A crack opening method

Abstract

The application provides a crack opening method and relates to the technical field of material analysis. The crack opening method comprises the following steps: cutting a sample with a preset length, and pretreating the sample; filling a crack of the sample with a protective liquid; performing an inlay operation on the sample filled with the protective liquid to form an inlay; and performing grinding and polishing on the inlay to open the crack of the sample in the inlay. The crack of the sample is filled with the protective liquid, so that the crack of the sample can be effectively prevented from being polluted. The crack of the sample can be accurately and nondestructively opened by using the inlay and grinding and polishing, so that the crack morphology of the sample can be ensured to be as complete as possible.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of material analysis, and in particular, to a crack opening method. BACKGROUND

[0002] In the manufacturing process of steel materials, cracks are usually generated in the steel materials. At present, the detection of longitudinal cracks in steel materials mainly adopts metallographic detection, or uses a scanning electron microscope (SEM) and an energy spectrometer to detect the composition of the substances in the cross-section cracks. However, the morphology and composition of the crack opening surface cannot be directly analyzed. Moreover, the current crack opening method cannot accurately open the longitudinal cracks of the steel sample, and cannot guarantee that the crack morphology is as complete as possible. SUMMARY

[0003] The present application provides a crack opening method which can accurately and non-destructively open the longitudinal cracks of a steel sample.

[0004] Embodiments of the present application can be implemented as follows:

[0005] In a first aspect, the present application provides a crack opening method, comprising the following steps:

[0006] A sample with a preset length is cut off, and the sample is pretreated;

[0007] The crack of the sample is filled with a protective liquid;

[0008] The sample filled with the protective liquid is subjected to an inlay operation to form an inlay;

[0009] The inlay is polished to open the crack of the sample in the inlay.

[0010] In an optional embodiment, the step of pretreating the sample comprises:

[0011] The sample is longitudinally cut at the crack tip on the cross-section of the sample in a direction perpendicular to the crack direction of the sample.

[0012] In an optional embodiment, the crack of the sample extends a first preset distance on the cross-section, and the first preset distance is less than or equal to 0.5 mm.

[0013] In an optional embodiment, the step of subjecting the sample filled with the protective liquid to an inlay operation to form an inlay comprises:

[0014] The cut surface of the sample is mixed with inlay material in a vertically downward form;

[0015] The mixed sample and inlay material are inlaid to form an inlay;

[0016] The bottom surface of the inlay corresponds to the cut surface of the sample, and the height of the inlay is a first height.

[0017] In an optional embodiment, the step of polishing the bottom surface of the inlay includes:

[0018] The bottom surface of the inlay is polished, and the polishing thickness is measured.

[0019] In an optional embodiment, the step of polishing the bottom surface of the inlay and measuring the polishing thickness includes:

[0020] The bottom surface of the inlay is polished for a first preset time, and the height of the inlay after polishing is a second height.

[0021] The polishing thickness is obtained by the difference between the first height and the second height.

[0022] In an optional embodiment, the distance between the crack tip of the sample after longitudinal cutting and the cut surface is a second preset distance; the step of polishing the bottom surface of the inlay and measuring the polishing thickness is repeated until the crack of the sample is opened when the polishing thickness is equal to the second preset distance.

[0023] In an optional embodiment, the step of filling the crack of the sample with a protective liquid includes:

[0024] The sample is immersed in the protective liquid for a second preset time.

[0025] In an optional embodiment, the step of filling the crack of the sample with a protective liquid further includes:

[0026] Ultrasonic waves are emitted to the sample placed in the protective liquid.

[0027] In an optional embodiment, the step of the crack opening method further includes:

[0028] The polished body after opening is cleaned, and the crack of the polished body after opening is observed and detected after cleaning.

[0029] The beneficial effects of the crack opening method provided by the embodiments of the present application include: the crack of the sample is filled with a protective liquid, which can effectively prevent the crack of the sample from being contaminated; the crack of the sample is opened accurately and non-destructively by inlaying and polishing, which ensures that the crack morphology of the sample is as complete as possible. BRIEF DESCRIPTION OF DRAWINGS

[0030] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following will briefly introduce the drawings needed to be used in the embodiments. It should be understood that the following drawings only show some of the embodiments of the present application, and therefore should not be regarded as limiting the scope. For those skilled in the art, other related drawings can also be obtained without creative labor.

