CN108801820A - A kind of speed micro round-robin method of detection superplastic metal optimal strain rate - Google Patents
A kind of speed micro round-robin method of detection superplastic metal optimal strain rate Download PDFInfo
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- CN108801820A CN108801820A CN201810789148.6A CN201810789148A CN108801820A CN 108801820 A CN108801820 A CN 108801820A CN 201810789148 A CN201810789148 A CN 201810789148A CN 108801820 A CN108801820 A CN 108801820A
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- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N3/00—Investigating strength properties of solid materials by application of mechanical stress
- G01N3/32—Investigating strength properties of solid materials by application of mechanical stress by applying repeated or pulsating forces
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N2203/00—Investigating strength properties of solid materials by application of mechanical stress
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- G01N2203/0005—Repeated or cyclic
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N2203/00—Investigating strength properties of solid materials by application of mechanical stress
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Abstract
The invention belongs to metallicity detection technique fields, disclose a kind of speed micro round-robin method of detection superplastic metal optimal strain rate, setting initial velocity V0, time interval Δ t and speed Tiny increment dt Δ V；With initial velocity V0Tension test is carried out, record experimental data V is just detected every Δ ti、Pi, after having speedup twice, calculating speed sensitivity indicesCyclic tension, according toVariation tendency adjusts speedup direction, until sample is broken, detection sample deformation amount and deformation total time.The present invention need to only do primary experiment at a set temperature, then calculate the optimal strain rate being obtained under set temperature by formulaMultiple strain rates are conventionally designed, general to set 7, then efficiency of the invention can be improved 7 times；The present invention can greatly reduce test number (TN), achieve the purpose that it is energy-efficient, while experimental result have higher accuracy.
Description
Technical field
The invention belongs to metallicity detection technique field more particularly to a kind of detection superplastic metal optimal strain rates
Speed micro round-robin method.
Background technology
Currently, the prior art commonly used in the trade is such：
Superplasticity is metal material in specified conditions (strain rateDeformation temperature, material microcrystalline structure) it lower is presented
Abnormal high plasticity.Using superplasticity can with form metal complex component, therefore, Superplastic Forming be a kind of extraordinary plasticity at
Shape technique has a very important role in manufacturing fields such as aerospace military projects.In order to formulate rational SPF Technology
Parameter, it is necessary to detection or the above-mentioned three kinds of deformation conditions for obtaining metal material, wherein optimal strain rateDetection particularly
It is important.Conventional experiment detection method needs to do a large amount of constant strain rate stretching experiment, time-consuming and laborious.
Conventional experiment detection method is at a set temperature, within the scope of certain strain rate, to be answered according to certain
Multiple strain rates (generally requiring 7, number is more, and precision is higher) are designed, then according to these judgement of speed change in variable Rate interval
Rate does constant strain rate stretching experiment, and then according to analysis of experimental results, selection obtains that maximum strain rate of elongation percentage
As optimal strain rate under this set temperature.Certainly, this set temperature is not necessarily best deformation temperature, to obtain most
Good deformation temperature does the experiment of N groups it is necessary to set N number of temperature.This test experience method is time-consuming and laborious, and error is larger.
In conclusion problem of the existing technology is：
Conventional superplastic metal experiment detection needs to do a large amount of constant strain rate stretching experiment, time-consuming and laborious, error
It is larger.This is because in conventional superplasticity plan design, it is necessary first to set a strain rate model by rule of thumb
It encloses, then within the scope of this strain rate, is tested according to certain multiple strain rates of line space design.If detection
It is a kind of novel metal material, due to inexperienced, this conceptual design just inevitably carries blindness, to experiment
As a result it is possible that it is undesirable.At this moment it just needs to reset multiple strain rates.It can be seen that such experiment is fairly time consuming laborious
's.On the other hand, even if Comparison of experiment results is ideal, since the strain rate spacing point of setting is just fallen in optimal strain rate
It is a small probability event on point, therefore acquisition that maximum strain rate of elongation percentage is selected inevitably as optimal strain rate
There is larger error.
