A small size wire rod artificial fracture preparation clamp and an artificial fracture preparation method

Abstract

The application discloses a clamp for preparing an artificial fracture of small-size wire and rod materials and a preparation method of the artificial fracture, and relates to the technical field of physical and chemical analysis of metal materials. The clamp for preparing the artificial fracture of the small-size wire and rod materials comprises a lower clamp used for fixedly mounting a sample, clamp blocks are arranged at the two ends of the lower clamp and used for tightly pressing the two sides of the sample, upper clamps are arranged on the clamp blocks located on the two sides of the sample, the inner ends of the two upper clamps are tightly pressed on the sample, and the gap between the two upper clamps corresponds to the crack on the sample. The end of the lower clamp is fixedly connected with the clamp blocks and the upper clamps located above. The application can conveniently and efficiently prepare the artificial fracture sample used for fracture analysis when the crack on the small-size wire and rod material is shallow and short, and the subsequent defect analysis is more accurate.

Description

Technical Field

[0001] This invention relates to the field of physical and chemical analysis technology of metallic materials, and more specifically, to a fixture and method for preparing artificial fracture surfaces of small-diameter wire rods. Background Technology

[0002] During the manufacturing process of wire rods with diameters ranging from 6mm to 40mm, various cracks and defects may appear on the surface and end faces of the wire rods due to fluctuations in material composition, smelting process, and rolling process. The treatment and analysis of these defects are important tasks in the quality control of wire rod products.

[0003] When analyzing cracks in wire rods, the crack must be completely severed across the entire cross-section to form a fracture sample. Fracture analysis is then performed on the fracture surface to determine the location of the fracture origin, whether defects exist at the fracture origin, the direction and speed of crack propagation, and the microscopic characteristics of the fracture surface (distinguishing between ductile, brittle, or mixed fracture). If the fracture analysis sample has not undergone secondary sample preparation, it can provide the most comprehensive defect information. Conversely, if a metallographic sample is prepared first, and then the fracture surface on the metallographic sample is analyzed, abrasive particles and polishing paste components may be introduced during the metallographic sample preparation process, affecting the determination of the defect cause.

[0004] Therefore, to make the defect judgment more accurate, the fracture surface analysis sample needs to be analyzed without metallographic sample preparation. When the crack on the fracture surface analysis sample is shallow and short and does not penetrate the entire fracture surface, how to open the crack to prepare an artificial fracture surface sample for analysis without introducing other impurities is a major challenge in fracture surface analysis. Summary of the Invention

[0005] The purpose of this invention is to provide a fixture and method for preparing artificial fracture surfaces of small-diameter wire rods, so that when the cracks on small-diameter wire rods are shallow and short, artificial fracture surface samples that meet the requirements for fracture analysis can be prepared conveniently and efficiently, making subsequent defect analysis more accurate.

[0006] To achieve the objective of this invention, the technical solution adopted is as follows: This invention provides a fixture for preparing artificial fracture surfaces of small-diameter wire rods, comprising a lower fixture, a fixture pad, and an upper fixture. The upper fixture, fixture pad, and lower fixture are all rectangular plate structures. The widths of the lower fixtures of the upper fixture and fixture pad are equal. During use, the lower fixture is a consumable part and cannot be reused after use. The fixture pad and upper fixture, on the other hand, experience less wear during use and can be reused depending on the deformation.

[0007] In use, the artificial fracture surface preparation fixture consists of two parts: a lower clamp for securing the sample with fine cracks, and a clamp for fixing the sample in the middle of the lower clamp, prioritizing alignment of the sample's central axis with the lower clamp's width axis and ensuring the crack's length aligns with the clamp's width direction. Clamp pads are installed at both ends of the lower clamp, their inner ends pressing against the sample's sides to restrict movement. Two upper clamps are installed on the clamp pads on either side of the sample, together pressing against the top of the sample to restrict movement. To ensure stable clamping, the lower clamp ends, clamp pads on the same side, and upper clamps are all fixed together. This coordinated action of the lower clamp, clamp pads, and upper clamps restricts the sample's movement in all directions, thus securing it within the artificial fracture surface preparation fixture.

