阅读说明：本技术 轧制钢板的金属组织评价装置、轧制钢板的金属组织评价方法、钢材的制造设备、钢材的制造方法以及钢材的品质管理方法 (Device for evaluating microstructure of rolled steel sheet, method for evaluating microstructure of rolled steel sheet, steel product manufacturing facility, steel product manufacturing method, and st) 是由 尾关孝文 松井穣 安达健二 岛村纯二 于 2020-04-17 设计创作，主要内容包括：本发明涉及的轧制钢板的金属组织评价装置具备：磁特性测量部,通过向轧制钢板的表面上的一个方向施加磁场并针对至少2个以上的不同的磁化方向进行测量轧制钢板的表面上的评价对象点的磁特性的处理,从而针对评价对象点测量至少2个以上的不同的磁化方向的磁特性；及判定部,使用由磁特性测量部测量的磁特性来判定评价对象点处的金属组织。(The device for evaluating the microstructure of a rolled steel sheet according to the present invention includes: a magnetic property measurement unit configured to measure magnetic properties of at least 2 different magnetization directions for an evaluation target point by applying a magnetic field in one direction on a surface of a rolled steel sheet and performing a process of measuring the magnetic properties of the evaluation target point on the surface of the rolled steel sheet for at least 2 different magnetization directions; and a determination unit that determines the metal structure at the evaluation target point using the magnetic characteristics measured by the magnetic characteristic measurement unit.)

1. A device for evaluating a microstructure of a rolled steel sheet, comprising:

a magnetic property measurement unit configured to measure magnetic properties of at least 2 or more different magnetization directions for an evaluation target point on a surface of a rolled steel sheet by applying a magnetic field in one direction on the surface of the rolled steel sheet and performing a process of measuring the magnetic properties of the evaluation target point for at least 2 or more different magnetization directions; and

and a determination unit configured to determine the metal structure at the evaluation target point using the magnetic characteristics measured by the magnetic characteristic measurement unit.

2. The apparatus for evaluating a microstructure of a rolled steel sheet according to claim 1,

the determination unit calculates a periodic component that can distinguish the metal structure from a periodic variation component of the magnetic characteristic with respect to the magnetization direction, and determines the metal structure at the evaluation target point based on the periodic variation component.

3. The apparatus for evaluating a microstructure of a rolled steel sheet according to claim 1,

the determination unit determines the metal structure at the evaluation target point based on a difference between magnetic characteristics of different magnetization directions, which can determine a fluctuation range of the magnetic characteristics, among the magnetic characteristics of each of the magnetization directions.

4. The device for evaluating a microstructure of a rolled steel sheet according to any one of claims 1 to 3,

the magnetic property measurement unit includes:

a probe array in which at least 2 or more probes having a mechanism for applying a magnetic field in one direction on the surface of the rolled steel sheet and a mechanism for measuring the magnetic characteristics of an evaluation target point on the surface of the rolled steel sheet are arranged so that the magnetization directions thereof are different from each other; and

and a moving mechanism for relatively moving the rolled steel sheet and the probe array.

5. The device for evaluating a microstructure of a rolled steel sheet according to any one of claims 1 to 3,

the magnetic property measurement unit includes:

a probe array in which a plurality of probes are arranged in the width direction of the rolled steel sheet, the plurality of probes having a mechanism for applying a magnetic field to one direction on the surface of the rolled steel sheet and a mechanism for measuring the magnetic characteristics of an evaluation target point on the surface of the rolled steel sheet, the mechanism being provided for at least 2 or more different magnetization directions; and

and a moving mechanism for relatively moving the rolled steel sheet and the probe array.

6. A method for evaluating a microstructure of a rolled steel sheet, comprising:

a magnetic property measurement step of measuring magnetic properties of at least 2 or more different magnetization directions for an evaluation target point on a surface of a rolled steel sheet by applying a magnetic field in one direction on the surface of the rolled steel sheet and performing a process of measuring the magnetic properties of the evaluation target point for at least 2 or more different magnetization directions; and

a determination step of determining a metal structure at the evaluation target point using the magnetic characteristics measured in the magnetic characteristic measurement step.

7. A manufacturing device of a steel material is provided,

the steel product manufacturing facility includes a rolled steel sheet manufacturing facility and the rolled steel sheet microstructure evaluation device according to any one of claims 1 to 5, and manufactures a steel product while evaluating the microstructure of the rolled steel sheet manufactured by the rolled steel sheet manufacturing facility by the microstructure evaluation device.

