CN101561382B - Aluminum alloy melt hydrogen partial pressure dynamic measuring method - Google Patents
Aluminum alloy melt hydrogen partial pressure dynamic measuring method Download PDFInfo
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- CN101561382B CN101561382B CN200810064302XA CN200810064302A CN101561382B CN 101561382 B CN101561382 B CN 101561382B CN 200810064302X A CN200810064302X A CN 200810064302XA CN 200810064302 A CN200810064302 A CN 200810064302A CN 101561382 B CN101561382 B CN 101561382B
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Abstract
The invention relates to an aluminum alloy melt hydrogen partial pressure dynamic measuring method. Aluminum and hydrogen in aluminum alloy have remarkable influence on the mechanical properties such as plasticity, toughness, fatigue lifetime and stress corrosion resistance. The rejection ratio caused by excessive hydrogen amount occupies half of all waste aluminum casting. Therefore, people adopts various methods to refine aluminum melt in the production process of aluminum casting so as to reduce hydrogen content in the aluminum melt. In the invention, a vacuum pump is firstly used for a vacuum chamber to enter the preliminary vacuum state, a probe is inserted into aluminum liquid, a valve between the probe and the vacuum chamber is opened, a speed reducer unit is started, and the volumeof the vacuum chamber of a hydrogen measuring system gradually reduces so as to reduce the vacuum degree in the system, thereby the melt hydrogen partial pressure is measured in the process that the pressure varies in the vacuum, namely, the melt hydrogen partial pressure is measured dynamically. The invention is used for accurately measuring the hydrogen content in aluminum melt before pouring.
Description
Technical field:
The invention belongs to innovation and creation metallurgical and casting field, the rapid assay methods of a kind of new aluminum alloy melt hydrogen dividing potential drop of proposition that concrete is.
Background technology:
Research shows, the hydrogen in aluminium and the aluminium alloy is to having remarkable influence such as mechanical properties such as plasticity, toughness, fatigue lifetime, stress corrosion resistances, because of the too high rejection rate that causes of hydrogen amount accounts for the half the of whole aluminium casting waste products.People take several different methods that aluminum melt is carried out refining in the production run of aluminium casting for this reason, to reduce the hydrogen richness in the aluminum melt.Obviously, before cast, accurately measure the hydrogen richness in the aluminum melt, have great importance for control casting quality and the effect of estimating degassing process.
The method that is used for measuring the aluminium alloy melt hydrogen content at present is existing many, kind surplus the hydrogen-measuring apparatus nearly 20 of various countries' development.In numerous survey hydrogen methods, what often use in the production is that Decompressing Solidification Method, first bubble method, inert gas are carried method, directly pressure measurement and concentration cell method etc.Wherein Decompressing Solidification Method belongs to the qualitative determination method, and other method then is the quantitative Analysis method.The concentration cell method has the fast advantage of test speed, but its testing cost is apparently higher than other method.Except that the concentration cell method, other method is many to be the basic test condition with " decompression ", through measuring the aluminum alloy melt hydrogen dividing potential drop, utilizes formula to calculate the melt hydrogen content.In order accurately to record the hydrogen dividing potential drop, must there be enough test durations fully to diffuse out to guarantee the hydrogen in the melt, directly influenced test speed.Therefore, attach most importance to diffusion time to shorten hydrogen, research aluminum alloy melt hydrogen dividing potential drop rapid assay methods has very important significance for the quick hydrogen meter of Development of New Generation.
Summary of the invention:
The present invention proposes a kind of dynamic rapid assay methods of aluminum alloy melt hydrogen dividing potential drop; Compare with existing similar assay method; Can significantly shorten the test duration, improve testing efficiency; Can obtain more reliably simultaneously, more accurate test result, the present invention is through changing the purpose that the volume of surveying the hydrogen system vacuum chamber reaches dynamic measurement melt hydrogen dividing potential drop.
Above-mentioned purpose realizes through following technical scheme:
Aluminum alloy melt hydrogen partial pressure dynamic measuring method at first utilizes vacuum pump to make vacuum chamber get into predetermined vacuum state, will pop one's head in and insert in the aluminium liquid; Open the valve between probe and vacuum chamber; Start the reductor unit,, intrasystem vacuum tightness is reduced gradually through constantly reducing to survey the volume of hydrogen system vacuum chamber; Record melt hydrogen dividing potential drop in vacuo in the process of pressure change, i.e. dynamic measurement melt hydrogen dividing potential drop.
