CN1182390C - Detection method for movable flaw produced by stress or fatigue - Google Patents
Detection method for movable flaw produced by stress or fatigue Download PDFInfo
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- CN1182390C CN1182390C CNB031006116A CN03100611A CN1182390C CN 1182390 C CN1182390 C CN 1182390C CN B031006116 A CNB031006116 A CN B031006116A CN 03100611 A CN03100611 A CN 03100611A CN 1182390 C CN1182390 C CN 1182390C
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Abstract
The present invention relates to a method for detecting movement deficiency caused by stress work or fatigue, which belongs to the technical field of electromagnetic lossless detection. The method provided by the present invention comprises the following procedures: a material having the same material quality, the same thermal processing state and the same thickness with a member detected is adopted and is made into a test sample of movement deficiency. Work stress or fatigue is applied to the test sample to make the test sample generate the deficiency in accordance with a prescriptive scale in a fault detection normative requirement. A magnetic sensor is used to detect the magnetic field intensity in a defect area on the test sample by a fixed extractive value. An average value of an absolute value of the magnetic field intensity in each sampling point in a detection length is used as a threshold value. The magnetic sensor is used to detect the magnetic field intensity in each point at the same extractive value height of the surface of the member detected, and the magnetic field intensity is compared with the detection threshold value. When the magnetic field intensity value exceeds the detection threshold value, the position is determined to have movement deficiency. The present invention dispenses with additional excitation, can directly detect the movement deficiency on the surface of workpieces, avoids the problem that the traditional detection methods can not distinguish the natures of deficiency, and especially avoids misdeclaration.
Description
Technical field
The detection method of a kind of stress or the tired mobile defect that causes belongs to the electromagnetic nondestructive testing field, relates in particular to stress or tired mobile defect detection technique field of causing.
Background technology
Mobile defect is meant the defective that in use produces and will continue expansion, comprises stress or the tired crackle that causes, plastic yield, corrosion etc.For at labour ferrimagnet member,, and finally cause the member fracture failure because stress and the tired mobile defect that causes in use often continue expansion easily.Therefore, press for and seek a kind of mobile defect detection method that can find that reasons such as stress and fatigue cause with distortion of field.
Conventional detection method, as Ultrasonic Detection, ray detection etc., can detect the defective such as crackle, burn into wearing and tearing of member, whether but all existing these conventional sense technology all can't be distinguished detected defective is mobile defect, and these methods tend to defective is treated as in the out-of-flatness of component surface, produce wrong report.
Patent retrieval finds that application number is 93112349.6, and publication number is CN1076783A, and open day is Chinese invention patent-detection method of surface crack for smooth cylinder parts of 1993.09.29, and this invention relates to the detection method of smooth cylindrical part surface blind crack.It utilizes the light principle of reflection, adopt the surface of light sheets and collimating point light source irradiation cylindrical part respectively according to the bright and clean degree of piece surface, part rotates along with self and its surface is scanned one time, as judging that piece surface has flawless foundation, photoreceptor array and respective electronic equipment produce the automatic rapid screening of relevant detection signal and control detection equipment realization part with light distribution situation in the clear zone of reflecting back formation.This invention is had relatively high expectations to workpiece surface finish, and can not determine the character of surface crack.
Summary of the invention
The present invention will solve in the existing detection method, can't detect stress or the tired mobile defect that causes and maybe can't distinguish the problem whether detected defective is dangerous mobile defect.
Ferrimagnet can germinate defect areas such as crackle, plastic yield under stress or fatigue effect, magnetic characteristic can obviously change, and has influence on the magnetic domain orientation of ferrimagnet inside, shows as the surperficial stray field that produces of ferrimagnet stress and tired defect area.The mobile defect detection method that the present invention proposes just can be found stress or tired defective by detecting this stray field.
