CN112119302A - Nondestructive inspection method for steel material - Google Patents
Nondestructive inspection method for steel material Download PDFInfo
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- CN112119302A CN112119302A CN201980032421.3A CN201980032421A CN112119302A CN 112119302 A CN112119302 A CN 112119302A CN 201980032421 A CN201980032421 A CN 201980032421A CN 112119302 A CN112119302 A CN 112119302A
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- 238000007689 inspection Methods 0.000 title claims abstract description 247
- 239000000463 material Substances 0.000 title claims abstract description 200
- 239000010959 steel Substances 0.000 title claims abstract description 120
- 229910000831 Steel Inorganic materials 0.000 title claims abstract description 119
- 238000000034 method Methods 0.000 title claims abstract description 52
- 230000035515 penetration Effects 0.000 claims abstract description 75
- 238000002360 preparation method Methods 0.000 claims abstract description 9
- 230000002950 deficient Effects 0.000 claims description 59
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- 238000003754 machining Methods 0.000 claims description 16
- 230000008859 change Effects 0.000 claims description 11
- 238000002847 impedance measurement Methods 0.000 claims description 3
- 230000000149 penetrating effect Effects 0.000 claims description 2
- 239000000203 mixture Substances 0.000 abstract description 31
- 238000012545 processing Methods 0.000 abstract description 5
- 238000012360 testing method Methods 0.000 abstract description 4
- 239000000047 product Substances 0.000 description 65
- 238000004519 manufacturing process Methods 0.000 description 17
- VNTLIPZTSJSULJ-UHFFFAOYSA-N chromium molybdenum Chemical compound [Cr].[Mo] VNTLIPZTSJSULJ-UHFFFAOYSA-N 0.000 description 6
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- 238000006243 chemical reaction Methods 0.000 description 4
- 238000010438 heat treatment Methods 0.000 description 4
- 238000005480 shot peening Methods 0.000 description 4
- 229910001220 stainless steel Inorganic materials 0.000 description 4
- 238000010586 diagram Methods 0.000 description 3
- 238000005242 forging Methods 0.000 description 3
- 238000005259 measurement Methods 0.000 description 3
- 238000005498 polishing Methods 0.000 description 3
- VYZAMTAEIAYCRO-UHFFFAOYSA-N Chromium Chemical compound [Cr] VYZAMTAEIAYCRO-UHFFFAOYSA-N 0.000 description 2
- ZOKXTWBITQBERF-UHFFFAOYSA-N Molybdenum Chemical compound [Mo] ZOKXTWBITQBERF-UHFFFAOYSA-N 0.000 description 2
- 230000003321 amplification Effects 0.000 description 2
- 238000005266 casting Methods 0.000 description 2
- 229910052804 chromium Inorganic materials 0.000 description 2
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- 229910052750 molybdenum Inorganic materials 0.000 description 2
- 239000011733 molybdenum Substances 0.000 description 2
- 238000003199 nucleic acid amplification method Methods 0.000 description 2
- 239000012466 permeate Substances 0.000 description 2
- 229920005989 resin Polymers 0.000 description 2
- 239000011347 resin Substances 0.000 description 2
- 238000004804 winding Methods 0.000 description 2
- 229910000669 Chrome steel Inorganic materials 0.000 description 1
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 description 1
- 238000000137 annealing Methods 0.000 description 1
- 238000009954 braiding Methods 0.000 description 1
- 238000010276 construction Methods 0.000 description 1
- 229910052802 copper Inorganic materials 0.000 description 1
- 239000010949 copper Substances 0.000 description 1
- 238000005520 cutting process Methods 0.000 description 1
- 230000001066 destructive effect Effects 0.000 description 1
- 238000001035 drying Methods 0.000 description 1
- 239000003822 epoxy resin Substances 0.000 description 1
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- 229920001187 thermosetting polymer Polymers 0.000 description 1
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N27/00—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means
- G01N27/72—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating magnetic variables
- G01N27/82—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating magnetic variables for investigating the presence of flaws
- G01N27/90—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating magnetic variables for investigating the presence of flaws using eddy currents
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Abstract
Provided is a nondestructive inspection method for a steel material, which can inspect the acceptance of the material composition of the steel material to be inspected with high accuracy. A nondestructive inspection method for a steel material according to an aspect of the present invention includes: a preparation step (S1) in which a nondestructive inspection device is prepared; a placement step (S2) in which the steel material that has undergone the mechanical processing and has undergone the deformation is used as an inspection object, and the inspection object is placed so that an alternating-current magnetic field excited by a coil penetrates into the interior of the inspection object; an eddy current generation step (S3) in which an eddy current is generated in the test object; a frequency changing step (S4) in which the penetration depth of the alternating-current magnetic field into the inspection object is continuously changed; an impedance calculation step (S5) for calculating the impedance ratio per penetration depth of the inspection object; and a component inspection step (S6) in which the material component of the object to be inspected is inspected for acceptability by comparing the resistance ratio per penetration depth with the resistance ratio per penetration depth in a steel material composed of the correct material component.
