SU868559A1 - Method of flaw detection of magnetic articles - Google Patents

Description

The invention relates to non-destructive testing and can be used to detect defects in products from magnetic materials. <

A known method of defectoscopy of magnetic products, which consists in the registration of static magnetic fields scattering from defects fl).

The closest in technical essence to the proposed one is the method of defectoscopy of magnetic products, based on modulation of static magnetic fields of scattering by ultrasound * !. It consists in the fact that the product is magnetized, excite ultrasonic vibrations and register the electromagnetic fields of scattering from defects (2}.

The disadvantage of these methods is the inability to detect internal defects.

The purpose of the invention is the expansion of functionality.

This goal is achieved in that they excite ultrasonic vibrations with a polarization vector normal to the surface of the product above the defective zone, and the scattering electromagnetic field is recorded at a magnetization field strength corresponding to the magnetoelastic coupling maximum.

In FIG. 1 shows an embodiment of this method using a surface wave; in FIG. 2 - the same, using a zigzag propagating volumetric shear wave.

| On the implementation diagrams of the method (Fig. | 1 and 2), a controlled product 1 is shown, a transducer 2 for emitting ultrasonic vibrations in a controlled product, an exciting generator 3, an amplifier 4 for amplifying the electromagnetic fields recorded by the receiver 5 and an indicator 6.

The method is as follows. During the magnetization of controlled products, effective secondary charges are formed on the faces of internal defects, which, in turn, form secondary magnetic oscillations emitted by the transducer, propagating in the controlled product, produce acoustic modulation of surface secondary charges caused by magnetostriction and leading to the emergence of electromagnetic scattering fields, which are recorded by the receiver are amplified by the amplifier and fed to the indicator.

Such acoustic modulation is ensured by ultrasonic vibrations with a certain polarization, in which the polarization vector is normal to the product surface above the defective soHofy i.e. the ultrasonic wave contains ¹ displacement component normal to the surface of the product.

On the other hand, the coefficient of magnesium · elastic-elastic coupling, which determines the efficiency of acoustic modulation of magnetic charges, extremely depends on the magnitude of the magnetic field strength, which necessitates the registration of electromagnetic fields 15 scattering at a magnetization field strength corresponding to the maximum magnetoelastic coupling.

In FIG. Figure 1 shows the detection of an internal defect using a surface wave in which the displacement vector has both a tangent and a normal component, which modulates the secondary magnetic charges.

In FIG. Figure 2 shows the detection of a defect using a zigzag propagating volumetric transverse wave.

The angle of entry of this wave into the product is chosen so that the displacement vector has a significant normal component that is 30 to the surface of the product.

With this option, the distance between the emitter 2 and the receiver 5 is fixed, and the electromagnetic fields of defect scattering are recorded at the moment when the defective zone in the process of moving the product relative to the transducers is under the receiver 5.

Claims (2)

The invention relates to non-destructive testing and can be used to detect defects in articles made of magnetic materials. A flaw detection method for magnetic products is known, which consists in registering static magnetic fields scattered from defects 1. Technically, the closest to the present invention is a method of flaw detection of magnetic products, based on modulation of static magnetic fields of ultrasound scattering. It lies in the fact that the product is magnetized, excites ultrasonic vibrations, and records electromagnetic fields scattered from G2 defects}. The disadvantage of these methods is the impossibility of detecting internal defects. The purpose of the invention is to expand the functionality. This goal is achieved by exciting ultrasonic vibrations with a polarization vector normal to the surface of the product over the defective area, and the registration of the electromagnetic scattering field is carried out at a magnetic field strength corresponding to the maximum of the magnetoelastic coupling. FIG. 1 shows an embodiment of this method using a surface wave; in fig. 2 - the same, with the help of a zigzag propagating bulk shear wave. I The diagrams of the method implementation (Fig. 1 and 2) show the controlled article 1, the transducer 2 for emitting ultrasonic vibrations in the controlled product, the excitation generator 3, the amplifier 4 for amplification, the electromotive fields recorded by the receiver 5 and the indicator 6. The method is as follows. By magnetizing controlled products, effective secondary contagion is formed on the edges of the internal defects, which, in turn, form secondary magnetic oscillations emitted by the converter, propagating in the controlled product, produce acoustic modulation of surface secondary charges, about / word magnetostriction and resulting in the occurrence of an EI of $ 10 hygienic stray fields, which are recorded by the receiver, are amplified by the amplifier and fed to the indicator. Such acoustic modulation is provided by ultrasonic vibrations with a certain polarization, at which the polarization vector is normal to the surface of the product over the defective 3OHoi, i.e. the ultrasound wave contains normal to the product surface of the displacement component. On the other hand, the magnetoelastic coupling coefficient, which determines the efficiency of acoustic modulation of magnetic charges, is extremely dependent on the magnitude of the magnetic field strength, and necessitates the registration of electromagnetic fields of scattering at the intensity of the bias field corresponding to the maximum magnetoelastic coupling. Fig. 1 shows the detection of an internal defect by means of a surface wave, in which the displacement vector has both a tangential and a normal component, by means of which the modulation of the secondary magnetic charges is carried out. FIG. Figure 2 shows the detection of a defect using a zigzag-spreading volume shear wave. The input angle of this wave into the product is chosen so that the displacement vector has a significant normal to the component surface. In this embodiment, the distance between the radiator 2 and the receiver 5 is fixed, and the electromagnetic fields of the scattered defect are recorded at the moment when the defect the zone in the process of moving the product relative to the transducers is under the receiver 5. Claims The method of flaw detection of magnetic products, consisting in the fact that the product is magnetized, excites the of an ultrasonic oscillation and record the electromagnetic field scattering from defects, characterized in that, in order expansion: functionality excite ultrasonic vibrations with vektorssh polarization normal to the surface of the article ngsch; defective zone, and the registration of the electromagnetic field of the dispersion is carried out at the intensity of the bias field, corresponding to the maximum of the magneto-elastic coupling. Sources of information, taken into account in the examination of the experts 1. Zatsepin N.N., Shcherbinin V.E. Flaw detection, 1966, No. 5, p. 59-65. 2. The patent of France 2., cl. G01N 29/00 ,,, 1971.