CN102494812A - Method for detecting permanent set stress of metal material - Google Patents
Method for detecting permanent set stress of metal material Download PDFInfo
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- CN102494812A CN102494812A CN2011104098096A CN201110409809A CN102494812A CN 102494812 A CN102494812 A CN 102494812A CN 2011104098096 A CN2011104098096 A CN 2011104098096A CN 201110409809 A CN201110409809 A CN 201110409809A CN 102494812 A CN102494812 A CN 102494812A
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Abstract
The invention provides a method for detecting the permanent set stress of a metal material, belonging to the technical field of metal material detection. The method is as follows: adopting a manual mode for a grouping test, and finding the influence law of the test result caused by the duration time, the loading and unloading circulation times, loading speed ratio, sample sizes and processing quality; finding and controlling key factors, determining the optimal test parameters, compiling test control programs, and changing the manual control into automatic program control. The program control method is adopted for detecting the permanent set stress of the metal material, the operation process is simple and standard, the errors caused by artificial operation are eliminated greatly, the test data is stable, the mechanical properties of the materials can be reflected truly, the test efficiency is improved, and the test requirement of the scientific research and the production can be met.
Description
Technical field
The invention belongs to metal material detection technique field, be specifically related to a kind of method that detects the metal material predetermined residual elongating stress.
Background technology
The detection method of relevant metal material predetermined residual elongating stress in existing relevant international standard, navigation mark and every profession and trade standard, is not all clearly stipulated.And the GB/T228-2002 standard only provides a kind of example that can adopt manual control detection method in appendix Ι, and therefore illustrations more general, exist certain problem in actual detected:
At first, just mention the detection method of certain material in giving an example, improper to the detection of some material, inapplicable to the sample of different size, there is limitation during detection.Secondly, adopt manually control, has bigger personal error, sample control is lack of standardization, and the success ratio that causes testing is lower, and data are disperseed unstable, detect the cost height, and the experimental result comparability is poor.
Address the above problem; Needing the laboratory to carry out many-sided sample explores; Find out the influence rule of correlative factor to test findings, to material different specific technology parameter, the rotten control program that detects of the function that develops software; Manual control technology is improved to automatic control technology, promotes breadboard detectability.
For solving the detection difficult problem of metal material predetermined residual elongating stress, need set up a kind of new test method, fill up this aspect and detect blank, satisfy the detection demand of research and production.
Summary of the invention
To the deficiency that prior art exists, the present invention provides a kind of method that detects the metal material predetermined residual elongating stress.
With reference to the method for GB/T228-2002 standard in for example, the preparation sample is connected to sample on the testing machine, and extensometer is installed, and measures the sample deformation amount, and the inventive method is specifically carried out as follows:
Step 1: according to different materials, set initial parameter, comprise preloading F
0=R
R0.2* S
0* 10%, loading speed (mm/min), guarantor's lotus time (s), loaded cycle number of times and each circular buffering time; Apply and preload, write down the extensometer elongation automatically;
Step 2: be loaded on total elongation on the basis the 1st time preloading, the 1st total elongation=gauge length * 0.2%th lasts till guarantor lotus time of setting;
Step 3: be offloaded to original state, promptly preload state, automatically the 1st permanent elongation amount of record measured material this moment and the corresponding power that applies size stop the surge time of setting;
Step 4: i total elongation of loading force to the; I=2,3 ... N lasts till guarantor lotus time of setting; The i time total elongation=the i-1 time total elongation+(i-1 permanent elongation amount of the i-1 time total elongation-Di) writes down the i time total elongation and correspondence automatically and applies the power size;
Step 5: be offloaded to original state, write down the i time permanent elongation amount and correspondence automatically and apply the power size, stop the surge time of setting;
Step 6:, then stop if the i time permanent elongation amount surpasses regulation permanent elongation amount; Write down this permanent elongation amount and correspondence and apply the power size, and draw stress-strain curve, finish.