Description
Technical Field
The present invention relates to a nondestructive inspection method for steel material.
Background
Conventionally, since various steel materials have been used in a manufacturing process of steel materials, steel materials (different materials) having the same shape but different materials may be mixed in a manufacturing line by mistake.
If the operator visually checks the mixture of such different materials, there is a problem that the efficiency is poor, and it is easy to be influenced by the ability of the operator, and it is difficult to obtain stable inspection accuracy. Therefore, various methods have been proposed for automatically and highly accurately detecting different materials in the manufacturing process.
For example, a dissimilar material determination method using an eddy current inspection apparatus capable of inspecting whether or not steel materials are dissimilar materials by conveying the steel materials to be inspected on a manufacturing line and penetrating the conveyed steel materials through a cylindrical coil has been proposed.
In this dissimilar material determination method, a pulse current is caused to flow from an eddy current inspection apparatus into a cylindrical coil so that an eddy current flows into a steel material to be inspected that passes through the coil, and a change in impedance of the coil caused by the induced eddy current is detected in the steel material as an inspection signal. Then, it is determined whether or not the inspection object is a different material based on whether or not the peak amplitude of the inspection signal and the phase at the peak amplitude are detected to be within a predetermined determination region (see patent document 1).
Documents of the prior art
Patent document
Patent document 1: japanese laid-open patent publication No. 2012-42333.
Disclosure of Invention
Problems to be solved by the invention
In the above dissimilar material determination method, a predetermined current is caused to flow into the cylindrical coil, so that an eddy current is caused to flow into the steel material passing through the coil, and a change in impedance of the coil caused by the eddy current is detected.
However, in this dissimilar material determination method, since the inspection is not performed while changing the penetration depth of the magnetic field into the steel material, there are problems as follows: the inspection area in the steel material is narrow, and the acceptance inspection of the material composition of the steel material cannot be performed with high accuracy.
An aspect of the present invention has been made in view of the above problems, and an object thereof is to provide a nondestructive inspection method for a steel material, which can inspect the qualification of the material composition of the steel material to be inspected with high accuracy.
Means for solving the problems
A nondestructive inspection method for a steel material according to an aspect of the present invention for solving the above-described problems is a nondestructive inspection method for a steel material including a preparation step, a placement step, an eddy current generation step, a frequency changing step, an impedance calculation step, and a component inspection step. In the preparation step, a nondestructive inspection apparatus having a frequency variable circuit and a coil is prepared. The frequency variable circuit can change the frequency of alternating current, and the coil can excite an alternating current magnetic field by adopting the alternating current. In the arranging step, the inspection object is arranged so that the alternating-current magnetic field excited by the coil penetrates into the inspection object. The test object is the steel material that has been deformed after machining. In the eddy current generating step, the alternating magnetic field penetrates into the inspection object, thereby generating an eddy current in the inspection object.
In the frequency changing step, the frequency of the alternating current is continuously changed by the frequency variable circuit, so that the penetration depth of the alternating current magnetic field into the inspection object is continuously changed. In the impedance calculating step, a value related to the impedance per penetration depth of the inspection target is calculated based on a potential difference between both ends of the coil and a current value flowing through the coil. In the component inspection step, the inspection of the acceptance of the material component of the inspection object is performed by comparing the value related to the impedance per the penetration depth of the inspection object calculated in the impedance calculation step with the value related to the impedance per the penetration depth of the steel material composed of a correct material component.
ADVANTAGEOUS EFFECTS OF INVENTION
According to one aspect of the present invention, the acceptance of the material composition of the steel material to be inspected can be inspected with high accuracy.
Drawings
Fig. 1 is a circuit diagram of a nondestructive inspection apparatus according to an embodiment of the present invention.
Fig. 2 is a schematic diagram showing an ac magnetic field generated in the coil according to the embodiment of the present invention.
Fig. 3 is a flowchart illustrating a nondestructive inspection method for a steel material according to an embodiment of the present invention.
Fig. 4 is a flowchart showing a flow of processing in the component inspection step according to the embodiment of the present invention.
Fig. 5 is a flowchart showing a flow of the manufacturing process according to the embodiment of the present invention.
Fig. 6 is a diagram showing the impedance ratio of the inspection object in the component inspection process according to the embodiment of the present invention.
Detailed Description
An embodiment of the present invention will be described below with reference to fig. 1 to 6.
[ nondestructive inspection apparatus ]
The nondestructive inspection apparatus 1 of the present embodiment is configured to include an oscillator 10, a detector 20, and a meter 30, as shown in fig. 1. The oscillator 10 includes an ac power supply 11 and a frequency variable circuit 12. The frequency variable circuit 12 is connected to the ac power supply 11 and changes the frequency of the ac current output from the ac power supply 11.
