CN101811179A - Magnesium alloy wide plate casting-rolling method - Google Patents

Abstract

The invention relates to a magnesium alloy wide plate casting-rolling method, which casts and rolls liquid magnesium alloy into a wide thin plate blank by using a magnesium alloy three-roll wide plate casting-rolling machine. The method is characterized in that the magnesium alloy three-roll wide plate casting-rolling machine has a pair of equal diameter double-drive rolls with the diameter of 800 to 1,200 millimeters and the same turning directions, namely an upper driving roll 1 and a lower driving roll 3, and has a driven roll 2 with the diameter of 200 to 600 millimeters, wherein the lower driving roll 3 and the driven roll 2 form a casting-rolling roll pair which has an internal water-cooled structure, the upper driving roll 1 is a supporting roll for the driven roll 2, and the plane of the axes of the three rolls is inclined towards one side of a casting nozzle; and during use, a casting-rolling flow distribution method which controls a transverse temperature difference, a thickness difference and a flow rate difference within 10 percent is applied to the liquid magnesium alloy, a rolling area is in a composite half solid, the pressing rate is 50 to 60 percent of casting and rolling, and the cast-rolled plate is subjected to on-line plate control.

Description

A kind of magnesium alloy wide plate casting-rolling method

The method field

The present invention relates to a kind of casting of magnesium alloy rolling method, relate in particular to the method for using three-roll casting-rolling mill to produce magnesium alloy wide cut thin plate.

The method background

The density of magnesium alloy is about 1/4 of steel, 2/3 of aluminium, close with plastics, have specific strength and specific stiffness height, heat conductivity is good, damping shock absorption is good, machinability is good, accessory size is stable and advantage such as easy recovery, have excellent value and wide application prospect, be described as " 21 century tool development prospect green engineering material ".Magnesium alloy has been widely used in the industries such as automobile, Aeronautics and Astronautics, metallurgy, chemical industry, communication, electronics and sports goods now.Particularly since earlier 1990s, the urgent day by day energy and environmental problem have greatly stimulated the development of magnesium alloy, and the demand to magnesium alloy in the global range presents growth trend powerful, that continue.Magnesium-alloy material is in the majority with die casting at present, though pressure casting method obtains baroque part easily, the production efficiency of die casting is also high, but defective such as tissue looseness, pore, crystal grain are thick, component segregation that die casting exists, performance is difficult to satisfy higher instructions for use, has restricted the Application of Magnesium scope greatly.The market demand has proposed harsh day by day requirement to the performance of magnesium-alloy material, and therefore, research emphasis is steering behaviour excellence, the high distortion of reliability magnesium alloy product just gradually.By the magnesium alloy parts that processing methods such as forging, extruding, rolling, drawing and punching press are prepared, can be used as the parts such as housing, automobile panel, car wainscot of electronic product and household electrical appliance, the market demand is huge.Sheet metal is used at most in fields such as electronics, communication, traffic, Aero-Space.The application of magnesium alloy plate at present is very limited, and main cause is that magnesium alloy plate process unit and process are not mature enough, and mechanical property also needs further to improve, and production cost need reduce etc.For efficient, the reduction that improves plate rolling consumes, improves the sheet material forming manufacturability, except the rolling mill practice of routine, also developed many new milling methods, driven rolling, asymmetrical rolling, two roller tandem rolling, continuous casting and rolling, equal channel angular rolling etc. as single roller.It is the ingot casting split rolling method that the magnesium alloy split rolling method is used more, and its production procedure is: ingot mill surface → ingot homogenization → heating → slab preparation → slab shearing blanking → slab heating → roughing → pickling → heating → in roll → interrupt or blanking → heating → finish rolling → product annealing → finish rolling → oxidation colouring → oiling is packed.In the magnesium alloy plate operation of rolling, adopt multi-pass, light reduction technology to be rolled, carry out intermediate annealing between passage.Such technology is backward relatively, is suitable for the small lot processing of magnesium alloy plate.Extrusion blooming is rolling mainly to be to utilize extruding method, and the good magnesium alloy of obtained performance is slab in a narrow margin.Because complex manufacturing, the cycle of magnesium alloy wide cut thin plate are long, cause production cost very high.