Adopt linear interpolation computational rules permanent elongation power value F
R0.2, try to achieve predetermined residual elongating stress R
R0.2=F
R0.2/ S, S are original cross-sectional area, and through maximum load tensile strength calculated R
m
Beneficial effect: the present invention adopts control method to detect the metal material predetermined residual elongating stress; Operating process is simple, standard; Eliminated the error that manual operation produces greatly, test figure is stable, can truly reflect the mechanical property characteristic of material; Improve test efficiency, satisfy the detection requirement of research and production.
Description of drawings
Fig. 1 national standard R7 circular specimen figure;
Fig. 2 embodiment of the invention predetermined residual elongating stress and guarantor lotus time relation curve;
The relation curve of Fig. 3 embodiment of the invention predetermined residual elongating stress and cycle index;
Fig. 4 embodiment of the invention cycle index and the relation curve of protecting the lotus time ratio;
The stress-strain curve that 1 programmed control of Fig. 5 embodiment of the invention detects;
Fig. 6 the inventive method control program process flow diagram.
Embodiment
Below in conjunction with accompanying drawing and embodiment the present invention is further specified.
Selecting titanium alloy ZTC4 bar for use is example, preparation sample, testpieces adopt with batch, with the blank of heat (batch) number, adopt machining to process R7 (φ 5mm) circular specimen of GB/T228-2002 standard code, sample is as shown in Figure 1, extensometer gage length L
0=25mm.Testing machine is selected for use on day island proper Tianjin AG-IS50KN electronic tension tester and is carried out, in test scale load measuring accuracy ± 0.5%.Adopt electronic extensometer; Model: SSG25-10; Adopting the off-load method to carry out the metal predetermined residual elongating stress detects: 1) manual mode group experiment, seek cycle index, loading speed, specimen size and the crudy of guarantor lotus time, loading and unloading the rule that influences to test findings; 2) find out key factor and control, confirm best test parameters, establishment test control program will manually be controlled and change procedure auto-control into.
Sample is connected on the testing machine, and it is the extensometer of 25mm that gauge length is installed, and measures the sample deformation amount, applies pre-load value F
0, F
0=R
R0.2* S
0* 10%, record F
0With the extensometer reading, from F
0Play to apply force to sample for the first time on the length of extensometer gage length, to produce total overhang be 0.05mm, guarantor lotus 10s-12s is offloaded to F
0, record extensometer permanent elongation amount; For the second time applying power reaches on the length of sample at extensometer gage length: the total elongation 0.05mm+ first time (0.05mm-permanent elongation for the first time amount), protect lotus 10s-12s, and be offloaded to F
0, record extensometer permanent elongation amount, by that analogy, after loading off-load several times, when the permanent elongation amount reach or during just over regulation permanent elongation amount till, at this moment, adopt interpolation method to obtain F
R0.2, try to achieve predetermined residual elongating stress R
R0.2=F
R0.2/ S.
Test findings analysis is shown; Protecting lotus time and cycle index has considerable influence to experimental result, and it is improper to select, and experimental data can occur than mistake; Directly influence the authenticity and the reliability of test findings; Adopt control variate method, divide into groups to protecting lotus time and cycle index experiment Analysis and the result being depicted as curve, like Fig. 2, shown in 3.
Can find out that by Fig. 2 and Fig. 3 cycle index and Bao He change of time consider that to result's the trend that influences both interact, with cycle index and the ratio of Bao He time, the unified action rule that characterizes both to permanent elongation stress, as shown in Figure 4.
The regulation unrelieved stress is minimum in the time of in ratio is the 0.58-0.61 scope; It is lower that plastic deformation ability is resisted in expression in this state; Predetermined residual elongating stress value in this scope is at 825MPa-836MPa; The applied stress of ZTC4 material can not be lower than estimated value, should be the permissible stress on the engineering.Therefore test parameters should be selected: cycle index is 6-7 time, and protecting the lotus time is 11-12 second, is consistent with the GB228-2002 standard.