Solve the difficulty and meaning of above-mentioned technical problem：In order to reduce the error that routine experiment method is brought, just have to
New strain rate testing site is supplemented near the left and right of that maximum strain rate point of above-mentioned acquisition elongation percentage, is brought in this way
The problem of be that entire experiment is more time-consuming and laborious.It is the key that difficult in Study of Superplasticity for how improving conventional efficient and data precision
Topic is difficult to obtain the breach solved a problem according to traditional research method.The present invention looks for another way, from superplasticity to the speed of material
Sensibility is started with, it is proposed that speed micro round-robin method, in superplastic deformation process, and dynamic detection speed sensitivity exponent m i,
Set about with tracking the most sensitive speed of speed, and the data by once testing substitute into the theoretical formula independently created
Calculate, find the optimal strain rate of superplastic deformation.This method is not only novel but also efficient, is the superplasticity of metal material
Research opens a brand-new approach.
Invention content
In view of the problems of the existing technology, the present invention provides a kind of speed of detection superplastic metal optimal strain rate
Spend fine motion round-robin method.
Foremost mechanics of superplasticity flow equation is Backofen formula, is shown below：
In formula, σ is flow stress,For strain rate, K is material constant, and m is strain rate sensitivity exponent.Super modeling
Property deformation it is extremely sensitive to strain rate, so, m values are to weigh a superplastic extremely important parameter, it reflects material
Expect the anti-constriction ability in draw-texture process, it is considered that m values are bigger, and superplasticity is better.Therefore, corresponding with maximum m values
Be exactly optimal strain rate, if with this optimal strain rate carry out superplastic deformation can obtain best superplasticity.
Generally using velocity jump method, specific practice is for the detection of m values：First with a certain constant speed V1It stretches, works as stretching
To when the deformation for testing setting, a velocity jump is given, at this point, speed is by original V1Rise to V2(usual V2/V1=2~3),
Cause to deform pulling force increase, tensile load is by P1It jumps to P2.The expression formula that m values can be obtained by formula (1) is：
σ in formula1、σ2With2 points of flow stress and strain rate respectively before and after velocity jump.
The m values detected with velocity jump method are relatively rough, its only first shallow analyses to material superplasticity parameter.Its
Problem has two：First, low precision, corresponding strain rate is indefinite；Second is that this method may not apply to During Superplastic Deformation
Control.
The present invention proposes original speed micro round-robin method to detect m values, and the increasing regulated the speed according to m values tendency
Subtract, corresponding strain rate when to approach m value maximums.Since entire During Superplastic Deformation levels off to best judgement of speed change
Rate, therefore optimum hyper-plastic can be obtained.Two important parameters can be obtained after experiment：Overall strain ε (elongation percentage δ) and change
Shape total time t.
Now we assume that：If with optimal strain rateCarry out superplastic tension experiment, then it should be with above-mentioned
Speed micro, which recycles, completes overall strain ε superplastic deformation total time t.In other words, the superplastic ability of the two is equivalent, such
Strain rate is exactly optimal strain rate.
The invention is realized in this way a kind of speed micro round-robin method of detection superplastic metal optimal strain rate includes
Following steps：
First, an initial velocity V is set0, and set the time interval Δ t and a speed Tiny increment dt of a very little
ΔV；
Then, with this initial velocity V0Tension test is carried out, one group of experimental data V of record is just detected every a Δ ti,
Pi(the speed V in time i and load p), then give speed ViOne speed increment Δ V (here it is " fine motions "), increases twice having
After speed, it is calculated by the following formula a speed sensitive sex index
mVi=lg (Pi/Pi-1)/lg(Vi/Vi-1)
Compare currentWith it is previousIfThen Δ V=Δs V (pressing equidirectional speedup)；Such as
FruitThen Δ V=- Δs V (pressing negative direction speedup)；Move in circles stretching, formed tensile speed " fine motion follows
Ring " so that entire stretching experiment process is in maximum speed sensitiveness, to ensure that whole experiment process is in best super
Mecystasis, tension test are broken up to sample, detection sample deformation amount ε and deformation total time t.