The invention discloses the detection method of a kind of stress or the tired mobile defect that causes, it is characterized in that this method comprises the steps:
1) employing is identical with detected ferromagnetic component material, condition of heat treatment is identical and the thickness identical materials is made the mobile defect sample, gives sample stress application or the tired defective that makes its generation meet identification dimensions in the flaw detection code requirement;
2) detect the magnetic field intensity of defect area on the described sample with Magnetic Sensor with fixing lift-off value, the scanning direction is the direction of vertical defective;
To the crack defect on the sample, the scanning scope is inspection center with the crack defect, and scanning length is the twice of described lift-off value;
To the plastic yield defective on the sample, the scanning scope is an inspection center with the plastic yield defective, and scanning length is the twice of plastic yield section length sum on described lift-off value and the scanning direction;
The magnetic field intensity signal that Magnetic Sensor records by amplification, filtering, A/D conversion and computer sampling after, on display device, show the signal waveform that each sampled point field strength values of recording forms;
3) with the magnetic field intensity average absolute of each sampled point on the described scanning length as detection threshold;
4) detect the magnetic field intensity of each point on the identical lift-off value height of tested component surface with the used Magnetic Sensor of above-mentioned steps, the magnetic field intensity signal that records by amplification, filtering, A/D conversion and computer sampling after, on display device, show the signal waveform that each sampled point field strength values of recording forms;
5) with the 4th) field strength values of each sampled point of getting of pacing is with the 3rd) detection threshold determined of step compares, and when field strength values surpasses described detection threshold, just thinks the mobile defect of this place existence.
In said method, the span of described lift-off value is greater than 0mm and smaller or equal to 100mm.
The Magnetic Sensor that uses in said method is differential Magnetic Sensor or non-differential Magnetic Sensor.
The present invention need not to add any excitation, directly the stray field feature on measuring workpieces surface finds that workpiece is had dangerous stress or tired defective, avoided traditional detection method can't distinguish the problem of defect property, particularly avoided the irregular wrong report of component surface.Simultaneously, this method also is accurately to detect the new developing direction of stress or the tired mobile defect that produces.
Description of drawings
Fig. 1 is a detection method principle schematic of the present invention.
Fig. 2 is a kind of differential Magnetic Sensor synoptic diagram in the embodiment of the invention pick-up unit.
Fig. 3 is the hardware block diagram of a kind of pick-up unit of realizing that the inventive method can be used.
Fig. 4 is the mobile defect assay maps of the tested member of embodiment 1.
Fig. 5 is the magnetic field intensity signal oscillogram at the sample crack defect place of embodiment 1, and detecting lift-off value in the embodiment is 5mm.
Fig. 6 is the magnetic field intensity signal oscillogram at crack defect place on the tested member of embodiment 1, and detecting lift-off value in the embodiment is 5mm.
Fig. 7 is the magnetic field intensity signal oscillogram at the sample crack defect place of embodiment 1, and detecting lift-off value in the embodiment is 10mm.
Fig. 8 is the magnetic field intensity signal oscillogram at crack defect place on the tested member of embodiment 1, and detecting lift-off value in the embodiment is 10mm.
Fig. 9 is the magnetic field intensity signal oscillogram of the sample plastic yield fault location of embodiment 1, and detecting lift-off value in the embodiment is 5mm.
Figure 10 is the magnetic field intensity signal oscillogram of plastic yield fault location on the tested member of embodiment 1, and detecting lift-off value in the embodiment is 5mm.
Figure 11 is the mobile defect assay maps of the tested member of embodiment 2.
Figure 12 is the magnetic field intensity signal oscillogram at the sample crack defect place of embodiment 2, and detecting lift-off value in the embodiment is 5mm.
Figure 13 is the magnetic field intensity signal oscillogram at crack defect place on the tested member of embodiment 2, and detecting lift-off value in the embodiment is 5mm.
Embodiment
Describe content of the present invention in detail below in conjunction with drawings and Examples.
Fig. 1 is a detection method principle schematic of the present invention, and detected member 1 is a ferromagnetic component, and stress or the tired defective 3 that causes are arranged on detected member 1, and Magnetic Sensor is to detect on the magnetic field intensity detection faces 2 of h in lift-off value.Described lift-off value is meant the distance between Magnetic Sensor and the detected component surface, and the span of lift-off value is greater than 0mm and smaller or equal to 100mm.
