CN116356234B - Vortex-based non-contact metal grain accurate regulation and control system - Google Patents
Vortex-based non-contact metal grain accurate regulation and control system Download PDFInfo
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- 229910052751 metal Inorganic materials 0.000 title claims abstract description 29
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- 230000000694 effects Effects 0.000 abstract description 7
- 230000001939 inductive effect Effects 0.000 abstract description 2
- 229910000861 Mg alloy Inorganic materials 0.000 description 33
- 238000001953 recrystallisation Methods 0.000 description 24
- 230000005012 migration Effects 0.000 description 18
- 238000013508 migration Methods 0.000 description 18
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- NEWKHUASLBMWRE-UHFFFAOYSA-N 2-methyl-6-(phenylethynyl)pyridine Chemical compound CC1=CC=CC(C#CC=2C=CC=CC=2)=N1 NEWKHUASLBMWRE-UHFFFAOYSA-N 0.000 description 1
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 1
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 description 1
- 229910017518 Cu Zn Inorganic materials 0.000 description 1
- FYYHWMGAXLPEAU-UHFFFAOYSA-N Magnesium Chemical compound [Mg] FYYHWMGAXLPEAU-UHFFFAOYSA-N 0.000 description 1
- 238000000342 Monte Carlo simulation Methods 0.000 description 1
- 229910000831 Steel Inorganic materials 0.000 description 1
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22F—CHANGING THE PHYSICAL STRUCTURE OF NON-FERROUS METALS AND NON-FERROUS ALLOYS
- C22F3/00—Changing the physical structure of non-ferrous metals or alloys by special physical methods, e.g. treatment with neutrons
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C23/00—Alloys based on magnesium
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y02P10/00—Technologies related to metal processing
- Y02P10/25—Process efficiency
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Abstract
The invention provides a non-contact metal grain accurate regulation and control system based on vortex, which comprises a pulse generator and a plate to be treated; the pulse generator comprises an energy storage module, a discharge module and a pulse coil; the first end of the discharge input of the discharge module is connected with the first end of the energy storage output of the energy storage module, the second end of the discharge input of the discharge module is connected with the second end of the energy storage output of the energy storage module, the pulse coil is connected in series with the loop of the discharge module, and the plate to be processed is arranged near the pulse coil; the energy storage module can store energy with different voltage specifications; and adjusting parameters of the discharge module, and processing the plate to be processed by the pulse current flowing through the pulse coil. The invention can achieve the effect of improving the amplitude through the current waveform under the same energy, and has better effect of inducing the refinement of the high-conductivity metal grains.
Description
Technical Field
The invention relates to the field of metal materials, in particular to a non-contact metal grain accurate regulation and control system based on vortex.
Background
Grain refinement is the only way to improve both metal plasticity and strength. Current grain refinement methods include adding grain refiners, stirring, etc. during casting. After casting is completed, the metal is often treated using a deforming process. Considering that the casting process is irreversible and the original assembly needs to be maintained in the actual application scene so as not to deform first, a method for realizing precise regulation and control of metal grain refinement without changing the original assembly mode is needed to be searched.
Disclosure of Invention
The invention aims at least solving the technical problems in the prior art, and particularly creatively provides a non-contact metal grain accurate regulation and control system based on vortex.
In order to achieve the above object, the present invention provides a non-contact metal grain accurate control system based on eddy current, comprising a pulse generator and a plate to be processed;
The pulse generator comprises an energy storage module, a discharge module and a pulse coil;
The first end of the discharge input of the discharge module is connected with the first end of the energy storage output of the energy storage module, the second end of the discharge input of the discharge module is connected with the second end of the energy storage output of the energy storage module, the pulse coil is connected in series with the loop of the discharge module, and the plate to be processed is arranged near the pulse coil;
The energy storage module can store energy with different voltage specifications;
And adjusting parameters of the discharge module, and processing the plate to be processed by the pulse current flowing through the pulse coil.