Double-roller rolling is with continuous casting and rolling combination, bears rolling deformation in the time of melt solidifying, promptly directly metal bath " rolling " is become semi-finished product made-up belt or finished product band.Crystallizer is the rotation casting roller of two band water-cooling systems, and melt is finished between its roll gap and solidified and two processes of hot rolling, and whole process time is very short.The advantage of double-roller rolling comprises: simplified operation, shortened flow process, improved lumber recovery, significantly energy savings, reduce various consumption.At present, the twin roll casting rolling method of magnesium alloy has been obtained progress, and German ThyssenKrupp Stahl adopts the magnesium alloy plate casting-rolling method to produce the cast-rolled block of wide 700mm, thick 6mm; Australia CSIRO just is devoted to the research of magnesium alloy plate casting-rolling method, and has carried out the industrialization trial production, and the sheet material width can reach 630mm, thickness 2.3-5mm.SUMITOMO CHEMICAL Aluminum, three is assisted Aluminums, Mitsubishi's Aluminum in addition, and mechanical investigations institute of Korea S country is all obtaining bigger achievement aspect the magnesium alloy plate casting-rolling method.Domesticly also twin roll casting rolling method is researched and developed, Foochow Hua Mei company has successfully developed the two asynchronous continuous castings of roller of magnesium alloy plate, and, directly the liquid magnesium alloy rolling is become to have the sheet material of even tissue, grain refinement in conjunction with adopting rapid solidification, semi-solid processing.Shanxi silver light magnesium has already been set up casting and rolling the production line, has realized commercially producing.Though the magnesium alloy plate material casting-milling technology is launched a large amount of research, and obtained bigger progress, with respect to steel and aluminium alloy, problem such as magnesium alloy thin strip inferior quality, yield rate are low.These problems have all seriously hindered the industrialization process of casting of magnesium alloy rolling sheets.Magnesium alloy wide plate punching press automobile internal hilar plate, hood and luggage-boot lid etc. are succeeded.Magnesium alloy plate is widely used in automobile, at first presses high problem of workout cost and the demand that satisfies punch process.The hot rolling of magnesium alloy wide cut thin plate is bigger than the difficulty of hot-rolled steel plate, and reason is that the parameter area of magnesium alloy plate hot rolling is very narrow, and hot thin plate heat radiation is fast again, and making to increase heating number of times and rolling pass.The temperature distributing disproportionation of thin plate is even also to bring a difficult problem to Rolling Production, and the error of rolled piece head and the tail temperature makes the product size precision exceed standard.Therefore, exploitation magnesium alloy wide cut thin plate hot-rolling method has become the eager task that present magnesium alloy is produced.Obtained under the situation of initial success at magnesium alloy narrow boards casting-rolling method, the above wide magnesium alloy wide cut thin plate three-roll casting-rolling mill of research and development 1200mm is also succeedd.

Magnesium alloy wide cut thin plate three-roll casting-rolling mill has been created condition for implementing wide plate casting-rolling technology, but will produce high-quality product, also needs advanced casting-rolling technology and cooperates.

