RU1779954C - Method for determining residual stresses in articles of ferromagnetic materials - Google Patents

Abstract

SUMMARY OF THE INVENTION: The maximum value of the residual stresses acting in the direction coinciding with the direction of the measured magnetic field is determined from the measured maximum value of the magnetic field strength. 2 ill.

Description

The invention relates to methods for controlling the stress-strain state of ferromagnets by the remanent magnetization of the metal and can be used in various fields: in the energy sector for monitoring pipeline systems, in the oil and gas industry for monitoring gas and oil pipelines, and in railway transport for monitoring rail in any structures made of ferromagnetic materials.

Known methods for measuring stresses in machine parts based on the use of the phenomenon of magnetoelastic anisotropy arising under the action of applied loads and strains 1 and

21

From the analysis of the known methods 1 and 2, two essential conditions for their application follow. Firstly, they use magnetizing devices, and secondly, they are used provided that the places of concentration of mechanical stresses in the controlled part are known in advance. Obviously, the use of magnetic methods for measuring mechanical stresses, for example, in pipes of heating surfaces of power boilers under such conditions is impossible. To magnetize a pipe system, the total length of which on a modern boiler reaches 500 km, the task is unrealistic.

Measurement of mechanical stresses by means of strain gauging, for example, according to method 2, using micro-magnetostrictive sensors glued to a controlled surface, or by applying a pre-calibrated ferromagnetic coating to the surface via spoils for long pipelines and other structures in operation , almost impossible. For this, it is necessary to know in advance the place of concentration of mechanical stresses, which is not possible due to the influence of various structural and operational factors on their formation. Magnetic methods 1 and 2 do not allow

Vj

ha &

i t

and the invention is taller .ft t

IP t v. 1st part from ferromagnetic

ts l || 1g due to r o | mos and determine s b the smallest value of voltage

i, cm4 G Odd Yeshenchi

 dntVr / ne i I ° M

t 11 L J

C 0 Jl L -1

j with G10 T PP

, - n i

  I1

ice i ° f J ° 4

I11V, t g

a n ii llipp reni i i - i tyn o HOI i j o mzg rphennosg | / lhpitnog h

 Г r I П iCX 6 ГП i- 1 Ii i I г I i

Pv, n i K fj H lf AND ОDy

I I O ti i Ii

i T 1 ID C 1 g D g iI

r r iinn o r m i) i t p i

h1 t j4C n 1 i I

Method 31 gpp i gt-i

1 i / T J I 1 i Ч i (g

1UCI °

P2Ia

Pj j tg L

J1P I TP- | j | R

  n (° 3 P i I iI

KOCH1 I) 1 Iiъ G UC

4r O 0 ti

5ss t sig

r 111 -p I 1) ° I 1

P (-5

||| I-II 1

P f i C IMl I

pipe oot n n r r ri ° r

TURNER I- 1st) i j I

FROM i I HP FROM TOUCH II SP

mokhet grmmsn state to about g p p / sky tsform tsip p ns r p, fi | i) strange hr region p i

Except.htw wo ncm st h nr 1 M

f OliCl pyKU44 AFRICA With ril.

IMRRTGlbSTOUPO / GO-PLRGTI1 U (1G t

qi Therefore, there is no trace of residual stresses in the bottom of the cathodel, which is of great elasticity qe i p i is very large ieimc for ov „f

The equipment has a confluent / ROS RF; the maximum determination was carried out and -ILI tr i the voltage of the voltage was ensured by i / t, extraneous loading, or the voltage of the i iyT-i voltage during cyclic i ii CnocofiPlr1 allows you to)

i ootazggnio and spruce is achieved by the fact that

ii not both i Ochtrol East voltage

V eri№- ij of fluorinated materials,

ttpcha j cement n measurement n of course i i | 1gnit1 010 floor, in order to increase

i v CAPACITIES due to the possibility of determining s i t a s i (My residual i r / rl acting in

for the sake of and / and cojr h) i no direction 3 i i sofioro DI i 1

 Y y h h nv

C and about which are defined

i s j, l g iv iy residual

1 ui of residual on i ft / Yumata and plastic in

1 SIMONOON

1 i of Kechia due to u / iM on the basis of Henism or i) ° h i pin cyclic

f iy to produce no more than 1 m i Jt under intense deformation iDio g ,. n iii i ferromagnet in

