RU2376595C2 - Magnetic method of detecting flaws in blades of turbo-machines made from nickel alloys in mechanical load conditions - Google Patents

Abstract

FIELD: physics.

SUBSTANCE: invention can be used for magnetic flaw detection of blades of turbo-machines. A magnetic flaw detection device is setup in order to determine parametres of material using a standard flawless control object with dimensions and material which correspond to the inspected blades, without application of a mechanical load. Using the magnetic flaw detection device, parametres of an inspected blade are determined under similar conditions and extent of damage to material of the blade is determined from the difference in parametre values obtained from the standard and inspected blades. Parametres of the material of the blade are also recorded while loading, for which the standard control object is loaded in the region of elastic stress by applying a load P₃, and the magnetic flaw detection device is setup. Similarly, the inspected blade is loaded by applying a load P₃, and repeated scanning is done using a measuring device. Change in the state of the material of the inspected blade before and after loading is determined from the change in the obtained parametre values.

EFFECT: increased information content and accuracy of assessing extent of damage to material of blades made from nickel alloys taking into account effect of mechanical loads, arising during operation of the components.

7 cl, 3 tbl, 1 ex

Description

The invention relates to methods for magnetic flaw detection of metal products and can be used in the inspection of blades of turbomachines made of nickel alloys, taking into account the impact of operational loads.

During operation, guide and rotor blades of turbines of gas turbine engines and gas turbines are subjected to significant dynamic and static loads, high temperatures, and also corrosion and erosion destruction.

In this regard, for the timely repair of turbomachines and the prevention of emergencies, non-destructive express methods for monitoring and diagnosing blades are necessary, taking into account the influence of operational factors on the change in the state of the material of the blade.

A known method of electromagnetic defectoscopy, based on scanning the product with an electromagnetic transducer, counting the total number of pulses from the edges and defects of the product and highlighting information about its defectiveness by determining the excess of the total number of pulses over the number of pulses from the edges [see A.S. USSR No. 333460, IPC G01N 27/86, 1970].

The disadvantage of this method is its low information content. Closest to the proposed method is a method for recognizing defects in a magnetoprobe probe (see Hvatov L.A., Lisitsin V.I., Krasin A.I., Zhukova G.A. Defect recognition in a magnetoprobe probe // Defectoscopy. - 1984. - 6. - P.63-71), including measuring the distribution of the magnetic field of a group of defects of a ferromagnetic product, approximating the topography of a given magnetic field through triangles, changing the parameters of triangular signals and their superposition with reproducing the waveform from the group’s magnetic field defects. The magnetic field of a group of defects over a ferromagnetic product is equal to the superposition of the magnetic fields of individual defects.

The disadvantage of this method is the low information content and the reliability of assessing the degree of degradation of the material of the blade during operation.

It should be noted that the known non-destructive methods for assessing the degradation of metallic materials, based on magnetic effects, do not allow to assess the change in the state of the material of the blade when the stress state in the part changes as a result of mechanical stress, which significantly reduces the reliability of assessing the nature of the degradation of the material of the part. In addition, magnetic methods are mainly used to assess the condition of products made from ferromagnetic materials.

The technical result of the invention is to increase the information content and reliability of assessing the degree of degradation of the material of the blade made of nickel alloys, taking into account the influence of mechanical loads that arise during the operation of parts.

The technical result is achieved by the fact that in the method of magnetic defectoscopy of the blades of turbomachines made of nickel alloys, which includes tuning the device of magnetic defectoscopy to determine material parameters from a reference defect-free object of control, in size and material corresponding to the controlled blades, without applying mechanical load to it (P ₀ = 0), determination, under similar conditions, by a magnetic flaw detector of the parameters of the controlled blade and assessment of the degree of damage to the material of the blade at times the parameter values obtained from the reference and controlled blades, additionally take the parameters of the material of the blade under load, for which they load the reference object of control in the field of elastic stresses, applying a load R ₃ to it, adjust the magnetic flaw detector on it, then similarly load the controlled blade applying thereto the load F _Z, and produce its repeated scanning of the measuring device, and to change the values of parameters obtained is judged to change the state of the material to trolley blades before and after loading.

The technical result is also achieved in that the magnetic flaw detection method vanes amount of load to be applied for reference object and to control the blade corresponds to the operational load (P _W = P _eq); as a variant of the process - to a reference object and to control the blade making alternating load corresponding to the operational load (P _W = P _{eq / zp.).}

The technical result is also achieved by the fact that in the method of magnetic defectoscopy of the blades, the difference in the values of the parameters taken from the controlled blade without application (P ₀ = 0) and with the application (P _Z = P _ek and / or P _Z = P _{ek / zp} ) load; as a variant of the method, as parameters, by the value of which they judge the change in the state of the material of the controlled blade, choose the difference between the values of the parameters taken at a load of _RZ from the reference and controlled blades.

