SU896569A1 - Method of non-destructive inspection of mechanical properties of ferromagnetic materials - Google Patents

Description

(54) METHOD. NON-DESTRUCTIVE CONTROL OF MECHANICAL PROPERTIES OF FERROMAGNETIC MATERIALS

one

The invention relates to non-destructive testing and can be used to determine the mechanical properties of ferromagnetic materials.

The known method of measuring the elastic and strength characteristics of metals and alloys, which consists in the fact that ultrasound vibrations are excited in the controlled material and their propagation velocity is measured, depending on 11; from elastic constant media p.

The disadvantage of this method is low sensitivity.

The closest to the invention in its technical essence is a method for non-destructive testing of the mechanical properties of ferromagnetic materials, which consists in that a controlled ultrasonic wave is excited by a standing ultrasonic wave, the material is placed in a magnetic field and, according to a measuring signal

coils judge its mechanical properties 2.

The disadvantage of this method is the low quality of control due to the insufficient level of the EMF of the measuring coil and the need for accurate installation of the coil in the antinode of the standing wave, as well as the influence of the magnetic history of the material on the output signal

10 coils.

  The purpose of the invention is to improve the quality of control.

This goal is achieved by

15 that the controlled material is magnetized by an alternating magnetic field, the amplitude of which is sufficient for nonlinear magnetization reversal of the material, and the frequency by two or more

30 times less than the frequency of the excited wave in the material, and the measuring coil is placed in the standing wave nodes, its length is measured and

judge the mechanical properties of the controlled material.

The quality of the control is improved by increasing the sensitivity, which is determined by the specificity of the joint action on the ferromagnetic material of weak ultrasonic excitation (linear acoustics region) and a powerful low-frequency magnetic field (nonlinear magnetization region). In addition to the TGO, the use of a low-frequency field contributes to the reproducibility of the measurement results.

The drawing shows the device realizes the specified method -.

The device contains a high-frequency generator 1, a sinusoidal signal, an emitter connected to it

2, ultrasonic vibrations, magnetizing coil 3, a low-frequency sinusoidal generator 4 connected to it, a measuring coil 5 and a selective amplifier 6 and an indicator 7 connected to it, and a unit 8 for moving and counting connected to the measuring coil 5. In the control process, the measuring coil covers the material being monitored 9.

The method is implemented as follows.

The high-frequency voltage of the sinusoidal signal generator 1 is converted into ultrasonic oscillations in the emitter 2 and introduced into the controlled ferromagnetic material 9 (of finite length) in which the ultrasonic standing wave is formed. At the same time, material 9 is magnetized by a low-frequency alternating field by means of a magnetizing coil

3 connected to the generator output

4, Using the measuring coil 5 of the selective amplifier 6 and the indicator 7, the magnitude of the first harmonic component passed through the oscillation material, which depends on the location of the measuring coil, is measured. The installation of the measuring coil in the antinodes of pressure of the standing wave gives the maximum value of the signal, and the installation in the nodes of the standing wave - its zero value. The distance between the antinodes or nodes of the standing wave does not depend on the power of ultrasonic and electromagnetic radiation, the installation of the measuring coil in the nodes the standing wave is preferable, since the rate of change of the value of the peak harmonic signal in the position of the antinodes of the standing wave is less than the rate of change of the value of this signal in the position of the node the standing wave, and therefore, the location of the position of the standing wave nodes is carried out with greater accuracy, the distance is calculated between the nodes of the standing wave equal to half the length (l) of the ultrasonic oscillations wave propagating in the ferromagnetic material and is an indicator of mechanical properties controlled material is produced using the block 8 movement and reference. By knowing the wavelength, according to known ratios, the velocity of the ultrasonic wave is calculated, based on the relationship between the velocity of propagation of the ultrasonic wave and Young's modulus, as well as the dependence of strength on the Inga module, the mechanical properties of the material under test are judged.

Thus, the method improves the quality of control and allows non-destructive testing of the structural characteristics of the material (quenching temperature, ballon, etc.) in the presence of correlation with its mechanical characteristics.

Claims (2)

Invention Formula The method of nondestructive control of the mechanical properties of ferromagnetic materials, which consists in the fact that a controlled ultrasonic wave is excited by a standing ultrasonic wave, the material is placed in a magnetic field and, by a signal from the measuring coil, it is judged that its mechanical properties are the control, the controlled material is magnetized by an alternating magnet HbiM field, the ampered range of which is sufficient for nonlinear magnetization reversal of the material, and the frequency is two or more times less than the excitation frequency of the determined wave in the material, and the measuring coil is placed in the nodes of the standing wave, its length is measured, and it is judged on the mechanical properties of the controlled material. Sources of information taken into account in the examination of 96569 1.Ultrasound, .. Ed. I.P.Gol mine. M., Sovetsk Encyclopedia, 1979, p. 166, 2. USSR author's certificate number 552553, cl. G About N 29/00, 1977 (prototype).