[0008] When using the small-diameter wire rod artificial fracture preparation fixture provided by this invention to clamp the sample, in order to ensure the stability of the sample installed in the artificial fracture preparation fixture and the stability of the sample in the artificial fracture preparation fixture during the subsequent three-point bend test, the inner ends of the two upper fixtures must be pressed together during installation, and the gap between the inner ends of the two upper fixtures must correspond to the crack on the sample. This ensures that when the crack on the sample opens during the subsequent three-point bend test, the two upper fixtures can still press and fix the two sides of the sample after the opening, preventing the upper fixtures from losing their clamping grip on the sample during the three-point bend test, and ensuring that the sample can fully open along the crack to form a fracture surface.

[0009] The fixture for preparing artificial fracture surfaces of small-diameter wire rods provided by this invention, after clamping the sample, is used in the subsequent three-point bending test. The two upper fixtures are tightened, and the position on the lower fixture where the crack on the sample is on the same vertical plane is the stress point. After being subjected to force, the force is transmitted to the sample, so that the back side of the crack on the sample is stressed. As a result, the crack on the sample opens to both sides along the direction of tensile stress, thus forming a cross-section along the crack.

[0010] To ensure that the lower clamp is able to transfer force to the sample when subjected to force, thus ensuring that the cracks on the sample are stressed on the back side, and to allow for maximum reuse of the upper clamp and clamp pads, the design of the fixture for artificial fracture preparation of small-diameter wire rods specifies that the hardness of the lower clamp is less than that of the upper clamp and clamp pads, and the thickness of the lower clamp is also less than that of the upper clamp and clamp pads. Specifically, the hardness of the lower clamp is less than HRB50, while the hardness of the clamp pads and the lower clamp is not less than HRC45. The lower clamp is made of hot-rolled carbon steel, while the clamp pads and upper clamp are made of alloy steel. All three fixtures—lower clamp, clamp pads, and upper clamp—are manufactured using wire cutting. The thickness of the lower clamp is 1mm–1.5mm, the upper clamp is 5mm–8mm, and the clamp pads are 1mm–6mm.

[0011] In this invention, the widths of the lower clamp, the clamp pad, and the upper clamp can be determined based on the length of the sample. All widths of these components must be no less than the sample length. While the widths of the lower clamp, the clamp pad, and the upper clamp can be equal or unequal, for ease of sample mounting and assembly, the widths of these components are preferably designed to be equal. This ensures that after assembly, the outer edges of the lower clamp, the clamp pad, and the upper clamp are flush. Here, the width of the lower clamp can be selected from 10mm to 20mm.

[0012] In this invention, when selecting the clamping pad, there can be one or more clamping pads located between the lower clamping end and the upper clamping end. However, regardless of the number of clamping pads between the lower clamping end and the upper clamping end, the overall thickness of the clamping pads between the lower clamping end and the upper clamping end should be slightly less than the thickness of the sample. This is to ensure that the lower clamping end, the clamping pad located at the same end, and the upper clamping end can press the sample together after being fixed together, thus ensuring the stability of the sample in the fixture for preparing artificial fracture surfaces of small-diameter wire rods.

[0013] In order to fix the lower clamp end together with the clamp pad and the upper clamp located at the same end, both ends of the lower clamp have straight slots and bolt holes. The bolt holes are located on the outside of the straight slots, and the two bolt holes and the two straight slots are symmetrically arranged on the lower clamp. At the same time, the clamp pad and the upper clamp are both provided with strip holes. The length direction of the strip holes is consistent with the length direction of the straight slots, and the strip holes on the clamp pad and the upper clamp are used in conjunction with the straight slot and bolt holes at one end of the lower clamp. When the end of the lower clamp needs to be fixed together with the clamp pad and the upper clamp located at the same end, bolts are inserted into the straight groove on the lower clamp, the strip hole on the clamp pad, and the strip hole on the upper clamp. The two ends of the bolts are locked and fixed by nuts. At the same time, bolts are also inserted into the bolt holes on the lower clamp, the strip hole on the clamp pad, and the strip hole on the upper clamp. The two ends of the bolts are locked and fixed by nuts. This makes the end of the lower clamp fixed together with the clamp pad and the upper clamp located at the same end by two bolts, which makes the fastening effect of the end of the lower clamp and the clamp pad and the upper clamp located at the same end better, thus making the sample clamping more stable.

