CN102607948A - Method for characterizing steel fatigue crack propagation behavior for casing drilling - Google Patents
Method for characterizing steel fatigue crack propagation behavior for casing drilling Download PDFInfo
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Abstract
The invention discloses a method for characterizing a steel fatigue crack propagation behavior for casing drilling. The method comprises the steps of: firstly, sampling casing drilling steel, preparing a sample and cleaning; secondly, carrying out low-frequency noise testing on the sample before fatigue; thirdly, carrying out fatigue testing on the sample; fourthly, carrying out low-frequency noise testing on the sample after fatigue; and fifthly, analyzing, extracting and processing low-frequency noise data before and after the fatigue testing according to low-frequency l/f noise information before and after the fatigue, and characterizing a fatigue crack propagation behavior of the sample. Through two times of low-frequency l/f noise testing before and after the fatigue propagation, the influence of background noise of the sample is eliminated, more complex formula derivation and mathematical calculation in common characterizing methods are avoided, no strict requirements are required for the shape of the sample, the fatigue testing quantity is favorably reduced, the testing cost is lowered, and the fatigue crack propagation behaviors of various samples can be conveniently subjected to sampling and fatigue service life estimation; and the method has the characteristics of convenience in use, low cost and convenience in popularization.
Description
Technical field
The present invention relates to the Casing Drilling Technique field; Be specifically related to the characterizing method of a kind of casing drilling with the behavior of steel crack Propagation; Relate to the low-frequency noise characterizing method of N80 casing drilling with the steel crack Propagation; Be mainly used in of the analysis of low frequency 1/f noise,, thereby obtain the tired information and the crack propagation information of N80 casing steel through the low-frequency noise information of contrast and fatigue analysis crack propagation front and back to N80 casing drilling steel crack Propagation performance.
Background technology
In the actual oil-gas mining operation, the stressing conditions of sleeve pipe is very complicated.When sleeve pipe was on active service, not stopping under the effect of periodicity alternation cyclic loading, fatigure failure began germinating to begin increase by a small margin at fatigue crack after damage after a while.It is generally acknowledged that the germinating of fatigue crack often occurs in the position of stress high concentration.The continuous opening and closing of crackle, expansion gradually increases, and under the situation of stress less than the strength of materials, does not have the sudden change of omen at last.This inefficacy is a kind of destruction that accumulates formula, has irreversible character.In case take place and to bring the economic loss that is difficult to estimate to oil gas field.The conventional characterizing method of crack Propagation is to utilize the Paris formula.This method is thought; In second stage of crack propagation; Be stable or linear flaws spreading rate district, crack Propagation rate controlled in the stress-intensity factor range of crack tip, and the exponential relationship between fatigue crack growth rate and the stress intensity factor is described.
Discover that further C and m are material constant, environmental factor such as temperature, humidity, medium, loading frequency etc. all lie among the constant, are obtained by test data fitting usually.But find seldom that in test C and m are the phenomenons of constant, find that in some documents C increases along with the increase of stress ratio, m reduces along with the increase of stress.In other documents, m then increases along with the increase of stress ratio.But the variation of m is random in most of documents.The heterogeneous microstructure of material, the frequency of cyclic loading and waveform, environment, temperature and load ratio R use influence to C and m, and the constant relevant with the material microstructure obtains very difficulty in the formula, seriously influenced the promotion and application of this formula.
Because this model hypothesis is too simple, influence factor is too much, and therefore, the physical significance of extracting parameter is unclear from this model, can't analyze the local message of crack Propagation.All the time, through constantly correction and improved Paris formula have tens of kinds more than.
Noise comes from fluctuation.The physical characteristics fluctuation research of condensed state matter is as existing many decades in an active research field, and these researchs have caused the attention of people's pair physical phenomenon relevant with fluctuation.All the time, comprised many important information in the low-frequency noise, usually ignored by people.The most noticeable research topic is the research of ubiquitous 1/f noise in this field.1/f noise is a kind of of low-frequency noise; Name origin that it is generally acknowledged 1/f noise is because the fluctuation of lot of materials shows as: its power spectrum s (f) is directly proportional with
;
is generally near 1; 1/f noise is with a wide range of applications; The 1/f noise of " surplus " (
is generally about 1) has confidential relation with some imperfection of system on the one hand, thereby can be as latent defect in detected electrons and the material; On the other hand; Noise has reflected natural perfection and harmony again near the 1/f of " intrinsic " (
=1), yet uses it for aspect such as musical composition to obtain the effect from create an aesthetic feeling.The most important thing is that the characterization method of low frequency 1/f noise is a kind of lossless detection method of sensitivity.Conventional Pairs characterizing method is to measure FATIGUE CRACK GROWTH through on fatigue tester, carrying out destructive torture test, often takes time and effort, and has the restriction of many objective factors and range estimation factor.And of preamble, the physical significance of the parameter that it obtains is often clear and definite inadequately.Utilize low-frequency noise to characterize casing drilling and can avoid above shortcoming and defect, because in the process of crack Propagation, from the germinating of crackle with the crack Propagation of steel; Expand to the termination of crackle; All be accompanied by the formation (through doing methods such as SEM, AFM) of sample interior defective and the variation of sample electrical quantity, these variations; Can gather out through data collecting card, through handling the low frequency 1/f noise information that changes into.
