SU1727043A1 - Method of magnetic-tape test of materials - Google Patents

Abstract

The invention relates to the field of magnetic tape testing and can be used to control the quality of welded joints. The aim of the invention is to increase the reliability of the magnetographic control of welded joints. For this, a controlled weld is magnetized together with a magnetic tape laid on its surface by a constant magnetic field and the signal read from the tape is compared with a signal obtained in a similar way on a reference article. The presence of defects in the weld root is judged by the decrease in the amplitude of the signals from the edges of the weld as compared to the amplitude of the signals from the edges of the weld of the defect-free product.

Description

The invention relates to magnetic tape detection and can be used to control the quality of welded joints.

A known method of controlling ferromagnetic products consists in magnetizing the product together with a magnetic tape laid on its surface, removing the tape from the product and scanning an indicator through it that converts the field of the magnetic tape into an electrical signal that is fed to an oscilloscope. By the appearance of the signal patterns, the presence of defects in the product is judged.

The closest in technical result to the achieved result is a method of magnetographic control of ferromagnetic materials, which means that the magnetic tape is placed on the surface of the controlled product, magnetized by a constant field, creating an additional field from the back side of the product. the tape signal is compared with the signal taken from the reference sample in a similar way.

The disadvantage of this method is that two-way access to the control zone is necessary, moreover, the artificial defect field is recorded on the tape, which makes it difficult to analyze information from the tape.

The aim of the invention is to increase the reliability of the magnetographic control of welded joints.

. This goal is achieved by magnetizing a controlled weld joint with a magnetic tape laid on its surface by a constant magnetic field, and the read

XI YU VI

ABOUT

СО CO

tape signal with a signal obtained in a similar manner on the reference product. The presence of defects in the weld root is judged by the decrease in the amplitude of the signals from the edges of the weld as compared to the amplitude of the signals from the edges of the weld of the defect-free product.

A superposition of the tangential components of the magnetostatic fields is recorded on the magnetic tape: seam reinforcement, Hrd defect and applied Hgo field, Hrn Hro + Hrd-Hro. The field of reinforcement of the seam due to the action of the demagnetizing factor and the field of the defect is always of a different sign. If the magnetic imprint of a defect in the weld root on the surface of the welded joint coincides in width with the weld bead, then the roll field will be bridged by the defect field, which will reduce the amplitude of the signals from the weld edges when reading information from the magnetically carrier on the detector. In this case, the two-pole signal from the defect between the signals from the edges of the seam will be absent, and the presence of a defect can be judged by the decrease in the amplitude of signals from the edges of the seam compared to the amplitude from the edges of the seam of the defect-free sample.

The application of the proposed control method allows to increase the reliability of the magnetographic control of welded joints.

PRI me R. A magnetic tape of 16 mm with a width of 24 mm and a height of 2 mm was placed on a defect-free welded specimen of steel 3 with a magnetic tape, after which the product was magnetized by a U-shaped electromagnetic current of 10 A. After turning off the electromagnet, reading information from the tape on the flaw detector

MD-11G, determined the magnitude of the amplitude of the signals from the edges of the seam.

The monitored steel product of the same brand and the same geometrical dimensions of the seam roller and the thickness of the base metal, which had a lack of penetration in the root of the seam 3 mm wide and 2.5 mm high, were placed on a magnetic tape, after which the product was magnetized by the same electromagnet at a current of 10 A After the electromagnet was turned off, the information from the tape was read on the MD-11 G flaw detector.

Then the information recorded on the tape of the defect-free sample was compared with the information recorded on the tape of the test sample. The amplitude of the signals from the edges of the seam of the defect-free sample was 12 divisions of the scale on the flaw detector screen. The amplitude of the corresponding signals of the test sample at the site with the defect at the root was 8 divisions. The bipolar signal from the defect at the root of the seam was not observed on the screen. Therefore, a decrease in the amplitude of signals from the edges of the seam indicates the presence of a defect in the root of the seam.

Claims (1)

Invention Formula The method of magnetographic control, which consists in magnetizing the controlled product together with a magnetic tape laid on its surface with a constant magnetic field and comparing the signal read from the tape with a signal obtained in a similar way on the reference product, characterized in that reliability control of welded joints, the presence of defects in the root of the seam is judged by reducing the amplitude of the signals from the edges of the weld as compared to the amplitude of signals from the edges of the weld without defect-free Delhi