CN113295327B - Zero-stress sample for ultrasonic stress measurement method and preparation method thereof - Google Patents
Zero-stress sample for ultrasonic stress measurement method and preparation method thereof Download PDFInfo
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- CN113295327B CN113295327B CN202010108643.3A CN202010108643A CN113295327B CN 113295327 B CN113295327 B CN 113295327B CN 202010108643 A CN202010108643 A CN 202010108643A CN 113295327 B CN113295327 B CN 113295327B
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- 238000002360 preparation method Methods 0.000 title abstract description 20
- 238000000691 measurement method Methods 0.000 title description 9
- 238000005520 cutting process Methods 0.000 claims abstract description 65
- 238000000034 method Methods 0.000 claims abstract description 50
- 238000005259 measurement Methods 0.000 claims abstract description 44
- 238000001514 detection method Methods 0.000 claims abstract description 43
- 238000000137 annealing Methods 0.000 claims abstract description 23
- 238000012360 testing method Methods 0.000 claims abstract description 18
- 239000013072 incoming material Substances 0.000 claims abstract description 14
- 239000000463 material Substances 0.000 claims description 71
- 238000005096 rolling process Methods 0.000 claims description 48
- 238000012545 processing Methods 0.000 claims description 11
- 238000005516 engineering process Methods 0.000 claims description 4
- 229910000831 Steel Inorganic materials 0.000 abstract description 10
- 239000010959 steel Substances 0.000 abstract description 10
- 238000007789 sealing Methods 0.000 abstract description 3
- 238000002372 labelling Methods 0.000 abstract 1
- 238000010438 heat treatment Methods 0.000 description 9
- 238000005070 sampling Methods 0.000 description 5
- 238000004321 preservation Methods 0.000 description 4
- 238000001816 cooling Methods 0.000 description 3
- 239000002994 raw material Substances 0.000 description 3
- 230000007547 defect Effects 0.000 description 2
- 238000003754 machining Methods 0.000 description 2
- 238000004519 manufacturing process Methods 0.000 description 2
- 238000005464 sample preparation method Methods 0.000 description 2
- 238000002441 X-ray diffraction Methods 0.000 description 1
- 239000010953 base metal Substances 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 238000011161 development Methods 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 238000009826 distribution Methods 0.000 description 1
- 230000008030 elimination Effects 0.000 description 1
- 238000003379 elimination reaction Methods 0.000 description 1
- 230000002349 favourable effect Effects 0.000 description 1
- 230000017525 heat dissipation Effects 0.000 description 1
- 230000014759 maintenance of location Effects 0.000 description 1
- 239000002184 metal Substances 0.000 description 1
- 239000003208 petroleum Substances 0.000 description 1
- 238000004080 punching Methods 0.000 description 1
- 238000009763 wire-cut EDM Methods 0.000 description 1
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01L—MEASURING FORCE, STRESS, TORQUE, WORK, MECHANICAL POWER, MECHANICAL EFFICIENCY, OR FLUID PRESSURE
- G01L25/00—Testing or calibrating of apparatus for measuring force, torque, work, mechanical power, or mechanical efficiency
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N1/00—Sampling; Preparing specimens for investigation
- G01N1/28—Preparing specimens for investigation including physical details of (bio-)chemical methods covered elsewhere, e.g. G01N33/50, C12Q
- G01N1/286—Preparing specimens for investigation including physical details of (bio-)chemical methods covered elsewhere, e.g. G01N33/50, C12Q involving mechanical work, e.g. chopping, disintegrating, compacting, homogenising
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N29/00—Investigating or analysing materials by the use of ultrasonic, sonic or infrasonic waves; Visualisation of the interior of objects by transmitting ultrasonic or sonic waves through the object
- G01N29/22—Details, e.g. general constructional or apparatus details
- G01N29/30—Arrangements for calibrating or comparing, e.g. with standard objects
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N1/00—Sampling; Preparing specimens for investigation
- G01N1/28—Preparing specimens for investigation including physical details of (bio-)chemical methods covered elsewhere, e.g. G01N33/50, C12Q
- G01N1/286—Preparing specimens for investigation including physical details of (bio-)chemical methods covered elsewhere, e.g. G01N33/50, C12Q involving mechanical work, e.g. chopping, disintegrating, compacting, homogenising
- G01N2001/2873—Cutting or cleaving