[0014] Based on the aforementioned fixture for preparing artificial fracture surfaces of small-diameter wire rods, this invention also provides a method for preparing artificial fracture surfaces of small-diameter wire rods, comprising the following steps:

[0015] Step 1: Cut samples from small-diameter wire rods using machining. During the sample cutting process, ensure that the crack location is not damaged by grinding and that the crack is located as close as possible to the center of the top of the sample. At the same time, machine the bottom surface of the sample into a flat surface, so that the sample thickness does not exceed 2mm, the sample width does not exceed 20mm, and the crack length accounts for less than 32% of the sample length.

[0016] Step 2: Fix the sample in the center of the lower clamp, and make the length direction of the crack on the sample consistent with the width direction of the lower clamp.

[0017] Step 3: Install clamp pads at both ends of the lower clamp, making the outer side of the clamp pads flush with the outer side of the lower clamp. The inner end of the clamp pads should press against the side of the sample, restricting the sample's horizontal displacement. If the sample's cross-section is semi-circular, the inner end of the clamp pads pressing against the side of the sample will restrict the sample's horizontal displacement, and at the same time, the inner end of the clamp pads will cooperate with the lower clamp to restrict the sample's vertical displacement.

[0018] Step 4: Attach the two upper clamps to the clamp pads on both sides of the sample, with the outer sides of the upper clamps flush with the outer sides of the clamp pads. Ensure the inner ends of the two upper clamps are pressed together, aligning the gap between the inner ends with the cracks on the sample. Then, fix the lower clamp end together with the clamp pads and upper clamps on the same side. The inner ends of the two upper clamps press against the cracks on both sides of the sample. The sample is then fixedly clamped onto the small-diameter wire rod artificial fracture preparation fixture. The two ends of the fixture serve as the lever arms of the sample, ensuring the lever arm length on one side exceeds 50mm.

[0019] Step 5: Perform a three-point bending test using a universal testing machine or a hammer forging machine. During the three-point bending test, the two mandrels on the universal testing machine or hammer forging machine, which serve as supports, are pressed against the outer surfaces of the two upper clamps, and are kept as far away from the inner ends of the two upper clamps as possible. This ensures that the two mandrels on the universal testing machine or hammer forging machine are symmetrically arranged on the clamp for preparing artificial fracture surfaces of small-diameter wire rods. At the same time, the mandrels on the universal testing machine or hammer forging machine that serve as bends gradually apply force to the outer surface of the lower clamp, ensuring that the force application point of the lower clamp is on the same vertical plane as the crack on the sample. As the mandrels on the universal testing machine or hammer forging machine that serve as bends move, they push the center of the lower clamp to lift up, causing the lower clamp to deform. The lower clamp transfers the force to the sample, causing the sample to be lifted from the back of the crack, causing the crack to open along the direction of tensile stress, and finally forming a fracture surface.

[0020] In step two, in order to quickly attach and fix the sample to the lower fixture, the sample can be fixed to the lower fixture with quick-drying adhesive, such as 502 glue.

[0021] In steps three and four, to facilitate the rapid assembly of the lower clamp, clamp pad, and upper clamp for sample clamping, an installation mold can be used. This installation mold includes a mold body with a mounting groove longer than the lower clamp. The bottom of the mounting groove has a stepped surface adapted to the length of the lower clamp, and the stepped surface also has a bolt placement groove. The length of the bolt placement groove covers the two straight slots and two bolt holes on the lower clamp. When using this installation mold to clamp the sample, the assembly steps for the lower clamp, clamp pad, and upper clamp are as follows:

[0022] Four bolts are installed upside down in the bolt placement groove, and the lower clamp with the sample bonded to it is installed on the step surface. The stop formed by the two ends of the step surface and the bottom of the installation groove limits the two ends of the lower clamp to prevent the lower clamp from displacing in the length direction within the mold body. While installing the lower clamp, the four bolts pass through the two straight slots and two bolt holes on the lower clamp respectively. When ensuring that the bolts pass through the straight slots and bolt holes on the lower clamp, the bolts passing through the straight slots should move as far as possible to the middle of the lower clamp.

