CN106370719B - A kind of magnetic NDT method method of ferromagnetic metallic material strain hardening exponent - Google Patents
A kind of magnetic NDT method method of ferromagnetic metallic material strain hardening exponent Download PDFInfo
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- CN106370719B CN106370719B CN201610680951.7A CN201610680951A CN106370719B CN 106370719 B CN106370719 B CN 106370719B CN 201610680951 A CN201610680951 A CN 201610680951A CN 106370719 B CN106370719 B CN 106370719B
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- G—PHYSICS
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- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N27/00—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means
- G01N27/72—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating magnetic variables
- G01N27/80—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating magnetic variables for investigating mechanical hardness, e.g. by investigating saturation or remanence of ferromagnetic material
Abstract
The present invention relates to a kind of magnetic NDT method methods of ferromagnetic metallic material strain hardening exponent, it is the following steps are included: (a) is tested and recorded the strain hardening exponent and magnetic hardness coefficient of ferromagnetic metallic material sample original state；(b) strain hardening exponent and magnetic hardness coefficient of the ferromagnetic metallic material sample under the conditions of different cold deformation drafts are measured and recorded；(c) it is ordinate using the magnetic hardness coefficient of the ferromagnetic metallic material sample as abscissa, strain hardening exponent, establishes model using linear fit；(d) the magnetic hardness coefficient a for testing and recording ferromagnetic metallic material sample to be measured, is substituted into the model of step (c), is calculated to correspond to the strain hardening exponent of sample under the conditions of cold deformation, is determined its strain hardening behavior.It may be implemented to be quickly obtained subsequent sample strain-hardening property in lossless mode, save tensile sample processing and tension test process, it can not only improve efficiency, and cost can be reduced, while solve the problems, such as that tension test can not be carried out under the conditions of material shortage.
Description
Technical field
The invention belongs to field of metal material detection, are related to a kind of magnetic NDT method method, and in particular to a kind of ferromagnetic
The magnetic NDT method method of metal material strain hardening exponent.
Background technique
Strain hardening exponent n reflects the ability that metal material resists uniform plastic deformation, is characterization metal material strain
The performance indicator of Temperature measurement, the n value of most metals material is between 0.1 ~ 0.5.Strain hardening exponent n has significant work
Cheng Yiyi, the n value such as metal material is larger, then the parts being processed into bear the ability accidentally overloaded when being on active service with regard to bigger,
The certain weak parts of parts can be prevented to continue to be plastically deformed, to guarantee that parts are on active service safely.Meanwhile strain hardening exponent n
Plate cold deformation technique is had a major impact；N big material, strain hardening effect is high, and uniformly, reduction is thinning and increases pole for deformation
Deformation extent is limited, crackle is not likely to produce.N value is also significant to strain hardening effect.The big person of n value, strain hardening effect is just
Very prominent, if 18-8 stainless steel n value is high, intensity is R before deformingp0.2=196MPa, Rm=588MPa；After 40% rolling, Rp0.2=
784 ~ 980MPa improves 3 ~ 4 times, Rm=1174MPa improves 1 times.
However, being had no at present directly and efficiently method for the measurement of n value.The method generallyd use is first to carry out simply
Tension test obtain stress-strain diagram, then to curve data carry out handle and n value is obtained by data the Fitting Calculation.Base
In this, to obtain metal material n value, each sample surveyed under normal condition must first be processed into tensile sample and be stretched
Test is fitted again after obtaining stress-strain diagram.The process is related to the development of processing and the tension test of tensile sample, step
Rapid relatively more, consuming time is long, and the larger required materials of tensile sample are more, and tension test belongs to destructive testing again, in material
The occasion of anxiety relatively is unfavorable for the development of test job.
Summary of the invention
A kind of ferromagnetic metallic material strain hardening exponent is provided the invention aims to overcome the deficiencies in the prior art
Magnetic NDT method method.