[0031] Figure 1 One of the schematic diagrams of the crack opening method provided by the embodiments of the present application;

[0032] Figure 2 The schematic diagram of the cross section of the cut sample provided by the embodiments of the present application;

[0033] Figure 3 The schematic diagram of the inlaid inlay provided by the embodiments of the present application;

[0034] Figure 4 The second schematic diagram of the crack opening method provided by the embodiments of the present application;

[0035] Figure 5 The schematic diagram of the secondary electron morphology after the 0.1mm crack opening provided by the embodiments of the present application;

[0036] Figure 6 The schematic diagram of the secondary electron morphology after the 0.3mm crack opening provided by the embodiments of the present application;

[0037] Figure 7 The schematic diagram of the backscattering morphology after the 0.5mm crack opening provided by the embodiments of the present application. DETAILED DESCRIPTION

[0038] In order to make the purpose, technical solutions and advantages of the embodiments of the present application more clear, the following will combine the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are some of the embodiments of the present application, but not all the embodiments. The components of the embodiments of the present application described and shown in the drawings can be arranged and designed in various different configurations.

[0039] Therefore, the following detailed description of the embodiments of the present application provided in the drawings is not intended to limit the scope of the claimed present application, but only represents selected embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor are within the scope of the present application.

[0040] It should be noted that: similar labels and letters represent similar items in the following drawings, and therefore, once an item is defined in one drawing, it does not need to be further defined and explained in the subsequent drawings.

[0041] In the description of the present application, it should be noted that if the terms "upper", "lower", "inner", "outer" and the like indicate the orientation or positional relationship shown in the drawings, or the orientation or positional relationship commonly used when the product of the present application is used, only for the convenience of describing the present application and simplifying the description, and therefore cannot be understood as indicating or implying that the device or element referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as limiting the present application.

[0042] In addition, if the terms "first", "second" and the like appear, they are only used to distinguish the description and cannot be understood as indicating or implying relative importance.

[0043] It should be noted that the features in the embodiments of the present application can be combined with each other without conflict.

[0044] In the continuous casting process of steel, due to factors such as composition segregation, surface cracks and intermediate cracks of the casting blank often occur, among various defects, the proportion of casting blank cracks is more than 50%; and in the rolling process, due to the state of organization, chemical composition and internal inclusions, rolling cracks will occur; in addition, in the heat treatment process, due to the large heat treatment stress, quenching cracks will also occur.

[0045] At present, the detection of longitudinal cracks of steel mainly adopts metallographic method detection, which is to observe the cross-section crack morphology and organization in the transverse plane by multiple times of intercepting transverse plane samples; or to detect the composition of the material in the cross-section crack by using SEM scanning electron microscope and energy spectrometer, however, the morphology and composition in the crack opening surface are lack of intuitive analysis. In other words, how to accurately open the crack along the longitudinal direction and ensure that the crack morphology is as complete as possible is the difficulty of detecting the longitudinal crack of steel.

[0046] To solve the above problems, the present application provides a crack opening method for opening the longitudinal crack of steel, and is particularly suitable for opening the longitudinal crack of free-cutting steel strip-shaped sample to facilitate subsequent analysis.

[0047] Please refer to Figure 1 The crack opening method provided by the embodiment includes the following steps:

[0048] Step S100, intercepting a sample of a predetermined length, and pretreating the sample.

[0049] In the embodiment, the sample can be a long strip-shaped steel, and mechanical cutting or wire cutting is used to cut the steel sample along the radial direction of the steel at the crack of the steel sample to obtain a steel sample of a predetermined length, and then the steel sample of a predetermined length is pretreated to facilitate the subsequent opening step of the steel sample.

[0050] Optionally, the preset length can be 3-5 cm.

[0051] In this embodiment, step S100 can include the following sub-steps:

[0052] Sub-step S110, longitudinally cutting the sample at the crack tip on the cross section of the sample in a direction perpendicular to the crack direction of the sample.

[0053] It can be understood that, as shown in Figure 2 , the cross section of the steel sample is the cutting surface when the sample is cut into a preset length, and the crack usually extends along the length direction of the steel sample, so that the crack in a linear shape can be seen on the cross section, and one end of the cross section of the crack extends to the surface of the steel sample, and the other end extends to the inside of the steel sample, i.e. the crack tip.

[0054] In this embodiment, the sample is cut at a preset distance from the crack tip on the cross section of the sample and in a direction perpendicular to the extension direction of the crack on the cross section by using a wire cutting or precision cutting machine, and the cutting direction is the extension direction of the sample, and the cutting surface formed by the cutting is a plane as shown by the dotted line in Figure 2 .

[0055] Optionally, the preset distance can be 2-3 mm.