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N1/00—Sampling; Preparing specimens for investigation
- G01N1/28—Preparing specimens for investigation including physical details of (bio-)chemical methods covered elsewhere, e.g. G01N33/50, C12Q
- G01N2001/2893—Preparing calibration standards
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N2291/00—Indexing codes associated with group G01N29/00
- G01N2291/02—Indexing codes associated with the analysed material
- G01N2291/028—Material parameters
- G01N2291/02827—Elastic parameters, strength or force
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- Biochemistry (AREA)
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- Investigating Strength Of Materials By Application Of Mechanical Stress (AREA)
Abstract
The invention discloses a zero-stress sample for ultrasonic stress measurement and a preparation method thereof, and the method mainly comprises the following steps: (1) selecting and preparing a zero-stress sample calibrated incoming material; (2) sample preparation and labeling; (3) first zero stress detection; (4) determining a zero stress sample stress relief annealing process; (5) sample stress relief annealing treatment; (6) second zero stress detection; (7) wire cutting to further relieve stress; (8) third zero stress detection; and (9) cross sample sealing. The invention provides a new technical means for preparing and calibrating the zero-stress test sample, can solve the difficult problem that the ultrasonic-method stress measurement high-accuracy zero-stress test sample is difficult to process and evaluate due to uneven residual stress level of the in-service steel pipe and plate, can provide the ultrasonic-method stress measurement of the high-steel grade pipeline steel with the zero-stress test sample represented in a higher accuracy and larger range, and has important significance for standardizing the preparation of the ultrasonic zero-stress test sample and improving the residual stress test precision of the pipeline steel.
Description
Technical Field
The invention relates to the technical field of residual stress measurement, in particular to a zero-stress sample for an ultrasonic stress measurement method and a preparation method thereof.
Background
The residual stress is one of main factors for controlling the quality of the pipe, is one of factors causing the expansion and failure of the defects of the in-service pipeline, is one of important parameters for evaluating the applicability of the defects, and has important significance for nondestructive measurement of the residual stress in the structure of the in-service pipeline and the plate. The method for measuring the residual stress is many, but the currently applied method has great limitation, such as the small hole method is accurate but damages the workpiece, and the measuring depth of the X-ray diffraction method is too low. The traditional residual stress measurement method is difficult to meet the requirement of stress measurement in the service state of the pipeline and the plate, and the ultrasonic method based on the acoustic elastic principle can be used for nondestructively detecting the stress in the pipeline, so that the nondestructive property and the portability determine that the method is one of the most promising technologies for measuring the residual stress and the working stress of the in-service pipeline.
Before each measurement of the ultrasonic method, an absolute zero stress sample must be calibrated, and the proximity of the zero stress sample to the absolute zero is one of the main factors affecting the stress accuracy of the ultrasonic method measurement. The existing ultrasonic stress measurement zero-stress test sample generally adopts an annealing process, however, for pipeline steel with relatively large wall thickness (such as wall thickness of more than 10 mm) or a plate with relatively thick wall thickness (such as thickness of more than 10 mm), even if a strict annealing process is adopted, temperature field difference caused by uneven thickness heat dissipation cannot be avoided in a cooling stage, so that new residual stress is brought, and absolute zero of zero stress is difficult to achieve; the existing zero-stress sample processing and manufacturing has no strict process flow, the original parent metal is sampled randomly, the non-batch sampling processing is carried out, and the representativeness of different factories, thicknesses and areas is poor; the stress release degree of the existing zero-stress sample by annealing is not enough. Therefore, the development of a novel zero-stress sample has important significance for the ultrasonic stress measurement and calibration on the in-service pipeline and plate integrity management.