Fig. 2 is a differential Magnetic Sensor synoptic diagram used in the embodiment of the invention; in differential Magnetic Sensor; the 7 parallel placements of two magnetic-sensitive elements; and sensitive direction is with identical apart from sensor bottom surface lift-off value; differential Magnetic Sensor survey magnetosensitive sense normal plane 5 is the detection faces in the sensor use; differential Magnetic Sensor outer package 6 is in order to protect Magnetic Sensor to avoid wearing and tearing, and plays the shell that the nonferromugnetic material of part electromagnetic shielding action is made.
Fig. 3 is the hardware block diagram of a kind of pick-up unit of realizing that the inventive method can be used, by magnetic-sensitive elements 7, amplifying circuit 8, differential amplifier circuit 9, comb filtering and A/D change-over circuit 10, single-chip microcomputer 11, magnetic resistance put/reset circuit 12, EPROM13, SRAM14 and liquid crystal display 15 form.Reach single-chip microcomputer 11 behind two magnetic-sensitive elements 7 measure in the differential Magnetic Sensor magnetic field intensity signal process amplifying circuit 8, differential amplifier circuit 9, filtering and the A/D change-over circuit 10, and be presented on the liquid crystal display.EPROM13 stores Single Chip Microcomputer (SCM) program, and SRAM14 storage detects data, and the Single-chip Controlling magnetic resistance puts/and reset circuit 12 sends to magnetic-sensitive elements 7 and puts/reset signal.
At first determine material, condition of heat treatment and the thickness situation of detected ferromagnetic component, and according to above-mentioned situation adopt identical with detected ferromagnetic component material, condition of heat treatment is identical, the thickness identical materials is made the mobile defect sample.
Shown in Figure 4 is the mobile defect assay maps of detected ferromagnetic component, and sample adopts 45# steel hot-pressed board according to detected member, through mill, line is cut into elongate in shape, sample thickness is 10mm, specimen surface roughness is 6.3.Clamping sample two ends on the stretching experiment machine apply tensile load and measure existing crackle until one of sample elliptical aperture major axis, and the width of crackle is 0.1mm, and length is 5mm, and the degree of depth is 0.5mm.Sample is taken off horizontal positioned, then the field strength values that has crackle one to survey with 5mm lift-off value test samples surface elliptical aperture with ear Magnetic Sensor suddenly.
Guarantee fixing lift-off value, a lot of schemes are arranged in engineering.Present embodiment is by on the little inspection vehicle that Magnetic Sensor is installed in belt wheel, and the Magnetic Sensor sensitive area is apart from inspection vehicle wheel bottom surface 5mm, and makes wheel contact detected all the time in testing process to guarantee the constant of lift-off value.The survey magnetosensitive sense direction of Magnetic Sensor is the specimen surface normal direction, and the scanning direction is a vertical crack defective direction, and the scanning scope is for being inspection center with the crack defect, and scanning length is 10mm.
The output signal of Magnetic Sensor is transferred to computing machine behind amplifier AD627, filtering and A/D converter CS5509, draw detection signal waveform and calculated threshold on graphoscope, and testing result as shown in Figure 5.As calculated, the magnetic field intensity average absolute of each sampled point on the scanning length is 0.88Gauss, so detection threshold is made as 0.88Gauss.
Detect the magnetic field intensity signal of each point on the 5mm lift-off value height of tested component surface with the used Magnetic Sensor of above-mentioned steps, described magnetic field intensity signal by amplification, filtering, A/D conversion and computer sampling after, the signal waveform that on display device, shows each the sampled point field strength values formation that records, as shown in Figure 6.
The field strength values of each measured sampled point is compared with described detection threshold 0.88Gauss, when field strength values surpasses described detection threshold, just think the crack defect that this place exists stress to cause.Testing result is represented, has crack defect on the tested member in the present embodiment, and the crackle on the described tested member is greater than the crack defect on the sample.