Be used to detect the AG-IS50KN electronic tension tester of permanent elongation stress, by its operation of computer control, the subsidiary software that detects of computing machine; Stretch, compression, bending test; Automatically the acquisition test test figure is drawn trial curve, prints examining report.
Stretch function can be selected: unilateral stretching, cyclic tension and control stretching; Wherein, when unilateral stretching and cyclic tension test, do the simple parameters setting and can accomplish the detection test; And control stretching provides the platform of editor's process of the test for the operator; Testing machine manufacturer uses for the convenience of the user, adopts very simple computerese (not being the computer major language) to edit and gets final product, and adopts the mode of Chinese and English shuffling to edit trace routine exactly; Control process of the test, can be to concrete conditions such as the difference of test item, sample size, cycle index, loading sizes by operator's layout voluntarily.
The detection software that computing machine is subsidiary; Do not have alternative concrete control program, each the step action in the process of the test, purpose, demonstration, record etc. all need the own design programming of operator, and just the language of programming is comparatively simple; The platform that needs the operator to provide according to software is the editor of a whole set of test procedure; The instruction in each step is all very clear and definite, generally will edit 200～300 steps, could accomplish the detection task.Simple example: under test model, select " control test " → test type → stretching → entering test to set: to adopt Chinese and English word command mode to set: DPStart → Forcespeed 800N/min →-----Dpstop.
The establishment test procedure, technical indicator adopts the test parameters of selecting by analysis, carries out concrete steps of the present invention.
Detect the predetermined residual elongating stress (R of ZTC4 bar material
R0.2):
Sample adopts the circular proportional test bar of R7 (Φ 5mm), and selecting model for use is the deflection of the extensometer measurement sample of SSG25-10, extensometer gage length 25mm, then the permanent elongation amount 25mm * 0.2%=0.05mm of regulation.Technical standard requires Rr0.2>=820MPa, preloads F
0=R
R0.2* S
0* 10%=820 * 3.14 * (5/2)
2* 10%=1609N, round numbers 1600N.Set when cycle index reaches 6 times and suspend, manually shift out extensometer, the peak value of setting then to be not less than 21000N power (fracture of warranty test spare) is continuously applied load, until the sample coupon fracture, writes down the test figure in each stage automatically.The present invention detects the method for metal material predetermined residual elongating stress, and flow process is as shown in Figure 6, specifically carries out as follows:
Step 1: set and preload F
0=1600N, loading speed 3mm/min, guarantor lotus time 11s, loaded cycle number of times 6 times and each circular buffering time are 1s; Apply and preload the elongation 0.01719mm of record extensometer;
Step 2: be loaded on total elongation 0.123mm on the basis the 1st time preloading, keep 11s, the load 11622N of record this moment automatically,, accomplish the 1st circulation;
Step 3: be offloaded to original state, promptly preload state 1600N, write down the elongation 0.0144mm of extensometer automatically, obtain permanent elongation amount 0.0002mm, surge time is 1s;
Step 4: on the basis that preloads, be loaded on extensometer and reach 0.0147mm, record load 12197N at this moment keeps 11s automatically;
Step 5: be unloaded to and preload 1600N, write down the elongation 0.0147mm of extensometer automatically, obtain permanent elongation amount 0.0003mm, accomplish the 2nd circulation, surge time is 1s;
Step 6: repeat above-mentioned steps, record permanent elongation amount when reaching the permanent elongation amount 0.05mm of (or just over) regulation, stops CYCLIC LOADING, Bao He and uninstall process, and draws stress-strain curve, finishes.Stress-strain curve is as shown in Figure 5.
The unloading extensometer is with the speed stretching of 5mm/min, until sample fracture.Adopt interpolation method to calculate the predetermined residual elongating stress R of material
R0.2Through maximum load tensile strength calculated R
m,
Adopt linear interpolation computational rules permanent elongation power value F
R0.2, try to achieve predetermined residual elongating stress R
R0.2=F
R0.2/ S
0
R
R0.2---predetermined residual elongating stress, units MPa;
F
R0.2---regulation permanent elongation power value, the N of unit;
S
0。---the original cross-sectional area of sample, the mm of unit.