Further, the energy storage module comprises M direct current power supplies, M charging switches and a capacitor bank, wherein M is a positive integer greater than or equal to 2;
The M direct current power supplies are respectively a 1st direct current power supply, a2 nd direct current power supply, a3 rd direct current power supply, … … th direct current power supply and an M direct current power supply, the 1st direct current power supply, the 2 nd direct current power supply, the 3 rd direct current power supply, … … th direct current power supply and the M direct current power supply are power supplies with gradually increased voltages, and the M charging switches are respectively a 1st charging switch, a2 nd charging switch, a3 rd charging switch, … … and an M charging switch;
The first end of the power supply voltage output of the mth direct current power supply is connected with the first end of the mth charging switch, M is a positive integer smaller than or equal to M, the second end of the mth charging switch is connected with the first end of the capacitor bank, the second end of the power supply voltage output of the mth direct current power supply is connected with the second end of the capacitor bank, and the on-off control end of the mth charging switch is connected with the M end of the charging on-off of the controller. The first end of the power supply voltage output of the 1 st direct current power supply is connected with the first end of the 1 st charging switch, the second end of the 1 st charging switch is connected with the first end of the capacitor bank, the second end of the power supply voltage output of the 1 st direct current power supply is connected with the second end of the capacitor bank, and the on-off control end of the 1 st charging switch is connected with the 1 st charging on-off end of the controller; the first end of the power supply voltage output of the 2 nd direct current power supply is connected with the first end of the 2 nd charging switch, the second end of the 2 nd charging switch is connected with the first end of the capacitor bank, the second end of the power supply voltage output of the 2 nd direct current power supply is connected with the second end of the capacitor bank, and the on-off control end of the 2 nd charging switch is connected with the 2 nd charging on-off end of the controller; the first end of the power supply voltage output of the 3 rd direct current power supply is connected with the first end of the 3 rd charging switch, the second end of the 3 rd charging switch is connected with the first end of the capacitor bank, the second end of the power supply voltage output of the 3 rd direct current power supply is connected with the second end of the capacitor bank, and the on-off control end of the 3 rd charging switch is connected with the 3 rd charging on-off end of the controller; … …; the first end of the power supply voltage output of the Mth direct current power supply is connected with the first end of the Mth charging switch, the second end of the Mth charging switch is connected with the first end of the capacitor bank, the second end of the power supply voltage output of the Mth direct current power supply is connected with the second end of the capacitor bank, and the on-off control end of the Mth charging switch is connected with the M th end of the charging on-off of the controller. The controller sends a conduction signal to the mth charging switch, the mth charging switch is conducted, and the mth direct current power supply charges the capacitor bank, so that the capacitor bank can obtain energy storage with different voltage specifications.
Further, the discharging module comprises a discharging switch, a discharging inductor, K discharging resistors and K-1 resistor switches, wherein K is a positive integer greater than or equal to 2;
the K discharge resistors are respectively a1 st discharge resistor, a 2 nd discharge resistor, a 3 rd discharge resistor, … … th discharge resistor and a K discharge resistor, and the K-1 resistance switches are respectively a 2 nd resistance switch, a 3 rd resistance switch, a … … th resistance switch and a K resistance switch;
the on-off control end of the kth resistor switch is connected with the on-off kth end of the controller, K is a positive integer smaller than or equal to K and larger than or equal to 2, the first end of the kth resistor switch is connected with the first end of the kth discharge resistor, the first end of the 1 st resistor and the second end of the kth resistor switch form a first end of resistor adjustment, and the second end of the 1 st resistor and the second end of the kth discharge resistor form a second end of resistor adjustment; the on-off control end of the 2 nd resistor switch is connected with the on-off 2 nd end of the controller, the first end of the 2 nd resistor switch is connected with the first end of the 2 nd discharging resistor, the on-off control end of the 3 rd resistor switch is connected with the on-off 3 rd end of the controller, the first end of the 3 rd resistor switch is connected with the first end of the 3 rd discharging resistor, the on-off control end of the 4 th resistor switch is connected with the on-off 4 th end of the controller, the first end of the 4 th resistor switch is connected with the first end of the 4 th discharging resistor, … …, the on-off control end of the K resistor switch is connected with the on-off K end of the controller, and the first end of the K resistor switch is connected with the first end of the K discharging resistor; the first end of the 1 st resistor, the second end of the 2 nd resistor switch, the second end of the 3 rd resistor switch, the second end of the 4 th resistor switch, … … and the second end of the K resistor switch are respectively connected to form a first end for resistance adjustment; the second end of the 1 st resistor, the second end of the 2 nd discharging resistor, the second end of the 3 rd discharging resistor, the second end of the 4 th discharging resistor and the second end of the … … th discharging resistor are respectively connected to form a second end for regulating the resistor; the resistance values of the 1 st discharge resistor, the 2 nd discharge resistor, the 3 rd discharge resistor, the … … th discharge resistor and the K discharge resistor can be identical, can not be completely identical, can also be completely identical, and the controller sends a conducting signal to the K resistance switch, the K resistance switch is conducted, and the total resistance value of the K resistance switch is changed.