Disclosure of Invention
The invention aims to provide a zero-stress sample for an ultrasonic stress measurement method and a preparation method thereof, and aims to solve the problem that the ultrasonic stress measurement high-accuracy zero-stress sample is difficult to process and evaluate due to uneven residual stress level of a steel pipe, provide a zero-stress sample with higher precision and larger range representation for ultrasonic stress measurement, and have important significance for standardizing ultrasonic zero-stress sample preparation and improving residual stress test precision.
In order to achieve the above purpose, the following technical scheme is adopted:
a preparation method of a zero-stress sample for ultrasonic stress measurement comprises the following steps:
step 1, selecting incoming materials of a zero-stress sample;
Step 2, cutting a stock line into a plurality of samples, and performing wire cutting on the incoming material along a parallel material rolling direction and a perpendicular material rolling direction during wire cutting, wherein the wire cutting is performed to obtain cuboid samples;
Step 3, selecting a plurality of samples obtained in the step 2 to carry out zero stress detection, and detecting the stress in the parallel material rolling direction and the perpendicular material rolling direction on the samples when the samples are subjected to zero stress detection, wherein if the absolute value of the stress measured value of the detected samples is not greater than a first preset value, the samples obtained in the step 2 are taken as zero stress samples; if the absolute value of the stress measured value of the detected sample is larger than a first preset value, performing step 4, and voiding the sample after zero stress detection;
Step 4, carrying out stress relief annealing on the residual sample obtained in the step 2;
step 5, carrying out zero stress detection on the sample obtained in the step 4, and taking the sample obtained in the step 4 as a zero stress sample if the absolute value of the stress measurement value of the detected sample is not larger than a first preset value; if the absolute value of the stress measured value of the detected sample is larger than the first preset value and not larger than the second preset value, the sample after zero stress detection is invalidated, and then step 4 is carried out; if the absolute value of the stress measurement value of the detected sample is larger than a second preset value, the sample after zero stress detection is invalidated, and then the step 6 is carried out;
Step 6, performing linear cutting on the sample obtained in the step 4, releasing stress, and performing linear cutting on the incoming material along the parallel material rolling direction and the perpendicular material rolling direction when performing linear cutting, wherein the length ratio of the cut sample in the parallel material rolling direction and the perpendicular material rolling direction is (1:1) - (1:3), or the length ratio of the cut sample in the perpendicular material rolling direction and the parallel material rolling direction is (1:1) - (1:3); the length of the sample in the parallel material rolling direction and the perpendicular material rolling direction is not more than 1/6 of the height of the sample;
and 7, taking the sample subjected to the wire cutting stress release in the step 6 as a zero-stress sample.
In the step 1, when the incoming material of the zero-stress sample is selected, the material which has the same processing technology process as the material used by the residual stress and stress test object is selected.
And cutting the selected material by adopting linear cutting, flame or plasma cutting, and cutting the heat affected zone of the material by adopting linear cutting after the cutting is completed when the flame or plasma cutting is adopted.
In the step 3, when the sample is subjected to zero stress detection, a small hole method is adopted to carry out stress measurement, a plurality of detection points are measured, and an average value of stress of each detection point is taken as a stress measurement value.
In step 5, when the sample is subjected to zero stress detection, a small hole method is adopted to carry out stress measurement, a plurality of detection points are measured, and an average value of stress of each detection point is taken as a stress measurement value.
The first preset value is 12Mpa, and the second preset value is 30Mpa.
A zero stress sample is prepared by the preparation method of the invention.
The shape of the zero-stress sample is cuboid.
When the shape of the zero-stress sample is cuboid, the length direction of the zero-stress sample is parallel to the rolling direction of the material, the width direction of the zero-stress sample is perpendicular to the rolling direction of the material, and the height direction of the zero-stress sample is the thickness direction of the material.