[0023] Next, select a clamping pad that matches the height of the sample, and place the clamping pad into the mounting slot from both ends. Press the inner end of the clamping pad against the sample surface, and when placing the clamping pad, make sure the bolt passes through the slot on the clamping pad. At the same time, place the upper clamps into the mounting slot from both ends, press the two upper clamps against each other, and make sure the bolt passes through the slot on the upper clamp. Finally, tighten the nut onto the bolt.

[0024] To ensure that the inner end of the clamping pad and the inner ends of the two upper clamps are always pressed against the sample while the clamping pad and upper clamp are placed in the mounting slot but the nuts are not tightened, a wedge block can be inserted between the outer end of the clamping pad and the wall of the mounting slot after the clamping pad is installed, and a wedge block can be inserted between the outer end of the upper clamp and the wall of the mounting slot after the upper clamp is installed. Tighten the nuts while the inner ends of the clamping pad and the two upper clamps are pressed against the sample, so that the sample is clamped in the fixture for preparing artificial fracture of small-diameter wire rod. Then, the clamping pad and upper clamp press the sample firmly onto the lower clamp.

[0025] In step five, when performing a three-point bending test using a universal testing machine or a hammer forging machine, the width of the base on the universal testing machine or hammer forging machine must be greater than the width of the fixture used for preparing the artificial fracture surface of small-diameter wire rods, and the movement speed of the mandrel that performs the bending action must be no less than 10 mm / min.

[0026] The beneficial effects of this invention are:

[0027] The artificial fracture preparation fixture provided by this invention allows for the preparation of artificial fracture surfaces by fixing cracked samples within the fixture during the process of opening the cracks. With the two upper clamps of the fixture pressed together, a force is applied to the lower clamp, which then transfers this force to the sample, causing the sample to open along the direction of tensile stress from the crack, forming a fracture surface. Throughout this process, no abrasive particles, polishing compound, or other contaminants are introduced into the fracture surface, resulting in more accurate subsequent defect analysis.

[0028] This invention enables the preparation of artificial fracture samples that meet the requirements for fracture analysis when the cracks on small-diameter bars and wires are shallow and short. By fixing the sample with cracks in the artificial fracture preparation fixture, the force is directly applied to the artificial fracture preparation fixture and then transferred to the sample, thereby extending the lever arm of the sample. This can open up the tiny cracks on the sample and can conveniently and efficiently prepare artificial fracture samples that meet the requirements for fracture analysis. Attached Figure Description

[0029] The accompanying drawings illustrate exemplary embodiments of the invention and, together with the description thereof, serve to explain the principles of the invention. These drawings are included to provide a further understanding of the invention and are incorporated in and constitute a part of this specification.

[0030] Figure 1 This is a schematic diagram of the round steel sample in Example 1;

[0031] Figure 2 This is a schematic diagram of the sample in Example 1;

[0032] Figure 3 This is a schematic diagram of the sample mounted on the lower fixture in Example 1;

[0033] Figure 4 This is a schematic diagram of the lower clamp, clamp pad, and upper clamp assembled in the mounting mold in Embodiment 1;

[0034] Figure 5 This is a schematic diagram of the lower clamp, clamp pad, and upper clamp assembled in the mounting mold in Example 1.

[0035] Figure 6 This is a schematic diagram of the lower clamp, clamp pad, and upper clamp after they have been assembled and removed from the installation mold in Example 1.

[0036] Figure 7 This is a schematic diagram of the three-point bending test performed after clamping the sample in the fixture for preparing the artificial fracture surface of small-diameter wire rods in Example 1.

[0037] Figure 8 This is a schematic diagram of the round steel sample in Example 2;

[0038] Figure 9 This is a schematic diagram of the sample in Example 2;

[0039] Figure 10 This is a schematic diagram of the sample mounted on the lower fixture in Example 2;

[0040] Figure 11 This is a schematic diagram of the lower clamp, clamp pad, and upper clamp being assembled inside the mounting mold in Embodiment 2;

[0041] Figure 12This is a schematic diagram of the lower clamp, clamp pad, and upper clamp assembled in the mounting mold in Example 2;

[0042] Figure 13 This is a schematic diagram of the lower clamp, clamp pad, and upper clamp after they have been assembled and removed from the installation mold in Example 2.