The detector 20 includes a coil 21 described later. One end side (point a in fig. 1) of the coil 21 is connected to the ac power supply 11, and supplies an ac current output from the ac power supply 11. The other end side (point B in fig. 1) of the coil 21 is connected to an I/V conversion circuit 34 described later. The detector 20 is used for the determination of the acceptability of the components of the inspection object M, which will be described later. The circuit symbols in the broken line showing the coil 21 in fig. 1 indicate the electrically equivalent circuit of the coil 21.
The coil 21 is a product formed by winding a plurality of conductive wire rods into a cylindrical shape, as shown in fig. 2. In the present embodiment, a product formed by bundling a plurality of fine conductive wires and forming the bundle as one wire is used as the wire material, whereby the resonance frequency of the coil 21 can be increased. As the coil 21, a coil formed by winding a wire around a hollow cylindrical core (cored coil) can be used. In addition, a single wire may be used for the wire.
In the method of manufacturing the coil 21 of the present embodiment, first, a wire material obtained by braiding and twisting several hundred enameled copper wires is wound around a resin cylinder, and then the wound wire material is bonded with an epoxy resin, and the cylinder is removed to manufacture the coil.
As another method for manufacturing the coil 21, for example, the following method is used: a wire material coated with a thermosetting resin is used, wound, and then heated with hot air, a drying oven, or the like to fix the wire material so as to maintain a coil-like shape. The method of producing the wire rod is not particularly limited as long as the wire rod can be made to retain a coil-like shape.
The meter 30 includes an amplification circuit 31, an absolute value circuit 32, a Low Pass Filter (LPF)33, an I/V conversion circuit 34, an absolute value circuit 35, an LPF36, a control unit 37, and a display 38. The meter 30 measures a change in impedance of the coil 21 based on a signal indicating an electrical characteristic of the alternating current flowing through the coil 21. The impedance represents a ratio of a potential difference between both ends of the coil 21 to a current value flowing through the coil 21.
One end side (left side in fig. 1) of the amplification circuit 31 is connected to both ends (points a and B in fig. 1) of the coil 21, while the other end side (right side in fig. 1) is connected to the absolute value circuit 32. A signal of the potential difference between both ends of the coil 21 is input to the amplifier circuit 31. The signal inputted to the amplifier circuit 31 is amplified and inputted to the absolute value circuit 32.
The absolute value circuit 32 is a full-wave rectifier circuit. The potential difference signal input to the absolute value circuit 32 is full-wave rectified and converted to a direct current by the LPF 33. The potential difference signal converted by the LPF33 is input to the control unit 37.
The I/V conversion circuit 34 is connected to the other end side (point B in fig. 1) of the coil 21. A signal indicating the current value of the current flowing through the coil 21 is input to the I/V conversion circuit 34 and converted into a signal indicating the potential difference. Then, full-wave rectification is performed by the absolute value circuit 35, and the full-wave rectified voltage is converted into a direct current by the LPF 36. The signal converted by the LPF36 is input to the control unit 37.
The control unit 37 is not shown, but includes a microprocessor, an interface circuit, a memory, and a program for operating the same. The control section 37 is connected to the frequency variable circuit 12, the LPF33, and the LPF 36. The control unit 37 receives signals indicating electrical characteristics of the coil 21, that is, signals of the frequency of the alternating current flowing through the coil 21, signals of the current value for each frequency, and signals of the potential difference. The control unit 37 calculates the impedance at each frequency based on the signal indicating the electrical characteristic of the coil 21.
The control unit 37 has a function of outputting a signal for automatically and continuously changing the frequency to the frequency variable circuit 12. In the present embodiment, the frequency is changed via the frequency variable circuit 12 in accordance with the control output from the control unit 37 in a state where the steel material to be inspected M is disposed inside the coil 21 (see fig. 2). Further, the frequency of the alternating current may be changed manually.
Further, the control unit 37 of the present embodiment calculates the impedance Z for each frequency that changes continuously2(value related to impedance), calculating the calculated impedance Z2Impedance Z with respect to untreated article0Impedance ratio of gamma2(Z2/Z0). The control unit 37 calculates the impedance Z per penetration depth in the case of a non-defective product1(value related to impedance) and impedance Z of untreated article0Impedance ratio of gamma1(Z1/Z0). Then, the impedance ratio gamma to the inspection object M is passed2(value related to impedance) to the impedance ratio γ of non-defective products1(values relating to impedance) are compared, and thereby also performedAnd a function of inspecting whether or not the material component of the inspection object M is acceptable.
In the notification step (S7) described later, the display 38 notifies the result of the component inspection obtained by the control unit 37 to indicate whether or not the inspection target M is a non-defective product. When the inspection object M is a defective product, an error sound may be output from the display 38. Further, when the component of the inspection target M is found based on the result of the component inspection by the control unit 37, the material component can be displayed on the display 38.