The first end of the discharge switch is connected with the first energy storage output end of the energy storage module, the first end of the discharge switch is connected with the first end of the resistor adjustment, the second end of the resistor adjustment is connected with the first end of the discharge inductor, the first end of the discharge inductor is connected with the second energy storage output end of the energy storage module, and the discharge on-off control end of the discharge switch is connected with the charge on-off end of the controller.
Further, the pulse coil includes: serpentine coils, single wire, archimedes coils.
Further, the method comprises the steps of:
The pulse generator is used for generating pulse current, the pulse current is applied to the plate to be processed in an induced eddy current mode or a conduction mode, and the grain boundary migration of metal is caused by the electron wind and the Joule heat generated by eddy current, so that recrystallization, namely grain refinement, is realized, the effect of improving the current amplitude is achieved, and the accurate regulation and control of grain refinement can be realized.
Why the pulse is used instead of other means such as direct current, alternating current, etc. -since joule heat generated at the same energy is the same, but the electron wind force generated by the pulse is larger, the migration degree of the driving grain boundary is higher, and thus grain refinement is easier to achieve.
The output pulse waveform is changed by changing the resistance of the coil in the circuit, the specific theory is as follows.
The characteristic root of the differential equation of the circuit is called the natural frequency of the circuit. When R, L, C are different in magnitude, the feature root may appear as follows
(1)In this case, S 1,S2 is the real root of the inequality, and the over-damping condition.
(2)At this time, S 1,S2 is two equal solid roots, critical damping case.
(3)And S 1,S2 is a conjugate plurality root and under-damping condition.
Further, the induced eddy current mode includes:
Electrifying the coil, and then placing the coil on the plate to be treated;
gaps are formed between the coil and the plate to be treated, theoretically, the smaller the gaps are, the better the gaps are, and the gaps are generally 0.01-0.5 mm;
Or an insulating medium exists between the coil and the plate to be treated.
Further, the conducting means includes:
Pulsed current is applied to the left and right sides of the panel to be treated.
Further, the pulses in the pulse current include:
Under-damped single pulse or over-damped single pulse;
Or/and the underdamped single pulse is a sinusoidal damped current waveform, the current waveform oscillates up and down, the amplitude is gradually decreased, and the peak amplitude of the first pulse is highest;
or/and the underdamped single pulse further comprises:
The pulse amplitude (peak value) of the underdamped single pulse is 10 kA-200 kA, and the pulse frequency is 3000 Hz-50000 Hz;
or/and the over-damped single pulse is a sine wave with only one wave crest, and is a bell-shaped curve with a middle height, gradually descending two ends and complete symmetry.
Further, the overdamping single pulse includes:
The pulse amplitude (peak value) of the over-damped single pulse is 10 kA-200 kA, and the pulse frequency is 3000 Hz-50000 Hz.
Further, the pulses further comprise a plurality of pulses, the plurality of pulses comprising:
a plurality of single pulses with the same waveform, wherein the rising time and the falling time of the single pulse are the same;
the multiple pulses differ from the overdamped single pulse in that the multiple pulses are of increased current amplitude and the overdamped single pulse is by increasing the number of pulses.
And a capacitor bank employed by a pulse generator that generates a plurality of pulses.
Or/and the pulse further comprises a plurality of pulses:
The pulse amplitude (peak value) is 2 kA-40 kA, the pulse frequency is 3000 Hz-50000 Hz, and the number of pulses in 1 second is 5-15.
In summary, by adopting the technical scheme, the invention can achieve the effect of improving the amplitude through the current waveform under the same energy, so that the effect of inducing the high-conductivity metal crystal grain to refine is better.
Additional aspects and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention.
