CN101670429A - Casting method for inhibiting bottom crack of ingot - Google Patents
Casting method for inhibiting bottom crack of ingot Download PDFInfo
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- CN101670429A CN101670429A CN200910182530A CN200910182530A CN101670429A CN 101670429 A CN101670429 A CN 101670429A CN 200910182530 A CN200910182530 A CN 200910182530A CN 200910182530 A CN200910182530 A CN 200910182530A CN 101670429 A CN101670429 A CN 101670429A
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Abstract
The invention relates to a casting method for inhibiting bottom crack of an ingot. The numerical values of casting speed and cooling water flow in the initial stage of casting are both 1/2-2/3 of those of casting speed and cooling water flow in the stable stage, when the length of the ingot achieves 20-100mm, the cooling water flow is kept still, the casting speed gradually reduces to zero within1-10s, after the casting machine stops running for 1-60s, the casting process is restarted, the numerical values of casting speed and cooling water flow are gradually restored to the initial preset values, the casting speed gradually reduces to zero after the initial stage, the stable stage and the ending stage of the casting process, and the casting machine suspends once in the midway during thewhole casting process. The technical scheme can effectively reduce overall inner-stress value of the ingot, achieve the aim of inhibiting crack and improve casting success ratio.
Description
Technical field
The present invention relates to a kind of casting method that suppresses bottom crack of ingot, belong to the aluminum alloy semi-continuous casting technical field.
Background technology
The direct water-cooling semi-continuous casting is the main technique of aluminum alloy round ingot and slab ingot preparation, and in the semi-continuous casting process, the bottom cracking is one of ingot casting common deficiency; Before the subsequent thermal distortion, be to guarantee product quality, the ingot casting bottom of cracking must be cut away, thereby seriously reduced the lumber recovery of product.And, cause scrapping of whole ingot casting product all the time thereby ftracture even can run through ingot casting bottom it for the serious aluminium alloy cast ingot of some tearing tendency.The reason that bottom crack of ingot produces mainly is owing to casting tool (as crystallizer, base etc.) temperature when beginning to cast is too low, violent liquid state contraction, solidification shrinkage and Solid State Contraction take place in aluminium alloy melt under the chilling condition, produce very big internal stress in the ingot casting bottom, the bottom cracking takes place in ingot casting when stress value bears the limit above the intensity of ingot casting.The description difference of alloy, the tendency of ingot casting bottom cracking is also different.For the high strength alumin ium alloy ingot casting of some alloying level high and low temperature plasticity difference, thereby the bottom crack at casting initial stage tends to extend to the failure that whole ingot casting causes whole casting process.
In order to suppress bottom crack of ingot, countries in the world Chinalco has developed many advanced persons' casting technique, waits as pulsating water foundry engieering, aerating foundry engieering and fine aluminium shop fixtures technology and suppresses to ftracture and obtained certain effect.In these advanced casting techniques China aluminium manufacturing enterprise most widely used be fine aluminium shop fixtures technology, the characteristics of this technology are at first to cast the commercial-purity aluminium ingot casting of certain-length before the casting alloy ingot casting, and then cast alloys ingot casting, utilize the good characteristics dilution of fine aluminium ingot casting plasticity and envelope alloy cast ingot bottom easy to crack, thereby realize suppressing the purpose of alloy cast ingot bottom cracking.
But, to adopt fine aluminium shop fixtures technology not only to need to increase extras such as commercial-purity aluminium melting furnace, and adopt the operation of fine aluminium shop fixtures casting also cumbersome, the success or failure of shop fixtures technology are closely related with cooperating of personnel and equipment.
At the deficiency that existing technology exists, the invention provides a kind of casting method of practicable inhibition bottom crack of ingot, realize improving the purpose of ingot casting yield rate by the improvement of casting technique.
Summary of the invention
The objective of the invention is to overcome the deficiency that prior art exists, a kind of casting method that suppresses bottom crack of ingot is provided, by the improvement raising ingot casting yield rate of casting technique.
Purpose of the present invention is achieved through the following technical solutions:
A kind of casting method that suppresses bottom crack of ingot, casting process comprises casting initial period, casting stabilization sub stage and casting ending stage, characteristics are: at the casting initial period, set initial casting speed and cooling water flow and be 1/2～2/3 of stabilization sub stage respective value, after ingot casting length reaches 20～100mm, keep cooling water flow constant, in the time of 1～10s, casting speed is decreased to gradually zero, keeps the constant or rising range value of crystallizer inner metal liquid face height less than 30mm; Keep casting machine to stop the 1～60s that descends, continue operation then, casting process restarts, and casting speed and cooling water flow increase to initial setting value gradually, and casting process continues to carry out, and experience casting stabilization sub stage and ending finished after the stage; Whole casting process casting machine Halfway Stopping 1 time.