[ control method of Eddy Current ]
Next, a method of controlling an eddy current in the nondestructive inspection apparatus 1 will be described. First, an ac current is applied to the coil 21 of the nondestructive inspection apparatus 1 from the ac power supply 11. When an alternating current is applied to the coil 21, an alternating magnetic field excited by the coil 21 permeates into an inspection object M (see fig. 2) disposed inside the coil 21 as described later. This generates an eddy current in the inspection object M.
In the nondestructive inspection apparatus 1 of the present embodiment, the control unit 37 outputs a control signal to the frequency variable circuit 12, thereby continuously changing the frequency of the alternating current. Further, by continuously changing the frequency of the alternating current by using the frequency variable circuit 12, it is possible to continuously change the penetration depth of the alternating current magnetic field into the inspection object M. Further, the control unit 37 continuously changes the penetration depth of the alternating-current magnetic field into the inspection object M, and calculates the impedance Z per the penetration depth of the inspection object M based on the potential difference between the two ends of the coil 21 and the current value flowing through the coil 212. In this case, the impedance has a value that differs depending on the magnetic properties resulting from the material composition of the steel material.
The control unit 37 calculates the impedance Z based on the potential difference between the two ends (points a and B in fig. 1) of the coil 21 and the current value flowing through the coil 212Calculating the calculated impedance Z2Impedance Z with respect to untreated article0Impedance ratio of gamma2(Z2/Z0)。
Wherein the so-called impedance ratio γ2Indicates by correctImpedance Z per penetration depth in steel material composed of material components0Impedance Z per penetration depth of the object M2The ratio of (a) to (b). In the present embodiment, the impedance ratio γ of the non-defective product is set as described below1At 1.0, if the impedance ratio γ of the inspection object M2If the content is within the predetermined range, the product is judged as a non-defective product.
Further, data obtained by summing impedances when the penetration depth of the ac magnetic field is continuously changed in a steel material composed of various material components in advance is stored in the memory of the control unit 37, and the data can be used in the component inspection step (S6) described later.
[ non-destructive inspection method ]
Next, a method of nondestructive inspection of a steel material using the nondestructive inspection apparatus 1 of the present embodiment will be described with reference to a flowchart shown in fig. 3. The flowchart shown in fig. 3 is an example, and is not limited to the order of the flowchart.
In the nondestructive inspection method for a steel material according to the present embodiment, first, a preparation step is performed in which the nondestructive inspection apparatus 1 described above is prepared together with the steel material to be inspected M (S1). As the steel material of the inspection object M, for example, a steel material used for a component (gear, turning device, etc.) of an automobile, an aircraft, a construction machine, etc., a spring, a mold, a tool, etc. is assumed. In the present embodiment, a case will be described where a steel material is a chrome steel (JIS standard: SCR420H), and a steel material is machined into a gear shape by a machining step (S22) after a forging step (S21) described later, as an inspection object M.
Next, a steel material arrangement step (S2) of arranging the inspection object M is performed. Specifically, the steel material of the inspection object M is disposed at the center of the circular cross section inside the cylindrical coil 21, and is in a state in which the alternating-current magnetic field excited by the coil 21 can permeate into the inspection object M. The arrangement method is not limited to this, and may be any arrangement as long as the alternating-current magnetic field of the coil 21 penetrates into the inspection object M, or the inspection object M may be arranged at a position facing the coil 21.
In the present embodiment, a steel material that is deformed after a machining step (S22) described later is used as the inspection object M. This is because, if the steel material after machining is a different material (defective product) having only a different material composition, the difference in magnetic properties between the defective product and the defective product becomes larger than that of the forged product before machining, and the different material is easily found.
After the arrangement step (S2), an eddy current generation step (S3) is performed to generate an eddy current in the inspection object M. Specifically, the control unit 37 operates the ac power supply 11 via the frequency variable circuit 12. When the ac power supply 11 is operated, an ac magnetic field is excited in the coil 21 (see fig. 2). When the ac magnetic field of the coil 21 penetrates into the inside of the inspection object M, an eddy current is generated inside the inspection object M.
Next, a frequency changing step of continuously changing the penetration depth of the ac magnetic field into the inspection object M is performed (S4). Specifically, the control section 37 outputs a control signal to the frequency variable circuit 12, thereby continuously changing the frequency of the alternating current output from the alternating current power supply 11. Thereby, the penetration depth of the ac magnetic field into the inspection object M continuously changes. In this case, the penetration depth of the ac magnetic field into the inspection object M varies depending on the internal composition of the inspection object M even if the same ac magnetic field is applied to the inspection object M.
In the present embodiment, the penetration depth of the alternating-current magnetic field into the inspection object M is changed to 0 μ M to 150 μ M, and the inspection for the acceptability of the material component of the inspection object M is performed (see fig. 6). Various conditions such as the current value of the alternating current and the frequency change range in the nondestructive inspection apparatus 1 are appropriately set in accordance with the inspection object M.