When detecting the mobile defect sample of tested member, be 10mm if select to detect lift-off value with Magnetic Sensor, the magnetic field intensity signal waveform of the sample that obtains after then handling by above-mentioned instrument as shown in Figure 7, this moment, detection threshold was 1Gauss.
In like manner, when detecting tested member with same Magnetic Sensor, detecting lift-off value still is 10mm, and the magnetic field intensity signal waveform of the sample that obtains after handling by above-mentioned instrument as shown in Figure 8.The field strength values of each measured sampled point is compared with described detection threshold 1Gauss, when field strength values surpasses described detection threshold, just think the crack defect that this place exists stress to cause.Certainly, after detecting lift-off value and changing 10mm into, coming to the same thing when detecting the result of tested member and lift-off value and being 5mm.
In embodiment 1, usefulness ear Magnetic Sensor suddenly detects the field strength values that specimen surface elliptical aperture shown in Figure 4 has plastic yield one to survey, plastic yield head of district 5mm on the sample, and it is the specimen surface normal direction that Magnetic Sensor is surveyed magnetosensitive sense direction.When detecting lift-off value is 5mm,, the scanning scope is an inspection center with the plastic yield defective, scanning length is 20mm.
The output signal of Magnetic Sensor is transferred to computing machine behind amplifier AD627, filtering and A/D converter CS5509, draw detection signal waveform and calculated threshold on graphoscope, and testing result as shown in Figure 9.As calculated, the magnetic field intensity average absolute of each sampled point on the scanning length is 0.84Gauss, so detection threshold is made as 0.84Gauss.
In like manner, when detecting tested member with same Magnetic Sensor, detecting lift-off value still is 5mm, and the magnetic field intensity signal waveform of the sample that obtains after handling by above-mentioned instrument as shown in figure 10.The field strength values of each measured sampled point is compared with described detection threshold 0.84Gauss, when field strength values surpasses described detection threshold, just think the plastic yield defective that this place exists stress to cause.Testing result is represented, has the plastically deforming area on the detected member of present embodiment, and the plastically deforming area on the described tested member is greater than the plastically deforming area on the sample.
At first determine material, condition of heat treatment and the thickness situation of detected ferromagnetic component, and according to above-mentioned situation adopt identical with detected ferromagnetic component material, condition of heat treatment is identical, the thickness identical materials is made the mobile defect sample.
Figure 11 is the mobile defect assay maps of another tested ferromagnetic component, and sample material is the 16MnR low-alloy high-strength steel, and sample is to prick steel plate welding fabrication after clod wash by heat.Sample has produced circumferential fatigue crack under the alternate loading, crackle width 0.05mm, length 5mm, degree of depth 0.5mm.Use the differential Magnetic Sensor of ear suddenly with 5mm lift-off value test samples Surface field value then.
It is the specimen surface normal direction that the differential Magnetic Sensor of ear is suddenly surveyed magnetosensitive sense direction, and the scanning direction is the direction of vertical crack, and the scanning scope is inspection center with the crackle, and scanning length is 10mm.
The output signal of the differential Magnetic Sensor of ear suddenly is transferred to computing machine behind amplifier AD627, filtering and A/D converter CS5509, draw detection signal waveform and calculated threshold on graphoscope, and testing result as shown in figure 12.As calculated, the magnetic field intensity average absolute of each sampled point on the scanning length is 0.3Gauss, so detection threshold is made as 0.3Gauss.
Detect the magnetic field intensity signal of each point on the 5mm lift-off value height of tested component surface with the used differential Magnetic Sensor of ear suddenly of above-mentioned steps, described magnetic field intensity signal by amplification, filtering, A/D conversion and computer sampling after, the signal waveform that on display device, shows each the sampled point field strength values formation that records, as shown in figure 13.
The field strength values of each measured sampled point is compared with described detection threshold 0.3Gauss, when field strength values surpasses described detection threshold, just think that there is the tired crack defect that causes in this place.Testing result is represented, has crack defect on the tested member in the present embodiment, and the crackle on the described tested member is greater than the crack defect on the sample.