Described aluminum alloy melt hydrogen partial pressure dynamic measuring method; Describedly utilize vacuum pump to make vacuum chamber get into the vacuum state process to refer to: with the dilatation of variable capacity vacuum chamber to maximum volume; Open the valve between vacuum chamber and vacuum pump, close other valve, this moment, sensor was started working; Vacuum pump vacuumizes vacuum chamber, and vacuum tightness reaches 10
3The Pa level is closed all valves, so that make the interior pressure of vacuum chamber rapidly near melt hydrogen dividing potential drop.
Described aluminum alloy melt hydrogen partial pressure dynamic measuring method; In the process that pressure raises in vacuum chamber; Carrying out described dynamic measurement melt hydrogen dividing potential drop measures; Be the indoor actual pressure value of dynamic monitoring with theory of computation pressure values in real time and with the difference of actual pressure value, the actual pressure value is higher than theoretical pressure values representative " suction hydrogen " process, the actual pressure value is lower than theoretical pressure values representative " exhaling hydrogen " process; Actual pressure value in the mobile equilibrium that hydrogen when the actual pressure value equals theoretical pressure values in the melt and the hydrogen in the vacuum chamber reach diffusion, this moment vacuum chamber is the hydrogen dividing potential drop of melt.
Described aluminum alloy melt hydrogen partial pressure dynamic measuring method; Described vacuum pump is for reaching the vacuum pump (1) of the required initial depression of test experiments; Described vacuum pump connects between a variable capacity vacuum chamber (2) that leans on deceleration unit to change volume, described vacuum chamber and the aluminum melt to be detected and connects through probe (5); The damage that prevents to pop one's head in also being housed on the described vacuum chamber, and afterwards aluminium alloy melt is inhaled into the isolated location (6) of vacuum chamber, described vacuum chamber directly links to each other with pressure unit, and the pressure transducer (7) that is installed on the described vacuum chamber is all sent into data acquisition and processing unit (10) with the signal of temperature sensor (8) output.
Described aluminum alloy melt hydrogen partial pressure dynamic measuring method, described data acquisition and processing unit comprise through the interconnective signal conditioning circuit of circuit, mould/number conversion module, serial communication interface and industrial control computer.
Beneficial effect of the present invention:
1. the present invention can significantly shorten the test duration, improve testing efficiency.Utilize vacuum pump to make vacuum chamber reach predetermined initial depression (the concrete numerical value of vacuum tightness can be confirmed according to concrete alloy) in the mensuration process; Through the volume that reduces vacuum chamber intrasystem vacuum tightness is reduced gradually, impel the interior pressure of vacuum chamber as early as possible near melt hydrogen dividing potential drop.In the process that pressure raises gradually in vacuum chamber the indoor actual pressure value of dynamic monitoring and real-time theory of computation pressure values and with the difference of actual pressure value.The actual pressure value is higher than theoretical pressure values representative " suction hydrogen " process; The actual pressure value is lower than theoretical pressure values representative " exhaling hydrogen " process (hydrogen in the aluminum melt is called " suction hydrogen " to the vacuum chamber diffusion, and " hydrogen " in the vacuum chamber spreads and is called " exhaling hydrogen ") in aluminium alloy melt.The actual pressure value equals the mobile equilibrium that hydrogen and the hydrogen in the vacuum chamber in the theoretical pressure values explanation melt reach diffusion, and the interior actual pressure value of vacuum chamber this moment is the hydrogen dividing potential drop of melt.Method of the present invention is through the hydrogen dividing potential drop in the dynamic fast measuring aluminum melt, and the hydrogen that need not in wait as long for vacuum chamber and the aluminum melt reaches the partial pressure balance, can shorten minute significantly;
2. utilize to subtract and hold pressure testing method and search for the equilibrium hydrogen dividing potential drop fast and can save and fill the hydrogen link, proving installation is greatly simplified.
Description of drawings:
Accompanying drawing 1 is a vacuum chamber transfiguration process synoptic diagram.
Accompanying drawing 2 is that the device of realizing the inventive method constitutes synoptic diagram.