Summary of the invention
In order to overcome the deficiency of above-mentioned prior art, the object of the present invention is to provide the characterizing method of a kind of casing drilling with the behavior of steel crack Propagation, adopt the low-frequency noise characterization method; (sample is processed compact tension specimen (CT) sample by ASTM E647 standard through the contrast standard specimen;) low-frequency noise (being white noise, 1/f noise amplitude and γ value wherein) before and after the crack Propagation, through the low-frequency noise information of comparative analysis crack Propagation front and back; Can realize exactly comparatively exact grasp and sign are carried out in the behavior of the crack Propagation of N80 casing steel; Help to reduce torture test quantity, reduce experimentation cost, and it is easy to use not exist potential safety hazard to have; Characteristics with low cost, as to be convenient to promote.
To achieve these goals; The technical scheme that the present invention adopts is: a kind of casing drilling is with the characterizing method of steel crack Propagation behavior; Utilize the characteristics of sample standard specimen low frequency 1/f noise before and after crack Propagation, in conjunction with the origin and the inherent crackle of the sample characteristics relevant of low frequency 1/f noise, through the size of twice comparative analysis noise parameter with defective; Analyze the crack Propagation behavior of casing steel, comprise the steps:
The first, the casing drilling steel to be taken a sample, sample preparation is also cleaned;
(stress is comparatively concentrated) is followed successively by according to the length and width height at the box cupling place
Size in the intercepting of carrying out of N80 well casing steel, make the CT sample according to ASTM E647 metric system then, the high size of the length and width of sample is followed successively by
, test is at first carried out presplitting to the CT sample before carrying out, and presplitting length is 2 millimeters, is the rust cleaning of 1.0%～5.0% hydrochloric acid (HCl) solution in volumetric molar concentration, and soak time is 1～3 minute; Clean with ethanol and deionized water respectively then, soak time is 1～3 minute, and after tangent plane ground polishing, adopting 200 milliliters of volumetric molar concentrations was 2%～5% HNO
3Solution cleans, and takes out and hangs up, and dries up;
The second, sample is carried out tired preceding low-frequency noise test;
Sample is carried out the low-frequency noise test, need under certain biasing, carry out, the present invention is with reference to the current potential reference point in the conventional torture test; In the precrack both sides of sample, weld two lead-in wires, and be connected on the noise testing platform respectively; The regulation voltage scope is 2.0～3.0V, waits when reaching needed biasing, puts sample into screened room together with bias unit; And carry out tired preceding low-frequency noise and test; Whole low frequency 1/f noise test is carried out in Cu net screened room, need carry out the test of ground unrest before the test, and adopts physical means to reduce ground unrest as much as possible;
The 3rd, sample is carried out torture test;
Sample is taken out from the low-frequency noise test macro, and being placed on model is on the microcomputer controlled electro-hydraulic servo fatigue tester of PLD-100, when command signal gets into amplifier; Control is from the hydraulic oil servo-valve of hydraulic power source; Make the piston motion of hydraulic cylinder, stretch or the compression sample, force transducer is measured load force (or distortion) and is given amplifier and command signal relatively with signal feedback; Form closed loop; The control of realization system, continuous recording load p and corresponding crack tip opening displacement V in loading procedure, the situation of crackle not crack initiation as yet, crack initiation, stable expansion and unstable propagation has been represented in the variation of crack tip opening displacement V; Setting stress ratio is 0.1～0.7, up to fatigue and cyclic 1 * 10
6Inferior crackle does not take place till the 0.1mm expansion, and corresponding △ K is corresponding crack propagation threshold value, when crack propagation to 5～20mm, stops torture test;
The 4th, the sample after the fatigue is carried out low-frequency noise test, sample is proceeded the low-frequency noise test after the torture test, identical in experimental technique and added biasing and the step 2, but with the comparative of assurance experimental data;
The 5th; According to low frequency 1/f noise information before and after tired; Low-frequency noise data to before and after the torture test are analyzed; Extract and handle, sample crack Propagation situation is characterized, theoretical according to low-frequency noise; Under the approaching situation of other noise parameters, the origin of the big or small direct and noise of
value is relevant with crackle, the defective of sample interior;
Described HNO
3Solution adopts straight alcohol to make solvent.