After the frequency changing step (S4), the impedance ratio γ is calculated for the unit penetration depth of the inspection object M2The impedance calculating step (S5). Specifically, the control unit 37 calculates the impedance Z of the coil 21 in a state where the inspection object M is disposed, based on the potential difference between the two ends (points a and B in fig. 1) of the coil 21 and the current value flowing through the coil 212Calculating the calculated impedance Z2Impedance Z with respect to untreated article0Impedance ratio of gamma2(Z2/Z0)。
Wherein the impedance Z of the untreated article0Preferably, the measurement results of 10 or more untreated products are averaged for each frequency, and the average value is used. Further, the impedance Z for a good product is calculated in advance1The impedance Z of the non-defective product is calculated in advance1Impedance Z with respect to untreated article0Impedance ratio of gamma1(Z1/Z0)。
Next, a component inspection step of inspecting whether or not the material component of the inspection object M is acceptable is performed (S6). In the component inspection step (S6), the impedance ratio γ per penetration depth of the inspection object M calculated in the impedance calculation step (S5) is used2Resistance ratio gamma to unit penetration depth in steel material composed of accurate material composition1The inspection is performed to check whether or not the material component of the inspection object M is acceptable. Further, the resistance ratio γ per penetration depth in the steel material composed of the correct material composition1Can calculate the impedance ratio gamma of the unit penetration depth of the inspection object M2And then the process is carried out.
Further, when the quality of the material composition is checked for a plurality of steel materials, the following may be performed: first, the impedance ratio γ per penetration depth in a steel material composed of accurate material components is calculated for the first time1This value is stored in the memory of the control unit 37. Then, after the 2 nd time, the impedance ratio γ calculated from the 1 st time1Resistance ratio gamma to unit penetration depth in steel material of the inspection object M2The comparison is performed to check whether the material composition of the inspection object M is acceptable or not.
Here, a specific flow of the process in the component inspection step will be described with reference to fig. 4. As shown in fig. 4, in the component inspection step, first, the control unit 37 determines the impedance ratio γ of the inspection target M2Whether or not the temperature is within a predetermined range (S11). Impedance ratio gamma of the object M to be inspected2When the inspection target M is within the predetermined range (YES in S11), the control unit 37 determines that the inspection target M is a non-defective product(S12). On the other hand, the impedance ratio γ of the inspection object M2If the inspection target M is not within the predetermined range (NO in S11), the control unit 37 determines that the inspection target M is a defective product (S13).
In a predetermined range, for example, the impedance ratio γ of a good product1If the impedance ratio gamma of the inspection object M is set to 1.02Impedance ratio gamma to non-defective product1If the difference is less than 0.01, the product is determined to be a non-defective product, and if there is a deviation of 0.01 or more, the product is determined to be a defective product (see fig. 6). The predetermined range is not limited thereto, and may be appropriately changed.
Next, after the component inspection step (S6), a notification step (S7) is performed to notify whether the inspection object M is a non-defective product or a defective product. In the notification step (S7), whether the inspection object M is a non-defective product is displayed on the display 38. When the inspection object M is a defective product, an error sound may be output from the display 38. Further, by using the data of the steel material composed of various material components stored in the memory in advance, it is possible to display what the material component of the defective product is, or to notify a different error sound depending on the type of the defective product.
In the present embodiment, in the notification step (S7), a graph is displayed in which the penetration depth is plotted on the horizontal axis and the impedance ratio is plotted on the vertical axis, as shown in fig. 6. In the example shown in FIG. 6, a case is shown in which a chromium steel (JIS standard: SCr420H) as a steel material is used as a non-defective product, and a chromium molybdenum steel (JIS standard: SCM420H) is used as a defective product. The chromium-molybdenum steel contains 0.15 to 0.25% of molybdenum (Mo), and the chromium steel does not contain molybdenum, and there is such a difference in composition.
In the present embodiment, the chromium steel is used as a non-defective product and the chromium molybdenum steel is used as a defective product, but the present invention is not limited thereto, and the settings of the non-defective product and the defective product may be changed as appropriate. For example, the ordinary steel may be a non-defective product and the special steel may be a defective product, or the special steel may be a non-defective product and the ordinary steel may be a defective product.
Specifically, the graph shows the resistance ratio γ of chromium steel1Resistance of chromium molybdenum steel at reference (1.000)Ratio gamma2. In this case, the deeper the penetration depth of the eddy current becomes, the higher the resistance ratio γ of the chromium molybdenum steel as a defective product (different material)2Resistance ratio gamma to chromium steel as a non-defective product1The larger the difference. That is, it is found that there is a difference in the response of the eddy current. Further, these chromium molybdenum steels and chromium steels have the same shape as that of the gear machined after forging.
[ production Process ]
Next, the flow of the manufacturing process of the steel material according to the present embodiment will be described with reference to the flowchart shown in fig. 5. The flowchart shown in fig. 5 is an example, and is not limited to this.
In the manufacturing process of the steel material according to the present embodiment, first, the casting process (S21) is performed, and then the machining process (S22) such as cutting is performed.