Summary of the invention

1. the application's purpose is that research and development are suitable for the production method that three-roll casting-rolling mill is produced magnesium alloy wide cut thin plate casting product.The target that manufacturing technique method need reach is in process of production can long-time steady operation, and can produce the magnesium alloy slab of multiple alloy designations and multiple thickness, and thin plate blanket shape is good.These cast-rolled blocks can be produced production board with less rolling drafts in follow-up attenuate finish rolling, and its precision and performance satisfy the method standard requirement.In order to satisfy the good casting strip of wide cut aximal deformation value, plate shape that the liquid magnesium alloy casting is become width 800mm～1800mm, the casting and rolling installation host design is become reducing three roller casting and rolling installations.The casting functional structure of casting and rolling installation main frame is that a pair of diameter is two drive rolls that drive of 800mm～1200mm, promptly go up drive roll 1 and following drive roll 3, a diameter is 200mm～600mm driven voller 2, it is right that following drive roll 3 and driven voller 2 are formed the casting roller, be interior water-cooling structure, last drive roll 1 is the backing roll of driven voller 2, on one side and the plane at the axis place of three rollers tilt to lip; In use liquid magnesium alloy all is controlled at 10% with interior casting cloth stream method at lip 5 along temperature difference, thickness difference and the current difference that the horizontal cloth of casting roller flows, rolling district is compound semisolid, reduction ratio is the casting of 50%-60%, the casting plate that casting goes out carries out online plate shape control, the angle of inclination is 0～15 degree, and the best is 5～10 degree.Following drive roll 3 and driven voller 2 are that the casting roller of interior water-cooled is right.Last drive roll 1 is the backing roll of driven voller 2, can be real core, or the interior water-cooled core identical with following drive roll 3, and water-cooled core roller can be used as down the replacement roller of drive roll in adopting.The application adopts two measures to realize the high casting ratio of casting and rolling installations, promptly big reduction ratio: the one, adopt the minor diameter driven voller, the 2nd, adopt minimum pressure greater than the oil hydraulic cylinder of 1800 tons of roll-forces to the major diameter roller to applying draught pressure.Two major diameter rollers adopt two the driving up and down, stepless time adjustment, and turning to of two rollers is identical, drives driven voller synchronously and rotates, and promptly the minor diameter driven voller is a driven voller.The linear resonance surface velocity scope of casting roller pair is 2 meters/minute～8 meters/minute, and linear resonance surface velocity changes according to thickness of slab.The casting and rolling installation of three roll structures is convenient to the casting of wide cut thin plate, also can guarantee the smooth implementation of casting-rolling technology, thus the deflection that to need and the slab and the strip of plate shape preferably.The design theory and the production experience of two roller casting and rolling installations and four roller casting and rolling installations continued to use in the application's design, comprises casting design of Roller, frame strength and rigidity Design, water-cooling system, bearing and lubricated, roll-force and driving etc.In order to tackle different needs to enlarge the scope of application of casting and rolling installation, allow to change the driven voller of different-diameter, need to reserve the open height of drive roll this moment.

The application has analyzed the production of two roller casting and rolling installations and four roller casting and rolling installations and has accumulated experience, and can't satisfy the reason of casting magnesium alloy wide cut thin plate and the method that remains to be remedied, and in conjunction with simulated test, has invented this casting and rolling installation structure.The design of three roller casting and rolling installations, according to the practice of 600 millimeters width roll-casting of magnesium alloy, driven voller is set at 200-600 millimeter scope, and the main roller that solidifies of upper support roller and following casting is the thick roller of water-cooled in the equal diameter, and diameter is roughly the 800-1200 millimeter.The casting-rolling force of three roller casting and rolling installations will satisfy the running parameter scope that the casting reduction ratio is wanted big and three roller casting and rolling installations, the resistance of deformation of magnesium alloy and distortion Set Status etc. under the state of rolled piece under roll casting conditions (casting distortion), equal the product of roll and the rolling drag of rolled piece contact area and unit by minimum roll-force, generally equal the offset yield strength that deformation extent, deformation temperature, deformation velocity influence coefficient multiply by material, casting pressure is got 400MPa in rolling district.General rolling force is about 1800 tons, and the actual set roll-force need be greater than 2000 tons.Under the condition of this rolling parameter, rolling drafts satisfies the rolling rate target greater than 40%.

In order to utilize three-roll casting-rolling mill, finish the production of wide cut casting thin plate in conjunction with the technology that adopts the application, at first make liquid magnesium alloy as much as possible little along temperature difference, thickness difference, the current difference of the horizontal cloth stream of casting roller at lip; Lower floor in the deformed area of roll gap solidifies, the upper strata more upwards, the amount of liquid progressively increases, the upper strata that is the rolling deformation district still is in semi-solid pasty state, when bearing big drafts casting, the solidification layer of bottom may produce crackle, but under huge compression, liquid in the semisolid can be extruded filtration, penetrates into crackle and filling crackle; Temperature was about 350 ℃ after the casting plate left roll, took advantage of waste heat this moment and stretched and can play good thermal straightening effect, and enter the online annealing of insulation annealing stove with being about to the coiled sheet that stretch rolls gets, and realized the casting strip of online plate shape control to obtain.Said method be the rolling thickness of having established of the attenuate of subsequent handling more near the production board thickness and the basis of the slab of good plate shape preferably, the production procedure that warm-rolling, cold rolling process are possessed with economy is rolled into last finished sheet.