The invention has the beneficial effects as follows:
The present invention utilizes the low frequency 1/f noise that nondestructive characterisation (NDC) is carried out in the crack Propagation behavior of N80 casing steel owing to having adopted; Through two infra-low frequency 1/f noises test before and after the fatigue expansion, eliminate sample copy and carried the scape The noise on the body, avoided the derivation of equation and mathematical computations comparatively complicated in the general characterizing method; Simultaneously because the present invention is a kind of method with statistical significance; Shape to sample does not have proper requirement, thereby the crack Propagation behavior of various samples is easily sampled and the assessment of fatigue lifetime, and formula is simple; Be easy to realize, and error is less.
Description of drawings
Fig. 1 is the position sample figure of torture test and low-frequency noise specimen in the embodiment of the invention.
Fig. 2 is the CT figure of torture test and low-frequency noise specimen in the embodiment of the invention.
Embodiment
Below in conjunction with specific embodiment the present invention is done further explain.
Embodiments of the invention are signs of the crack Propagation behavior in N80 casing steel compact tension specimen (CT) as shown in Figure 2, carried out.With reference to Fig. 2, the present invention provides following three embodiment to the low frequency 1/f noise sign of the crack Propagation behavior of N80 casing steel shown in Figure 1.
Embodiment one
A kind of casing drilling comprises the steps: with the characterizing method of steel crack Propagation behavior
The first, the CT sample of N80 casing steel is eliminated rust polishing and cleaning;
At first the CT sample is carried out presplitting, presplitting length is 2 millimeters, and using volumetric molar concentration is that 1.0% hydrochloric acid solution eliminates rust, and soak time is 1 minute; Clean with ethanol and deionized water respectively then, soak time is 2 minutes, and after tangent plane ground polishing, adopting 200 milliliters of volumetric molar concentrations was 2% HNO
3Solution, described HNO
3Solution adopts straight alcohol to make solvent, cleans, and takes out and hangs up, and dries up;
The second, N80 casing steel CT sample is carried out tired preceding low-frequency noise test;
1) welding that the CT sample of rust cleaning and cleaning back N80 casing steel is gone between, the present invention is the current potential reference point with fatigue crack monitoring point in the conventional torture test, respectively in the precrack both sides of sample, two lead-in wires of burn-oning;
2) sample is carried out the low-frequency noise test before tired, wherein a lead-in wire is connected in the biasing circuit of making in advance, for the sake of assurance, one 50 ohm the wire resistor of connecting, regulation voltage level is 2.0V then; Another root lead-in wire connects the low-noise preamplifier on the noise testing platform; The low-frequency noise signal amplifies the capture card that computer is inserted in the back, carries out data acquisition and spectrum analysis, when setting needed voltage; Put sample into screened room together with bias unit; And carry out tired preceding low-frequency noise test, need to prove that whole low frequency 1/f noise test is carried out in Cu net screened room; Need carry out the test of ground unrest before the test, and adopt physical means to reduce ground unrest as much as possible.
Utilize the 1/f noise model:
(1)
Wherein f is a frequency; A is the amplitude of white noise; B is the amplitude of 1/f noise;
is the NF factor.Test data is handled result such as following table:
The 3rd, sample is carried out torture test;
Sample is taken out from the low-frequency noise test macro, be placed on model and be on the anchor clamps of microcomputer controlled electro-hydraulic servo fatigue tester of PLD-100, test temperature is a room temperature; Frequency is 10Hz, and the loading waveform is a sinusoidal waveform, and maximum load is 1.4kN; Setting stress ratio is 0.1; Sample is exchanged high-cycle fatigue test, and crack length is by the auxiliary potential method monitoring of microcomputer, and classification is fallen year number percent and remained on 5%; Guarantee that simultaneously crack extension under every grade of load is 4～6 times of plastic zone size under the upper level load, up to fatigue and cyclic 1 * 10
6Inferior crackle does not take place till the 0.1mm expansion; Continuous recording load p and corresponding crack tip opening displacement V in loading procedure; The situation of crackle not crack initiation as yet, crack initiation, stable expansion and unstable propagation has been represented in the variation of crack tip opening displacement V; When crack propagation during, stop torture test to 5mm;
The 4th, sample is carried out the low-frequency noise test after the fatigue;
Sample is proceeded the low-frequency noise test after the torture test; Identical in experimental technique and added biasing and the step 2; Measure when the low frequency 1/f noise of crack propagation during, utilize 1/f noise model (1) test data to be handled result such as following table to 5mm:
The 5th, according to low frequency 1/f noise information before and after tired, the crack Propagation situation of N80 casing steel is characterized; Before and after the contrast torture test; The result of the low frequency 1/f noise data of N80 casing steel can be found, no matter is the white noise amplitude in the low-frequency noise information; 1/f noise amplitude and 1/f noise exponential factor all obviously increase than corresponding noise figure before tired; Secondly, along with the increase of crack Propagation length, more than the numerical value of three kinds of parameters all be monotonically increasing trend, according to the correlation theory of low-frequency noise, the size of γ value and the defective of material internal are closely related.Therefore, can realize the behavior of sample crack Propagation is characterized through analyzing the variation of γ value.
