Test piece for coil method magnetic particle testing and testing method for the test piece

Abstract

The present invention belongs to the technical field of non-destructive testing, and discloses a test piece for coil method magnetic powder testing and a testing method for the test piece. The testing method comprises the following steps: fixing the test piece between two chucks of a magnetic detection platform, so that the test piece is located at the center of the coil and kept horizontal; energizing the coil to form a magnetic field and applying magnetic powder or magnetic suspension to the test piece to obtain magnetic traces; recording the magnitude of the magnetization current and the length of the magnetic traces; and calculating the magnetic powder testing depth according to a formula. The test piece provided by the present invention can be used for the coil method magnetic powder testing of the detectable depth of near-surface circumferential defects. The test piece testing method can be used to verify the process sensitivity, resolution, and reliability of the detectable depth of near-surface circumferential defects of longitudinal workpieces made of ferromagnetic materials, optimize the process parameters of coil method magnetic powder testing, and improve the near-surface circumferential defect detection capability of this type of workpiece.

Description

Technical Field

[0001] The invention belongs to the technical field of nondestructive testing, and in particular relates to a test piece for coil method magnetic powder testing and a testing method for the test piece. Background Art

[0002] In the magnetic particle testing method standards, there are no specific requirements and related contents such as the testing method, operation process, sensitivity verification test block, process verification, etc. for the detectable depth range of near-surface circumferential defects of longitudinally long workpieces made of ferromagnetic materials. Therefore, it is necessary and urgent to carry out the above-mentioned related experimental research to improve the detection capability of near-surface circumferential defects and realize process verification, so that the coil method magnetic particle testing can truly cover the near-surface circumferential defect detection of butt welds, tube-sheet welds and longitudinally long workpieces such as crankshafts, shafts, pipes, bars, castings, and forgings. Summary of the invention

[0003] The present invention aims to solve the above technical problems at least to a certain extent. To this end, the present invention aims to provide a test piece for coil method magnetic particle testing and a testing method for the test piece.

[0004] The technical solution adopted by the present invention is:

[0005] A test piece for coil method magnetic powder testing comprises a metal pipe, the outer surface of the metal pipe is a testing surface, the inner surface of the metal pipe is circumferentially provided with at least two testing grooves of different widths, and the distance from the bottom of the testing groove to the testing surface changes continuously along the circumferential direction of the metal pipe.

[0006] Preferably, the detection grooves are electric spark cutting grooves, and the distances between adjacent detection grooves are equal.

[0007] Preferably, the width of the detection groove increases gradually along the axial direction of the metal pipe.

[0008] Preferably, the diameter of the metal pipe is 120 mm, and the detection grooves include three, the widths of the three detection grooves are 0.5 mm, 1.0 mm and 2.0 mm respectively, and the distance from the bottom of the detection groove to the detection surface changes continuously from 1.0-8.0 mm.

[0009] The above-mentioned test piece detection method for coil method magnetic particle detection comprises the following steps:

[0010] Fix the test piece between the two clamps of the magnetic detection table so that the test piece is located in the center of the coil and kept horizontal;

[0011] The coil is energized to form a magnetic field and magnetic powder or magnetic suspension is applied to the test piece to obtain magnetic traces;

[0012] Record the magnetizing current and the length L of the magnetic trace;

[0013] The magnetic particle inspection depth h is calculated according to the formula h=(ba)L / πd+a, where d is the diameter of the metal pipe, a is the shortest distance from the bottom of the inspection slot to the inspection surface, and b is the longest distance from the bottom of the inspection slot to the inspection surface.

[0014] Preferably, the coil is magnetized and magnetic powder or magnetic suspension is applied, and the magnetization is repeated for multiple times. After each magnetization, the magnetic traces are observed until the magnetic traces show stability and then the magnetization is stopped.

[0015] Preferably, the chuck is rotated to a suitable detection position before the coil is electromagnetized.

[0016] Preferably, the magnetizing current increases in sequence, and the length L of the magnetic trace corresponding to each magnetizing current is recorded respectively.

[0017] Preferably, the length L of the magnetic trace is recorded while the width k of the magnetic trace is recorded.

[0018] Preferably, the surface of the specimen is cleaned before the specimen is fixed.