8. A method for producing a steel material, comprising the steps of,

the method for producing a steel product includes the step of producing a steel product while evaluating the microstructure of the steel product by the method for evaluating a microstructure of a rolled steel sheet according to claim 6.

9. A method for managing the quality of a steel material,

the method for managing the quality of steel products comprises the step of managing the quality of steel products by classifying the steel products according to their metal structures by using the method for evaluating the metal structure of a rolled steel sheet according to claim 6.

Technical Field

The present invention relates to a rolled steel sheet microstructure evaluation device, a rolled steel sheet microstructure evaluation method, a steel product manufacturing facility, a steel product manufacturing method, and a steel product quality control method for evaluating a microstructure of a surface layer portion of a high-strength rolled steel sheet by electromagnetic measurement.

Background

Generally, high-strength steel sheets are manufactured using a so-called TMCP (Thermo-Mechanical Control Process) technique in which controlled rolling and controlled cooling are combined. In order to increase the strength of a steel sheet by the TMCP technique, it is effective to increase the cooling rate during cooling. However, in the case of controlled cooling at a high cooling rate, the surface layer portion of the steel sheet is rapidly cooled, and therefore, the metal structure of the surface layer portion is more likely to be uneven than that of the inside of the steel sheet. Therefore, the metal structure of the surface layer portion becomes a problem from the viewpoint of ensuring uniformity of the steel sheet characteristics. Under such a background, patent document 1 proposes a method of evaluating a metal structure of a steel sheet. Specifically, the method described in patent document 1 evaluates the work ferrite fraction by the EBSD (Electron Back scattering Diffraction patterns) method using an Electron microscope, and evaluates the area ratio of the martensite-austenite mixed layer by observation with an optical microscope after etching using an etching solution.

Documents of the prior art

Patent document

Patent document 1: japanese patent laid-open publication No. 2018-31069

Disclosure of Invention

Problems to be solved by the invention

However, the microstructure evaluation method using an electron microscope or an optical microscope as described in patent document 1 is an off-line evaluation method in which a sample is collected, and it is difficult to evaluate a microstructure in a nondestructive manner in an original state of a steel sheet.

The present invention has been made in view of the above problems, and an object thereof is to provide a microstructure evaluation apparatus and a microstructure evaluation method for a rolled steel sheet, which can evaluate a microstructure of the rolled steel sheet in a nondestructive manner. Another object of the present invention is to provide a steel material manufacturing facility, a steel material manufacturing method, and a quality control method, which can evaluate a metal structure of a steel material in a nondestructive manner and improve a steel material manufacturing yield.

Means for solving the problems

The device for evaluating the microstructure of a rolled steel sheet according to the present invention includes: a magnetic property measurement unit configured to measure magnetic properties of at least 2 or more different magnetization directions for an evaluation target point on a surface of a rolled steel sheet by applying a magnetic field in one direction on the surface of the rolled steel sheet and performing a process of measuring the magnetic properties of the evaluation target point for at least 2 or more different magnetization directions; and a determination unit that determines the metal structure at the evaluation target point using the magnetic characteristics measured by the magnetic characteristic measurement unit.

Preferably, the determination unit calculates a periodic component that can distinguish the metal structure from a periodic variation component of the magnetic characteristic with respect to the magnetization direction, and determines the metal structure at the evaluation target point based on the periodic variation component.

Preferably, the determination unit determines the metal structure at the evaluation target point based on a difference between magnetic characteristics of different magnetization directions, which can determine a fluctuation range of the magnetic characteristics, among the magnetic characteristics of the respective magnetization directions.

Preferably, the magnetic property measurement unit includes: a probe array in which at least 2 or more probes having a mechanism for applying a magnetic field in one direction on the surface of the rolled steel sheet and a mechanism for measuring the magnetic characteristics of an evaluation target point on the surface of the rolled steel sheet are arranged so that the magnetization directions thereof are different from each other; and a moving mechanism for relatively moving the rolled steel sheet and the probe array.

Preferably, the magnetic property measurement unit includes: a probe array in which a plurality of probes are arranged in the width direction of the rolled steel sheet, the plurality of probes having a mechanism for applying a magnetic field to one direction on the surface of the rolled steel sheet and a mechanism for measuring the magnetic characteristics of an evaluation target point on the surface of the rolled steel sheet, the mechanism being provided for at least 2 or more different magnetization directions; and a moving mechanism for relatively moving the rolled steel sheet and the probe array.