Realize that liquid magnesium alloy is along casting roller transverse temperature difference, thickness difference, even distribution that current difference is as far as possible little entering lip, leave bigger up and down space for preceding case, lip based on the design of three-roll casting-rolling mill, allow to strengthen the volume at preceding case and lip interior metal liquid, molten metal self is with the homogeneity of big thermal capacitance, hot-fluid and maintenance thermophysical property.Preceding case is the liquid storage tank that molten metal enters lip, and liquid level wherein increases, and simultaneously the lip shortening is become the sheet of spacing greatly of the very short flow process on case limit before being attached to, and this moment, the pouring temperature reduction with molten metal did not result in blockage yet.The thermal conductivity factor of low-temperature metal is higher, by self heat conduction, also is the molten metal more uniform temperature.The manufacturing of case and lip adopts the multilayer composite heat insulating material to avoid heat radiation too much before the short flow process, and insulation material mainly consists of lithium silicate bonding magnesium borate crystal whisker, crystal whisker of hexa potassium titanate, glass fibre and magnesium oxide powder.These measures guarantee to enter the molten metal of roll gap at several respects uniformities such as temperature, flow velocity and flows.The temperature of the liquid magnesium alloy of case is more than 720 ℃ before entering during general casting, just can avoid entering the lip process and occur solidifying and form obstruction, and the application allows the temperature of the liquid magnesium alloy of preceding case is reduced to 690 ℃.This cloth stream method is one of key that realizes magnesium alloy wide cut thin plate method.Because when the liquid magnesium alloy that enter lip in the temperature field, the uniformity of velocity field and flow accurately controls, make molten metal amount, temperature and resistance of deformation when entering the casting roller gap subsequently also laterally basic identical like this, until the outlet of strip all has uniformity, do not deposit be used for dominance that inconsistency causes and recessive plate shape bad, the plate shape that obtains the casting strip is inevitable well have been reached from the bad cause of source control panel shape.Be used for increasing at the amount of metal at preceding case and lip place, easier raising precision of liquid surface height controlling and stability also help the unanimity of thickness of slab.

The big amount of rolling of split rolling method mainly be for eliminate by repeat-rolling strand exist more component segregation, coarse-grain, loose, dredge hole, crackle, pore, casting flaw such as be mingled with.Two roller continuous casting and rollings are produced magnesium alloy thin strips, and strip is generally below 4 millimeters, and the basic improvement of its solidification mode reduces even eliminates multiple coagulation defect, and therefore, the drafts of casting drops to about 50-60% and the little rolling drafts of warm-rolling.Because later warm-rolling difficulty is big, in total amount of rolling, it is big that the drafts that the casting operation is distributed is wanted.But cracking can appear in excessive drafts during casting too.Generally just can obtain the board quality the same with traditional milling method, but the drafts of general casting is greater than 40%, serious raw edges also appears easily, therefore, in order to make casting should have big rolling rate, avoid amount of rolling excessive and crack the casting effect of defective again, need be to designing and transform by the needs of three length of an interval degree such as liquid phase region, mushy zone, solid phase area according to the application.The initial temperature that studies have shown that controlled rolling in the casting-rolling technology is very important, and test shows that in semi-solid-state metal, wherein the ratio of liquid phase was less than 10% o'clock, and to stable rolling deformation, the liquid phase that wherein comprises meets the hydrostatics law.When considering that semi-solid-state metal is that solid and liquid capsule are formed, solid phase is partly obeyed traditional plastic deformation law, the stability under static the stretching.In the thixotropic forming process, the birth particle is kept apart mutually by a small amount of liquid film, is easy to like this realize that distortion this moment does not evenly destroy, and can obtain the complete and continuous product by sliding through mutual distance.If but the ratio of liquid phase is greater than 10% o'clock or more dendrites are arranged, then distortion is labile state, and the hot tear crack phenomenon takes place.Begin rollingly too early, there is a large amount of liquid metals on the surface of solidification layer, does not reach the purpose of plastic deformation.It is rolling to spend evening, and the temperature of solidification layer is low, and roll-force increases, and amount of plastic deformation descends, so rolling temperature is too high and cross low all is disadvantageous.General rolling temperature should be controlled at liquidus temperature.The balance liquidus temperature that for example contains the magnesium alloy of 4～6% aluminium is approximately about 500 ℃, if remain in uneven liquid phase this moment, can solidify immediately when contacting with forming rolls.The temperature that causes cracking easily is approximately about in the of 510 ℃.For this reason, it is rational that controlled rolling initial temperature is approximately 500 ℃.At the characteristics of the reducing casting roller pair of three-roll casting-rolling mill, be easy to the relative position adjustment of liquid phase region, mushy zone, solid phase area at rolling deformation.In the application's three-roll casting-rolling mill, lower roll is thick, allow the bottom of lip to be designed to longer contact arc, so the solidification layer that lower roll forms is thicker; Top roll is thin, and intensity of cooling is low, and allowing on upper strata, casting deformed area is semisolid, and the amount of liquid can be regulated more accurately.There are mixture simultaneously in rolling liquid and solid, and liquid is subjected to high rolling hydrostatic, and the extremely strong ability of soaking into is arranged.No matter be infiltration and filtration, liquid all can be extruded to cavity or crack place, and extremely strong permeance property is full of utmost point slight gap.The liquid on upper strata promptly is extruded and is filled to cracks, plays the effect of healed cracks with after coagulation.Be the tissue that thin casting plate that the casting of compound semisolid heavy reduction obtains has tentatively possessed bigger rolling rate, can effectively avoid the appearance of last casting strip crackle simultaneously.This in addition soft depressing impels the secondary dendrite arm spacing of process of setting to reduce, in addition because semisolid is crushed with the semisolid dendrite that is pressed into the crack, enlarged the ratio of thin equiax crystal, the ratio of having dwindled the common herringbone crystalline substance of casting, strip organizes further refinement.