Embodiment two
A kind of low-frequency noise characterizing method of new casing steel crack Propagation behavior includes following steps:
The first, eliminate rust polishing and cleaning like the CT sample of N80 casing steel;
It is that 3.0% hydrochloric acid (HCl) solution carries out that volumetric molar concentration is used in rust cleaning, and soak time is 2 minutes; Clean with ethanol and deionized water respectively then, soak time is 2 minutes, and after tangent plane ground polishing, adopting 200 milliliters of volumetric molar concentrations was 4.0% HNO
3Clean with the etchant of ethanolic solution, take out and hang up, dry up;
The second, N80 casing steel sample is carried out tired preceding low-frequency noise test;
1) welding that the CT sample of rust cleaning and cleaning back N80 casing steel is gone between.The present invention is the current potential reference point with fatigue crack monitoring point in the conventional torture test, respectively in the precrack both sides of sample, and two lead-in wires of burn-oning;
2) sample is carried out the low-frequency noise test before tired, wherein a lead-in wire is connected in the biasing circuit of making in advance, for the sake of assurance, one 50 ohm the wire resistor of connecting, regulation voltage level is 2.5 V then; Another root lead-in wire connects the low-noise preamplifier on the noise testing platform; The low-frequency noise signal amplifies the capture card that computer is inserted in the back, carries out data acquisition and spectrum analysis, when setting needed voltage; Put sample into screened room together with bias unit; And carry out tired preceding low-frequency noise test, need to prove that whole low frequency 1/f noise test is carried out in Cu net screened room; Need carry out the test of ground unrest before the test, and adopt physical means to reduce ground unrest as much as possible;
Utilize the 1/f noise model:
(1)
Wherein f is a frequency; A is the amplitude of white noise; B is the amplitude of 1/f noise;
is the NF factor.Test data is handled result such as following table:
The 3rd, sample is carried out torture test;
Sample is taken out from the low-frequency noise test macro, be placed on model and be on the anchor clamps of microcomputer controlled electro-hydraulic servo fatigue tester of PLD-100, test temperature is a room temperature; Frequency is 10Hz, and the loading waveform is a sinusoidal waveform, and maximum load is 1.4kN; The fixed stress ratio is 0.1; Sample is exchanged high-cycle fatigue test, and crack length is by the auxiliary potential method monitoring of microcomputer, and classification is fallen year number percent and remained on 5%; Guarantee that simultaneously crack extension under every grade of load is 4～6 times of plastic zone size under the upper level load, up to fatigue and cyclic 1 * 10
6Inferior crackle does not take place till the 0.1mm expansion; Continuous recording load p and corresponding crack tip opening displacement V in loading procedure; The situation of crackle not crack initiation as yet, crack initiation, stable expansion and unstable propagation has been represented in the variation of crack tip opening displacement V; When crack propagation during, stop torture test to 15mm;
The 4th, sample is carried out the low-frequency noise test after the fatigue;
Sample is proceeded the low-frequency noise test after the torture test; Identical in experimental technique and added biasing and the step 2; Measure when the low frequency 1/f noise of crack propagation during, utilize 1/f noise model (1) test data to be handled result such as following table to 15mm:
The 5th, according to low frequency 1/f noise information before and after tired, the crack Propagation situation of N80 casing steel is characterized; Before and after the contrast torture test; The result of the low frequency 1/f noise data of N80 casing steel can be found, no matter is the white noise amplitude in the low-frequency noise information; 1/f noise amplitude and 1/f noise exponential factor all obviously increase than corresponding noise figure before tired; Secondly; Along with the increase of crack Propagation length, more than the numerical value of three kinds of parameters all be monotonically increasing trend, according to the correlation theory of low-frequency noise; The size of γ value and the defective of material internal are closely related; Therefore, can realize the behavior of sample crack Propagation is characterized through analyzing the variation of γ value.