Drawings
The foregoing and/or additional aspects and advantages of the invention will become apparent and may be better understood from the following description of embodiments taken in conjunction with the accompanying drawings in which:
FIG. 1 is a schematic waveform diagram of an underdamped single pulse, an overdamped single pulse, and multiple pulses of the present invention.
Fig. 2 is a schematic diagram of an assembly of the present invention employing a pulsed induced eddy current approach.
Fig. 3 is a schematic diagram of a pulse generator of the present invention.
FIG. 4 is a schematic diagram of a die of the simulation result of the present invention.
FIG. 5 is a schematic view of the eddy current density of a magnesium alloy sheet of the present invention.
FIG. 6 is a schematic view of the eddy current density at the center of a magnesium alloy sheet at different voltage levels in accordance with the present invention.
FIG. 7 is a graph showing the current distribution obtained by simulation using the method of measuring the eddy current of magnesium alloy by using the Rogowski coil approximation in the present invention.
FIG. 8 is a graph showing the statistical distribution of grain size after processing at different pulse current amplitudes according to the present invention.
Detailed Description
Embodiments of the present invention are described in detail below, examples of which are illustrated in the accompanying drawings, wherein like or similar reference numerals refer to like or similar elements or elements having like or similar functions throughout. The embodiments described below by referring to the drawings are illustrative only and are not to be construed as limiting the invention.
The invention provides a non-contact metal grain accurate regulation and control system based on vortex, taking magnesium alloy as an example.
1 Brief description of the invention
Magnesium alloys are currently one of the lightest metallic materials, with densities (1.8 g/cm 3) less than 25% of the steel densities (7.8 g/cm 3). In addition, the magnesium alloy has higher specific strength and damping performance, so the magnesium alloy has great development prospect in industrial light weight. However, magnesium alloys have poor ductility, plasticity and corrosion resistance, which hinders industrial application and popularization of magnesium alloys. It was found that grain refinement is the only way to improve both metal plasticity and strength. And the refined grains obtain a homogeneous microstructure, which is favorable for inhibiting segregation and pore formation and improving corrosion resistance.
For magnesium alloys in the casting process (liquid state), grain refinement is usually achieved by adding grain refiner, adding other substances such as carbon or FeCl 3, stirring, and the like. For solid metals, deformation is often used.
It has been found that when an electric current is applied to the formed metal, the flow stress of the metal deformation is reduced and its plasticity is significantly enhanced. Since the electrical treatment is completed only in a few microseconds, a lot of time cost is saved compared with the conventional heat treatment, and the processed magnesium alloy has a more excellent microstructure. Therefore, this technique has attracted the interests of a large number of researchers.
It is observed in experiments by the official epitaxy et al that the AZ31 magnesium alloy can complete the static recrystallization process in a very short time under the action of electric pulse, the grain structure is obviously refined, and the deformation resistance is also reduced. Liu Yang et al found that the electric pulse greatly promoted the recrystallization of AZ31 magnesium alloy and refined the grain structure of the magnesium alloy. Grain refinement can activate grain boundary sliding, and simultaneously acts on dislocation movement of magnesium alloy, shortens dislocation movement stroke, and enhances coordinated deformation capacity, thereby reducing deformation resistance of magnesium alloy. The functional epitaxy et al studies found that the mechanism of current versus recrystallization behavior is the migration of electron wind and joule heat to dislocations and drive grain boundaries.
At present, the mechanism research of the electro-plasticity is more systematic and deep, and unfortunately, the existing processing modes such as electric assistance and the like can be applied to the whole magnesium alloy workpiece, so that the whole plate is finally hardened and is difficult to apply to the functionally graded material. Because in the structure of the functional gradient material, the material performance varies with the position, so that certain functions of the whole functional gradient material are optimized, and the requirements of various different environments are met. It is therefore desirable to find a way to locally induce recrystallization, increase the hardness of the metal, and leave the remainder of the workpiece in the original grain size.
In a practical and complex application scene, metals are required to have different grain size distribution to meet different application requirements, and aiming at the difficulty, a processing mode of non-contact area selective induced recrystallization grain refinement is provided, a pulse induced vortex mode is adopted to apply current, and the provided method can also realize static recrystallization and a dynamic recrystallization mode. The conversion efficiency of coil current is researched, the dynamic response rule and the spatial distribution of electromagnetic parameters are ascertained, a mechanism of vortex-induced metal static recrystallization and a novel method of directional-induced recrystallization weakening texture are obtained according to the grain boundary migration theory, the research results can promote the development and application of an electric auxiliary processing technology in magnesium alloy manufacturing and provide a reference basis for preparing magnesium alloy gradient materials in the future.