Wide cut casting plate behind little transverse temperature difference cloth stream and the compound semisolid heavy reduction rate need possess the good characteristics of plate shape simultaneously, becomes easy when making follow-up attenuate warm-rolling; Otherwise, if but plate shape is poor, and then be difficult to adopt limited warm-rolling to correct.Based on the casting plate temperature in casting roll gap exit still about 350 ℃, substantially be in the scope of best hot-stretch aligning, for this reason, when utilizing the coiling machine of casting and rolling machine system and tension coiling tension force is controlled at the hot-stretch tension value, can reaches and batch and the tension straingtening dual purpose.Roughly about 150MPa, big if different alloys changes, also test draws the stress of hot-stretch tension force easily.Have estimated value to calculate the tension force setting value of coiling machine according to the wide and thickness of slab of plate, the control system of milling train keeps the range of stress of hot-stretch automatically then.

There is residual stress in strip after casting and the hot-stretch, and casting strip is routinely batched the nature cooling, and it is bad that these stress may become recessive plate shape.Recessive plate shape bad and effect and bad same being harmful to of dominance.There is residual stress in strip after the hot-stretch, and eliminating while hot is the best approach.The online strip that hot-stretch is aligned and batched twists in line and enters holding furnace annealing, and it is bad then to eliminate recessive plate shape.Because the surface temperature of the casting plate after the hot-stretch is still more than 200 ℃, the application covers accurate Coil Box on coiling machine, accurate Coil Box is actual to be the heat tracing stove, casting volume is heated to answer and recrystallization temperature and keeps always, be transferred to solution heat treatment furnace again after batching end at strip casting process.Accurate Coil Box is positioned on the railcar, can cover on the outside of the coiling machine rotating shaft position that installs roll coil of strip blank exactly, can remove again when unloading the roll coil of strip conveniently to get the volume operation.

Casting coiled sheet after solution heat treatment is softening is transferred in the reversible reciprocal operation of rolling of four rollers, the roll coil of strip overwhelming majority time all is in accurate Coil Box, accurate Coil Box is eliminated the work hardening that the coiled material internal stress causes, and coiled material makes the roll heating of reversable cold-rolling machine through conduction, to the reversible repeat-rolling of coiled material, the single pass reduction ratio is generally in the 5%-10% range, and mill speed can both realize rolling smoothly in very wide scope.Once dress rolls into and needs the wide cut of thickness thin plate to simplify the production procedure of magnesium alloy wide cut thin plate greatly, can be rolled down to very thinly usually from initial thickness always, generally can reach 0.3 millimeter or thinner, and thickness is selected according to product needed.Owing in a rolling process, finish whole finish rolling tasks.After being rolled down to the thickness that needs, suspending and open accurate Coil Box and get the volume operation, then carry out the rolling of next volume.The insulation annealing stove of the online plate shape of casting plate control is designed on guide rail the bell furnace form that can straight line moves, can conveniently remove and cover, and temperature also allows to regulate.So that press the rolling operation technological requirement adjustment of casting of concrete alloy and product.