[0043] Figure 14 This is a schematic diagram of the three-point bending test performed after clamping the sample in the fixture for preparing the artificial fracture surface of small-diameter wire rods in Example 2.

[0044] The attached diagram shows the markings and corresponding component names:

[0045] 1. Lower clamp, 2. Clamp pad, 3. Upper clamp, 4. Bolt, 5. Nut, 6. Mold mounting, 7. Mandrel;

[0046] 11. Straight groove; 12. Bolt hole;

[0047] 21. Long, narrow hole;

[0048] 61. Mounting groove; 62. Stepped surface; 63. Bolt placement groove. Detailed Implementation

[0049] The present invention will now be described in further detail with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are for illustrative purposes only and are not intended to limit the scope of the invention. Furthermore, it should be noted that, for ease of description, only the parts relevant to the present invention are shown in the accompanying drawings.

[0050] It should be noted that, unless otherwise specified, the embodiments and features described in this invention can be combined with each other. The invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0051] Example 1

[0052] In this embodiment 1, a 6mm round steel sample was selected. The surface of this round steel sample had small longitudinal cracks, such as... Figure 1 As shown. The following is a method for preparing an artificial fracture surface of a small-diameter wire rod, using this round steel sample as an example, including the following steps:

[0053] Step 1: Use wire cutting to cut a sample from the round steel specimen. The sample height is 2mm. The crack on the sample is located on the top surface of the arc. Figure 2 As shown.

[0054] Step 2: Use 502 glue to attach and fix the sample to the center of the lower clamp 1, with the length direction of the crack aligned with the width direction of the lower clamp 1. Figure 3 As shown.

[0055] Step 3: Select the installation mold 6 of the corresponding size, place the four bolts 4 head-down in the bolt placement groove 63, and install the lower clamp 1 with the sample attached on the stepped surface 62. Simultaneously with the installation of the lower clamp 1, ensure that the four bolts 4 pass through the straight slot 11 and bolt hole 12 on the lower clamp 1, respectively. Based on the height of the sample, select two sets of 1mm thick clamp pads 2. Place two clamp pads 2 from the same set into the installation groove 61 from above the end of the lower clamp 1, ensuring that the inner end of the clamp pad 2 is pressed against the arc surface of the sample. Simultaneously with the installation of the clamp pads 2, ensure that the bolts 4 pass through the elongated hole 21 on the clamp pad 2. Figure 4 As shown.

[0056] Step 4: Place the upper clamp 3 above the clamp pad 2. While installing the upper clamp 3, ensure the bolt 4 passes through the elongated hole 21 on the upper clamp 3, and align the gap between the inner ends of the two upper clamps 3 with the crack at the top of the sample. Next, tighten the nut 5 onto the bolt 4, locking the upper clamp 3, clamp pad 2, and lower clamp 1 together. The sample is then clamped and fixed within the fixture for preparing artificial fracture surfaces of small-diameter wire rods. Figure 5 As shown.

[0057] Step 5: Remove the fixture for preparing the artificial fracture surface of the small-diameter wire rod, which has been clamped and fixed to the sample, from the mounting mold 6, and proceed as follows... Figure 6 As shown in the diagram; the fixture for preparing the artificial fracture surface of a small-diameter wire rod with the sample clamped and fixed is installed on the bending testing machine, such as... Figure 7 As shown, the two top heads 7 at the top of the bending tester press down against the two upper clamps 3, and the top head 7 at the bottom of the bending tester pushes upward from the middle of the lower clamp 1. At the same time as the top head 7 at the bottom of the bending tester pushes upward, the lower clamp 1 deforms and drives the sample on the lower clamp 1 to open along the crack direction, thereby obtaining an artificial fracture sample.

[0058] Example 2

[0059] In this Example 2, a round steel sample with a diameter of 30 mm was selected. An incomplete crack appeared in the middle of the end face of this round steel sample. Figure 8 As shown. The following is a method for preparing an artificial fracture surface of a small-diameter wire rod, using this round steel sample as an example, including the following steps:

[0060] Step 1: Use a band saw to directly cut a sample piece, 6mm thick. The crack on the sample is located in the middle of the upper surface. Trim any excess material. The resulting sample is shown below. Figure 9 As shown.