Embodiment three
A kind of low-frequency noise characterizing method of new casing steel crack Propagation behavior includes following steps:
The first, eliminate rust polishing and cleaning like the CT sample of N80 casing steel;
The available volumetric molar concentration that eliminates rust is that 5.0% hydrochloric acid (HCl) solution carries out, and soak time is 3 minutes; Clean with ethanol and deionized water respectively then, soak time is 2 minutes, and 200 milliliters of volumetric molar concentrations of employing were 5% HNO after tangent plane ground and polishes
3Solution, described HNO
3Solution adopts straight alcohol to make solvent, cleans, and takes out and hangs up, and dries up;
The second, N80 casing steel sample is carried out tired preceding low-frequency noise test;
1) welding that the CT sample of rust cleaning and cleaning back N80 casing steel is gone between, the present invention is the current potential reference point with fatigue crack monitoring point in the conventional torture test, respectively in the precrack both sides of sample, two lead-in wires of burn-oning;
2) sample is carried out the low-frequency noise test before tired, wherein a lead-in wire is connected in the biasing circuit of making in advance, for the sake of assurance, one 50 ohm the wire resistor of connecting, regulation voltage level is 3.0V then; Another root lead-in wire connects the low-noise preamplifier on the noise testing platform; The low-frequency noise signal amplifies the capture card that computer is inserted in the back, carries out data acquisition and spectrum analysis, when setting needed voltage; Put sample into screened room together with bias unit; And carry out tired preceding low-frequency noise test, need to prove that whole low frequency 1/f noise test is carried out in Cu net screened room; Need carry out the test of ground unrest before the test, and adopt physical means to reduce ground unrest as much as possible;
Utilize the 1/f noise model:
(1)
Wherein f is a frequency; A is the amplitude of white noise; B is the amplitude of 1/f noise;
is the NF factor.Test data is handled result such as following table:
The 3rd, sample is carried out torture test;
Sample is taken out from the low-frequency noise test macro, be placed on model and be on the anchor clamps of microcomputer controlled electro-hydraulic servo fatigue tester of PLD-100, test temperature is a room temperature; Frequency is 10Hz, and the loading waveform is a sinusoidal waveform, and maximum load is 1.4kN; The fixed stress ratio is 0.1; Sample is exchanged high-cycle fatigue test, and crack length is by the auxiliary potential method monitoring of microcomputer, and classification is fallen year number percent and remained on 5%; Guarantee that simultaneously crack extension under every grade of load is 4～6 times of plastic zone size under the upper level load, up to fatigue and cyclic 1 * 10
6Inferior crackle does not take place till the 0.1mm expansion; Continuous recording load p and corresponding crack tip opening displacement V in loading procedure; The situation of crackle not crack initiation as yet, crack initiation, stable expansion and unstable propagation has been represented in the variation of crack tip opening displacement V; When crack propagation during, stop torture test to 20mm;
The 4th, sample is carried out the low-frequency noise test after the fatigue;
Sample is proceeded the low-frequency noise test after the torture test; Identical in experimental technique and added biasing and the step 2; Measure when the low frequency 1/f noise of crack propagation during, utilize 1/f noise model (1) test data to be handled result such as following table to 20mm:
The 5th, according to low frequency 1/f noise information before and after tired, the crack Propagation situation of N80 casing steel is characterized.Before and after the contrast torture test; The result of the low frequency 1/f noise data of N80 casing steel can be found, no matter is the white noise amplitude in the low-frequency noise information; 1/f noise amplitude and 1/f noise exponential factor all obviously increase than corresponding noise figure before tired; Secondly; Along with the increase of crack Propagation length, more than the numerical value of three kinds of parameters all be monotonically increasing trend, according to the correlation theory of low-frequency noise; The size of γ value and the defective of material internal are closely related; Therefore, can realize the behavior of sample crack Propagation is characterized through analyzing the variation of γ value.
Referring to Fig. 1, the N80 well casing steel sample position figure of box cupling place.
Referring to Fig. 2, Fig. 1 sample thief is made into the dimensional drawing of CT sample according to ASTM E647 standard.