Since above-mentioned entire speed micro cyclic process is in optimum hyper-plastic state, if there are one comparable judgement of speed change
Rate interior at the same time can complete same superplastic deformation amount, and the comparable strain rate is to be detected most
Good strain rate
Optimal strain rate formula proving is as follows：In constant strain rate drawing process, tensile speed VtWith stretching
Length can be expressed as：
The elongation Δ L of sample is the function about time t：
The total length of t time samples：
Formula both sides can obtain the derivation of time t：
The differential equation is solved, brings initial value L intot=L0, can acquire style length at any time with the relationship of strain rate：
It can acquire
Arrangement can obtain
In formula：ε is engineering strain of having no progeny；Δ L is sample elongation (mm)；T is stretching time (s)；L0For original sample
Length (mm)；vtFor tensile speed (mm/s)；v0For starting velocity (mm/s)；For optimal strain rate (s-1)；
Engineering strain (ε) and stretching time (t) can be tested from fine motion cyclic tension to be obtained.
Another object of the present invention is to provide a kind of speed micros for realizing detection superplastic metal optimal strain rate
The computer program of round-robin method.
Another object of the present invention is to provide a kind of information data processing terminals equipped with the computer program.
Another object of the present invention is to provide a kind of computer readable storage mediums, including instruction, when it is in computer
When upper operation so that computer executes the speed micro round-robin method of the detection superplastic metal optimal strain rate.
In conclusion advantages of the present invention and good effect are：The present invention is using speed micro round-robin method substitution routine
Then constant strain rate stretching experiment is obtained with by need to only do primary experiment at a set temperature by formula calculating
Optimal strain rate under set temperatureMultiple strain rates are conventionally designed, generally setting 7, then this hair
Bright efficiency can be improved 7 times.Therefore, the present invention can greatly reduce test number (TN), achieve the purpose that energy-efficient, test simultaneously
As a result there is higher accuracy.
Description of the drawings
Fig. 1 is the speed micro round-robin method flow of detection superplastic metal optimal strain rate provided in an embodiment of the present invention
Figure.
Specific implementation mode
In order to make the purpose , technical scheme and advantage of the present invention be clearer, with reference to embodiments, to the present invention
It is further elaborated.It should be appreciated that the specific embodiments described herein are merely illustrative of the present invention, it is not used to
Limit the present invention.
As shown in Figure 1, the speed micro cycle of detection superplastic metal optimal strain rate provided in an embodiment of the present invention
Method includes the following steps：
S101：Set an initial velocity V0, and set the time interval Δ t and a speed Tiny increment dt of a very little
ΔV；
S102：With initial velocity V0Tension test is carried out, record experimental data V is just detected every a Δ ti、Pi；
S103：Give speed ViOne speed increment Δ V is calculated by the following formula a speed after having speedup twice
Sensitivity indices：mVi=lg (Pi/Pi-1)/lg(Vi/Vi-1)；
S104：Compare currentWith it is previousIfThen Δ V=Δs V presses equidirectional increasing
Speed；IfThen Δ V=- Δs V presses negative direction speedup；
S105：Move in circles stretching, until sample is broken, detection sample deformation amount and deformation total time.
Optimal strain rate formula proving is as follows：
In constant strain rate drawing process, tensile speed VtIt can be expressed as with tensile elongation：
The elongation Δ L of sample is the function about time t：
The total length of t time samples：
Formula both sides can obtain the derivation of time t：
The differential equation is solved, brings initial value L intot=L0, can acquire style length at any time with the relationship of strain rate：
It can acquire
Arrangement can obtain：
In formula：ε is engineering strain of having no progeny；Δ L is sample elongation (mm)；T is stretching time (s)；L0For original sample
Length (mm)；vtFor tensile speed (mm/s)；v0For starting velocity (mm/s)；For optimal strain rate (s-1)；
Computer-controlled program is worked out on material electronics cupping machine, respectively with common aeronautical material TC4 and TC6
For titanium alloy, experimental verification is carried out, as shown in Tables 1 and 2 experimental data：
1 TC4 titanium alloy test results of table
2 TC6 titanium alloy test results of table
Test result shows：Optimal strain rate obtained by calculation has better superplasticity, and this method is not only
It is accurate and efficient.