The technical result is also achieved by the fact that in the method of magnetic defectoscopy of the blades they take an additional reference object of control, in size and material corresponding to the controlled blades and having defects corresponding to the limiting operating conditions of the blades, it is used to additionally configure the magnetic flaw detector in an unloaded condition (Р ₀ = 0) and loaded (Р _З = Р _Ek and / or Р _З = _{PEC / З.П.} ) conditions, and the degree of damage to the material of the blade is judged by the degree of approximation of the signal to the signal of the reference th object of control having these defects.

The technical result is also achieved by the fact that in the method of magnetic defectoscopy of the blades take at least one additional reference control object, in size and material corresponding to the controlled blades and having defects corresponding to the intermediate states of operation of the blades, it is used to additionally configure the device magnetic flaw detection in unloaded (P ₀ = 0) and loaded (P ₃ = P _EC and / or

P _W = P _{eq / zp.} ) conditions, and the degree of damage to the material of the blade is judged by comparing the signals from the controlled blade and the reference objects of control.

When studying the degree of degradation of the material of the blades of nickel alloys, the authors experimentally established that magnetic flaw detection methods allow us to assess the change in the state of the material of the blade under various loaded states. The results obtained allowed us to develop a method for assessing the degree of degradation of the material of the blade, which allows us to determine the effect of mechanical, including alternating, loads on the condition of the material of the part.

The proposed method is implemented as follows. One of the known methods is the measurement of the magnetic parameters of the material of the scapula. To do this, first configure the device by measuring the magnetic parameters of the material on a number of reference blades having a different (predetermined) degree of degradation of the material. In this case, standards are used made of the same source material as the controlled blades, as well as having the same dimensional and geometric parameters. To assess the nature of the dependence of the magnetic parameters of the material on the degree of its degradation in the entire studied range, take the initial reference sample corresponding to the zero degree of degradation, and the final reference sample - the maximum possible (ultimate) degree of degradation of the material. To increase the reliability of the assessment results, additional intermediate reference samples with a fixed value of material degradation are used. Then, using a scale from zero to one hundred percent degradation of the material, the device is tuned to measure the magnetic parameters according to the specified standards in fixed areas of the blade. Similarly, the second device is tuned according to reference samples under the influence of a given mechanical load.

The values of the magnetic parameters of the controlled blade are measured and the dependence “magnitude of the magnetic parameters - degree of degradation” is determined according to the determined value of the degradation of the material of the controlled blade at the specified values of the mechanical load.

After assessing the degree of degradation of the material of the controlled blade under various mechanical loads, the effect of the latter on the state of the material of the controlled blade is evaluated.

Having information about the change in the state of the degraded material of the blade, one can judge the dominant mechanism of destruction of the blades and take appropriate technological or operational measures to extend or increase the service life of parts of turbomachines.

To increase the degree of reliability, it is possible to additionally separate the identified defective areas of the material of the scapula according to their size and location.

An example implementation of the method

To assess the degree and nature of the degradation of the material of the turbine blades, reference samples of the blades were made of nickel alloy ZhS-6U with various degrees of degradation. Magnetic characteristics were measured at various mechanical loads by a magnetic flaw detector. After obtaining data from the reference samples, magnetic characteristics were measured from the blades, the degradation of the material of which was carried out during operation. For the control assessment of the degree of degradation of the materials of the reference and controlled blades, destructive control methods were used with the preparation of thin sections and metallographic studies. The results of the evaluation of the parameters of the materials of the reference and controlled blades at various loads are given in tables 1-3.

Table 1.
Reference vanes No. The degree of degradation of the material,% The average value of the magnetic parameters, Ht _cp , (unit scale of the device) Note one 2 3 four one 0 5,6 No defects 2 eleven 7.8 - 3 19 12.1 - four 32 13.1 - 5 42 14.6 - 6 53 15.8 - 7 58 16,4 - 8 77 17,2 - 9 90 18.0 Limit state

Table 2.
Reference vanes No. The initial degree of degradation of the material,% The values of a bending load, P, (N) The average value of the magnetic parameters, Nr _cf , (unit scale of the device) The magnitude of the change in the values of the magnetic parameters, ΔHr _cf The value of the background from the applied load,
ΔНр _f The magnitude of the change in the values of the magnetic parameters characterizing the state of the material from the load, ΔHr _cf The equivalent degree of degradation of the material at
P _e.ism ,% one 2 3 four 5 6 7 8 one 0 0 5,6 0 0 0 0 2 0 fifty 6.0 0.4 0.4 0 2 3 19 0 12.1 0 0 0 19 four 19 fifty 12.9 0.8 0.4 0.4 28 5 53 0 15.8 0 0 0 53 6 53 fifty 16.9 1,1 0.4 0.7 69 7 90 0 18.0 0 0 0 90 8 90 fifty 19.5 1,5 0.4 1,1 one hundred