The invention has the following beneficial effects:
The zero stress sample preparation method for the ultrasonic stress measurement method provides a new technical means for preparing the zero stress sample, the stress sample which is closer to zero can be obtained through comprehensively eliminating stress annealing, wire cutting stress release and calibration performed during zero stress detection, and the stress value of the sample can be quantified through the calibration performed during zero stress detection, so that the precision of ultrasonic stress detection is improved, the applicability of ultrasonic stress detection is improved, technical support is provided for in-service pipeline stress detection, and the method has important significance for standardizing ultrasonic zero stress sample preparation and improving the residual stress test precision of in-service pipeline steel and plates. In the invention, when the stress is released by wire cutting, the incoming material is wire-cut along the parallel material rolling direction and the perpendicular material rolling direction, a cuboid sample is wire-cut, the length ratio of the cut sample in the parallel material rolling direction and the perpendicular material rolling direction is (1:1) - (1:3), or the length ratio of the cut sample in the perpendicular material rolling direction and the parallel material rolling direction is (1:1) - (1:3); the length of the sample in the parallel material rolling direction and the perpendicular material rolling direction is not more than 1/6 of the height of the sample; according to the cutting direction and the cutting into the cuboid sample, the stress of the sample in all directions can be effectively released, the shrinkage stress caused by uneven heat distribution due to the anisotropy of the material can be eliminated, and meanwhile, the stress release of the sample is thorough, so that the sample has stable performance, can be stored for a long time and is favorable for measurement. In conclusion, by the method for preparing the zero-stress sample, the zero-stress sample with lower residual stress can be obtained, and more accurate results can be obtained by an ultrasonic stress measurement method.
The zero-stress sample has low residual stress, and the ultrasonic stress test precision can be improved by taking the sample as a standard sample.
Drawings
FIG. 1 is a process diagram of a zero stress specimen processing technique according to the present invention;
FIG. 2 (a) is a left side view showing a structure of a wire cut into a plurality of test pieces according to an embodiment of the present invention;
FIG. 2 (b) is a front view of the wire cut into a plurality of test pieces according to the embodiment of the present invention;
FIG. 2 (c) is a top view of the wire cut electrical discharge machining of multiple samples according to the embodiment of the present invention;
FIG. 2 (d) is a left side view of the sample wire cut into a plurality of samples according to the embodiment of the present invention;
fig. 2 (e) is a plan view of a sample wire cut into a plurality of samples according to an embodiment of the present invention.
Detailed Description
The following detailed description of the invention is provided in connection with the accompanying drawings that are presented to illustrate the invention and not to limit the scope thereof. The invention will be described in detail below with reference to the attached drawings:
The invention is mainly applied to zero stress calibration before stress measurement by an ultrasonic method, and performs calibration work before stress measurement is performed on different materials with different structures, so as to facilitate accurate stress measurement.
As shown in FIG. 1, the preparation method of the zero-stress sample for the ultrasonic stress measurement method provided by the invention obtains the zero-stress sample by the process method of comprehensive annealing, linear cutting and multiple small hole detection and calibration, and provides guarantee for engineering measurement precision of residual stress of the ultrasonic method, and the preparation method specifically comprises the following steps:
step 1: incoming material selection and preparation of zero-stress sample calibration
Specifically, when the incoming material for zero stress sample calibration is selected, selecting materials which have the same processing technology process as the materials used by the residual stress and stress test objects; when cutting, a wire cutting process is adopted to cut from a rolled plate and a base metal, if a processing mode of flame, plasma cutting and the like bringing heat influence is adopted, the heat-affected zone is removed by adopting 2 times of wire cutting on a sample which is cut off by heat;
Step 2: sample preparation and marking
As shown in fig. 2 (a) to 2 (e), in particular, the sample cutting requirement of the sample cannot bring additional heat input, so that batch sampling is performed from the incoming materials on the rolled plate and the base material by adopting a linear cutting process, and when the sample is taken, a cuboid sample is cut by linear cutting along a direction perpendicular to the rolling direction of the material and parallel to the rolling direction of the material, wherein the length direction of the sample is parallel to the rolling direction of the material, the width direction is perpendicular to the rolling direction of the material, and the height direction is the thickness direction of the material;
Step 3: first time zero stress detection