The method for evaluating the microstructure of a rolled steel sheet according to the present invention comprises: a magnetic property measurement step of measuring magnetic properties of at least 2 or more different magnetization directions for an evaluation target point on a surface of a rolled steel sheet by applying a magnetic field in one direction on the surface of the rolled steel sheet and performing a process of measuring the magnetic properties of the evaluation target point for at least 2 or more different magnetization directions; and a determination step of determining a metal structure at the evaluation target point using the magnetic characteristics measured in the magnetic characteristic measurement step.

The steel product manufacturing facility according to the present invention includes a rolled steel sheet manufacturing facility and a rolled steel sheet microstructure evaluation device according to the present invention, and manufactures a steel product while evaluating the microstructure of a rolled steel sheet manufactured by the rolled steel sheet manufacturing facility by the microstructure evaluation device.

The method for producing a steel material according to the present invention includes a step of producing a steel material while evaluating the microstructure of the steel material by using the method for evaluating a microstructure of a rolled steel sheet according to the present invention.

The method for managing the quality of a steel material according to the present invention includes a step of managing the quality of a steel material by classifying the steel material according to its microstructure by using the method for evaluating the microstructure of a rolled steel sheet according to the present invention.

Effects of the invention

According to the apparatus and method for evaluating a microstructure of a rolled steel sheet according to the present invention, the microstructure of the rolled steel sheet can be evaluated in a nondestructive manner. Further, according to the manufacturing facility, manufacturing method, and quality control method of a steel material according to the present invention, the metal structure of the steel material can be evaluated in a nondestructive manner, and the manufacturing yield of the steel material can be improved.

Drawings

Fig. 1 is a block diagram showing the configuration of a microstructure evaluation apparatus for rolled steel sheets according to an embodiment of the present invention.

FIG. 2 is a view showing the structure of the probe shown in FIG. 1.

Fig. 3 is a diagram showing a configuration of a modification of the probe shown in fig. 2.

Fig. 4 is a flowchart showing a flow of a microstructure evaluation process of a rolled steel sheet according to an embodiment of the present invention.

Fig. 5 is a schematic diagram for explaining the processing of steps S1 to S3 shown in fig. 3.

Fig. 6 is a schematic diagram showing the structure of the probe rotation mechanism and the elevation mechanism.

Fig. 7 is a schematic diagram showing a configuration example of the probe array.

Fig. 8 is a schematic diagram showing a configuration example of the probe array.

Fig. 9 is a diagram showing an example of measuring the magnetic properties of a rolled steel sheet for each magnetization direction.

FIG. 10 is a view showing an example of evaluation of the microstructure of a rolled steel sheet.

FIG. 11 is a view showing an example of evaluation of the microstructure of a rolled steel sheet.

Detailed Description

Hereinafter, an apparatus and a method for evaluating a microstructure of a rolled steel sheet according to an embodiment of the present invention will be described with reference to the drawings.

[ Structure ]

First, the structure of a microstructure evaluation apparatus for rolled steel sheets according to an embodiment of the present invention will be described with reference to fig. 1 to 3. Fig. 1 is a block diagram showing the configuration of a microstructure evaluation apparatus for rolled steel sheets according to an embodiment of the present invention. Fig. 2 (a) and (b) are a side view and a plan view showing the structure of the probe 2 shown in fig. 1. Fig. 3 (a) and (b) are a side view and a plan view showing a structure of a modification of the probe 2 shown in fig. 2.

As shown in fig. 1, a microstructure evaluation apparatus 1 of a rolled steel sheet according to an embodiment of the present invention includes: a probe 2 for measuring magnetic characteristics of at least 2 different magnetization directions with respect to an evaluation target point by applying a magnetic field in one direction on the surface of a rolled steel sheet and performing a process for measuring the magnetic characteristics of the evaluation target point on the surface of the rolled steel sheet with respect to at least 2 different magnetization directions; and a determination device 3 for determining a metal structure having a size of the order of several to several tens mm at the evaluation target point by using the magnetic characteristics measured by the probe 2.

As shown in fig. 2 (a) and (b), the probe 2 includes a magnetizing yoke 21 and a magnetic sensor 22.