[0056] It should be noted that the extension length of the crack of the sample on the cross section is a first preset distance (as shown by a in Figure 2 ), and the first preset distance is less than or equal to 0.5 mm, in other words, this method can be used to open the steel sample with a crack depth less than or equal to 0.5 mm, thereby solving the problem that the longitudinal crack of the small-size steel or other black and non-ferrous metal parts cannot be opened. In addition, the distance between the crack tip of the sample after longitudinal cutting and the cutting surface is a second preset distance (as shown by b in Figure 2 ).

[0057] In addition, the cross section of the steel sample is usually circular, and the cross section of the steel sample after cutting is semicircular or partially circular; after cutting, the height of the cross section after cutting is measured and recorded by using a micrometer with the cutting surface as the bottom surface, and it is ensured that the measured height is greater than the first preset distance.

[0058] In this embodiment, the crack opening method further includes:

[0059] Step S200, filling the crack of the sample with a protective liquid.

[0060] In this embodiment, the crack of the sample is filled with a protective liquid, so as to protect the crack of the sample, avoid the sample from being contaminated in subsequent operations such as inlaying operation, and thus affect the opening precision of the crack.

[0061] In this embodiment, step S200 can include the following sub-steps:

[0062] Sub-step S210, the sample is placed in the protective liquid for soaking for a second preset time.

[0063] In this embodiment, the sample is placed in the protective liquid for soaking for a sufficient time to allow the protective liquid to soak into the cracks of the sample.

[0064] Optionally, the protective liquid can be vegetable oil, and the second preset time can be 30 minutes to ensure that the protective liquid is fully soaked into the cracks of the sample. Of course, the protective liquid and the second preset time can also be other settings, which can be adjusted according to actual needs, and are not limited here.

[0065] In other embodiments of the present application, step S200 can also include the following sub-steps:

[0066] Sub-step S220, ultrasonic waves are emitted to the sample placed in the protective liquid.

[0067] In this embodiment, in the case that the protective liquid cannot penetrate into the cracks, an ultrasonic device can be used to send ultrasonic waves to allow the protective liquid to be fully soaked into the cracks of the sample, thereby preventing the sample from being contaminated in the subsequent inlaying process.

[0068] In this embodiment, the crack opening method further includes:

[0069] Step S300, inlaying operation is performed on the sample filled with the protective liquid to form an inlay.

[0070] In this embodiment, as shown in Figure 3 , the inlaying operation is performed on the sample to prepare for the subsequent grinding and polishing operation.

[0071] In this embodiment, step S300 can include the following sub-steps:

[0072] Sub-step S310, the cutting surface of the sample is mixed with the inlaying material in a vertically downward manner; the mixed sample and inlaying material are inlaid to form an inlay.

[0073] In this embodiment, the cutting surface of the sample is placed in the inlaying device in a vertically downward manner, and the inlaying material is arranged on the surface around the sample, so that the sample and the inlaying material are formed into an inlay by the inlaying device.

[0074] It should be noted that the bottom surface of the formed inlay corresponds to the cutting surface of the sample, that is, the bottom surface of the inlay is the cutting surface of the sample; the height of the inlay is measured and recorded as a first height (as shown in Figure 3 c) using a micrometer with the bottom surface of the inlay as the bottom.

[0075] In this embodiment, the crack opening method further comprises:

[0076] In step S400, the inlay is polished to open the crack of the sample in the inlay.

[0077] In this embodiment, the inlay is polished multiple times to make the polishing surface close to the crack tip, so as to facilitate the opening of the crack of the sample in the inlay and avoid damage to the crack.

[0078] It can be understood that opening the crack means that the inlay with the crack is divided into two parts with the crack as the center, and the entire cross section of the crack is completely displayed.

[0079] In this embodiment, step S400 can include the following sub-steps:

[0080] In sub-step S410, the bottom surface of the inlay is polished and the polishing thickness is measured.

[0081] In this embodiment, the inlay is polished by using 400# and 800# sandpaper respectively to improve the polishing efficiency; the bottom surface of the inlay is polished to reduce the distance between the crack tip and the bottom surface, and the polishing thickness is measured to avoid damage to the crack due to excessive polishing.

[0082] Sub-step S410 can include the following sub-steps:

[0083] In sub-step S411, the bottom surface of the inlay is polished for a first preset time, and the height of the inlay after polishing is measured as a second height (as shown by d in FIG. 4B); the polishing thickness is obtained by the difference between the first height and the second height. Figure 3

[0084] Optionally, the first preset time can be 20s.