In the present embodiment, the above-described nondestructive inspection method is performed after the machining step (S22). In the machining step (S22), deformation occurs in the steel material. Therefore, in a state where the steel material after the machining is deformed, the impedance change of the coil due to the generation of the eddy current is increased as compared with a state where the steel material is not deformed. This makes it possible to detect different materials more reliably.
Further, if the dissimilar material can be detected by the nondestructive inspection method immediately after the machining step (S22), it is possible to prevent the defective product from being subjected to useless processing in the subsequent manufacturing steps.
Subsequently, a heat treatment step (S23) is performed. In the heat treatment step (S23), the steel material is subjected to heat treatment such as quenching and annealing, as appropriate.
After the heat treatment step (S23), a shot peening step (S24) is performed. In the shot peening step (S24), a shot peening apparatus is used to project a small spherical projection material onto the surface of the steel material, thereby performing a treatment of modifying and hardening the surface of the steel material.
Next, a finishing process (S25) is performed. In the finishing step (S25), the steel material is subjected to finishing treatment such as brush polishing, buff polishing, and barrel polishing, as appropriate.
[ Effect of the embodiment ]
According to the nondestructive inspection method of a steel material of the present embodiment, the impedance ratio γ per penetration depth of the inspection object M is set to be higher than the impedance ratio γ of the inspection object M (steel material) per penetration depth by generating an eddy current in the inspection object M (steel material) by using the nondestructive inspection apparatus 1 so that the penetration depth of the alternating-current magnetic field into the inspection object M continuously changes2Resistance ratio gamma per penetration depth of steel material composed of correct material composition1The change of (a) is compared, and thus, the inspection of the acceptance or rejection of the material component of the inspection object M can be performed with high accuracy without damaging the inspection object M. Further, by using a steel material that is deformed after machining as the inspection object M, the difference in magnetic characteristics between the non-defective product and the defective product is made significant, and the non-defective inspection can be performed more accurately.
In particular, the impedance ratio γ per penetration depth of the inspection object M is calculated based on a steel material composed of a correct material composition1Therefore, by appropriately setting the range of the impedance ratio used for the determination of the quality, the quality of the material composition of the steel material of the inspection object M can be more accurately inspected.
Further, since the component inspection step (S6) is followed by the notification step (S7) of whether the inspection object M is a non-defective product or a defective product, when a dissimilar material is mixed in the manufacturing step, the worker can immediately recognize the steel material of the inspection object M as a defective product (dissimilar material) by visually recognizing the display 38. This enables the operator to quickly remove the dissimilar material, and prevents the dissimilar material from being mixed in the subsequent manufacturing process at an early stage.
[ other embodiments ]
In the above embodiment, the resistance ratio γ per penetration depth in the steel material composed of the correct material composition is determined in the composition checking step (S6)1Impedance ratio gamma to unit penetration depth of the inspection object M2The inspection is performed to check whether or not the material component of the inspection object M is acceptable by performing the comparison, but the component inspection method is not limited thereto. The component inspection step (S6) may be performed to check whether or not the material component to be inspected is acceptable by comparing the values of the impedances of the non-defective product and defective product. That is, the "value related to impedance" used in the quality inspection of the material component to be inspected is not limited to the impedance ratio γ1、γ2The impedance value, the distribution of the impedance values, the maximum value of the impedance values, and the like are included.
For example, the material composition of the inspection object M can be inspected for acceptability by comparing the distribution of the resistance values per penetration depth of the inspection object M with the distribution of the resistance values per penetration depth of a steel material composed of an accurate material composition to determine whether or not the distribution of the resistance values per penetration depth of the inspection object M is within a predetermined range.
That is, if the distribution map in which the impedance value per penetration depth of the inspection object M is plotted is within a predetermined range, it is determined as a non-defective product, and if it is outside the predetermined range, it is determined as a defective product. As the predetermined range, for example, with respect to the distribution of the impedance values of the non-defective products, if the error range is less than 0.5%, the non-defective products are determined, and if the error range is 0.5% or more, the non-defective products are determined. This is an example, and can be changed as appropriate depending on the material composition of the inspection object M.
Further, the distribution map in which the impedance per penetration depth of the inspection object M is plotted can be determined as a non-defective product if the distribution map is within a predetermined area, and can be determined as a defective product if the distribution map is outside the predetermined area.
According to the nondestructive inspection method for steel material described above, since it is not necessary to calculate the impedance ratio, the trouble of the calculation process of the control unit 37 can be eliminated, and the pass/fail inspection can be easily and accurately performed by setting the threshold value to an accurate range.
Further, the inspection of the acceptance of the material component of the inspection object M can be performed by comparing the distribution of the resistance values per penetration depth of the inspection object M with the distribution of the resistance values per penetration depth of the steel material composed of the correct material component to determine whether or not the maximum value of the distribution of the resistance per penetration depth of the inspection object M is within a predetermined range.
