis result, which specifically includes: Performing a first defect surface analysis on the sample body to obtain a first analysis result; Removing the zinc layer from the sample body to obtain a sample without the zinc layer; Performing a second defect surface analysis on the zinc-free layer sample to obtain a second analysis result; Obtaining a surface analysis result according to the first analysis result and the second analysis result; The first defect surface analysis adopts a method including energy spectrum point analysis and / or energy spectrum surface analysis; and the second defect surface analysis adopts a method including energy spectrum point analysis and / or energy spectrum surface analysis.

2. The method for analyzing and locating the cause of crack defects in automobile outer panel steel according to claim 1, characterized in that: The pretreatment further comprises: performing paint stripping treatment on the sample.

3. The method for analyzing and locating the cause of crack defects in automobile outer panel steel according to claim 1, characterized in that: In the energy spectrum point analysis, the number of analysis points at the defect is ≥10.

4. The method for analyzing and locating the cause of crack defects in automobile outer panel steel according to claim 1, characterized in that: The inlay is bakelite powder.

5. The method for analyzing and locating the cause of crack defects in automobile outer panel steel according to claim 1, characterized in that: The cross-sectional analysis includes energy spectrum point analysis and / or energy spectrum surface analysis.

6. The method for analyzing and locating the cause of crack defects in automobile outer panel steel according to claim 1, characterized in that: The set magnifications include 50 times, 100 times, 150 times, 200 times, 250 times and 300 times.

Images