2. Materials and methods
2.1 Material
In the experiment, AZ31 magnesium alloy was selected as an experimental object, the dimensions of the plate were 100mm×50mm×1mm, and the elemental composition of the magnesium alloy plate was shown in Table 1.
TABLE 1AZ31 magnesium alloy chemical composition
| Mg | Cu | Zn | V | Fe | Mg | Ti | Mn | Si |
| 99.6 | 0.05 | 0.05 | 0.05 | 0.35 | 0.03 | 0.03 | 0.03 | 0.25 |
2.2 Grain boundary migration simulation model
In order to analyze the effect of pulse current on recrystallization, a simulation model of current-induced grain boundary migration recrystallization is built according to a grain boundary migration theory, so that a reference basis is provided for current parameter dosage, and the grain boundary migration rate is according to a grain growth dynamics equation
v＝MP
M is the grain boundary mobility, P is the driving force of grain boundary migration, v is the grain boundary migration rate
M 0 is a constant, T is temperature, Q is crystal migration activation energy, and R is a gas constant.
P＝PV+PR
Where P V is the volumetric energy and P R is the grain boundary energy. The thermal and electrical coupling effect caused by the electric pulse promotes the migration of grain boundaries, and the driving force during recrystallization can be expressed as
ΔP＝Pth+Path
Wherein P th is thermal compression stress, and P ath is electronic wind power
Wherein DeltaS is the difference in entropy between the grain boundary and the matrix, T is the temperature gradient, 2a is the thickness of the grain boundary,Is atomic volume
Where e is a natural constant, ρ D is a resistivity, N D is a dislocation density, N e is an electron density, j is a current density, and thus the total recrystallization driving force is
PEP＝P+ΔP
＝PV+PR+Pth+Path
Migration grain boundary rate under the action of electric pulse is
vEP＝MPEP
When the eddy current acts, the driving force of the recrystallized grain boundary migration includes deformation caused by electromagnetic force and electron wind and joule heat generated by the eddy current.
2.3 Finite element simulation model
After the eddy current is confirmed to induce recrystallization, a three-dimensional multi-physical field coupling model is constructed by COMSOL Multiphysics in order to study the space-time response rule of electromagnetic parameters in the pulse action process and verify whether the eddy current spatial distribution has specific region selectivity.
The simulated geometric model consists of a coil and a plate to be processed. The model structural parameters are the same as the actual dimensions of the device. The coil has a cross-sectional area of 8 x10 mm, a plate thickness of 1mm, a length and width of 100mm and 50mm respectively, a coil material of copper, a plate material of magnesium, and multiple physical fields including electromagnetic fields and solid mechanics. All of the electromagnetic field solution domains set forth herein include spheres having a radius of 40. The relevant electromagnetic and material parameters for solving for the material in the domain are shown in table 1.
TABLE 1
2.4 Pulse generator
Studies show that when the current density flowing in the metal reaches 1kA/mm 2, the electro-plastic effect is more remarkable, and under certain energy conditions, the pulse width is reduced by increasing the current amplitude. In order to realize higher current density and lower pulse width, a set of pulse generator capable of generating high current is developed, a pulse system is shown in fig. 3, and the whole system comprises an energy storage module and a discharge module. The energy storage module comprises a 140uF capacitor bank, a high-voltage direct-current power supply and a relay, wherein the relay is disconnected after the capacitor is charged. The discharge module comprises a vacuum trigger switch, a coil and a sample to be processed. Wherein a trigger source triggers the vacuum trigger switch by generating a pulse with an amplitude of 10kV and a pulse width of 6 us. The sample and coil assembly is shown in detail in FIG. 3, wherein the coil cross-sectional area is 8mm by 10mm, and the thickness of the insulating layer is 60um. Since a large pulse current generates a lorentz force, a fixed plate is placed in the direction of movement of the sample.