In order to achieve the above objectives, the technical scheme adopted by the invention is as follows: a kind of ferromagnetic metallic material strain hardening exponent
Magnetic NDT method method, it the following steps are included:
(a) test and record the strain hardening exponent and magnetic hardness coefficient of ferromagnetic metallic material sample original state；
(b) strain hardening exponent of the ferromagnetic metallic material sample under the conditions of different cold deformation drafts is measured and recorded
And magnetic hardness coefficient；
It (c) is ordinate using the magnetic hardness coefficient of the ferromagnetic metallic material sample as abscissa, strain hardening exponent, benefit
Model is established with linear fit；
(d) the magnetic hardness coefficient a for testing and recording ferromagnetic metallic material sample to be measured, is substituted into the described of step (c)
In model, calculates to correspond to the strain hardening exponent of sample under the conditions of cold deformation, determine its strain hardening behavior.
Optimally, in step (a) and step (b), the measuring method of the strain hardening exponent the following steps are included:
(x1) tension test is carried out to the ferromagnetic metallic material sample and obtains stress-strain diagram, it is corresponding to obtain multiple groups
Trus stress σ and true strain ε；
(x2) the corresponding trus stress σ and true strain ε is substituted into and carries out linear fit in formula (1), slope is required
Strain hardening exponent value；
Lg σ=LgK+nLg ε (1).
Further, in step (a), step (b) and step (d), the measuring method of the magnetic hardness coefficient includes following
Step:
(y1) magnetism testing is carried out to the ferromagnetic metallic material sample and obtains magnetization curve, obtain the corresponding magnetic of multiple groups
Change intensity M and magnetic field strength H；
(y2) the corresponding magnetization M and magnetic field strength H are substituted into formula (2) and draws M ~ 1/H linear segment
Acquire magnetic hardness coefficient a；
(2)；
In formula, Ms is the saturation magnetization of ferromagnetic metallic material, and unit A/m, b are the magnetocrystalline anisotropy with material
Related parameter；The magnetic field strength H > 104A/m。
Due to the above technical solutions, the present invention has the following advantages over the prior art: feeromagnetic metal of the present invention
The magnetic NDT method method of material strain hardenability value, by the original state and different cold deformations of testing ferromagnetic metallic material
Strain hardening exponent and magnetic hardness coefficient under the conditions of drafts establish model, then the subsequent magnetic hardness coefficient measured is substituted into i.e.
Can, it may be implemented to be quickly obtained subsequent sample strain-hardening property in lossless mode, save tensile sample processing and stretch
Test process can not only improve efficiency, and can reduce cost, at the same solve material shortage under the conditions of can not be stretched
The problem of test.
Detailed description of the invention
Fig. 1 is lg σ ~ lg ε matched curve under ferromagnetic metallic material sample original state of the present invention；
Fig. 2 is lg σ ~ lg ε matched curve that ferromagnetic metallic material sample of the present invention is 20% in cold deformation drafts；
Fig. 3 is lg σ ~ lg ε matched curve that ferromagnetic metallic material sample of the present invention is 30% in cold deformation drafts；
Fig. 4 is lg σ ~ lg ε matched curve that ferromagnetic metallic material sample of the present invention is 40% in cold deformation drafts；
Fig. 5 is lg σ ~ lg ε matched curve that ferromagnetic metallic material sample of the present invention is 50% in cold deformation drafts；
Fig. 6 is ferromagnetic metallic material sample difference drafts sample M ~ 1/H matched curve of the present invention；
Fig. 7 is n ~ a matched curve of ferromagnetic metallic material sample of the present invention.
Specific embodiment
The preferred embodiment of the invention is described in detail below in conjunction with attached drawing.