[0019] The beneficial effects of the present invention are:

[0020] The test piece provided by the present invention can be used for the detectable depth of near-surface circumferential defects in magnetic powder testing using the coil method. The test piece detection method can be used to verify the process sensitivity, resolution, and reliability of detecting the detectable depth of near-surface circumferential defects in longitudinal workpieces made of ferromagnetic materials, optimize the process parameters of the coil method magnetic powder detection, and improve the near-surface circumferential defect detection capability of this type of workpiece. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 It is a cross-sectional view of a test piece used for coil method magnetic particle testing according to the present invention.

[0022] Figure 2 It is another cross-sectional view of the test piece used for coil method magnetic particle testing of the present invention.

[0023] Figure 3 It is a schematic diagram of the magnetic detection station of the present invention.

[0024] Figure 4 It is a schematic diagram of the magnetic trace of the present invention.

[0025] Figure 5 It is a schematic diagram of the magnetic trace of the present invention from another angle.

[0026] Figure 6 It is the side view of the specimen.

[0027] Figure 7 yes Figure 6 A partial enlarged view of . DETAILED DESCRIPTION

[0028] Embodiments of the present invention are described in detail below, examples of which are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are intended to be used to explain the present invention, and are not to be construed as limiting the present invention. The components of the embodiments of the present invention generally described and shown in the drawings herein may be arranged and designed in a variety of different configurations.

[0029] In the description of the embodiments of the present invention, it should be noted that the indicated orientation or position relationship is based on the orientation or position relationship shown in the accompanying drawings, or is the orientation or position relationship in which the product of the invention is usually placed when in use, or is the orientation or position relationship commonly understood by those skilled in the art. It is only for the convenience of describing the present invention and simplifying the description, and does not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention.

[0030] In the present invention, unless otherwise clearly stipulated and limited, terms such as "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, or it can be the internal connection of two elements.

[0031] like Figure 1 As shown, a test piece for coil method magnetic particle testing in this embodiment includes a metal pipe 1, and the material of the metal pipe 1 is 45 # Steel, the diameter of the metal pipe 1 is 120mm, the length is 300mm, and the wall thickness is 15mm. The outer surface of the metal pipe 1 is the detection surface, and the inner surface of the metal pipe 1 is circumferentially electrospark cut with three detection grooves 2 of different widths, and the distance between adjacent detection grooves 2 is 75mm. The widths of the three detection grooves 2 are 0.5mm, 1.0mm and 2.0mm respectively. Figure 2 As shown, the distance from the bottom of the detection groove 2 to the detection surface changes continuously from 1.0 to 8.0 mm in the clockwise direction along the circumference of the metal pipe 1 .

[0032] The above-mentioned specimen is placed in an energized coil to form a longitudinal magnetic field, and magnetic powder or magnetic suspension is applied to the specimen at the same time. At this time, due to the existence of simulated defects, the magnetic induction lines near the surface of the specimen are locally distorted to generate a leakage magnetic field, which adsorbs the magnetic suspension or magnetic powder applied to the back of the EDM cutting groove of the specimen to form a visible magnetic mark. The length of the visible magnetic mark is measured with a soft ruler, and the maximum detectable depth of the near-surface circumferential simulated defect is calculated based on the relationship between the magnetic mark length and the burial depth ratio.

[0033] like Figure 3-Figure 5As shown, the above-mentioned test piece detection method for coil method magnetic particle detection includes the following steps:

[0034] 1. Clean the outer surface of the test piece to ensure that there is no rust, oxide scale or dirt on the outer surface of the test piece;

[0035] 2. Place the test piece 400 between the two chucks 200 on the magnetic detection platform 100, and press the clamping button to keep the test piece and the chuck in good contact. At this time, the test piece is exactly located at the center of the coil 300 and remains horizontal;

[0036] 3. Select the AC continuous method, and the magnetizing currents are: I1 = 1600A, I2 = 2200A, I3 = 2500A;

[0037] 4. The coil is energized, and the current passes through the coil to form a longitudinal magnetic field. The magnetic suspension is applied while the chuck is rotated at a constant speed. The magnetization can be stopped after 1 second of stopping the application of the magnetic suspension. To ensure the magnetization effect, the magnetization is repeated twice, each time for 1-3 seconds, and the magnetic traces are observed;

[0038] 5. Record the length L and width k of the magnetic trace 500 displayed by the detection slot with a width of 0.5 mm, 1.0 mm, and 2.0 mm under different magnetizing current conditions;

[0039] 6. According to the formula h=(ba)L / πd+a, calculate the depth of the magnetic trace end point of the detection slot 2 from the outer surface, that is, the magnetic particle detection depth h of the detection slot 2 under the process parameters. Where d is the diameter of the metal pipe 1, a is the shortest distance from the bottom of the detection slot 2 to the detection surface, and b is the longest distance from the bottom of the detection slot 2 to the detection surface.