After casting is finished, the needs that can satisfy product that have, can post processing after shipment.But generally all needing to carry out follow-up warm-rolling obtains thickness and performance and has and further require product.The magnesium alloy plate flat appearance of producing by the application's method, flawless, no layering, do not have that perforation, no backfin, nothing are caved in, no pitted skin, the bright and clean no greasy dirt of surfacing is silvery white in color or the metallic luster of grey black.Plate paper tinsel gauge can guarantee that within the margin of tolerance, the degree of accuracy of plate shape is higher.The microcosmic group is even, and second is mutually tiny, is evenly distributed.The crystal grain of casting plate is in 15-20um, inorganization defective; When the final thickness of sheet material is controlled at about 0.28mm, when the grain size size reaches below 10 microns, average out to 4-5 micron.

Description of drawings

Accompanying drawing 1 is magnesium alloy wide cut thin plate three roller casting and rolling installation schematic diagrames

The last drive roll of 1-

The 2-driven voller

Drive roll under the 3-

4-casting plate

The 5-lip

The 6-hot channel

It is that 800mm～1800mm and thickness are the production of the cast-rolled block of 2mm～6mm that the application's three roller casting-rolling technologies are suitable for width.

The liquid magnesium alloy that transports through the heat seal pipeline from holding furnace is introduced into the bigger front case 12 of volume, enters then the with it lip 5 of one connection. Front case and lip are lithium silicate bonding magnesium borate crystal whisker, crystal whisker of hexa potassium titanate, glass fibre and magnesium oxide powder with ceramic material manufacturing heat-resisting and insulation, chief component. These measures guarantee to enter the molten metal of roll gap at several respects uniformities such as temperature, flow velocity and flows. Enter the temperature of liquid magnesium alloy of front case during general casting more than 720 ℃, just can avoid entering the lip process and occur solidifying and form obstruction, the temperature of the liquid magnesium alloy of front case is reduced to 690 ℃. Because the thermal capacitance that front case and lip heat-insulating property, metal are bigger and the high thermal conductivity coefficient of low-temperature metal, make along Casting Roller transverse temperature difference, thickness difference, current difference littlelyr, and be difficult for stopping up. During casting and rolling machine work, top roll (backing roll) 1 and lower roll (Casting Roller) 3, with identical rotational speed, passive driven voller (Casting Roller) 2 also rotates with identical roller surface linear velocity thereupon by clockwise. The Casting Roller 2 that contacts with magnesium alloy in the lip 5 and 3 surface begin to solidify. Lower Casting Roller 3 and molten metal contact arc are longer, and setting time is also longer, and to the close process of roll gap, solidification layer is thickening gradually at roll surface. It is very short that upper Casting Roller (driven voller) 2 is used for contact arc, substantially is in semisolid district 9 near roll gap. Therefore, be that contact in rolling lower floor is solid-state 8, the upper strata is pasty state semisolid 9, when bearing roll and depressing, when drafts surpassed the solid strain tolerant, the solid of bottom can produce crackle, at this moment, liquid in the semisolid of upper strata can be extruded and penetrate into crackle and filling crackle, so that crackle is made up by healing at last. The semisolid dendrite that enters crackle 11 is crushed, and strip is organized further refinement. Simultaneously, the drafts of casting is big and avoided cracking, and board quality is better. About 350 ℃ of roll gap outlet Casting Rolled Sheet temperature is in the scope that best hot-stretch is aligned substantially, and coiling machine is set at hot-stretch tension value (stress is roughly in the 100MPa-150MPa scope), reaches when take-up the purpose of tension straingtening. There is residual stress and avoids to become recessive plate shape bad in order to eliminate strip after the hot-stretch,, keep at strip casting process as the heat tracing annealing furnace in the accurate Coil Box of coiling machine upper cover always, be transferred to again solution heat treatment furnace after batching end. Temperature insulation annealing furnace is can straight line on guide rail repeatedly mobile, removes and covers, and temperature also allows to regulate.

Specific embodiment

1800mm is wide, the casting and rolling production process of 3.8 millimeters thickness AZ31B magnesium alloy three-roll casting-rolling mill casting thin plates.