Further, above-mentioned a kind of casting method that suppresses bottom crack of ingot, when casting initial period casting machine was in halted state, the constant or liquid level rising amplitude of crystallizer inner metal liquid face height was less than 30mm.
Further, above-mentioned a kind of casting method that suppresses bottom crack of ingot, bigger for the ingot casting specification, the very serious aluminium alloy cast ingot of bottom cracking, the process of descending at intermittence of stopping when casting during casting initial period casting machine can or continue to carry out in casting initial period 2～4 cycles of circulation, cross over the stable and ending stage of casting, finish until whole casting process.Stop the stage in when casting time, the frequency that casting machine stops is per minute 1～10 time, and the duration that single stops is 1～60s.
Substantive distinguishing features and obvious improvement that technical solution of the present invention is outstanding are mainly reflected in:
Adopt casting method of the present invention, after casting initial stage casting machine carries out the transition to stop phase by the decline process, the total amount of high temperature alloy melt will no longer increase or increase by a small margin in the crystallizer, and this moment, the crystallizer secondary cooling water continued ingot casting is implemented cooling, the temperature contrast that is accompanied by its inner zones of different of carrying out of ingot solidification will reduce gradually, and internal stress also reduces gradually; After beginning casting once more, the ingot casting inner-stress value will be accumulated on having obtained basis that part discharges early stage, and the overall internal stress of ingot casting continues casting with routine to be compared and can reduce, thereby avoids the tearing tendency of ingot casting bottom.For the very serious alloy cast ingot of tearing tendency, the mode of then selecting casting stop phase and casting process to hocket, make the internal stress of accumulating in the casting process constantly obtain discharging at the casting stop phase, thereby effectively reduce the ingot casting overall inner-stress value, reach the purpose that suppresses cracking.
Description of drawings
Below in conjunction with accompanying drawing technical solution of the present invention is described further:
Fig. 1: the casting speed schematic diagram of the inventive method;
Fig. 2: the casting speed schematic diagram that is suitable for the big ingot casting of tearing tendency.
The specific embodiment
The aluminum alloy semi-continuous casting process generally comprises three phases:
1) casting initial period: aluminium alloy melt slowly flows in the casting die of being made up of crystallizer and dummy ingot base through chute, under the common cooling effect of dummy ingot base and crystallizer inwall, solidify and form the skim metal-back, the dummy ingot base descends when the intensity of metal-back enough supports liquid metal, the metal surface that solidifies touches the cooling water in the crystallizer, and the semi-continuous casting process begins;
2) the casting stabilization sub stage: this stage casting technique is carried out according to will aspiring for stability of alloy cast ingot, casting machine descends continuously according to the setting value of casting speed, cooling water is followed casting speed according to setting technology and is done linear change, the interior liquid level of crystallizer remains unchanged in the casting process, and the melt temperature field and the field of flow of ingot casting inside tend towards stability;
3) the casting ending stage: this stage casting speed and cooling water flow drop to zero gradually, and casting enters and finishes the ending stage.
At the casting initial period, adopt control program to set initial casting speed and cooling water flow, when numerical value is stable casting 1/2～2/3 of speed and cooling water respective value, after ingot casting length reaches 20～100mm, keep cooling water flow constant, casting speed is decreased to gradually zero in the time of 1～10s, the flow that will supply with metal simultaneously in crystallizer also is decreased to zero gradually, keeps the constant or liquid level rising of crystallizer inner metal liquid face height less than 30mm; Retention time 1～60s after casting machine stops to descend, casting machine continues to start then, and casting speed and cooling water flow return to initial setting value, and casting process restarts.Casting process experiences the stabilization sub stage successively and ending is cast end after the stage.The operation of casting machine Halfway Stopping is 1 time in whole casting process.
For the higher aluminium alloy cast ingot of bottom tearing tendency, stop and alternation procedure 2～4 cycles capable of circulation that descend at casting initial period casting machine, perhaps continue circulation experience casting stabilization sub stage and ending after the stage whole casting process finish.Casting machine moves in the mode of stopping in when casting time always in casting process, and the frequency that this process casting machine stops is per minute 1～10 time, and the duration that single stops is 1～60s.