/ penalty i 1 requires construction

i m, and, with about i and gosfikov so is

i t, (state-of-the-art method identifies n i i y g y m / hectomy || action ostz || m 1rch yen

PPS, huh npp / ajiaiacMOM the method is1 according to / are relative values po-g-ulee as n in the method 3 measurement

i cut-off / special magnetization and

with j, 3rU i of a special measuring field at

ego rio kno use the phenomenon of namap and S chi achi in the magnetic pommel Zemlch Frenzy does not require any

f my floor oiuBki the surface of the product

О The method is based on the use of magnetic introvnoyroro and magnetomechanical effect GOR are known / about the physics of magnetic; ipenip The essence of detachment lies in the fact that, according to the proposed IIQS magnet, it becomes possible for the 18 maximum maxi- mum value to remain. and with plastic deformation.

The invention is illustrated by reviewing the accompanying drawing, which shows a diagram illustrating a method for determining residual stresses in a zone of a combined joint (a joint of different grades of steel and different pipe sizes) in a pipeline, where in FIG. 1 is a method for determining the concentration of residual stresses in a direction perpendicular to the controlled forming pipe at which the value of Hp changes; in FIG. 2 is a method for determining the concentration of residual stresses in the direction along the generatrix of the pipe at which the Hp value is measured.

. It should be noted that pipes 1 and 3 with a combined joint are in the design of the boiler stopped for repair.

The proposed method for determining residual stresses, for example, in the zone of the combined junction of two boiler pipes 1 and 3 (Fig. 1) is carried out as follows.

First, measure the magnitude of the magnetic field scattering Нр near the combined joint on the pipe 1 side (made of ferromagnetic material) by moving the sensor 2 along the outer diameter perimeter in direction 4 with the location of the measuring coil K perpendicular to the tangent line g in each control point (Fig. 1). In this measurement method, the maximum value HPY (max) characterizes the direction of action of the maximum residual stresses from the torques and bending moments at the control point A on the outer diameter of the pipe 1 near the welded joint. Then, the magnitude of the scattering magnetic field strength Hpx is measured near the combined joint on the pipe 1 side by moving the sensor 2 along the

meter of outer diameter in direction 4 with a horizontal arrangement of the measuring coil K (X axis of Fig. 2). In this measurement method, the maximum value Hp (max) characterizes the direction of action of the maximum residual stresses acting along the X axis at the control point B on the outer diameter of the pipe 1 near the welded joint. By virtue of the magnetomechanical effect, the sign of the measured value of Hpx coincides with the sign of mechanical stresses acting along the X axis, and the points where the values of Hpx O characterize the location of the points of change in the sign of mechanical stresses on the outer diameter of the pipe 1.

Based on the measured values HPY (max) and Нр (max), the stress-strain state of pipe 1 near the combined joint with pipe 3 is judged. In the direction of the maximum residual stresses during the measurements, the magnetization effect of pipe 1 and combined joint in operation under the action of external magnetic fields and workloads. Measurements of HPY and Hpx are carried out using any known field meter (flux probe, Hall sensor).

Claims (1)

SUMMARY OF THE INVENTION A method for determining residual stresses in products made of ferromagnetic materials, which consists in measuring the magnetic field strength, and so on, with the aim of increasing efficiency by determining the maximum value of residual stresses acting in the direction coinciding with the direction of the measured magnetic field, measure the maximum value of the magnetic field strength, which determines the maximum value of the residual stresses acting in the direction coinciding corresponding to the direction of the measured magnetic field. R Hpf / noj Mff / Tiffjt)