3. Results and discussion
3.1 Finite element simulation results
The results of the solution by the Monte Carlo method to obtain the metal crystal grain boundary driving are shown in the following figure 4, and simulation results show that under the condition of no deformation, the vortex can excite more crystal nuclei to drive the grain boundary to migrate so as to induce the recrystallization behavior to realize the grain refinement, so that the method of adopting the vortex-induced recrystallization behavior is considered to be effective.
The density distribution of the eddy current of the magnesium alloy sheet is shown in fig. 5, and the eddy current is mainly concentrated in the central portion of the magnesium alloy, and the shape thereof is substantially rectangular, wherein the width is about 8.2mm, which is substantially the same as the width of the coil parallel to the sheet. In addition, the density distribution of the vortex on the magnesium alloy plate is relatively uniform, and the density of the outer vortex is rapidly attenuated by the density of the central area to be about 3 multiplied by 10 4A/mm2.
The direction of the vortex is parallel to the width direction of the plate. The density of the eddy current is attenuated along the long edge of the plate, and the density after attenuation is about 2.2A/mm 2, and it is emphasized that the density of the eddy current in other parts except the central area is smaller and is approximately 0. Simulation results show that the eddy current type current can effectively and selectively control the spatial distribution of the current. The current density at different voltages is shown in fig. 6, and the result shows that as the voltage increases, the current density on the sample increases, and when the voltage increases from 5kV to 8kV, the eddy current density on the magnesium alloy plate increases from 3×10 4A/mm2 to 4.9×10 4A/mm2.
3.2 Crystal simulation results
The contrast current distribution and stress distribution find a difference between them, and therefore in practice it is necessary to design the geometry according to the specific coil. The recrystallisation caused by current driven grain boundary migration is essential for grain basal plane deflection, but it is pointed out in literature that deformation also promotes dislocation slip. However, the current application region and the deformation region are slightly different, and in order to accurately control the recrystallized region, it is necessary to fix the deformation region of the sheet, and in the study herein, according to the previous study results: the lorentz force direction is perpendicular to the plate and away from the coil, so in the device design herein we choose to fix the whole sample.
Simulation results (fig. 4) show that eddy currents are concentrated mainly in the region parallel to the coil width,
3.3 Influence of pulse amplitude on recrystallization induction
Fig. 8 shows the statistical distribution of the grain size after treatment at different pulse current amplitudes, the average grain size of the untreated region was 5.01 μm (fig. 8 a), the average grain size after 15 treatments (23.3 kJ) at 5kV was 3.45 μm (fig. 8 b), and the average grain size after 5 treatments (22.4 kJ) at 8kV was 2.31 μm (fig. 8 c), whereby it was seen that the recrystallization promoting effect was significantly enhanced with the increase of the current amplitude.
Conclusion 4
In order to meet the requirements of different environments in the actual application scene of the magnesium alloy, a regional selective recrystallization method based on vortex is provided, and the research on the effective selectivity, the mechanism of selective induction and the influence of parameters on recrystallization is developed to obtain the following conclusion:
(1) The eddy current treatment of the magnesium alloy can effectively and selectively induce the local static recrystallization of the magnesium alloy, realize the grain refinement of the magnesium alloy, improve the hardness, the plasticity and the corrosion resistance of the magnesium alloy and weaken the texture of the magnesium alloy
(2) The vortex is adopted to induce the magnesium alloy to perform static recrystallization, the vortex in the metal generates Joule heat and electron wind to drive the grain boundary migration of the metal, and the built simulation model can better reproduce the selectively induced area and the degree of the grain boundary migration.
(3) At the same energy, the efficiency of this approach can be improved by increasing the magnitude of the eddy currents, since the effective current energy driving the grain boundary migration is more. When the coil pulse current was increased from 90kA to 130kA, the current induced grain refinement increased from 3.5 μm to 2.3 μm.
While embodiments of the present invention have been shown and described, it will be understood by those of ordinary skill in the art that: many changes, modifications, substitutions and variations may be made to the embodiments without departing from the spirit and principles of the invention, the scope of which is defined by the claims and their equivalents.