The present invention compares with conventional cast technology, it mainly is the mode of not taking to continue decline at casting initial period casting machine, but set up casting machine Halfway Stopping process, and according to the variation of ingot casting kind and specification, casting machine operation and the alternate cycles cycle that stops can be designed to a plurality of, even extend to whole casting process end.This be because, at the casting beginning initial stage, the temperature of crystallizer and dummy ingot base is lower, and the liquid melt of aluminium alloy solidification shrinkage takes place and form the skim solidified shell after touching the dummy ingot base, and touching behind the secondary cooling water of crystallizer the solidification shrinkage of ingot casting when the ingot casting surface will be more violent.Being subjected to the interior high-temperature fusant of crystallizer constantly replenishes, crystallizer continues under the acting in conjunction of secondary cooling, ingot casting is outside to be the solid metallic after solidifying, and has formed the high-temperature fusant liquid core with certain depth in ingot casting inside, forms huge cooling difference at ingot casting center and limit portion simultaneously.In the semi-continuous casting process, the cooldown rate difference of this ingot casting different parts metal must cause the inconsistent of its solidification shrinkage, early stage, the metal that solidifies will inevitably hinder the contraction distortion of later stage frozen metal, thereby produced the solidification shrinkage internal stress and be accompanied by the carrying out of casting process and constantly accumulation.Can produce compression in zone, top layer that ingot casting solidifies at first generally speaking, and the central area of ingot casting final set can produce tension, when stress value surpass the ingot casting metal bear the limit time ingot casting ftracture.The casting initial period is that liquid metal solidification is more violent, and ingot casting and the extraneous thermally equilibrated process of setting up also are the easiest stages that the bottom cracking takes place of ingot casting.
After adopting casting method of the present invention, after casting initial stage casting machine carries out the transition to stop phase by the decline process, the total amount of high temperature alloy melt will no longer increase or increase by a small margin in the crystallizer, and this moment, the crystallizer secondary cooling water continued ingot casting is implemented cooling, the temperature contrast that is accompanied by its inner zones of different of carrying out of ingot solidification will reduce gradually, and internal stress also reduces gradually.After beginning casting once more, the ingot casting inner-stress value will be accumulated on having obtained basis that part discharges early stage, and the overall internal stress of ingot casting continues casting with routine to be compared and can reduce, thereby has cut down the tearing tendency of ingot casting bottom.For the very serious alloy cast ingot of tearing tendency, the mode of then selecting casting stop phase and casting process to hocket, make the internal stress of accumulating in the casting process constantly obtain discharging at the casting stop phase, thereby effectively reduce the ingot casting overall inner-stress value, reach the purpose that suppresses cracking.
This method is suitable for the semi-continuous casting process of bottom aluminium alloy easy to crack, and Fig. 1 has illustrated casting speed; And the casting speed that is suitable for the big ingot casting of tearing tendency as shown in Figure 2.
With φ 300mm 7050 aluminum alloy round ingot casting example, embodiment of the present invention is described further:
(1) melting and melt treatment:
Technical pure aluminium ingot and alloying ingot casting thereof are put into the induction furnace melting, changing insulation behind the alloy melting over to leaves standstill in the stove, and melt carried out furnace refining, degasification and other processing, and leaving standstill 10～20 minutes, body temperature degree fusion carries out semi-continuous casting when reducing to 720～740 ℃.
(2) semi-continuous casting:
Before semi-continuous casting begins, open water inlet manifold road flow control valve, setting the initial changes in flow rate scope of cooling water is 4～6m
3/ h, the initial casting speed of casting machine is 30mm/min.After casting process began, alloy liquid slowly flowed in the crystallizer by chute, and the dummy ingot base slowly descends according to the speed of setting.After ingot casting length is 30mm, casting process enters stop phase, change according to stop phase shown in Figure 1 at this stage casting speed curve, dummy ingot base decrease speed is reduced to 0mm/min gradually and keeps halted state 5s, casting machine continues to be increased to the velocity amplitude 60mm/min that stablizes cast sections from the 0mm/min linearity again according to the velocity amplitude of setting subsequently, the crystallizer cooling water flow is also followed the linear increase of casting speed, from 4～6m of initial period
3/ h slowly increases to 10～11m of casting stabilization sub stage
3/ h.In casting process, keep crystallizer inner metal liquid face position in ± 3mm scope, to fluctuate.Reach the numerical value of setting when ingot casting length after, casting speed and cooling water are reduced to zero gradually, and casting enters the ending stage.
Adopting casting method of the present invention to prepare φ 300mm7050 with the traditional semicontinuous casting technique of employing closes Gold circle ingot casting is the result compare, and casting is the result show, adopts traditional handicraft to cast 7050 ingot castings, The consistent extension of crackle and expansion after namely ftractureing, continue to cast in casting initial stage ingot casting bottom, casting is finished The logical heart cracking of rear ingot casting. And employing the inventive method, ingot casting bottom cracking is inhibited, and casting is finished Rear ingot casting has no crackle. As seen, the inventive method can ftracture establishment ingot casting bottom, improves casting Cause power.
What need to understand is: above-mentioned explanation is not to be limitation of the present invention, conceives model in the present invention In enclosing, the interpolation of carrying out, conversion, replacement etc. also should belong to protection scope of the present invention.