[0085] In sub-step S420, the bottom surface of the inlay is repeatedly polished and the polishing thickness is measured until the crack of the sample is opened when the polishing thickness is equal to a second preset distance.

[0086] In this embodiment, sub-step S411 is repeated, that is, the height of the inlay after polishing is measured by using a micrometer every 20 seconds of polishing of the inlay, and when the measured polishing thickness is equal to or approximately equal to the second preset distance, the crack tip is closest to the polishing surface, at which time the crack can be opened manually by an operator or by using a tool without damage and accurately.

[0087] Please refer to Figure 4 In this embodiment, the crack opening method further comprises:

[0088] ​Step S500, the opened polishing body is cleaned, and the crack of the opened polishing body is observed and detected after cleaning.

[0089] In the embodiment, the opened crack is cleaned multiple times by using alcohol, and ultrasonic vibration can be used during cleaning, and the sample after cleaning can be placed into an electron microscope, and the substance in the crack is observed and component detection is performed by using the electron microscope and an energy spectrometer.

[0090] As shown in FIGS. 1-4, Figures 5 to 7 As shown in FIGS. 1-4, Figure 5 The secondary electron morphology of the 0.1 mm crack after opening is shown, Figure 6 The secondary electron morphology of the 0.3 mm crack after opening is shown, Figure 7 The backscattering morphology of the 0.5 mm crack after opening is shown, and Figures 5 to 7 It can be known from the above method that the opened crack is not damaged, and the measurement and detection precision of the opened crack is significantly improved.

[0091] In summary, the embodiment of the present application provides a crack opening method, the present application adopts cutting and polishing, and the crack with a depth less than 0.5 mm can be opened, and the plant oil is used for sealing, the problem that the pin shaft cannot be set due to small sample size is avoided, and the problems of accidental damage in the knocking process or foreign matter pollution in the cracking process are also avoided, the method is simple and easy to operate, is suitable for opening of the longitudinal crack of the steel material, but is not limited to the black metal range, and has guiding significance for opening of the longitudinal crack of other metal materials.

[0092] The above is only a specific embodiment of the present application, but the protection scope of the present application is not limited to this, any person skilled in the art can easily think of changes or replacements within the technical range disclosed by the present application, which should be covered in the protection scope of the present application. Therefore, the protection scope of the present application should be subject to the protection scope of the claims.

Claims

1. A method for crack opening, characterized in that, Includes the following steps: Cut a sample to a predetermined length and pre-treat the sample; The crack in the sample is filled with a protective liquid; The sample filled with the protective liquid is then inlaid to form an inlay. The inlay is polished to open the cracks in the sample within the inlay. The pretreatment step of the sample includes: The specimen is longitudinally cut at the crack tip on its cross-section along a direction perpendicular to the crack.

2. The crack opening method according to claim 1, characterized in that, The extension length of the crack in the cross-section of the sample is a first preset distance, which is less than or equal to 0.5 mm.

3. The crack opening method according to claim 1, characterized in that, The step of embedding the sample filled with the protective liquid to form an embedding includes: The cut surface of the sample is mixed with the inlay material in a vertically downward orientation; The mixed sample and the insert material are then inserted to form an insert; The bottom surface of the inlay corresponds to the cut surface of the sample, and the height of the inlay is a first height.

4. The crack opening method according to claim 3, characterized in that, The step of polishing the inlay includes: The bottom surface of the inlay is polished, and the polishing thickness is measured.

5. The crack opening method according to claim 4, characterized in that, The steps of polishing the bottom surface of the inlay and measuring the polishing thickness include: The bottom surface of the inlay is polished for a first preset time, and the height of the inlay after polishing is measured as the second height. The polishing thickness is obtained by the difference between the first height and the second height.

6. The crack opening method according to claim 4, characterized in that, The distance between the crack tip of the longitudinally cut sample and the cut surface is a second preset distance; the bottom surface of the inlay is repeatedly polished and the polishing thickness is measured until the polishing thickness is equal to the second preset distance, at which point the crack of the sample is opened.

7. The crack opening method according to claim 1, characterized in that, The step of filling the crack in the sample with a protective liquid includes: The sample is immersed in the protective liquid for a second preset time.

8. The crack opening method according to claim 7, characterized in that, The step of filling the cracks in the sample with a protective liquid further includes: Ultrasonic waves are emitted at the sample placed in the protective liquid.

9. The crack opening method according to claim 1, characterized in that, The crack opening method further includes the following steps: The opened crack was cleaned, and the opened crack was then observed and inspected.

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