Claims (4)
1. a casing drilling is characterized in that with the characterizing method of steel crack Propagation behavior, comprises the steps:
The first, the casing drilling steel to be taken a sample, sample preparation is also cleaned;
(stress is comparatively concentrated) is followed successively by according to the length and width height at the box cupling place
Size in the intercepting of carrying out of N80 well casing steel, make the CT sample according to ASTM E647 metric system then, the high size of the length and width of sample is followed successively by
, test is at first carried out presplitting to the CT sample before carrying out, and presplitting length is 2 millimeters, is the rust cleaning of 1.0%～5.0% hydrochloric acid (HCl) solution in volumetric molar concentration, and soak time is 1～3 minute; Clean with ethanol and deionized water respectively then, soak time is 1～3 minute, and after tangent plane ground polishing, adopting 200 milliliters of volumetric molar concentrations was 2%～5% HNO
3Solution, described HNO
3Solution adopts straight alcohol to make solvent, cleans, and takes out and hangs up, and dries up;
The second, sample is carried out tired preceding low-frequency noise test;
Sample is carried out the low-frequency noise test, need under certain biasing, carry out, the present invention is with reference to the current potential reference point in the conventional torture test; In the precrack both sides of sample, weld two lead-in wires, and be connected on the noise testing platform respectively; The regulation voltage scope is 2.0～3.0V, waits when reaching needed biasing, puts sample into screened room together with bias unit; And carry out tired preceding low-frequency noise and test; Whole low frequency 1/f noise test is carried out in Cu net screened room, need carry out the test of ground unrest before the test, and adopts physical means to reduce ground unrest as much as possible;
The 3rd, sample is carried out torture test;
Sample is taken out from the low-frequency noise test macro, and being placed on model is on the microcomputer controlled electro-hydraulic servo fatigue tester of PLD-100, when command signal gets into amplifier; Control is from the hydraulic oil servo-valve of hydraulic power source; Make the piston motion of hydraulic cylinder, stretch or the compression sample, force transducer is measured load force (or distortion) and is given amplifier and command signal relatively with signal feedback; Form closed loop; The control of realization system, continuous recording load p and corresponding crack tip opening displacement V in loading procedure, the situation of crackle not crack initiation as yet, crack initiation, stable expansion and unstable propagation has been represented in the variation of crack tip opening displacement V; Setting stress ratio is 0.1～0.7, up to fatigue and cyclic 1 * 10
6Inferior crackle does not take place till the 0.1mm expansion, and corresponding △ K is corresponding crack propagation threshold value, when crack propagation to 5～20mm, stops torture test;
The 4th, the sample after the fatigue is carried out low-frequency noise test, sample is proceeded the low-frequency noise test after the torture test, identical in experimental technique and added biasing and the step 2, but with the comparative of assurance experimental data;
The 5th; According to low frequency 1/f noise information before and after tired; Low-frequency noise data to before and after the torture test are analyzed; Extract and handle, sample crack Propagation situation is characterized, theoretical according to low-frequency noise; Under the approaching situation of other noise parameters, the origin of the big or small direct and noise of
value is relevant with crackle, the defective of sample interior.
2. a kind of casing drilling according to claim 1 is characterized in that with the characterizing method of steel crack Propagation behavior, may further comprise the steps:
The first, N80 casing steel CT sample is eliminated rust polishing and cleaning;
At first the CT sample is carried out presplitting, presplitting length is 2 millimeters, and using volumetric molar concentration is that 1.0% hydrochloric acid solution eliminates rust, and soak time is 1 minute;
Clean with ethanol and deionized water respectively then, soak time is 2 minutes, and after tangent plane ground polishing, adopting 200 milliliters of volumetric molar concentrations was 2% HNO
3Solution, described HNO
3Solution adopts straight alcohol to make solvent, cleans, and takes out and hangs up, and dries up;
The second, N80 casing steel CT sample is carried out tired preceding low-frequency noise test;
1) welding that the CT sample of rust cleaning and cleaning back N80 casing steel is gone between, the present invention is the current potential reference point with fatigue crack monitoring point in the conventional torture test, respectively in the precrack both sides of sample, two lead-in wires of burn-oning;
2) sample is carried out the low-frequency noise test before tired, wherein a lead-in wire is connected in the biasing circuit of making in advance, for the sake of assurance, one 50 ohm the wire resistor of connecting, regulation voltage level is 2.0V then; Another root lead-in wire connects the low-noise preamplifier on the noise testing platform; The low-frequency noise signal amplifies the capture card that computer is inserted in the back, carries out data acquisition and spectrum analysis, when setting needed voltage; Put sample into screened room together with bias unit; And carry out tired preceding low-frequency noise test, need to prove that whole low frequency 1/f noise test is carried out in Cu net screened room; Need carry out the test of ground unrest before the test, and adopt physical means to reduce ground unrest as much as possible;
Utilize the 1/f noise model:
(1)
Wherein f is a frequency; A is the amplitude of white noise; B is the amplitude of 1/f noise;
is the NF factor, and test data is handled;
The 3rd, sample is carried out torture test;
Sample is taken out from the low-frequency noise test macro, be placed on model and be on the anchor clamps of microcomputer controlled electro-hydraulic servo fatigue tester of PLD-100, test temperature is a room temperature; Frequency is 10Hz, and the loading waveform is a sinusoidal waveform, and maximum load is 1.4kN; Setting stress ratio is 0.1; Sample is exchanged high-cycle fatigue test, and crack length is by the auxiliary potential method monitoring of microcomputer, and classification is fallen year number percent and remained on 5%; Guarantee that simultaneously crack extension under every grade of load is 4～6 times of plastic zone size under the upper level load, up to fatigue and cyclic 1 * 10
6Inferior crackle does not take place till the 0.1mm expansion; Continuous recording load p and corresponding crack tip opening displacement V in loading procedure; The situation of crackle not crack initiation as yet, crack initiation, stable expansion and unstable propagation has been represented in the variation of crack tip opening displacement V; When crack propagation during, stop torture test to 5mm;
The 4th, sample is carried out the low-frequency noise test after the fatigue;
Sample is proceeded the low-frequency noise test after the torture test, identical in experimental technique and added biasing and the step 2, measurement utilizes 1/f noise model (1) that test data is handled when the low frequency 1/f noise of crack propagation during to 5mm;
The 5th, according to low frequency 1/f noise information before and after tired, the crack Propagation situation of N80 casing steel is characterized; Before and after the contrast torture test; The result of the low frequency 1/f noise data of N80 casing steel, according to the correlation theory of low-frequency noise, the size of γ value and the defective of material internal are closely related; Through analyzing the variation of γ value, realize the behavior of sample crack Propagation is characterized.