Embodiment:
Embodiment 1:
Aluminum alloy melt hydrogen partial pressure dynamic measuring method; At first utilize vacuum pump to make vacuum chamber get into vacuum state, will pop one's head in and insert in the aluminium liquid, open the valve between probe and vacuum chamber; Start the reductor unit; Through constantly reducing to survey the volume of hydrogen system vacuum chamber, intrasystem vacuum tightness is reduced gradually, dynamic measurement melt hydrogen dividing potential drop.The test condition of this method is to guarantee vacuum system height airtight (promptly air tight), and vacuum chamber transfiguration speed must be confirmed, that is each pressure constantly must be able to calculate in the vacuum chamber.Shown in accompanying drawing 1, vacuum chamber length can change between 0-l, and the pressure of supposing a certain moment vacuum chamber is P
1, change volume (the overall process vacuum chamber keeps constant temperature and airtight) with v at the uniform velocity, after the time, pressure in vacuum tank becomes P through t
2, according to the imperial equation of carat uncle, P
2Can be calculated as:
Formula (1) is vacuum chamber when airtight, indoor theory pressure P
1Through the changing value of t after second.And in fact vacuum chamber communicates with aluminium alloy melt through parts such as spacer assembly and valves, vacuum chamber can be from aluminum melt " suction " or in aluminum melt " exhalation " hydrogen, thereby make the vacuum chamber actual pressure P that records
2' with Theoretical Calculation pressure P
2Produce deviation, i.e. Δ P=P
2'-P
2What of vacuum chamber " suction " or " exhalation " hydrogen are the size of this deviation depend on fully; The hydrogen process is inhaled in Δ P＞0 representative; The hydrogen process of exhaling is represented in Δ P＜0, and Δ P=0 representative is inhaled hydrogen and exhaled hydrogen to reach mobile equilibrium, and pressure equates with the interior hydrogen dividing potential drop of aluminum melt in the vacuum chamber.In the transfiguration process, monitor actual pressure variation in the vacuum chamber in real time, and at any time the theoretical pressure values of the actual pressure values that records and this point (except first measurement point) is subtracted each other and obtain difference.This difference (being Δ P value) equal zero or (, but can approach null value to greatest extent through the adjustment sampling period) near zero the time because the influence of interval sampling possibly cause absolute zero not occur pairing actual measurement pressure values be melt hydrogen dividing potential drop.
Embodiment 2:
In the embodiment 1 described aluminum alloy melt hydrogen partial pressure dynamic measuring method; Describedly utilize vacuum pump to make vacuum chamber get into the vacuum state process to refer to: with the dilatation of variable capacity vacuum chamber to maximum volume; Open the valve between vacuum chamber and vacuum pump, close other valve, this moment, sensor was started working; Vacuum pump vacuumizes vacuum chamber, and vacuum tightness reaches 10
3The Pa level is closed all valves, so that make the interior pressure of vacuum chamber rapidly near melt hydrogen dividing potential drop.
In the process that pressure raises in vacuum chamber; Carry out described melt hydrogen partial pressure dynamic measuring; Be meant the indoor actual pressure value of dynamic monitoring and real-time theory of computation pressure values and with the difference of actual pressure value; The actual pressure value is higher than theoretical pressure values representative " suction hydrogen " process; The actual pressure value is lower than theoretical pressure values representative " exhaling hydrogen " process, the mobile equilibrium that the hydrogen when the actual pressure value equals theoretical pressure values in the melt and the hydrogen in the vacuum chamber reach diffusion, and the interior actual pressure value of vacuum chamber this moment is the hydrogen dividing potential drop of melt.
Embodiment 3:
Described aluminum alloy melt hydrogen partial pressure dynamic measuring method; Described vacuum pump is the vacuum pump 1 that reaches the required initial depression of test experiments; Described vacuum pump connects between a variable capacity vacuum chamber 2 that leans on deceleration unit to change volume, described vacuum chamber and the aluminum melt to be detected and connects through probe 5; The damage that prevents to pop one's head in also being housed on the described vacuum chamber, and afterwards aluminium alloy melt is inhaled into the isolated location 6 of vacuum chamber, described vacuum chamber directly links to each other with pressure unit, and the pressure transducer 7 that is installed on the described vacuum chamber is all sent into data acquisition and processing unit 10 with the signal of temperature sensor 8 outputs.
Described data acquisition and processing unit comprise through the interconnective signal conditioning circuit of circuit, mould/number conversion module, serial communication interface and industrial control computer.