Claims (5)
1. The non-contact metal grain accurate regulation and control system based on vortex is characterized by comprising a pulse generator and a plate to be treated;
the pulse generator comprises an energy storage module, a discharge module and a pulse coil; generating pulse current through a pulse generator, and applying the pulse current to the plate to be processed in an induced eddy mode;
the pulse in the pulse current is as follows: under-damped single pulse or over-damped single pulse or multiple pulses;
The underdamped single pulse is a sinusoidal attenuated current waveform, the current waveform oscillates up and down, the amplitude is gradually decreased, and the peak amplitude of the first pulse is highest; the pulse amplitude of the underdamped single pulse is 10 kA-200 kA, and the pulse frequency is 3000 Hz-50000 Hz;
the over-damped single pulse is a sine wave with only one wave crest, and is a bell-shaped curve with a high middle and gradually descending two ends and being completely symmetrical; the pulse amplitude of the over-damped single pulse is 10 kA-200 kA, and the pulse frequency is 3000 Hz-50000 Hz;
The plurality of pulses are single pulses with the same waveforms, and the rising time and the falling time of the single pulses are the same; the pulse amplitude is 2 kA-40 kA, the pulse frequency is 3000 Hz-50000 Hz, and the number of pulses in 1 second is 5-15;
The first end of the discharge input of the discharge module is connected with the first end of the energy storage output of the energy storage module, the second end of the discharge input of the discharge module is connected with the second end of the energy storage output of the energy storage module, the pulse coil is connected in series in a loop of the discharge module, and the plate to be processed is arranged near the pulse coil;
The energy storage module can store energy with different voltage specifications;
And adjusting parameters of the discharge module, and processing the plate to be processed by the pulse current flowing through the pulse coil.
2. The vortex-based non-contact metal grain accurate regulation system of claim 1, wherein the energy storage module comprises M direct current power supplies, M charging switches and a capacitor bank, wherein M is a positive integer greater than or equal to 2;
The M direct current power supplies are respectively a 1st direct current power supply, a2 nd direct current power supply, a3 rd direct current power supply, … … th direct current power supply and an M direct current power supply, the 1st direct current power supply, the 2 nd direct current power supply, the 3 rd direct current power supply, … … th direct current power supply and the M direct current power supply are power supplies with gradually increased voltages, and the M charging switches are respectively a 1st charging switch, a2 nd charging switch, a3 rd charging switch, … … and an M charging switch;
The first end of the power supply voltage output of the mth direct current power supply is connected with the first end of the mth charging switch, M is a positive integer smaller than or equal to M, the second end of the mth charging switch is connected with the first end of the capacitor bank, the second end of the power supply voltage output of the mth direct current power supply is connected with the second end of the capacitor bank, and the on-off control end of the mth charging switch is connected with the M end of the charging on-off of the controller.
3. The vortex-based non-contact metal grain accurate regulation system of claim 1, wherein the discharge module comprises a discharge switch, a discharge inductor, K discharge resistors and K-1 resistor switches, wherein K is a positive integer greater than or equal to 2;
the K discharge resistors are respectively a1 st discharge resistor, a 2 nd discharge resistor, a 3 rd discharge resistor, … … th discharge resistor and a K discharge resistor, and the K-1 resistance switches are respectively a 2 nd resistance switch, a 3 rd resistance switch, a … … th resistance switch and a K resistance switch;
The on-off control end of the kth resistor switch is connected with the on-off kth end of the controller, K is a positive integer smaller than or equal to K and larger than or equal to 2, the first end of the kth resistor switch is connected with the first end of the kth discharge resistor, the first end of the 1 st resistor and the second end of the kth resistor switch form a first end of resistor adjustment, and the second end of the 1 st resistor and the second end of the kth discharge resistor form a second end of resistor adjustment;
The first end of the discharge switch is connected with the first energy storage output end of the energy storage module, the first end of the discharge switch is connected with the first end of the resistor adjustment, the second end of the resistor adjustment is connected with the first end of the discharge inductor, the first end of the discharge inductor is connected with the second energy storage output end of the energy storage module, and the discharge on-off control end of the discharge switch is connected with the charge on-off end of the controller.
4. The vortex-based non-contact metal grain accurate conditioning system of claim 1, wherein the pulse coil comprises: serpentine coils, single wire, archimedes coils.
5. The vortex-based non-contact metal grain accurate control system of claim 1, wherein the induced vortex mode comprises:
Electrifying the coil, and then placing the coil on the plate to be treated;
A gap is formed between the coil and the plate to be treated, and the gap is 0.01-0.5 mm;
Or an insulating medium exists between the coil and the plate to be treated.
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