Electromagnetic acoustic and magnetic leakage compounded detection method

Abstract

The invention discloses an electromagnetic acoustic and magnetic leakage compounded detection method and relates to a nondestructive detection method. The detection method comprises the following steps of: on the basis of a fundamental principle of magnetic leakage detection, increasing an EMAT (Electro Magnetic Acoustic Transducer) exciting coil capable of generating a dynamic alternating magnetic field and an EMAT detection coil for receiving ultrasonic echoes; when pulse current is excited in the EMAT exciting coil, generating electromagnetic ultrasonic waves propagated to the other side of a detected steel plate, wherein when the electromagnetic ultrasonic waves is encountered with the outer wall of the detected steel plate, acoustic echoes can be generated, and picking up the acoustic echoes by utilizing the EMAT detection coil; analyzing the pick-up acoustic echoes to obtain a position with a defect to realize the positioning of layers of an inner wall and the outer wall; and finally, forming a compound nondestructive detection effect by fusing defect form information provided by magnetic leakage detection signals so as to reconstruct an actual form and depth of the detect. According to the detection method, the defects of non-ideal evaluation effect and low accuracy to the defect of the prior art are effectively overcome, and the detection method has the advantages of simple structure and non-contact measurement.

Description

technical field [0001] The invention relates to a non-destructive testing method, in particular to a testing method based on electromagnetic ultrasonic and magnetic flux leakage composite. Background technique [0002] As the magnetic flux leakage method is widely used in the detection of steel plates such as storage tanks and pipelines, the location of defect depth is becoming more and more important. On the one hand, it is beneficial to accurately describe the cause of corrosion defects in the flaw detection report; on the other hand, with the positioning of the corrosion inner and outer wall layers (ie depth), the detection signal can be more accurately evaluated and the quantitative accuracy of the detection results can be improved. The magnetic flux leakage detection method widely used at present, because similar leakage magnetic fields can be generated on both sides of the steel plate to be tested, it is difficult to evaluate the specific depth of corrosion. For the m...

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Problems solved by technology

However, this method can only obtain the information of whether there are defects on the surface of the measured object and the information of the surface of the measured object and the depth below it, and cannot obtain the actual shape information of the defect

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