SU785751A1 - Method of monitoring magnetostrictive articles - Google Patents

Description

(54) METHOD FOR MONITORING MAGNETOSTRICTED

one

The invention relates to non-destructive testing of materials and products and can be used in testing products made from ferromagnetic metals, 5 with magnetostrictive properties.

There is a method of non-destructive quality control of heat treatment of materials, which consists in measuring the coercive force, saturation magnetization, and the stray field from various types of defects. The method involves magnetizing the tested product to saturation and measuring the saturation magnetization J to measure the average residual field in the product, which is proportional to the coercive force} measuring the inhomogeneity of the magnetic field under the surface of the tested part. All this makes it possible to judge about the defect density and the quality of heat treatment, t-ij.

The disadvantages of this method are the complexity of the operations that are required to carry out the control, and the necessity of implementing-30 products.

NIN three consecutive operations, which limits the speed control.

The closest in technical essence to the invention is a method of controlling magnetostrictive products, which consists in exciting and receiving ultrasonic vibrations due to magnetostrictive interaction in the presence of a polarizing magnetic field 21,

The disadvantage of this method is that it does not allow controlling the heat treatment of products and the amount of external mechanical loads; In addition, it is difficult to control small parts, which limits its scope.

The aim of the invention is to expand the scope of the method of control.

Claims (2)

This goal is achieved by removing the dependence of the ultrasonic signal on the polarizing field, measuring the maximum value of this signal and the value of the corresponding field, comparing these parameters with the corresponding parameters of the product taken as exemplary, and judging by their deviation value t about the quality of the test product. The method is implemented as follows: In the excitation zone, a constant polarizing magnetic field is created, as well as a high-frequency electromagnetic field (using an inductance coil). As a result of these operations, magnetostrictive excitation of ultrasound occurs. In the receiving zone located at a certain distance, a constant magnetic field is also created and, using a high-frequency inductance coil, they perceive the arising alternating field of the ultrasonic frequency, transforming it into the EMF of the coil, which is then measured. The dependence of the received ultrasonic signal on the magnitude of the polarizing field is removed. This dependence has a maximum, since in the region of weak and strong magnetization fields the coefficient of electro-magneto-acoustic conversion for magnetostrictive materials is small. The value of the field at which this maximum is reached is then measured. It depends on the magnetic state of the monitored product, which in turn is related to the controlled characteristics (depth and degree of hardening, hardness, surface hardening, chemical composition). The next step is to compare the magnitude of the signal and the field, measured at the maximum point, with the corresponding parameters of the product, taken as exemplary. A decrease in the signal indicates the presence of a continuity defect in the monitored product, leading to the scattering of ultrasound (shadow control), and the deviation of the specified field value gives information about the deviation of the monitored characteristics from the sample. Thus, a simultaneous control of the integrity of the product and its properties is carried out, thus achieving the goal. The field can be changed simultaneously in the excitation and reception area or only in one of them. The invention of the method of controlling magnetostrictive products, which consists in exciting and receiving ultrasonic vibrations due to the magnetostrictive interaction in the presence of a polarizing magnetic field, characterized in that, in order to expand, the application of the control method removes the dependence of the ultrasonic signal on the polarizing field. , the maximum value of this signal and the value of the corresponding field are measured, these parameters are compared with the corresponding parameters of the product adopted for exemplary and judging by the magnitude of their deviation judged on the quality of the tested product. Sources of information taken into account during the examination 1. USSR author's certificate No. 261755, cl. G 01 N 27/72, 1970. 2. US patent number 3555887, cl. G 01 N 9/04, 1971 (prototype).