Before the impedance calculating step (S5), the reference impedance ratio γ per penetration depth may be measured for the test object M and the steel material having the same accurate material composition after the same process1A reference impedance measuring step of measuring a reference impedance (a value relating to an impedance to be a reference). Then, the component inspection step (S6) can be performed on the reference impedance γ measured in the reference impedance measurement step1The impedance ratio γ of the value of (d) to the impedance ratio γ of the unit penetration depth of the inspection object M calculated in the impedance calculation step (S5)2The inspection is performed to check whether or not the material component of the inspection object M is acceptable.
According to the nondestructive inspection method for a steel material, the reference resistance γ per penetration depth of the steel material consisting of the correct material composition after the same processing as the inspection target M is measured in advance1Accordingly, the quality of the material composition can be inspected one by one for a plurality of steel materials, and the composition inspection step (S6) can be performed quickly and with high accuracy.
The flow of each step of the nondestructive inspection method shown in fig. 3 is an example, and may be changed as appropriate. For example, the preparation step (S1) and the arrangement step (S2) may be replaced by different sequences.
The flow of the manufacturing process shown in fig. 5 is an example, and may be changed as appropriate as long as the machining process (S22) is included. For example, the casting step and the sintering step may be performed instead of the forging step (S21), or the shot peening step (S24) may be omitted.
The present invention is not limited to the above embodiments, and various modifications can be made within the scope shown in the claims, and embodiments obtained by appropriately combining technical means disclosed in the respective different embodiments are also included in the technical scope of the present invention.
(conclusion)
A nondestructive inspection method for a steel material according to an aspect of the present invention is a nondestructive inspection method for a steel material including a preparation step, a placement step, an eddy current generation step, a frequency changing step, an impedance calculation step, and a component inspection step. In the preparation step, a nondestructive inspection apparatus having a frequency variable circuit and a coil is prepared. The frequency varying circuit varies the frequency of the alternating current with which the coil excites the alternating magnetic field. In the arranging step, the inspection object is arranged so that the alternating-current magnetic field excited by the coil penetrates into the inspection object. The test object is the steel material that has been deformed after machining. In the eddy current generating step, the alternating magnetic field penetrates into the inspection object, thereby generating an eddy current in the inspection object.
In the frequency changing step, the frequency of the alternating current is continuously changed by the frequency variable circuit, so that the penetration depth of the alternating current magnetic field into the inspection target is continuously changed. In the impedance calculating step, a value related to the impedance per penetration depth of the inspection target is calculated based on a potential difference between both ends of the coil and a current value flowing through the coil. The component inspection step is characterized in that the inspection of the acceptance of the material component of the inspection object is performed by comparing the value relating to the resistance per penetration depth of the inspection object calculated in the resistance calculation step with the value relating to the resistance per penetration depth in the steel material composed of the correct material component.
According to the nondestructive inspection method for a steel material described above, by generating an eddy current in an inspection target by using the nondestructive inspection apparatus, continuously changing the penetration depth of the alternating-current magnetic field into the inspection target, and comparing the change in the resistance of the inspection target with respect to the unit penetration depth with the change in the resistance with respect to the unit penetration depth in the case of a steel material composed of an accurate material component, it is possible to inspect the acceptance of the material component of the inspection target with high accuracy without damaging the inspection target. Further, by using a steel material that is deformed after machining as an inspection target, a difference in magnetic characteristics between a non-defective product and a defective product is made significant, and a non-defective inspection can be performed more accurately.
In the nondestructive inspection method for a steel material according to one aspect of the present invention, it is preferable that the composition inspection step compares the distribution of the values relating to the resistance per penetration depth of the inspection target with the distribution of the values relating to the resistance per penetration depth of the steel material composed of the correct material composition, and determines whether or not the distribution of the values relating to the resistance per penetration depth of the inspection target is within a predetermined range, thereby performing the inspection of the acceptance of the material composition of the inspection target.
According to the nondestructive inspection method for a steel material described above, since the inspection of the acceptability of the material component of the inspection target can be performed by determining whether or not the distribution of the values relating to the resistance per penetration depth of the inspection target is within the predetermined range, the acceptability inspection of the material component of the steel material of the inspection target can be easily and reliably performed by appropriately setting the range of the values relating to the resistance used for the acceptability determination.
In the nondestructive inspection method for a steel material according to one aspect of the present invention, it is preferable that the composition inspection step calculate an impedance ratio between an impedance per penetration depth in the steel material composed of a correct material composition and an impedance per penetration depth of the inspection target, and determine whether or not the impedance ratio is within a predetermined range, thereby performing the inspection of the acceptance or rejection of the material composition of the inspection target.
According to the nondestructive inspection method for a steel material described above, since the inspection of the acceptability of the material component of the inspection target is performed based on the calculation of the resistance ratio of the unit penetration depth of the inspection target with respect to the steel material having the correct material component, the acceptability inspection of the material component of the steel material to be inspected can be performed more accurately by appropriately setting the range of the resistance ratio used for the acceptability determination.