Drawing two samples in the step 2, wherein one of the two samples measures stress in the length direction and the other one of the two samples measures stress in the width direction, stress measurement is carried out by adopting a small hole method during measurement, three points are measured by each sample, an average value is taken, the stress measurement value is sigma 1, and the punched and measured samples are invalidated; detecting the absolute value of the calibrated stress according to a small hole method, determining whether the sample can be used as a zero stress sample according to a zero judging condition, if sigma 1 is not more than 12Mpa, taking the sample obtained in the step 2 as the zero stress sample, otherwise, carrying out the step 4;
step 4: annealing process for determining zero stress sample stress relief
According to the heat treatment temperature of different materials, the annealing temperature, the heating rate, the heating speed, the heat preservation time and the cooling speed of each steel material are determined by considering the phase change curve; the heat treatment furnace ensures uniform furnace temperature and can also anneal under vacuum condition;
step 5: stress relief annealing of samples
Stress relief annealing treatment is carried out on samples in the same batch according to the annealing process in the step 4;
step 6: second time zero stress detection
Extracting two samples in the samples obtained in the step 5, wherein one of the samples measures the stress in the length direction and the other of the samples measures the stress in the width direction, the stress is detected by adopting a small hole method, three points are measured, an average value is taken, the measured value of the marked stress is sigma 2, if the absolute value of sigma 2 is reduced by not more than 12MPa, the samples obtained in the step 5 are taken as zero-stress samples, the step 9 is carried out, if the absolute value of sigma 2 is more than 30MPa, the stress elimination annealing treatment is carried out again according to the step 5, if the absolute value of sigma 2 is not more than 30MPa and more than 12MPa, the step 7 is carried out, and the samples after punching measurement are wasted;
Step 7: wire cutting to further relieve stress
The cutting process requires that no additional heat input can be brought, so that the stress of the rest samples is further released by adopting linear cutting, and the samples are cut into cuboid shapes by linear cutting along the direction perpendicular to the rolling direction of the materials and the direction parallel to the rolling direction of the materials; generally, the sample is longer than it is wide, the width is greater than the thickness, the thickness is minimal, the ratio of width to length is (1:1) - (1:3), and the minimal cut size (i.e., width) is generally recommended to be 4mm;
Step 8: third time zero stress detection
Extracting two samples subjected to the wire cutting stress release in the step 7, wherein one of the samples is used for measuring the stress in the length direction, the other is used for measuring the stress in the width direction, a small hole method is adopted for stress detection during measurement, three points are measured, an average value is taken, a stress measurement value is marked as sigma 3, and the punched and measured sample is invalidated;
step 9: and (3) sealing the other samples to obtain a zero-stress sample, wherein the zero-stress sample is not less than 2, 1 is used for field measurement, and 1 is used for preservation.
Examples
The zero stress sample preparation method for the ultrasonic stress measurement method comprises the following steps:
step 1: incoming material selection and preparation of zero-stress sample calibration
Aiming at the residual stress measurement requirement of a certain X80 high-steel pipeline structure (wall thickness 21.5 mm) of a certain station of a long-distance oil and gas pipeline of a certain petroleum company, the original record information of purchase, production and the like is consulted, and an X80 high-steel pipeline material with the same supplier and the same pipe machining process as the material for a tested object is selected as a zero-stress sample machining sampling material.
The raw material for preparing the sample is obtained by cutting the X80 base material by adopting a linear cutting process, and a processing sampling mode of heat influence caused by flame, plasma cutting and the like is avoided as much as possible.
If the X80 base material is sampled by adopting a processing mode with heat influence caused by flame, plasma cutting and the like, the heat influence area of four sides of the heat cutting sample is required to be removed by adopting a linear cutting process again, and the cutting position of each single side of the four sides is required to be more than 100mm away from the edge of the material by adopting the linear cutting process so as to eliminate the influence of heat cutting caused by flame and the like.
Step 2: sample preparation and marking
And (3) performing sample preparation on the raw materials obtained by wire cutting in the step (1) by adopting a wire cutting process, and performing wire cutting along the direction perpendicular to the rolling direction and parallel to the rolling direction during sample preparation to cut a cuboid sample, wherein the length direction of the sample is parallel to the rolling direction of the material, the width direction of the sample is perpendicular to the rolling direction of the material, the height direction is the thickness direction of the material, a batch of samples which are not lower than 8 are generally taken, 4 samples are used for measuring residual stress parallel to the rolling direction, and 4 samples are used for measuring residual stress perpendicular to the rolling direction.