Embodiment 4:
The present invention realizes through following proposal: shown in accompanying drawing 2, this test macro can be made up of following several sections: vacuum pump 1, variable capacity vacuum chamber 2, deceleration unit 3, vacuum valve group 4-1,4-2, probe 5, isolated location 6, pressure transducer 7, temperature sensor 8, calibration cell 9 and data acquisition and processing unit 10.Vacuum pump is used to make vacuum chamber to reach the required initial depression of experiment; The variable capacity vacuum chamber changes volume through deceleration unit, and its internal pressure is changed continuously; Probe is used to be communicated with " suction hydrogen " and " exhaling hydrogen " passage between vacuum chamber and the aluminum melt, requires to have enough thermal stabilitys, high-temperature machinery intensity and moderate air penetrability, does not decompose, do not produce gas and gas-permeable, liquid-impermeable to guarantee to insert in the aluminum melt; Isolated location is used to prevent that probe from damaging the back aluminium alloy melt and being inhaled into vacuum chamber; Pressure unit directly links to each other with vacuum chamber, monitors room pressure in real time and changes; Temperature sensor is used for monitoring in real time melt temperature.The signal of pressure transducer and temperature sensor output is all sent into data acquisition and processing unit.Data acquisition and processing unit comprise signal conditioning circuit, mould/number conversion module, serial communication interface and industrial control computer etc.The effect of signal conditioning circuit is that the signal to the output of pressure transducer and temperature sensor carries out the amplitude processing and amplifying, to satisfy the inlet requirement of data acquisition module.Temperature, pressure signal after data acquisition module will be nursed one's health reach computing machine with the universal serial bus mode through communication interface modules, accomplish various calculating and differentiation by computing machine.
Test process: the first step: the dilatation of variable capacity vacuum chamber to maximum volume, is opened the valve between vacuum chamber and vacuum pump, close other valves, this moment, sensor was started working, and vacuum pump vacuumizes vacuum chamber, when vacuum tightness reaches 10
3During the Pa level, close all valves.Second step: will pop one's head in and insert in the aluminium liquid, and open the valve between probe and vacuum chamber.The 3rd step: start the reductor unit; Computing machine calculates the dilatation and the theoretical pressure values in a certain moment automatically according to rotational time; Actual pressure data in pressure transducer collection vacuum chamber this moment, the temperature signal of temperature sensor collection melt this moment will be surveyed pressure values and subtracted each other with the calculating pressure values; Find out that difference equals zero or pairing actual pressure value near zero time, be melt hydrogen partial pressure value.
Above-mentioned all switches and the start-stop action of reductor unit and calculation of parameter and recognition function are all accomplished under computer control automatically.
Claims (4)
1.
a kind of aluminum alloy melt hydrogen partial pressure dynamic measuring method is characterized in that: at first utilize vacuum pump to make vacuum chamber get into predetermined vacuum state, will pop one's head in and insert in the aluminium liquid; Open the valve between probe and vacuum chamber; Start the reductor unit,, intrasystem vacuum tightness is reduced gradually through constantly reducing to survey the volume of hydrogen system vacuum chamber; Test condition is to guarantee that the vacuum system height is airtight; Vacuum chamber transfiguration speed must be confirmed, that is each pressure constantly must be able to calculate in the vacuum chamber, in the process that pressure raises in vacuum chamber; Carrying out described dynamic measurement melt hydrogen dividing potential drop measures; Be the indoor actual pressure value of dynamic monitoring with theory of computation pressure values in real time and with the difference of actual pressure value, the actual pressure value is higher than theoretical pressure values representative " suction hydrogen " process, the actual pressure value is lower than theoretical pressure values representative " exhaling hydrogen " process; Actual pressure value in the mobile equilibrium that hydrogen when the actual pressure value equals theoretical pressure values in the melt and the hydrogen in the vacuum chamber reach diffusion, this moment vacuum chamber is the hydrogen dividing potential drop of melt.
2.
Aluminum alloy melt hydrogen partial pressure dynamic measuring method according to claim 1; It is characterized in that: describedly utilize vacuum pump to make vacuum chamber get into predetermined vacuum state process to refer to: with the dilatation of variable capacity vacuum chamber to maximum volume; Open the valve between vacuum chamber and vacuum pump, close other valve, this moment, pressure transducer and temperature sensor were started working; Vacuum pump vacuumizes vacuum chamber, and vacuum tightness reaches 10 3 The Pa level is closed all valves, so that make the interior pressure of vacuum chamber rapidly near melt hydrogen dividing potential drop.