The magnetizing yoke 21 is formed of an コ -shaped member, and the コ -shaped member is composed of a member 21a and members 21b and 21c extending from both ends of the member 21a toward the surface of the rolled steel sheet S, and the exciting coil 23 is wound around the member 21 a. The magnetizing yoke 21 applies a magnetic field in a magnetization direction indicated by an arrow to the surface layer portion of the rolled steel sheet S by supplying a current to the exciting coil 23.

The magnetic sensor 22 measures the magnetic characteristics of the rolled steel sheet S to which the magnetic field is applied by the magnetizing yoke 21, and outputs the measured data of the magnetic characteristics to the determination device 3. As shown in fig. 3 (a) and (b), the exciting coil 23 may be used as the magnetic sensor 22 by detecting a change in current flowing through the exciting coil 23 according to the magnetic characteristics of the rolled steel sheet S.

[ method ]

Next, a method for evaluating a microstructure of a rolled steel sheet according to an embodiment of the present invention will be described with reference to fig. 4 to 9. Fig. 4 is a flowchart showing a flow of a microstructure evaluation process of a rolled steel sheet according to an embodiment of the present invention. Fig. 5 is a schematic diagram for explaining the processing of steps S1 to S3 shown in fig. 3.

As shown in fig. 4, in the microstructure evaluation process of the rolled steel sheet according to the embodiment of the present invention, first, the probe 2 is installed so as to apply a magnetic field having a predetermined magnetization direction to the rolled steel sheet S (step S1), and a magnetic property is measured by applying a magnetic field having a predetermined magnetization direction to the rolled steel sheet S (step S2). Next, it is checked whether or not the measurement of the magnetic properties is completed for all of at least 2 or more magnetization directions for which the magnetic properties should be measured (step S3), and if the measurement is not completed (step S3: No), the probe 2 is set so that a magnetic field of a magnetization direction that is not measured is applied, and the magnetic properties are measured. On the other hand, when the measurement is completed (YES in step S3), the judging device 3 evaluates (judges) the microstructure of the rolled steel sheet S based on the magnetic characteristics for each magnetization direction measured by the probe 2 (step S4).

More specifically, as shown in fig. 5, the processing of steps S1 to S3 repeats the steps of measuring the magnetic properties by rotating the probe 2 by a degree a in the horizontal plane so that the magnetization direction is changed while keeping the evaluation target point P on the surface of the rolled steel sheet S at the center position of the probe 2. In the measurement of each magnetic property, for example, as in the method described in japanese patent application laid-open No. 2-504077, an alternating current magnetic field based on a sinusoidal signal is applied, and a tangential magnetic field strength and a high-frequency component (described later) at each time are measured as the magnetic property, and a maximum value, an average value, a retained magnetic field strength, a coefficient of the high-frequency component, and the like of the tangential magnetic field strength are calculated.

Here, as the ac magnetic field, a low-frequency (50Hz to 500Hz) sine wave signal serving as a reference is applied with a high-frequency sine wave signal having an amplitude of about 1 to 1/100 of the amplitude of the sine wave signal and a superimposed frequency of about 1KHz to 10 KHz. The high-frequency component mentioned above refers to an observed signal for the superimposed high-frequency component among the magnetization signals measured by the probe 2 (or the current signals observed in the case where the probe 2 is not used). The tangential magnetic field strength corresponds to the amplitude of the high frequency component.

In this case, the probe 2 may be automatically rotated and magnetized in a predetermined magnetization direction by using a rotation mechanism 4 for rotating the probe 2 in a horizontal plane and a lifting mechanism 5 for lifting and lowering the probe 2 as shown in fig. 6, and the operation of measuring the magnetic characteristics may be repeated by the predetermined number of magnetization directions. As shown in fig. 7, the magnetic properties in each magnetization direction may be measured by using a probe array in which probes 2 are arranged in each magnetization direction to be measured, and repeating the operation of relatively moving the rolled steel sheet S and the probe array while measuring the magnetization properties. As shown in fig. 8, the magnetic properties in each magnetization direction may be measured by using a probe array in which a plurality of probes 2 are arranged in the width direction of the rolled steel sheet S and provided for each magnetization direction to be measured, and repeating an operation of relatively moving the rolled steel sheet S and the probe array while measuring the magnetization properties.