[0061] Step 2: Use 502 glue to attach and fix the sample to the center of the lower clamp 1, with the length direction of the crack aligned with the width direction of the lower clamp 1. Figure 10 As shown.

[0062] Step 3: Select the installation mold 6 of the corresponding size, place the four bolts 4 head-down in the bolt placement groove 63, and install the lower clamp 1 with the sample attached on the stepped surface 62. Simultaneously with the installation of the lower clamp 1, ensure that the four bolts 4 pass through the straight groove 11 and bolt hole 12 on the lower clamp 1, respectively. Based on the height of the sample, select a set of 6mm thick clamp pads 2. Place two clamp pads 2 from the same set into the installation groove 61 from above both ends of the lower clamp 1, ensuring that the inner ends of the clamp pads 2 are pressed against the arc surface of the sample side. Simultaneously with the installation of the clamp pads 2, ensure that the bolts 4 pass through the elongated hole 21 on the clamp pad 2. Figure 11 As shown.

[0063] Step 4: Place the upper clamp 3 above the clamp pad 2. While installing the upper clamp 3, ensure the bolt 4 passes through the elongated hole 21 on the upper clamp 3, and align the gap between the inner ends of the two upper clamps 3 with the crack at the top of the sample. Next, tighten the nut 5 onto the bolt 4, locking the upper clamp 3, clamp pad 2, and lower clamp 1 together. The sample is then clamped and fixed within the fixture for preparing artificial fracture surfaces of small-diameter wire rods. Figure 12 As shown.

[0064] Step 5: Remove the fixture for preparing the artificial fracture surface of the small-diameter wire rod, which has been clamped and fixed to the sample, from the mounting mold 6, and proceed as follows... Figure 13 As shown in the diagram; the fixture for preparing the artificial fracture surface of a small-diameter wire rod with the sample clamped and fixed is installed on the bending testing machine, such as... Figure 14 As shown, the two top heads 7 at the top of the bending tester press down against the two upper clamps 3, and the top head 7 at the bottom of the bending tester pushes upward from the middle of the lower clamp 1. At the same time as the top head 7 at the bottom of the bending tester pushes upward, the lower clamp 1 deforms and drives the sample on the lower clamp 1 to open along the crack direction, thereby obtaining an artificial fracture sample.

[0065] The fixture and method for preparing artificial fracture surfaces of small-sized wire rods provided by this invention can complete the preparation of artificial fracture surfaces of small-sized wire rods. It can conveniently and efficiently prepare artificial fracture surface samples that meet the requirements for fracture analysis, providing reliable detection technology support for subsequent product quality defect analysis and accurate judgment of the causes of product quality defects.

[0066] This invention utilizes the principle of three-point bending and employs mechanical loading to generate significant tensile stress at both ends of the crack, causing the crack to open along the direction of the tensile stress and eventually form a cross-section.

[0067] Those skilled in the art should understand that the above embodiments are merely for illustrating the present invention and are not intended to limit the scope of the invention. Those skilled in the art can make other changes or modifications based on the above disclosure, and these changes or modifications still fall within the scope of the present invention.

Claims

1. A fixture for preparing artificial fracture surfaces of small-diameter wire rods, characterized in that, The sample includes a lower clamp (1) for fitting and fixing the sample. The two ends of the lower clamp (1) are fitted with clamp pads (2) that press against the two sides of the sample. Upper clamps (3) are installed on the clamp pads (2) on both sides of the sample. The inner ends of the two upper clamps (3) press against and press against the sample. The gap between the two upper clamps (3) corresponds to the crack on the sample. The end of the lower clamp (1) is fixed together with the clamp pads (2) and the upper clamps (3) located above.

2. The fixture for preparing artificial fracture surfaces of small-diameter wire rods according to claim 1, characterized in that, The lower clamp (1) is made of hot-rolled carbon steel with a hardness less than HRB50. The clamp pad (2) and the upper clamp are made of steel. The thickness of the lower clamp (1) is 1mm to 1.5mm, the thickness of the upper clamp (3) is 5mm to 8mm, and the thickness of the clamp pad (2) is 1mm to 6mm.

