Steel plate surface material property testing device and steel plate surface material property testing method
AssigneePosco
InventorsJu-Seung Lee, Seong-Ung Koh
Life of this patent
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Abstract
The steel plate material property testing device determining a material property of a surface of the steel plate by generating the eddy current in the steel plate includes: an eddy current tester disposed so as to face the steel plate; and a frame to which the eddy current tester is fixed, in which the eddy current tester includes: a coil disposed so as to form an alternating-current (AC) magnetic field in only one direction; an AC power supply unit connected to the coil; a sensor unit connected to the coil; and a material property determination unit connected to the sensor unit and determining the material property of the steel plate based on a measured signal obtained through the sensor unit.
Claims11
A steel plate high-hardness defects detecting device detecting high-hardness defects of a surface of a steel plate caused by accelerated cooling by generating an eddy current in the steel plate, the device comprising:
- an eddy current tester disposed so as to face the steel plate;
- and
- a frame to which the eddy current tester is fixed,
- wherein the eddy current tester includes:
- a yoke unit having both ends disposed so as to face a steel material, and having a “⊏”-shape, a “C”-shape, a “U”-shape, or a “V”-shape;
- a coil unit comprising a coil wound around a central portion of the yoke unit and disposed so as to form an alternating-current (AC) magnetic field in only one direction at the both ends of the yoke unit through the coil and the yoke unit;
- an AC power supply unit connected to the coil;
- a sensor unit connected to the coil;
- a material property determination unit connected to the sensor unit and determining the material property of the steel plate based on a measured signal obtained through the sensor unit and
- a lift-off compensation unit connected to the coil, measuring a lift-off compensation value, and providing the lift-off compensation value to the material property determination unit,
- wherein the both ends of the yoke unit are parallel,
- the AC power supply unit supplies a current of 0.5 kHz to 10 kHz to the coil unit,
- the material property determination unit determines the material property in consideration of a distance between the steel plate and the sensor unit, and
- the lift-off compensation unit measures a Q factor when a resonant frequency of a current frequency provided by the AC power supply unit is provided, and provides the Q factor to the material property determination unit.
A steel plate high-hardness defects detecting method in which high-hardness defects of a surface of a steel plate caused by accelerated cooling are detected by generating an eddy current, the steel plate high-hardness defects detecting method comprising:
- a magnetic field forming step of forming an AC magnetic field in only one direction by using a coil;
- a signal measuring step of measuring a signal through a sensor connected to the coil;
- a material property determination step of determining the material property of the steel plate at a measurement portion based on the signal obtained in the signal measuring step;
- and
- a lift-off compensation value measuring step of measuring a lift-off compensation value through a lift-off compensation unit connected to the coil,
- wherein the coil is wound around a yoke unit having both ends disposed so as to face a steel material, and having a “⊏”-shape, a “C”-shape, a “U”-shape, or a “V”-shape,
- the magnetic field forming step form the AC magnetic field in only one direction at the both ends of the yoke unit through the coil and the yoke unit,
- wherein in the material property determination step, the material property of the steel plate is determined in consideration of a distance between the steel plate and the sensor and based on a signal obtained by converting the signal measured by the sensor with the compensation value of the lift-off compensation unit as a compensation coefficient,
- wherein the AC magnetic field is formed by a current having a frequency of 0.5 to 10 kHz, and
- wherein in the lift-off compensation value measuring step, the lift-off compensation unit measures a Q factor in response to a resonant frequency of a current frequency provided by an AC power supply being provided.
Dependencies are inferred from the claim text.