3.
aluminum alloy melt hydrogen partial pressure dynamic measuring method according to claim 1 and 2; It is characterized in that: described vacuum pump is for reaching the vacuum pump (1) of the required initial depression of test experiments; Described vacuum pump connects between a variable capacity vacuum chamber (2) that leans on deceleration unit to change volume, described vacuum chamber and the aluminium alloy melt to be detected and connects through probe (5); The damage that prevents to pop one's head in also being housed on the described vacuum chamber, and afterwards aluminium alloy melt is inhaled into the isolated location (6) of vacuum chamber, described vacuum chamber directly links to each other with pressure unit, and the pressure transducer (7) that is installed on the described vacuum chamber is all sent into data acquisition and processing unit (10) with the signal of temperature sensor (8) output.
4.
aluminum alloy melt hydrogen partial pressure dynamic measuring method according to claim 3, it is characterized in that: described data acquisition and processing unit comprise through the interconnective signal conditioning circuit of circuit, mould/number conversion module, serial communication interface and industrial control computer.
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| CN200810064302XA CN101561382B (en) | 2008-04-15 | 2008-04-15 | Aluminum alloy melt hydrogen partial pressure dynamic measuring method |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN102721710B (en) * | 2012-07-06 | 2014-04-09 | 哈尔滨工业大学 | Device and method for acquiring dynamic distribution of diffusible hydrogen under static load gradient tensile stress |
| CN104678074B (en) * | 2015-03-03 | 2017-01-11 | 湖南镭目科技有限公司 | Hydrogen content detection method and system |
| CN106568673A (en) * | 2015-10-12 | 2017-04-19 | 哈尔滨理工大学 | Negative pressure back-rising rate method used for rapidly detecting melt gas content |
| CN106770518A (en) * | 2016-12-22 | 2017-05-31 | 东北大学 | It is a kind of for aluminium and aluminium alloy melt in determine hydrogen production device and method |
| CN111289405B (en) * | 2020-03-02 | 2022-07-01 | 哈尔滨理工大学 | Aluminum alloy melt hydrogen partial pressure inert gas circulation on-line continuous detection device and detection method thereof |
| CN111289404B (en) * | 2020-03-16 | 2022-07-05 | 哈尔滨理工大学 | Method for rapidly detecting hydrogen partial pressure for aluminum alloy melt dynamic respiration hydrogen measuring device |
Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP0212371A2 (en) * | 1985-08-07 | 1987-03-04 | Aluminum Company Of America | Method and apparatus for determining soluble gas content |
| US5191786A (en) * | 1991-06-28 | 1993-03-09 | Amoco Corporation | Method for detecting the presence and concentration of relatively low molecular weight components in a liquid |
| CN2727730Y (en) * | 2004-08-25 | 2005-09-21 | 中国科学院金属研究所 | A hydrogen charging-discharging performance testing device by volumetric method |
| CN1699957A (en) * | 2005-06-16 | 2005-11-23 | 华中科技大学 | Method and apparatus for quantitative determination of hydrogen content in casting aluminum alloy liquation |
-
2008
- 2008-04-15 CN CN200810064302XA patent/CN101561382B/en not_active Expired - Fee Related
Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP0212371A2 (en) * | 1985-08-07 | 1987-03-04 | Aluminum Company Of America | Method and apparatus for determining soluble gas content |
| US5191786A (en) * | 1991-06-28 | 1993-03-09 | Amoco Corporation | Method for detecting the presence and concentration of relatively low molecular weight components in a liquid |
| CN2727730Y (en) * | 2004-08-25 | 2005-09-21 | 中国科学院金属研究所 | A hydrogen charging-discharging performance testing device by volumetric method |
| CN1699957A (en) * | 2005-06-16 | 2005-11-23 | 华中科技大学 | Method and apparatus for quantitative determination of hydrogen content in casting aluminum alloy liquation |
Non-Patent Citations (3)
| Title |
|---|
| 秦涛等.《一种快速检测铝合金液含氢量的方法》.《金属铸锻焊技术》.2010,第39卷(第21期),55-56，60. * |
| 谷健等.《用于液态铝合金含氢量现场检测的单片机测控系统》.《铸造设备研究》.2007,(第2期),15-18. * |
| 陈叙.《铝及铝合金用测氢仪的新进展》.《铝加工》.1994,第17卷(第6期),8-14. * |
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