The magnetic NDT method of ferromagnetic metallic material (domestic RPV steel is chosen in the present embodiment) strain hardening exponent of the present invention
Method, it the following steps are included:
(a) it tests and records answering for ferromagnetic metallic material sample original state (state when i.e. cold deformation drafts is 0%)
Become hardenability value n0With magnetic hardness coefficient a0:
Specifically: (x1) carries out tension test to the ferromagnetic metallic material sample of original state and obtains engineering stress strain song
Line obtains the corresponding trus stress σ of multiple groups according to stress-strain diagram0, true strain ε0And corresponding trus stress really strains song
Line；Trus stress really strains and the conversion relation of engineering stress strain are as follows: σ0 =σi(1+ εi), ε0=ln(1+ εi)；
(x2) by the corresponding trus stress σ of multiple groups0With true strain ε0(uniform plastic i.e. on selection true stress-strain curve becomes
Shape segment data) formula (1) (formula 1 is derived by by Ludwik-Hollomon equation) middle progress linear fit is substituted into, slope is
Required strain hardening exponent value；
Lg σ=LgK+nLg ε (1)；In formula, K is the strength factor of material；
In the present embodiment, as shown in Figure 1, final formula (1) is Lg σ=2.975+0.1876Lg ε, n=0.1876.
The measuring method of magnetic hardness coefficient the following steps are included:
(y1) magnetism testing is carried out to the ferromagnetic metallic material sample of original state and obtains magnetization curve, obtain multiple groups pair
The magnetization M answered0With magnetic field strength H0；
(y2) by the corresponding magnetization M of multiple groups0With magnetic field strength H0M ~ 1/H line is drawn and (fitted) in substitution formula (2)
Sexual intercourse part can acquire magnetic hardness coefficient a；
(2)；
In formula, Ms is the saturation magnetization of ferromagnetic metallic material, and unit A/m, b are the magnetocrystalline anisotropy with material
Related parameter；The magnetic field strength H > 104A/m, as magnetic field strength H > 104When A/m, a/H aft section parameters are to M's
Influencing very little can ignore；In the present embodiment, the curve of fitting is as shown in Figure 6；
Formula (2) is from formula (3) simplification:
(3)；
In formula,χ p For the magnetic susceptibility of paramagnetic magnetic history, and paramagnetic item is only just showed when external magnetic field strength is very strong
Out, therefore the paramagnetic magnetic history of normal condition can ignore magnetized contribution.
(b) measuring and recording different cold deformation drafts conditions, (i.e. cold deformation drafts is respectively 20%, 30%, 40% and
50%) strain hardening exponent and magnetic hardness coefficient of the ferromagnetic metallic material sample under；In specific test method and step (a)
Consistent, magnetic hardness coefficient a matched curve such as Fig. 2 to Fig. 5 institute when cold deformation drafts is respectively 20%, 30%, 40% and 50%
Show；
It (c) is ordinate using the magnetic hardness coefficient of the ferromagnetic metallic material sample as abscissa, strain hardening exponent, benefit
Model is established with linear fit；Resulting n and a data are fitted by step (a) and step (b), and are vertical by abscissa, n of a
Coordinate carries out linear fit, establishes n ~ a model, as shown in fig. 7, the relational expression in present case between n and a is n=1.381-
0.0011a；
(d) test and record the specific test method of magnetic hardness coefficient a(and step (a) of ferromagnetic metallic material sample to be measured
In it is consistent, calculate 10% drafts RPV sample a=1102), substituted into the model of step (c), calculate pair
Strain hardening exponent n=1.381-0.0011 × 1102=0.16 for answering sample under the conditions of cold deformation, determines its strain hardening behavior.
The above embodiments merely illustrate the technical concept and features of the present invention, and its object is to allow person skilled in the art
Scholar cans understand the content of the present invention and implement it accordingly, and it is not intended to limit the scope of the present invention.It is all according to the present invention
Equivalent change or modification made by Spirit Essence, should be covered by the protection scope of the present invention.
Claims (3)
1. a kind of magnetic NDT method method of ferromagnetic metallic material strain hardening exponent, which is characterized in that it includes following step
It is rapid:
(a) test and record the strain hardening exponent and magnetic hardness coefficient of ferromagnetic metallic material sample original state；
(b) strain hardening exponent and magnetic of the ferromagnetic metallic material sample under the conditions of different cold deformation drafts are measured and recorded
Hardness factor；
(c) it is ordinate using the magnetic hardness coefficient of the ferromagnetic metallic material sample as abscissa, strain hardening exponent, utilizes line
Property fitting establish model；
(d) the magnetic hardness coefficient a for testing and recording ferromagnetic metallic material sample to be measured, is substituted into the model of step (c)
In, it calculates to correspond to the strain hardening exponent of sample under the conditions of cold deformation, determines its strain hardening behavior.