The foregoing is merely illustrative of the preferred embodiments of the present invention, is not intended to limit the invention, all essences in the present invention
Any modification made by within refreshing and principle, equivalent replacement and improvement etc., should all be included in the protection scope of the present invention.
Claims (5)
1. a kind of speed micro round-robin method of detection superplastic metal optimal strain rate, which is characterized in that the detection metal
The speed micro round-robin method of superplasticity optimal strain rate includes the following steps：
First, an initial velocity V is set0, and set the time interval Δ t and a speed Tiny increment dt Δ V of a very little；
Then, with initial velocity V0Tension test is carried out, record experimental data V is just detected every a Δ ti、Pi。Vi、PiRespectively
It indicates the speed V and load p in time i, then gives speed ViOne speed increment Δ V, after having speedup twice, by following
Formula calculates a speed sensitive sex index
Compare currentWith it is previousIfThen Δ V=Δs V presses equidirectional speedup；IfThen Δ V=- Δs V presses negative direction speedup；
Move in circles stretching, formed tensile speed fine motion cycle, tension test until sample break, detection sample deformation amount and
Deform total time.
2. the speed micro round-robin method of detection superplastic metal optimal strain rate as described in claim 1, which is characterized in that most
Good strain rate calculation formula is as follows：
In formula：ε is engineering strain of having no progeny；T is stretching time (s)；For optimal strain rate (s-1)。
3. a kind of realizing the speed micro cycle for detecting superplastic metal optimal strain rate described in claim 1-2 any one
The computer program of method.
4. a kind of information data processing terminal equipped with computer program described in claim 3.
5. a kind of computer readable storage medium, including instruction, when run on a computer so that computer is executed as weighed
Profit requires the speed micro round-robin method of the detection superplastic metal optimal strain rate described in 1-2 any one.
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN113176140A (en) * | 2020-01-24 | 2021-07-27 | 株式会社岛津制作所 | Material testing machine and control method of material testing machine |
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| CN102566425A (en) * | 2011-12-26 | 2012-07-11 | 南昌航空大学 | Isothermal superplastic forming method for constructing titanium alloy with optimal deformation rate |
| CN102626735A (en) * | 2012-03-15 | 2012-08-08 | 南昌航空大学 | Method for controlling superplasticity bulging air pressure loading based on largest m value method |
| CN103091177A (en) * | 2013-01-15 | 2013-05-08 | 南昌航空大学 | Drawing method of relationship of strain rate sensitivity index m value and ductility delta |
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2018
- 2018-07-18 CN CN201810789148.6A patent/CN108801820A/en active Pending
Patent Citations (4)
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|---|---|---|---|---|
| CN102297806A (en) * | 2011-05-26 | 2011-12-28 | 南昌航空大学 | Method for constructing superplastic constitutive relation by adoption of strain rate cycling tensile test |
| CN102566425A (en) * | 2011-12-26 | 2012-07-11 | 南昌航空大学 | Isothermal superplastic forming method for constructing titanium alloy with optimal deformation rate |
| CN102626735A (en) * | 2012-03-15 | 2012-08-08 | 南昌航空大学 | Method for controlling superplasticity bulging air pressure loading based on largest m value method |
| CN103091177A (en) * | 2013-01-15 | 2013-05-08 | 南昌航空大学 | Drawing method of relationship of strain rate sensitivity index m value and ductility delta |
Non-Patent Citations (1)
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| 仲威铭: "TC6钛合金基于最大m值的超塑性等温锻工艺优化研究", 《中国优秀硕士学位论文全文数据库 工程科技II辑》 * |
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| CN113176140A (en) * | 2020-01-24 | 2021-07-27 | 株式会社岛津制作所 | Material testing machine and control method of material testing machine |
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