3. The fixture for preparing artificial fracture surfaces of small-diameter wire rods according to claim 1, characterized in that, The number of clamping pads (2) between the end of the lower clamp (1) and the upper clamp (3) is at least one, and the thickness of the clamping pads (2) between the end of the lower clamp (1) and the upper clamp (3) is adapted to the thickness of the sample.

4. The fixture for preparing artificial fracture surfaces of small-diameter wire rods according to any one of claims 1 to 3, characterized in that, Both ends of the lower clamp (1) have straight slots (11) and bolt holes (12), and both the clamp pad (2) and the upper clamp (3) have strip holes that cooperate with the straight slots (11) and bolt holes (12). The straight slots (11) on the lower clamp (1) and the bolt holes (12) on the lower clamp (1) are connected to the strip holes on the clamp pad (2) and the strip holes on the upper clamp (3) for bolts (4) to pass through, and are locked and fixed by nuts (5).

5. A method for preparing artificial fracture surfaces of small-diameter wire rods, characterized in that, Including the fixture for preparing artificial fracture surfaces as described in claim 4, the method further includes the following steps: Step 1: Without damaging the crack, cut a sample from the product by machining, so that the crack is located at the center of the top of the sample and the bottom surface of the sample is flat. Step 2: Fix the sample to the lower clamp (1) and make the length direction of the crack on the sample consistent with the width direction of the lower clamp (1); Step 3: Install clamp pads (2) on both ends of the lower clamp (1), with the inner end of the clamp pads (2) pressing against the side of the sample; Step 4: Place the two upper clamps (3) onto the clamp pads (2) on both sides of the sample respectively. The inner ends of the two upper clamps (3) should be pressed together and aligned with the cracks on the sample. Then fix the end of the lower clamp (1), the clamp pads (2), and the upper clamps (3) together. The inner end of the upper clamps (3) should be pressed against the top of the sample. The sample is then fixed in the clamp for preparing artificial fracture surfaces. Step 5: Use the equipment to conduct a three-point bending test. During the three-point bending test, the two supporting mandrels (7) on the equipment press against the outer surfaces of the two upper clamps (3) respectively, and the bending mandrel (7) gradually applies force on the lower clamp (1) at the corresponding point of the sample crack, and the crack is gradually opened.

6. The method for preparing artificial fracture surfaces of small-diameter wire rods according to claim 5, characterized in that, In step two, the sample can be glued and fixed to the lower fixture (1) using quick-drying adhesive.

7. The method for preparing artificial fracture surfaces of small-diameter wire rods according to claim 5, characterized in that, In steps three and four, the assembly of the lower clamp (1), clamp pad (2), and upper clamp (3) can be completed by using the installation mold (6).

8. The method for preparing artificial fracture surfaces of small-diameter wire rods according to claim 7, characterized in that, The installation mold (6) includes a mold body, which has an installation groove (61) with a length greater than that of the lower clamp (1). The bottom of the installation groove (61) has a stepped surface (62) that matches the length of the lower clamp (1), and the stepped surface (62) also has a bolt placement groove (63). The length of the bolt placement groove (63) covers the two straight slots (11) and two bolt holes (12) on the lower clamp (1).

9. The method for preparing artificial fracture surfaces of small-diameter wire rods according to claim 8, characterized in that, The assembly steps of the lower clamp (1), clamp pad (2), and upper clamp (3) are as follows: Four bolts (4) are installed upside down in the bolt placement groove (63), and the lower clamp (1) with the sample attached is installed on the step surface (62). The four bolts (4) pass through the two straight slots (11) and two bolt holes (12) on the lower clamp (1), respectively. When installing the clamp pad (2) and the upper clamp (3), the clamp pad (2) and the upper clamp (3) are inserted directly from both ends of the mounting groove (61), and the bolt (4) is passed through the strip hole on the clamp pad (2) and the upper clamp (3). Finally, the nut is tightened on the bolt (4).

10. The method for preparing artificial fracture surfaces of small-diameter wire rods according to claim 8, characterized in that, In step five, during the three-point bending test, the movement speed of the mandrel (7) that plays a bending role shall not be less than 10 mm / min.

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