SU1388776A2 - Method of determining mechanical properties of ferromagnetic articles - Google Patents

Abstract

The invention relates to the field of non-destructive testing of products made of ferromagnetic materials and is intended for use in the control of heat treatment and the determination of the mechanical properties of ferromagnetic products in any industry. To improve the accuracy of determining the mechanical properties, the magnetic field value of the residual magnetization after magnetization of the product under test is measured by a series of magnetic field pulses of increasing and then decreasing amplitude, the change in the magnetic field gradient of the residual magnetization at a given distance and magnitude of the square of the gradient magnitude to its change at a given distance is determined by mechanical properties. 1 il. with S (L

Description

with

00

sc

05

1H

The invention relates to non-corrosion testing of products made of ferromagnetic materials, is intended for use in controlling the quality of heat treatment and determining the mechanical properties of ferromagnetic products in any industry, and is an improvement of the invention according to the authors. No. 708795.

The purpose of the invention is to improve the accuracy of the determination of mechanical properties by eliminating the influence of the oscillations of the gap.

The drawing shows a block diagram of an apparatus for carrying out the proposed method.

The device consists of a transducer 1, a vibrator 2, a filter 3, a magnetic field gradient measurement block 4, a magnetic field gradient change measurement block 5, a square squaring block, a dividing block 7, a display block 8, a puller 9 pulses and a magnetizing block 10 .

The method is carried out as follows.

The transducer 1 is placed on a controlled surface, while the magnetizing solenoid is connected to the source of pulsed current. A series of current pulses is passed through the magnetizing solenoid, the amplitude of which in the series increases first and then decreases. The value of the residual field gradient is measured: the residual field gradient is measured at a predetermined distance from the product, the change in gradient is determined, and the ratio of the square of the residual field gradient value to its change at a given distance is determined. This relationship and the correlation equation + bx determine the mechanical properties (hardness, tensile strength, yield strength, etc.), where y is the corresponding mechanical value, x is the ratio of the square of the residual field gradient to its change over a given distance. The quotas t quotes are determined from the processing of statistical data on the determination of mechanical properties and the measurement of the ratio of the above values. The value of the ratio does not depend

on the size of the gap between the transducer and the controlled product.

The dependence of the magnitude of the field of residual magnetization to a controlled surface can be approximated with sufficient accuracy by the expression

V so -

where vH is the value of the magnetic field gradient at any distance from the surface of the test item; vH - value of the magnetic field gradient On the surface of the product;

h is the distance to the surface; k - coefficient. The change in the gradient at a given distance Db will be equal to

() -TShN71

Designating

vH

 (llEHD A T + kh

30 and

 (1 PC

get the ratio

A (r + kli) vHro. In TT + khT vH fkTii kah

Since the values of k –i / ih are constant,

then the relation is determined

five

0

five

only the value of H, in turn, is determined by the mechanical properties of the product and does not depend on the size of the gap.

A device for implementing the proposed method works as follows.

After switching on the device, the pulse shaper 9 generates a sequence of pulses of increasing and then decreasing amplitude, which are fed to the magnetizing unit 10. The controlled product is magnetized using a solenoid located in the converter 1 and included in the magnetizing unit 10. The gradient of the atomic magnetization is read by a ferro probe graph and a grathed graph 10 of the magnetizing unit 10. located in the transducer 1 and mechanically coupled to the vibrator 2. The vibrator 2 informs the ferro probe gradiometer oscillations at a constant amplitude. The signal from the flux-gate gradiometer is fed to the filter 3, where signals from it are proportional to the magnetic field gradient and changed. When the fluorescent-wave gradiometer with a constant amplitude oscillates, they go to the magnetic field gradient measuring unit 4 and unit 5 for measuring the change in the magnetic field gradient. From the magnetic field gradient measurement unit 4, the signal enters the squaring unit 6 and then into the dividing unit 7, the second input of which is to the post /

The signal from block 5 measuring the change in the gradient of the magnetic field is lost. A signal proportional to the ratio of the two signals enters the display unit 8. Judging by the ratio and the correlation equation, the mechanical properties of the products are judged.

Claims (1)

Invention Formula The method of determining the mechanical properties of products made of ferromagnetic materials according to ed.St. No. 708795, j characterized in that, in order to improve accuracy, the residual local field gradient is additionally measured along the symmetry axis at a given distance from product surfaces and take into account the change in the gradient when determining the mechanical properties of products. N /