In the nondestructive inspection method for a steel material according to one aspect of the present invention, it is preferable that the reference resistance measurement step of measuring in advance a value relating to the resistance serving as a reference per unit penetration depth with respect to the inspection target and a steel material composed of a correct material component after the same processing be performed before the component inspection step, and the component inspection step be performed to compare the value relating to the resistance serving as the reference measured in the reference resistance measurement step with the value relating to the resistance of the inspection target per unit penetration depth calculated in the resistance calculation step, thereby performing the inspection of the acceptability of the material component of the inspection target.
According to the nondestructive inspection method for a steel material described above, by measuring in advance a value relating to the resistance per penetration depth of a steel material composed of a correct material component serving as a reference, it is possible to inspect whether or not the material component is acceptable for a plurality of steel materials one by one, and it is possible to quickly and reliably perform the component inspection step.
In the nondestructive inspection method for a steel material according to one aspect of the present invention, it is preferable that the component inspection step be followed by a notification step of notifying whether the inspection target is a non-defective product or a defective product.
According to the nondestructive inspection method for steel products described above, when a defective product is mixed in the manufacturing process, the notification step notifies the operator that the inspection target is a defective product. The worker can quickly remove the defective product (different material) and can prevent the different materials from being mixed in the subsequent manufacturing process at an early stage.
Description of reference numerals
1 nondestructive inspection device
11 AC power supply
12 frequency variable circuit
21 coil
37 control unit
38 display
M object of examination
Z0，Z1，Z2Impedance (value related to impedance)
γ1，γ2Impedance ratio (value related to impedance)
Two ends of A, B coil
S1 preparation step
S2 arrangement step
S3 Eddy Current Generation step
S4 frequency changing process
S5 impedance calculating step
S6 ingredient inspection step
Step S7 is reported.
Claims (5)
1. A nondestructive inspection method for a steel material, comprising:
a preparation step of preparing a nondestructive inspection apparatus having a frequency variable circuit capable of changing the frequency of an alternating current and a coil capable of exciting an alternating current magnetic field by using the alternating current;
a placement step of placing the steel material that has been deformed after machining as an inspection target so that an alternating-current magnetic field excited by the coil penetrates into the inspection target;
an eddy current generating step of generating an eddy current in the inspection target by penetrating the alternating-current magnetic field into the inspection target;
a frequency changing step of continuously changing a frequency of the alternating current by using the frequency variable circuit to continuously change a penetration depth of the alternating current magnetic field into the inspection object;
an impedance calculation step of calculating a value relating to impedance per the penetration depth of the inspection target based on a potential difference between both ends of the coil and a current value flowing through the coil; and
a component inspection step of comparing the value related to the impedance per penetration depth of the inspection target calculated in the impedance calculation step with the value related to the impedance per penetration depth of the steel material composed of a correct material component, thereby inspecting whether or not the material component of the inspection target is acceptable.
2. The method of nondestructive inspection of a steel material according to claim 1, wherein in the component inspection step, whether or not the distribution of the values relating to impedance per unit penetration depth of the inspection target is within a predetermined range is determined by comparing the distribution of the values relating to impedance per unit penetration depth of the inspection target with the distribution of the values relating to impedance per unit penetration depth of the steel material composed of an accurate material component, and thereby the inspection of the acceptance of the material component of the inspection target is performed.
3. The nondestructive inspection method for a steel material according to claim 1 or 2, wherein in the component inspection step, the inspection of the acceptability of the material component to be inspected is performed by calculating an impedance ratio between the impedance per penetration depth in the steel material composed of an accurate material component and the impedance per penetration depth of the inspection target, and determining whether or not the impedance ratio is within a predetermined range.
4. The nondestructive inspection method for a steel material according to any one of claims 1 to 3, characterized in that a reference impedance measurement step is performed before the component inspection step, in which a value relating to impedance serving as a reference per the penetration depth is measured in advance for the inspection target and the steel material made of an accurate material component after the same machining, and in the component inspection step, the inspection for the acceptability of the material component of the inspection target is performed by comparing the value relating to impedance serving as the reference measured in the reference impedance measurement step with the value relating to impedance serving as the reference per the penetration depth of the inspection target calculated in the impedance calculation step.
5. The nondestructive inspection method for a steel material according to any one of claims 1 to 4, characterized in that a notification step of notifying whether the inspection target is a non-defective product or a defective product is performed after the component inspection step.
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| JP2018192094A JP6965863B2 (en) | 2018-10-10 | 2018-10-10 | Non-destructive inspection method for steel materials |
| JP2018-192094 | 2018-10-10 | ||
| PCT/JP2019/021941 WO2020075339A1 (en) | 2018-10-10 | 2019-06-03 | Method for nondestructive assessment of steel |
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| CN112119302B (en) | 2024-10-18 |
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| TWI801617B (en) | 2023-05-11 |
| JP2020060454A (en) | 2020-04-16 |
| JP6965863B2 (en) | 2021-11-10 |
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