Fig. 9 (a) and (b) are diagrams showing an example in which the magnetic properties of the rolled steel sheet S having different metal structures are measured for each magnetization direction under the same magnetization condition. In this example, the magnetization direction is set to 0 °, 15 °, 30 °, …, and 345 ° every 15 ° while rotating the magnetization direction, and the magnetic characteristics corresponding to 360 ° are measured every 15 °. Furthermore, the angular spacing measured may be arbitrary and need not be a constant spacing. In the examples shown in fig. 9 (a) and (b), the dependence of the magnetization direction of the magnetic properties greatly differs depending on the metal structure. In particular, in the example shown in fig. 9 (a), a change in the magnetization direction at a period of 90 ° is clearly observed, and it is found that the anisotropy is strong. Thus, in this example, in order to capture the change in cycle 90 °, it is preferable to perform at least 1 measurement every 45 °. Instead of the evaluation of the magnetization direction by 360 °, the evaluation by 180 ° or 90 ° may be performed.

Next, in the processing of step S4, the determination device 3 determines the anisotropy of the magnetic properties from the magnetic properties for each magnetization direction measured by the probe 2. In the present embodiment, the determination device 3 evaluates the anisotropy of the magnetic properties by calculating the component of the fourier series expansion of the angle with respect to the magnetization direction. That is, the determination device 3 calculates the component F (P, n) represented by the following equation (1) when the magnetic characteristic value measured at the angle θ of the magnetization direction is P (θ) and the number of fourier series is n. In this calculation, for example, the component F (P, 4) and the cycle corresponding to n-4The variation component of the period 90 ° corresponds. Then, the determination device 3 determines the metal structure of the evaluation target point P based on the obtained component F (P, n). The determination method is determined in advance based on the correspondence between the magnetic properties of the material to be investigated and the metal structure. In the examples shown in (a), (b) of fig. 9, the component F (P, 4) is focused. Specifically, the determination is performed based on a predetermined determination threshold T_P，4When the absolute value of the component F (P, 4) is a predetermined determination threshold T_P，4In the above case, it is determined that the metal structure of the evaluation target point P is the metal structure a, and the component F (P, 4) is smaller than the predetermined determination threshold T_P，4In the case of (3), it is determined that the metal structure of the evaluation target point P is the metal structure B. Here, although an example of the period 90 ° is shown, since it is only necessary to be able to determine the difference in the metal structure, components other than the period 90 ° may be used as long as the difference is clear. That is, the intensity of the periodic component of the angle at which the metal structure can be discriminated is not limited to the specific angle.

[ mathematical formula 1 ]

In addition, a set of magnetic characteristic values { P (θ) } for each magnetization direction shown in the following mathematical formula (2)_θA conceivable method is to evaluate the range of variation of the value of P (θ) to determine the metal structure. For example, the maximum value maxP and the minimum value minP may be calculated, the difference Δ P between the maximum value maxP and the minimum value minP may be calculated by the following formula (3), and the difference Δ P may be a predetermined determination threshold T_ΔPIn the above case, the metal structure of the evaluation target point P is determined to be the metal structure a, and the difference Δ P is smaller than the predetermined determination threshold T_ΔPIn the case of (3), it is determined that the metal structure of the evaluation target point P is the metal structure B. Here, the difference between the maximum value maxP and the minimum value minP is calculated as the difference Δ P, but the present invention is not limited thereto. As long as it can be evaluated how much the value of P (θ) varies, it may be evaluated between specific angles at which the variation width of the magnetic characteristic can be determinedP (θ) of (a).

[ mathematical formula 2 ]

{P(θ)}_θ＝{P(θ₀)，P(θ₁)，P(θ₂)，…，P(θ_N-1)}…(2)

[ mathematical formula 3 ]

ΔP＝maxP-minP…(3)

As is clear from the above description, the microstructure evaluation apparatus 1 of the rolled steel sheet according to the embodiment of the present invention can evaluate the microstructure of the rolled steel sheet S in a nondestructive manner, because it focuses on that the magnetization direction dependency of the magnetic properties differs depending on the microstructure, and determines the microstructure of the rolled steel sheet S by measuring the magnetic properties with respect to at least 2 or more magnetization directions and calculating the magnetization direction dependency of the magnetic properties.