Choose two groups of data, i.e. the 5th circulation and the 6th loop-around data: permanent elongation amount 0.0417 mm counter stress value 15869N near 0.05 mm permanent elongation amount; Permanent elongation amount 0.0576 mm counter stress value 16188N tries to achieve regulation permanent elongation power F with linear interpolation
R0.2:
F
r0.2=[（0.0576-0.05）×16121+(0.05-0.0417)?×16288]/(0.0576-0.0417)=16208N
Obtain: R
R0.2=Fr0.2/S=16208/19.625=825.88MPa
Tensile strength R
m=16975/19.625=865 MPa.
Send test report, test finishes.
Detect the predetermined residual elongating stress (R of 1Cr18Ni9Ti sheet material
R0.2):
Sample adopts P4, and (the rectangle proportional test bar of specification 2mm * 20mm), selecting model for use is the deflection that the extensometer of SSG50-10 is measured sample, extensometer gage length 50mm, then the permanent elongation amount 50mm * 0.2%=0.1mm of regulation.Technical standard requires R
R0.2>=196MPa preloads F
0=R
R0.2* S
0* 10%=196 * 2 * 20 * 10%=784N, round numbers 800N.Sample coupon is connected on the testing machine through frock clamp, and extensometer is installed and zeroing.Set when cycle index reaches 6 times and suspend, manually shift out extensometer, the peak value of setting then to be not less than 3000N power (fracture of warranty test spare) is continuously applied load, until the sample coupon fracture, writes down the test figure in each stage automatically. Carry out the inventive method as follows:
Step 1: set and preload F
0=800N, loading speed 4mm/min, guarantor lotus time 11s, the loaded cycle number of times is 6 times, each circular buffering time is 1s; Apply and preload F
0=800N, the elongation 0.002mm of record extensometer;
Step 2: on the basis that preloads, be loaded on extensometer and reach 0.10mm, record load 10000N at this moment keeps 11s automatically;
Step 3: be unloaded to and preload 800N, write down the elongation 0.0023mm of extensometer automatically, obtain permanent elongation amount 0.0003mm, accomplish the 1st circulation, stop 1s;
Step 4: on the basis that preloads, be loaded on extensometer and reach 0.110mm, record load 12594N at this moment keeps 11s automatically;
Step 5: be unloaded to and preload 800N, write down the elongation 0.029mm of extensometer automatically, obtain permanent elongation amount 0.027mm, accomplish the 2nd circulation, stop 1s;
Step 6: repeat above-mentioned steps, record permanent elongation amount when reaching the permanent elongation amount 0.1mm of (or just over) regulation, stops CYCLIC LOADING, protects and carry and uninstall process; And the drafting stress-strain curve, finish.
The unloading extensometer is with the speed stretching of 10mm/min, until sample fracture.Adopt interpolation method to calculate the predetermined residual elongating stress Rr0.2 of material; Through maximum load tensile strength calculated Rm, choose two groups of data, i.e. the 5th circulation and the 6th loop-around data: permanent elongation amount 0.9987 mm correspondence load 14020N near 0.1 mm permanent elongation amount; The corresponding load 14063N of permanent elongation amount 0.118 mm, try to achieve regulation permanent elongation power Fr0.2 with linear interpolation:
F
r0.2=[（0.118-0.1）×14020+(0.1-0.097)?×14063]/(0.118-0.097)=14026N
Obtain: R
R0.2=F
R0.2R behind the/S=14026/40.6=345.47MPa revision of the convention
R0.2=345 MPa
Tensile strength R
m=24738/40.6=610 MPa.
Send test report, test finishes.