Step 3: first time zero stress detection
And 2, extracting two samples in the samples obtained in the step 2, wherein one of the samples is used for measuring the stress in the length direction, the other is used for measuring the stress in the width direction, a small hole method is adopted for measuring the stress, each sample is used for measuring three points, an average value is obtained, and the stress measurement value is sigma 1. The punched and measured sample is discarded.
If the absolute value of sigma 1 is smaller than 12MPa, the sample can be regarded as a zero-stress sample, and the subsequent process steps are avoided.
Step 4: annealing process for determining zero stress sample stress relief
According to the heat treatment temperature of the material, the annealing temperature, the heating rate, the heating speed, the heat preservation time and the cooling speed are determined by considering the phase change curve.
In the embodiment, the annealing temperature of the sample is 480 ℃, the heat preservation time is not less than 2 hours, and the sample is sampled after being cooled to room temperature along with the furnace.
The heat treatment furnace requires uniform furnace temperature, and the furnace temperature keeping precision is not lower than plus or minus 10 ℃; annealing may be performed under vacuum conditions if desired.
Step 5: stress relief annealing of samples
And (4) carrying out annealing treatment on the rest samples in a heat treatment furnace according to the annealing process of the step (4).
Step 6: second time zero stress detection
And (3) extracting two samples in the samples obtained in the step (5), wherein one of the samples measures the stress in the length direction, the other one of the samples measures the stress in the width direction, a small hole method is adopted for stress detection during measurement, three points are measured, an average value is taken, the measured value of the marked stress is sigma 2, if the absolute value of sigma 2 is reduced to be not more than 12MPa, the samples obtained in the step (5) are taken as zero-stress samples, the step (9) is carried out, if the absolute value of sigma 2 is more than 30MPa, the annealing treatment is carried out again according to the step (5), if the absolute value of sigma 2 is not more than 30MPa and is more than 12MPa, the step (7) is carried out, and the punched and measured samples are wasted.
Step 7: wire cutting to further relieve stress
And (3) further releasing stress on the residual sample after the detection by adopting linear cutting. The minimum block size of the wire cutting is 2mm for the pipeline structural material with the wall thickness of 20mm, and the reserved size of the sample in the thickness direction is not less than 3 mm.
Step 8: third time zero stress detection
And (3) extracting two samples subjected to the wire cutting stress release in the step (7), wherein one of the samples is used for measuring the stress in the length direction, the other is used for measuring the stress in the width direction, a small hole method is adopted for stress detection during measurement, three points are measured, an average value is taken, the stress measurement value is marked as sigma 3, and the punched and measured samples are discarded. The absolute value of sigma 3 is less than 12MPa.
Step 9: sealing and storing the mixed sample
The residual zero stress test sample is not less than 2 blocks, 1 block is used for field measurement, and 1 block is used for retention.
And meanwhile, numbering the zero samples, recording the processing technological process, including raw material furnace batch number information, a processing sampling cutting method, sigma 1、σ2、σ3, a small hole method for calibrating the strain gauge model, parameters and the like, and checking the strain gauge model and parameters after preparation.