3. a kind of casing drilling according to claim 1 is characterized in that with the characterizing method of steel crack Propagation behavior, may further comprise the steps:
The first, N80 casing steel CT sample is eliminated rust polishing and cleaning;
It is that 3.0% hydrochloric acid (HCl) solution carries out that volumetric molar concentration is used in rust cleaning, and soak time is 2 minutes; Clean with ethanol and deionized water respectively then, soak time is 2 minutes, and after tangent plane ground polishing, adopting 200 milliliters of volumetric molar concentrations was 4% HNO
3Solution, described HNO
3Solution adopts straight alcohol to make solvent, cleans, and takes out and hangs up, and dries up;
The second, sample is carried out tired preceding low-frequency noise test;
1) welding that the CT sample of rust cleaning and cleaning back N80 casing steel is gone between, the present invention is the current potential reference point with fatigue crack monitoring point in the conventional torture test, respectively in the precrack both sides of sample, two lead-in wires of burn-oning;
2) sample is carried out the low-frequency noise test before tired, wherein a lead-in wire is connected in the biasing circuit of making in advance, for the sake of assurance, one 50 ohm the wire resistor of connecting, regulation voltage level is 2.5 V then; Another root lead-in wire connects the low-noise preamplifier on the noise testing platform; The low-frequency noise signal amplifies the capture card that computer is inserted in the back, carries out data acquisition and spectrum analysis, when setting needed voltage; Put sample into screened room together with bias unit; And carry out tired preceding low-frequency noise test, need to prove that whole low frequency 1/f noise test is carried out in Cu net screened room; Need carry out the test of ground unrest before the test, and adopt physical means to reduce ground unrest as much as possible;
Utilize the 1/f noise model:
(1)
Wherein f is a frequency; A is the amplitude of white noise; B is the amplitude of 1/f noise;
is the NF factor, and test data is handled;
The 3rd, sample is carried out torture test;
Sample is taken out from the low-frequency noise test macro, be placed on model and be on the anchor clamps of microcomputer controlled electro-hydraulic servo fatigue tester of PLD-100, test temperature is a room temperature; Frequency is 10Hz, and the loading waveform is a sinusoidal waveform, and maximum load is 1.4kN; The fixed stress ratio is 0.1; Sample is exchanged high-cycle fatigue test, and crack length is by the auxiliary potential method monitoring of microcomputer, and classification is fallen year number percent and remained on 5%; Guarantee that simultaneously crack extension under every grade of load is 4～6 times of plastic zone size under the upper level load, up to fatigue and cyclic 1 * 10
6Inferior crackle does not take place till the 0.1mm expansion;
Continuous recording load p and corresponding crack tip opening displacement V in loading procedure, the variation of crack tip opening displacement V have been represented the situation of crackle not crack initiation as yet, crack initiation, stable expansion and unstable propagation;
When crack propagation during, stop torture test to 15mm;
The 4th, sample is carried out the low-frequency noise test after the fatigue;
Sample is proceeded the low-frequency noise test after the torture test, identical in experimental technique and added biasing and the step 2, measurement utilizes 1/f noise model (1) that test data is handled when the low frequency 1/f noise of crack propagation during to 15mm;
The 5th, according to low frequency 1/f noise information before and after tired, the crack Propagation situation of N80 casing steel is characterized; Before and after the contrast torture test; The result of the low frequency 1/f noise data of N80 casing steel, according to the correlation theory of low-frequency noise, the size of γ value and the defective of material internal are closely related; Through analyzing the variation of γ value, realize the behavior of sample crack Propagation is characterized.