Claims (2)
1. method that detects the metal material predetermined residual elongating stress is characterized in that: specifically carry out as follows:
Step 1: according to different materials, set initial parameter, comprise preload, loading speed, guarantor lotus time, loaded cycle number of times and each circular buffering time; Apply and preload, write down the extensometer elongation automatically;
Step 2: be loaded on total elongation on the basis the 1st time preloading, the 1st total elongation=gauge length * 0.2%th lasts till guarantor lotus time of setting;
Step 3: be offloaded to original state, promptly preload state, automatically the 1st permanent elongation amount of record measured material this moment and the corresponding power that applies size stop the surge time of setting;
Step 4: i total elongation of loading force to the; I=2,3 ... N lasts till guarantor lotus time of setting; The i time total elongation=the i-1 time total elongation+(i-1 permanent elongation amount of the i-1 time total elongation-Di) writes down the i time total elongation and correspondence automatically and applies the power size;
Step 5: be offloaded to original state, write down the i time permanent elongation amount and correspondence automatically and apply the power size, stop the surge time of setting;
Step 6:, then stop if the i time permanent elongation amount surpasses regulation permanent elongation amount; Write down this permanent elongation amount and correspondence and apply the power size, and draw stress-strain curve, finish.
2. the method for detection metal material predetermined residual elongating stress according to claim 1 is characterized in that: adopt linear interpolation computational rules permanent elongation power value F
R0.2, try to achieve predetermined residual elongating stress R
R0.2=F
R0.2/ S, S are original cross-sectional area, and through maximum load tensile strength calculated R
m
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Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103884591A (en) * | 2014-03-05 | 2014-06-25 | 上海交通大学 | Monotonic loading test method for residual stress of continuous fiber reinforced metal-matrix composite |
| CN108051124A (en) * | 2017-11-29 | 2018-05-18 | 中国兵器科学研究院宁波分院 | A kind of metal material provides the test method of remaining extension stress |
| CN110763575A (en) * | 2019-11-07 | 2020-02-07 | 建龙北满特殊钢有限责任公司 | Method for rapidly detecting residual elongation strength |
| CN112763318A (en) * | 2020-12-29 | 2021-05-07 | 中国航空工业集团公司西安飞机设计研究所 | Metal material residual stress simulation test device and method |
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| CN1263258A (en) * | 1999-02-09 | 2000-08-16 | 中国科学院金属研究所 | Determination method of residual stress |
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| CN1263258A (en) * | 1999-02-09 | 2000-08-16 | 中国科学院金属研究所 | Determination method of residual stress |
| JP2004251825A (en) * | 2003-02-21 | 2004-09-09 | Shimadzu Corp | Material testing machine |
| CN101661271A (en) * | 2009-09-16 | 2010-03-03 | 天津钢管集团股份有限公司 | Method for controlling whole-course displacement in program-controlled metal material stretching test |
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Cited By (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103884591A (en) * | 2014-03-05 | 2014-06-25 | 上海交通大学 | Monotonic loading test method for residual stress of continuous fiber reinforced metal-matrix composite |
| CN103884591B (en) * | 2014-03-05 | 2016-01-13 | 上海交通大学 | Continuous filament reinforced metallic matrix composite unrelieved stress dullness loads method of testing |
| CN108051124A (en) * | 2017-11-29 | 2018-05-18 | 中国兵器科学研究院宁波分院 | A kind of metal material provides the test method of remaining extension stress |
| CN110763575A (en) * | 2019-11-07 | 2020-02-07 | 建龙北满特殊钢有限责任公司 | Method for rapidly detecting residual elongation strength |
| CN110763575B (en) * | 2019-11-07 | 2022-01-25 | 建龙北满特殊钢有限责任公司 | Method for rapidly detecting residual elongation strength |
| CN112763318A (en) * | 2020-12-29 | 2021-05-07 | 中国航空工业集团公司西安飞机设计研究所 | Metal material residual stress simulation test device and method |
| CN112763318B (en) * | 2020-12-29 | 2024-04-09 | 中国航空工业集团公司西安飞机设计研究所 | Metal material residual stress simulation test device and method |
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Application publication date: 20120613 |