Claims (5)
1. A method for preparing a zero-stress sample for ultrasonic stress measurement, comprising the steps of:
step 1, selecting incoming materials of a zero-stress sample;
Step 2, cutting a stock line into a plurality of samples, and performing wire cutting on the incoming material along a parallel material rolling direction and a perpendicular material rolling direction during wire cutting, wherein the wire cutting is performed to obtain cuboid samples;
Step 3, selecting a plurality of samples obtained in the step 2 to carry out zero stress detection, and detecting the stress in the parallel material rolling direction and the perpendicular material rolling direction on the samples when the samples are subjected to zero stress detection, wherein if the absolute value of the stress measured value of the detected samples is not greater than a first preset value, the samples obtained in the step 2 are taken as zero stress samples; if the absolute value of the stress measured value of the detected sample is larger than a first preset value, performing step 4, and voiding the sample after zero stress detection;
Step 4, carrying out stress relief annealing on the residual sample obtained in the step 2;
step 5, carrying out zero stress detection on the sample obtained in the step 4, and taking the sample obtained in the step 4 as a zero stress sample if the absolute value of the stress measurement value of the detected sample is not larger than a first preset value; if the absolute value of the stress measured value of the detected sample is larger than the first preset value and not larger than the second preset value, the sample after zero stress detection is invalidated, and then step 4 is carried out; if the absolute value of the stress measurement value of the detected sample is larger than a second preset value, the sample after zero stress detection is invalidated, and then the step 6 is carried out;
Step 6, performing linear cutting on the sample obtained in the step 4, releasing stress, and performing linear cutting on the incoming material along the parallel material rolling direction and the perpendicular material rolling direction when performing linear cutting, wherein the length ratio of the cut sample in the parallel material rolling direction to the perpendicular material rolling direction is (1:1) - (1:3), or the length ratio of the cut sample in the perpendicular material rolling direction to the parallel material rolling direction is (1:1) - (1:3); the length of the sample in the parallel material rolling direction and the perpendicular material rolling direction is not more than 1/6 of the height of the sample;
Step 7, taking the sample subjected to the wire cutting stress release in the step 6 as a zero stress sample;
In the step 1, when selecting the incoming material of the zero stress sample, selecting the material which has the same processing technology process as the material used by the residual stress and stress test object;
cutting the selected material, wherein wire cutting, flame or plasma cutting is adopted during cutting, and when flame or plasma cutting is adopted, the heat affected zone of the material is cut off by wire cutting after cutting is completed;
In the step 3, when the sample is subjected to zero stress detection, a small hole method is adopted to carry out stress measurement, a plurality of detection points are measured, and the average value of stress of each detection point is taken as a stress measurement value;
in step 5, when the sample is subjected to zero stress detection, a small hole method is adopted to carry out stress measurement, a plurality of detection points are measured, and an average value of stress of each detection point is taken as a stress measurement value.
2. The method of claim 1, wherein the first predetermined value is 12Mpa and the second predetermined value is 30Mpa.
3. A zero stress test specimen produced by the method of any one of claims 1-2.
4. A zero-stress specimen according to claim 3, characterized in that the zero-stress specimen is rectangular in shape.
5. The zero-stress test specimen according to claim 4, wherein the zero-stress test specimen has a length direction parallel to a material rolling direction, a width direction perpendicular to the material rolling direction, and a height direction being a thickness direction of the material.
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| CN102818763A (en) * | 2012-07-30 | 2012-12-12 | 首钢总公司 | Hot-rolled steel plate residual stress calculating method suitable to production field |
| CN104913876A (en) * | 2015-06-23 | 2015-09-16 | 南车青岛四方机车车辆股份有限公司 | Device and method for manufacturing aluminum alloy vehicle body residual stress measurement zero-stress test block based on ultrasonic method |
| JP2017032478A (en) * | 2015-08-05 | 2017-02-09 | 株式会社神戸製鋼所 | Residual stress evaluation method |
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| US2439130A (en) * | 1943-11-20 | 1948-04-06 | United Aircraft Corp | Surface and shear wave method and apparatus |
| CN102608169A (en) * | 2012-03-01 | 2012-07-25 | 首钢总公司 | Method for determining precision of blind-hole method residual stress testing system |
| CN102818763A (en) * | 2012-07-30 | 2012-12-12 | 首钢总公司 | Hot-rolled steel plate residual stress calculating method suitable to production field |
| CN104913876A (en) * | 2015-06-23 | 2015-09-16 | 南车青岛四方机车车辆股份有限公司 | Device and method for manufacturing aluminum alloy vehicle body residual stress measurement zero-stress test block based on ultrasonic method |
| JP2017032478A (en) * | 2015-08-05 | 2017-02-09 | 株式会社神戸製鋼所 | Residual stress evaluation method |
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