[0040] The derivation process of the above formula is as follows:

[0041] like Figure 6 and Figure 7 As shown, AD is the length of the magnetic trace, the center of the test piece is O, where AB = a, AC = b, the arc length of AD is L, the central angle corresponding to the arc length of AD is θ, and a concentric circle of the ring is drawn through point B, intersecting with OD at point F;

[0042] Then DF=AB=a;

[0043] OD intersects the spark slot at point E;

[0044] Assuming DE = h, EF = h′, then h = h′ + a;

[0045] ∵The BEC of the spark slot increases along the circumferential direction,

[0046] BC=ba,

[0047] That is, the spark slot increases in equal parts from 0 to (ba) within the range of 0 to 360°;

[0048] ∴h′ / (ba)=θ / 360, that is, h′=θ(ba) / 360;

[0049] And according to the relationship between arc length and central angle,

[0050] θ / 360=L / πd,

[0051] h′=L(ba) / πd,

[0052] h=h′+a=L(ba) / πd+a;

[0053] In this embodiment, a=1 mm, b=8 mm, d=120 mm, and h=7L / π120+1.

[0054] For this specimen, the above detection method was used to obtain a series of detection experimental data under different detection process parameters, as shown in Table 1.

[0055] Table 1 Detection experimental data

[0056]

[0057] In addition to being used to verify the process sensitivity, resolution, and reliability of detecting the detectable depth of near-surface circumferential defects in longitudinal workpieces made of ferromagnetic materials, the above-mentioned detection method can also be used to optimize the process parameters of coil-based magnetic particle detection and improve the ability to detect near-surface circumferential defects of this type of workpiece.

[0058] The present invention is not limited to the above-mentioned optional implementation modes. Anyone can derive other various forms of products under the inspiration of the present invention. However, no matter what changes are made in the shape or structure, all technical solutions that fall within the scope defined by the claims of the present invention fall within the protection scope of the present invention.

Claims

1. A method for testing a test piece for coil method magnetic particle testing, the test piece comprising a metal pipe (1), the outer surface of the metal pipe (1) being a testing surface, the inner surface of the metal pipe (1) being circumferentially provided with at least two testing grooves (2) of different widths, the distance from the bottom of the testing groove (2) to the testing surface continuously changing along the circumferential direction of the metal pipe (1); the distances between adjacent testing grooves (2) being equal; the widths of the testing grooves (2) increasing in sequence along the axial direction of the metal pipe (1); characterized in that: The following steps are involved: Fix the test piece between the two clamps (200) so that the test piece is located at the center of the coil (300) and remains horizontal; The coil (300) is energized to form a magnetic field and magnetic powder or magnetic suspension is applied to the test piece to obtain magnetic traces; Record the magnetizing current and the length L of the magnetic trace; The magnetic particle inspection depth h is calculated according to the formula h=(ba)L / πd+a, wherein d is the diameter of the metal pipe (1), a is the shortest distance from the bottom of the inspection groove (2) to the inspection surface, and b is the longest distance from the bottom of the inspection groove (2) to the inspection surface; The detection method can be used to verify the process sensitivity, resolution, and reliability of the detectable depth of circumferential defects near the surface of longitudinal workpieces made of ferromagnetic materials, and to optimize the process parameters of coil-based magnetic particle testing.

2. The detection method according to claim 1, characterized in that: The coil (300) is magnetized and magnetic powder or magnetic suspension is applied, and the magnetization is repeated multiple times. After each magnetization, the magnetic traces are observed until the magnetic traces are stable and then the magnetization is stopped.

3. The detection method according to claim 1, characterized in that: Before the coil (300) is electromagnetized, the chuck (200) is rotated to a suitable detection position.

4. The detection method according to claim 1, characterized in that: The magnetizing current increases in sequence, and the length L of the magnetic trace corresponding to each magnetizing current is recorded respectively.

5. The detection method according to claim 1 or 4, characterized in that: The length L of the magnetic trace is recorded while the width k of the magnetic trace is recorded.

6. The detection method according to claim 1, characterized in that: Clean the specimen surface before fixing it.

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