[ example 1 ]

In example 1, a sine wave magnetic field of 125Hz was applied to the steel sheet, and the average value of the tangential magnetic field strength was measured as the magnetic property. The magnetization directions were set to 24 directions of 0 °, 15 °, 30 °, …, and 345 ° at 15 ° intervals with respect to the rolling direction. The component P (P, 4) corresponding to the variation component of the cycle 90 ° is evaluated. Furthermore, the threshold value T will be determined_P，4Set to 0.07, the absolute value of the component F (P, 4) is the decision threshold T_P，4In the following cases, it is determined that the metal structure at the evaluation target point P is a bainite structure, and the absolute value of the component F (P, 4) exceeds the determination threshold T_P，4In the case of (3), it is determined that the metal structure of the evaluation target point P is a ferrite + bainite structure having strong magnetic anisotropy. Further, the metal structure of the adjacent portion is observed by microscopic observation corresponding to the evaluation target point P, and the metal structure is classified. The metal structure of the evaluation target point is shown in table 1, and the value of the component F (P, 4) of each evaluation target point is shown in fig. 10. As shown in fig. 10, the metal structure can be determined by evaluating the dependency of the magnetization direction of the magnetic properties.

[ TABLE 1 ]

(Table 1)

No.	Base material	Metallic structure
			1	A	Ferrite + bainite
2	A	Ferrite + bainite
			3	A	Ferrite + bainite
4	B	Bainite for treating cancer
			5	B	Bainite for treating cancer
6	B	Bainite for treating cancer
			7	C	Bainite for treating cancer
8	C	Bainite for treating cancer
			9	C	Bainite for treating cancer

[ example 2 ]

In example 2, the measurement target and the magnetic properties were measured by the same method as in example 1, the difference Δ P was calculated, and the threshold T was determined_ΔPThe value of (d) was set to 0.03. Then, when the difference Δ P is a determination threshold T_ΔPIn the above case, the metal structure at the evaluation target point P is determined to be ferrite + bainite, and the difference Δ P is smaller than the determination threshold T_ΔPIn the case of (3), it is determined that the metal structure of the evaluation target point P is a bainite structure. The value of the difference Δ P for each evaluation target point is shown in fig. 11. As shown in fig. 11, the metal structure can be determined by evaluating the dependency of the magnetization direction of the magnetic properties.

The embodiments to which the invention made by the present inventors has been applied have been described above, but the present invention is not limited to the description and drawings constituting a part of the disclosure of the invention of the embodiments. For example, by installing the microstructure evaluation apparatus 1 of a rolled steel sheet according to an embodiment of the present invention in a known or unknown manufacturing facility of a rolled steel sheet and manufacturing a steel product while evaluating the microstructure of the rolled steel sheet manufactured by the manufacturing facility of a rolled steel sheet, the manufacturing yield of the rolled steel sheet can be improved. Further, the manufacturing facility of the rolled steel sheet provided with the microstructure evaluation device 1 of the rolled steel sheet according to the embodiment of the present invention is provided in a known or unknown manufacturing facility of the steel material, and the steel material is manufactured while evaluating the microstructure of the rolled steel sheet manufactured by the manufacturing facility of the rolled steel sheet, so that the manufacturing yield of the steel material can be improved. Further, by using the device 1 for evaluating a microstructure of a rolled steel sheet and the method for evaluating a microstructure as one embodiment of the present invention, a steel material (in particular, a rolled steel sheet produced or in the middle of the production of a steel material) is produced while evaluating the microstructure of the steel material, whereby the production yield of the steel material can be improved. In addition, the device 1 for evaluating a microstructure of a rolled steel sheet and the method for evaluating a microstructure according to an embodiment of the present invention can control the quality of a steel material by classifying the steel material according to the microstructure of the steel material (particularly, a rolled steel sheet produced or in the middle of the production of the steel material). As described above, other embodiments, examples, operation techniques, and the like, which are completed by those skilled in the art based on the present embodiment, are all included in the scope of the present invention. As described above, other embodiments, examples, operation techniques, and the like, which are completed by those skilled in the art based on the present embodiment, are all included in the scope of the present invention.

Industrial applicability

According to the present invention, it is possible to provide a rolled steel sheet microstructure evaluation device and a microstructure evaluation method capable of evaluating the microstructure of a rolled steel sheet in a nondestructive manner. Further, according to the present invention, it is possible to provide a steel material manufacturing facility, a steel material manufacturing method, and a quality control method that can evaluate a metal structure of a steel material in a nondestructive manner and improve a manufacturing yield of the steel material.

Description of the reference symbols

1 apparatus for evaluating microstructure of rolled steel sheet

2 Probe

3 judging device

4 rotating mechanism

5 lifting mechanism

21 magnetic yoke

21a, 21b, 21c parts

22 magnetic sensor

23 field coil

P evaluation object point

S rolling the steel plate.