2. the magnetic NDT method method of ferromagnetic metallic material strain hardening exponent according to claim 1, feature exist
In, step (a) and step (b), the measuring method of the strain hardening exponent the following steps are included:
(x1) tension test is carried out to the ferromagnetic metallic material sample and obtains stress-strain diagram, obtain that multiple groups are corresponding really to answer
Power σ and true strain ε；
(x2) the corresponding trus stress σ and true strain ε is substituted into and carries out linear fit in formula (1), slope is required answers
Being hardened index value；
Lg σ=LgK+nLg ε (1).
3. the magnetic NDT method method of ferromagnetic metallic material strain hardening exponent according to claim 1 or 2, feature
Be, in step (a), step (b) and step (d), the measuring method of the magnetic hardness coefficient the following steps are included:
(y1) magnetism testing is carried out to the ferromagnetic metallic material sample and obtains magnetization curve, it is strong to obtain the corresponding magnetization of multiple groups
Spend M and magnetic field strength H；
(y2) the corresponding magnetization M and magnetic field strength H are substituted into formula (2) and draws M ~ 1/H linear segment, can acquired
Magnetic hardness coefficient a；
(2)；
In formula, Ms is the saturation magnetization of ferromagnetic metallic material, and unit A/m, b are related with the magnetocrystalline anisotropy of material
Parameter；The magnetic field strength H > 104A/m。
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| CN102507326A (en) * | 2011-12-02 | 2012-06-20 | 西安石油大学 | Method for quickly determining metal material strain hardening index |
| CN104584147A (en) * | 2012-07-10 | 2015-04-29 | 罗伯特·博世有限公司 | Magnetic material, use thereof and method for the production thereof |
| CN105032926A (en) * | 2015-08-17 | 2015-11-11 | 江苏大学 | Method for rolling metal wire bars under magnetostatic field auxiliary effect |
| CN105259060A (en) * | 2015-10-26 | 2016-01-20 | 攀钢集团攀枝花钢铁研究院有限公司 | Detection method for strain hardening index n value of metal material |
| CN105466998A (en) * | 2015-12-31 | 2016-04-06 | 爱德森（厦门）电子有限公司 | Method for utilizing variable-frequency variable-magnetic field excitation to test hardness property of ferromagnetic material |
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2016
- 2016-08-18 CN CN201610680951.7A patent/CN106370719B/en active Active
Patent Citations (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4481470A (en) * | 1981-07-29 | 1984-11-06 | The United States Of America As Represented By The United States Department Of Energy | Method for determining the hardness of strain hardening articles of tungsten-nickel-iron alloy |
| JPH05142203A (en) * | 1991-04-30 | 1993-06-08 | Toshiba Corp | Method for diagnosing environmental stress cracking of high-strength material |
| CN101393167A (en) * | 2008-10-21 | 2009-03-25 | 中国航空工业第一集团公司北京航空材料研究院 | Low-cycle fatigue damage quantitatively characterizing method based on metal magnetic memory detection technology |
| CN102507326A (en) * | 2011-12-02 | 2012-06-20 | 西安石油大学 | Method for quickly determining metal material strain hardening index |
| CN104584147A (en) * | 2012-07-10 | 2015-04-29 | 罗伯特·博世有限公司 | Magnetic material, use thereof and method for the production thereof |
| CN105032926A (en) * | 2015-08-17 | 2015-11-11 | 江苏大学 | Method for rolling metal wire bars under magnetostatic field auxiliary effect |
| CN105259060A (en) * | 2015-10-26 | 2016-01-20 | 攀钢集团攀枝花钢铁研究院有限公司 | Detection method for strain hardening index n value of metal material |
| CN105466998A (en) * | 2015-12-31 | 2016-04-06 | 爱德森（厦门）电子有限公司 | Method for utilizing variable-frequency variable-magnetic field excitation to test hardness property of ferromagnetic material |
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