The present invention need not tested component surface is done any pre-service in testing process, and detection speed is fast.When the detection lift-off value further reduces, flaw detection sensitivity will further improve.To the member that was polluted by magnetic flaw detection, can adopt the inventive method to detect equally, at this moment should select for use differential Magnetic Sensor to remove ground unrest effectively, find the mobile defect that stress and fatigue etc. cause.
Claims (3)
1. the detection method of stress or the tired mobile defect that causes is characterized in that this method comprises the steps:
1) employing is identical with detected ferromagnetic component material, condition of heat treatment is identical and the thickness identical materials is made the mobile defect sample, gives sample stress application or the tired defective that makes its generation meet identification dimensions in the flaw detection code requirement;
2) detect the magnetic field intensity of defect area on the described sample with Magnetic Sensor with fixing lift-off value, the scanning direction is the direction of vertical defective;
To the crack defect on the sample, the scanning scope is inspection center with the crack defect, and scanning length is the twice of described lift-off value;
To the plastic yield defective on the sample, the scanning scope is an inspection center with the plastic yield defective, and scanning length is the twice of plastic yield section length sum on described lift-off value and the scanning direction;
The magnetic field intensity signal that Magnetic Sensor records by amplification, filtering, A/D conversion and computer sampling after, on display device, show the signal waveform that each sampled point field strength values of recording forms;
3) with the magnetic field intensity average absolute of each sampled point on the described scanning length as detection threshold;
4) detect the magnetic field intensity of each point on the identical lift-off value height of tested component surface with the used Magnetic Sensor of above-mentioned steps, the magnetic field intensity signal that records by amplification, filtering, A/D conversion and computer sampling after, on display device, show the signal waveform that each sampled point field strength values of recording forms;
5) with the 4th) field strength values of each sampled point of getting of pacing is with the 3rd) detection threshold determined of step compares, and when field strength values surpasses described detection threshold, just thinks the mobile defect of this place existence.
2. mobile defect detection method according to claim 1 is characterized in that: the span of described lift-off value is greater than 0mm and smaller or equal to 100mm.
3. mobile defect detection method according to claim 1 and 2 is characterized in that: the Magnetic Sensor that uses in the described method is differential Magnetic Sensor or non-differential Magnetic Sensor.
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| US7572360B2 (en) * | 2005-09-30 | 2009-08-11 | Fatigue Solutions Corp. | Electrochemical fatigue sensor systems and methods |
| CN100414292C (en) * | 2005-10-10 | 2008-08-27 | 中国石油天然气集团公司 | Metal magnetic memory detecting method of ferromagnetic material crack |
| CN100385235C (en) * | 2005-12-06 | 2008-04-30 | 天津大学 | Method of determining pipeline welding crack stress concentration using metal magnetic memory detection technology |
| CN100454018C (en) * | 2006-05-18 | 2009-01-21 | 沈睿 | Continuous non-destructive detection method for thermal treatment quality of long metal bar and device therefor |
| CN100489445C (en) * | 2007-11-20 | 2009-05-20 | 中国航空动力机械研究所 | Decelerator strain detection testing device and data processing method thereof |
| CN105760623A (en) * | 2016-03-16 | 2016-07-13 | 中国直升机设计研究所 | Method for determining allowable defects of helicopter composite main rotor blade |
| CN106198368B (en) * | 2016-06-30 | 2018-09-21 | 重庆交通大学 | Inside concrete steel bar corrosion method for detecting position |
| KR102457527B1 (en) * | 2018-01-25 | 2022-10-21 | 한화정밀기계 주식회사 | Method for coating state check of flux |
| CN109470574A (en) * | 2018-12-18 | 2019-03-15 | 江西众安职业危害评价检测有限公司 | Strength test equipment |
| CN111189906B (en) * | 2020-01-09 | 2023-09-29 | 中国石油大学(华东) | On-line intelligent judging and classifying identification method for alternating current magnetic field defects |
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