Table 3.
Controlled shoulder blades No. of scapula Measurement No. The value of the load when bending, P, (N) The average value of the magnetic parameters, Pt _cp , (unit scale of the device) The degree of degradation of the material at P _s ,% The equivalent degree of degradation of the material at P _e.izm ,% one 2 3 four 5 6 one one 0 13.3 32 32 2 fifty 14.1 32 36 2 3 0 15,2 44 44 four fifty 15.8 44 51 3 5 0 16.3 56 56 6 fifty 17.1 56 74

As can be seen from tables 2 and 3, the increase in the values of the equivalent degree of deformation ( _{ΔР e.izm} ) increases with increasing initial degradation of the material of the blade of nickel alloys, i.e. the greater the degree of degradation of the material of the blade, the more dangerous it becomes when the blade is loaded with the same mechanical load on (for example, with the initial value of material degradation of 32%, the equivalent degradation is 36%, i.e., the increase ΔР _{e .ism} = 4%, with an initial value of material degradation of 44%, the equivalent degradation is 51%, that is, an increase of _{ΔР e.ism} = 7%, and with an initial value of material degradation of 56%, the equivalent degradation is 74%, i.e., the increase _{ΔР e.ism} = 18%). Therefore, it is necessary to evaluate the degradation of the material in the state of operation of the blade, i.e. when certain mechanical loads act on it.

The data on the assessment of the degradation of the material using the proposed method for flaw detection of turbomachine blades made of nickel alloys showed that the proposed method of non-destructive testing improves the information content and the reliability of the results of evaluating the nature of the degradation of the material of the blade during operation, which confirms the claimed technical result.

Claims (7)

1. The method of magnetic flaw detection of turbomachine blades made of nickel alloys, including the adjustment of a magnetic flaw detector to determine material parameters from a reference defect-free test object, in size and material corresponding to the controlled blades, without applying mechanical load to it (P ₀ = 0), definition in similar conditions with a magnetic defectoscopy device for the parameters of the controlled blade and an assessment of the degree of damage to the material of the blade according to the difference in the values of the parameters obtained from the reference oh and controlled blades, characterized in that they additionally take the parameters of the material of the blade under load, for which they load the reference object of control in the field of elastic stresses, applying a load R ₃ to it, adjust the magnetic flaw detector on it, then similarly load the controlled blade, applying thereto the load F _Z, and produce its repeated scanning of the measuring device, and to change the values of parameters obtained is judged to change the state of a controlled blade material d and after loading. 2. A method for magnetic flaw blade according to claim 1, characterized in that the amount of load to be applied for reference object and to control the blade corresponds to the operational load (P _W = P _eq). 3. The method of magnetic defectoscopy of the blades according to claim 2, characterized in that an alternating load corresponding to the operational load is applied to the reference object and to the blade (P _Z = P _{eq / s.p.} ). 4. The method of magnetic defectoscopy of the blades according to claim 1, characterized in that as the parameters, according to the value of which they judge the change in the state of the material of the controlled blade, choose the difference between the values of the parameters taken from the controlled blade without application (P ₀ = 0) and with the application
(P _Z = P _ek and / or P _Z = P _{ek / zp} ) load. 5. The method of magnetic defectoscopy of the blades according to claim 1, characterized in that as the parameters, the magnitude of which is judged on the change in the state of the material of the controlled blade, choose the difference between the values of the parameters taken at load _RZ from the reference and controlled blades. 6. The method of magnetic defectoscopy of the blades according to any one of claims 1 to 5, characterized in that they take an additional reference object of control, in size and material corresponding to the controlled blades and having defects corresponding to the limiting operating conditions of the blades, it is used to additionally configure the magnetic device defectoscopy in unloaded (P ₀ = 0) and loaded (P _Z = P _ek and / or P _Z = P _{ek / zp} ) states, and the degree of damage to the material of the blade is judged by the degree of approximation of the signal to the signal of the reference object and a control having these defects. 7. The method of magnetic defectoscopy of the blades according to claim 6, characterized in that they take at least one additional reference control object, in size and material corresponding to the controlled blades and having defects corresponding to the intermediate states of operation of the blades, additional setting the magnetic flaw detector in unloaded (P ₀ = 0) and loaded (P ₃ = P _ek and / or P ₃ = P _{ek / zp} ) states, and the degree of damage to the material of the blade is judged by comparing signals from a controlled th blades and reference objects of control.