4. a kind of casing drilling according to claim 1 is characterized in that with the characterizing method of steel crack Propagation behavior, may further comprise the steps:
The first, eliminate rust polishing and cleaning like the CT sample of N80 casing steel;
The available volumetric molar concentration that eliminates rust is that 5.0% hydrochloric acid (HCl) solution carries out, and soak time is 3 minutes; Clean with ethanol and deionized water respectively then, soak time is 2 minutes, and after tangent plane ground polishing, adopting 200 milliliters of volumetric molar concentrations was 5% HNO
3Solution, described HNO
3Solution adopts straight alcohol to make solvent, cleans, and takes out and hangs up, and dries up;
The second, sample is carried out tired preceding low-frequency noise test;
1) welding that the CT sample of rust cleaning and cleaning back N80 casing steel is gone between, the present invention is the current potential reference point with fatigue crack monitoring point in the conventional torture test, respectively in the precrack both sides of sample, two lead-in wires of burn-oning;
2) sample is carried out the low-frequency noise test before tired, wherein a lead-in wire is connected in the biasing circuit of making in advance, for the sake of assurance, one 50 ohm the wire resistor of connecting, regulation voltage level is 3.0V then; Another root lead-in wire connects the low-noise preamplifier on the noise testing platform; The low-frequency noise signal amplifies the capture card that computer is inserted in the back, carries out data acquisition and spectrum analysis, when setting needed voltage; Put sample into screened room together with bias unit; And carry out tired preceding low-frequency noise test, need to prove that whole low frequency 1/f noise test is carried out in Cu net screened room; Need carry out the test of ground unrest before the test, and adopt physical means to reduce ground unrest as much as possible;
Utilize the 1/f noise model:
(1)
Wherein f is a frequency; A is the amplitude of white noise; B is the amplitude of 1/f noise;
is the NF factor, and test data is handled;
The 3rd, sample is carried out torture test;
Sample is taken out from the low-frequency noise test macro, be placed on model and be on the anchor clamps of microcomputer controlled electro-hydraulic servo fatigue tester of PLD-100;
Test temperature is a room temperature, and frequency is 10Hz, and the loading waveform is a sinusoidal waveform, and maximum load is 1.4kN, and the fixed stress ratio is 0.1, and sample is exchanged high-cycle fatigue test;
Crack length is by the auxiliary potential method monitoring of microcomputer, and classification is fallen and carried number percent and remain on 5%, guarantees that simultaneously crack extension under every grade of load is 4～6 times of plastic zone size under the upper level load, up to fatigue and cyclic 1 * 10
6Inferior crackle does not take place till the 0.1mm expansion;
Continuous recording load p and corresponding crack tip opening displacement V in loading procedure; The situation of crackle not crack initiation as yet, crack initiation, stable expansion and unstable propagation has been represented in the variation of crack tip opening displacement V; When crack propagation during, stop torture test to 20mm;
The 4th, sample is carried out the low-frequency noise test after the fatigue;
Sample is proceeded the low-frequency noise test after the torture test, identical in experimental technique and added biasing and the step 2, measurement utilizes 1/f noise model (1) that test data is handled when the low frequency 1/f noise of crack propagation during to 20mm;
The 5th, according to low frequency 1/f noise information before and after tired, the crack Propagation situation of N80 casing steel is characterized; Before and after the contrast torture test; The result of the low frequency 1/f noise data of N80 casing steel, according to the correlation theory of low-frequency noise, the size of γ value and the defective of material internal are closely related; Through analyzing the variation of γ value, realize the behavior of sample crack Propagation is characterized.
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| CN103594723A (en) * | 2012-08-13 | 2014-02-19 | 株式会社东芝 | Welding method of sealed storage battery, sealed storage battery, and cap body |
| CN103743636A (en) * | 2014-01-16 | 2014-04-23 | 清华大学 | Method for predicting fatigue crack propagation threshold value of welded joint |
| CN105004766A (en) * | 2015-07-07 | 2015-10-28 | 中冶建筑研究总院有限公司 | Method for monitoring fatigue crack of surface of engineering structure |
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| CN108918690A (en) * | 2018-04-27 | 2018-11-30 | 佛山科学技术学院 | A kind of antifatigue hot isostatic pressing of cast superalloy based on ultrasonic fatigue repairs Evaluation model |
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| CN103743636A (en) * | 2014-01-16 | 2014-04-23 | 清华大学 | Method for predicting fatigue crack propagation threshold value of welded joint |
| CN103743636B (en) * | 2014-01-16 | 2015-11-18 | 清华大学 | A kind of method predicting welding joint threshold in fatigue crack propagation |
| CN105004766A (en) * | 2015-07-07 | 2015-10-28 | 中冶建筑研究总院有限公司 | Method for monitoring fatigue crack of surface of engineering structure |
| CN105352800B (en) * | 2015-11-13 | 2018-01-02 | 武汉钢铁有限公司 | Steel box-girder fatigue crack growth rate method of testing |
| CN105352800A (en) * | 2015-11-13 | 2016-02-24 | 武汉钢铁(集团)公司 | Fatigue crack propagation rate testing method of steel box girder |
| CN105548281A (en) * | 2016-01-12 | 2016-05-04 | 中国地质大学（武汉） | Nondestructive testing system and method based on skin effect resistance excess noise |
| CN106053213A (en) * | 2016-08-02 | 2016-10-26 | 上海交通大学 | Manual loading device for in-situ tensile test by industrial CT (computed tomography) |
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