Claims (3)
1. casting method that suppresses bottom crack of ingot, casting process comprises the casting initial period, casting stabilization sub stage and casting ending stage, it is characterized in that: at the casting initial period, casting speed and cooling water flow be casting during the stabilization sub stage speed and cooling water flow respective value 1/2～2/3, after ingot casting length reaches 20～100mm, keep cooling water flow constant, in the time of 1～10s, casting speed is decreased to zero gradually, behind casting machine 1～60s out of service, casting process restarts once more then, casting speed and cooling water flow value return to initial setting value gradually, casting process experiences initial respectively, casting speed is reduced to zero, whole casting process casting machine Halfway Stopping 1 time gradually behind the stable and ending three phases.
2. a kind of casting method that suppresses bottom crack of ingot according to claim 1 is characterized in that: casting initial period casting machine is in halted state, and the constant or liquid level rising amplitude of crystallizer inner metal liquid face height is less than 30mm.
3. a kind of casting method that suppresses bottom crack of ingot according to claim 1, it is characterized in that: for the bigger aluminium alloy cast ingot of tearing tendency, stopping and decline process 2～4 cycles of circulation or continue to carry out finishing of casting initial period casting machine until casting process, the cycle stage that stops in when casting time, the casting machine stop frequency is per minute 1～10 time, and the duration that single stops is 1～60s.
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Cited By (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103192043A (en) * | 2013-04-07 | 2013-07-10 | 昆明理工大学 | Method for restraining cast ingot central crack from being generated |
| CN108160966A (en) * | 2017-12-29 | 2018-06-15 | 西南铝业（集团）有限责任公司 | A kind of Zn content is 9%~13% aluminum alloy semi-continuous casting method |
| CN108907131A (en) * | 2018-07-10 | 2018-11-30 | 邯郸钢铁集团有限责任公司 | A kind of secondary cooling scheme method reducing sheet billet continuous casting base face crack end to end |
| CN111168021A (en) * | 2019-12-11 | 2020-05-19 | 山东创新金属科技有限公司 | Casting process of aluminum alloy round ingot for forging hub |
| CN112139466A (en) * | 2020-10-09 | 2020-12-29 | 中国航发北京航空材料研究院 | Method for stepped intermittent pause type casting of 7000 series aluminum alloy direct-cooling semi-continuous ingot |
| CN112974742A (en) * | 2021-04-21 | 2021-06-18 | 中国航发北京航空材料研究院 | Method for reducing bottom cracking of large-size 2000-series aluminum alloy ingot |
Family Cites Families (2)
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| CN1090800A (en) * | 1993-02-10 | 1994-08-17 | 章仲禹 | Double-reverse pushing jiggering technique for horizontally continuous casting ingot |
| CN100369699C (en) * | 2006-04-29 | 2008-02-20 | 东北大学 | Method and equipment for inhibiting crack of high-alloying aluminium alloy square billet |
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Cited By (9)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103192043A (en) * | 2013-04-07 | 2013-07-10 | 昆明理工大学 | Method for restraining cast ingot central crack from being generated |
| CN103192043B (en) * | 2013-04-07 | 2016-01-20 | 昆明理工大学 | A kind of method suppressing ingot casting centre burst to produce |
| CN108160966A (en) * | 2017-12-29 | 2018-06-15 | 西南铝业（集团）有限责任公司 | A kind of Zn content is 9%~13% aluminum alloy semi-continuous casting method |
| CN108907131A (en) * | 2018-07-10 | 2018-11-30 | 邯郸钢铁集团有限责任公司 | A kind of secondary cooling scheme method reducing sheet billet continuous casting base face crack end to end |
| CN108907131B (en) * | 2018-07-10 | 2020-07-03 | 邯郸钢铁集团有限责任公司 | Secondary cooling control method for reducing surface cracks of head and tail blanks of slab continuous casting |
| CN111168021A (en) * | 2019-12-11 | 2020-05-19 | 山东创新金属科技有限公司 | Casting process of aluminum alloy round ingot for forging hub |
| CN111168021B (en) * | 2019-12-11 | 2022-01-25 | 山东创新金属科技有限公司 | Casting process of aluminum alloy round ingot for forging hub |
| CN112139466A (en) * | 2020-10-09 | 2020-12-29 | 中国航发北京航空材料研究院 | Method for stepped intermittent pause type casting of 7000 series aluminum alloy direct-cooling semi-continuous ingot |
| CN112974742A (en) * | 2021-04-21 | 2021-06-18 | 中国航发北京航空材料研究院 | Method for reducing bottom cracking of large-size 2000-series aluminum alloy ingot |
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Effective date of registration: 20171121 Address after: 102209 Changping District City, Beiqijia, the future of science and technology in the south area of the town of Beijing Patentee after: China Aluminum Material Applied Research Institute Co Ltd Address before: Suzhou City, Jiangsu province 215021 Industrial Park No. 200 Shen Hu Road Patentee before: Suzhou Non-ferrous Metal academy Co., Ltd. |
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