Preceding case and lip adopt integrative-structure, and actual is a container, and the magnesium liquid outlet of container is a lip, with ceramic material (heat-preservation cotton, glass fibre, magnesium borate crystal whisker, 6 potassium titanate crystal whiskers and lithium silicate bonding agent the are complex sintered) manufacturing of heat-resisting and insulation.The lateral length 1800mm of preceding chamber interior wall, vertical width 300mm, degree of depth 280mm, wide 35mm is stitched in the outlet of lip.The temperature of the magnesium alloy AZ31B molten metal of case is 690 ℃ before entering during casting.In normal casting production process, greatly about 35 kg/minute, the difference of transverse temperature, flow velocity, flow is controlled in 10% magnesium alloy by preceding case and lip flow.The difference of transverse temperature is directly read by thermo detector, and the difference of flow velocity and flow then adopts fluid simulation earlier and calculates estimation.Near the lip before the casting roll gap about 15: 85 of the ratio of semisolid and solid phase, this ratio can obtain from the fabric analysis of casting plate, regulates casting roller rotating speed, can reach the purpose of the ratio of regulating semisolid and solid phase.

The actual power of depressing of oil hydraulic cylinder is about 1800 tons about during casting.According to the measurement of online casting thickness of slab, regulate the roll gap at two ends, the roll left and right sides by changing both sides oil cylinder oil pressure respectively, to reach the purpose of control casting plate thickness of slab.The rotation direction of two driving rolls is identical, the speed governing of casting roller energy, and casting roller linear resonance surface velocity is about 4 meters/minute, and casting deformed area drafts reduces to 50%.The crackle of last casting strip is the raw edges form, and is the wideest about 6 millimeters.300 ℃ of temperature during casting plate hot-stretch aligning, the tensile stress setting value that coiling machine applies is kept the range of stress of hot-stretch automatically for 130MPa by control system.The design temperature of accurate Coil Box is greater than 300 ℃.

After casting was finished, fraction casting plate was as product, and the user is given in the shipment shipping after post processing.Major part needs further warm-rolling.The magnesium alloy plate flat appearance of producing by the application's method, flawless, no layering, do not have that perforation, no backfin, nothing are caved in, no pitted skin, the bright and clean no greasy dirt of surfacing is silvery white in color or the metallic luster of grey black.Sheet thickness dimension reaches within the margin of tolerance, and the degree of accuracy of plate shape is higher.The crystal grain of casting plate is in 35-50um, inorganization defective.Thin plate microcosmic group behind the further warm-rolling of casting plate is even, and second is mutually tiny, be evenly distributed, and after the warm-rolling plate thickness is less than 1 millimeter, when the grain size size reaches below 10 microns, average out to 4-5 micron.Thin plate can temperature strike out multiple shell part.

Claims (6)

1. magnesium alloy wide plate casting-rolling method, use magnesium alloy three roller wide plate casting-rolling machines, the liquid magnesium alloy casting is become the wide cut sheet billet, it is characterized in that: it is the isometrical pair of driven roller of 800mm～1200mm that these magnesium alloy three roller wide plate casting-rolling machines have a pair of identical diameter that turns to, promptly go up drive roll 1 and following drive roll 3, a diameter is 200mm～600mm driven voller 2, it is right that following drive roll 3 and driven voller 2 are formed the casting roller, be interior water-cooling structure, last drive roll 1 is the backing roll of driven voller 2, on one side and the plane at the axis place of three rollers tilt to lip; In use liquid magnesium alloy all is controlled at 10% with interior casting cloth stream method at lip 5 along temperature difference, thickness difference and the current difference that the horizontal cloth of casting roller flows, rolling district is compound semisolid, reduction ratio is the casting of 50%-60%, and the casting plate that casting goes out carries out online plate shape control.

2. as claims 1 described magnesium alloy wide plate casting-rolling method, it is characterized in that wherein the width of magnesium alloy wide plate is 800-1800mm, thickness is 2mm-6mm.

3. claims 1 described magnesium alloy wide plate casting-rolling method, it is characterized in that: the casting initial temperature is 500-520 ℃.

4. as claims 1 described magnesium alloy wide plate casting-rolling method, it is characterized in that: adopting rolling district lower floor is solid-state, the semi-solid compound semisolid casting in upper strata, and the liquid phase ratio is less than 10%.

5. as claims 1 described magnesium alloy wide plate casting-rolling method, it is characterized in that: the casting plate that casting goes out carries out online plate shape control and is meant the online hot-stretch aligning of casting plate, and the casting after batching twists in the line insulation annealing.

6. as claims 5 described magnesium alloy wide plate casting-rolling methods, it is characterized in that: the hot-stretch tension force of crimping machine is 100Mpa-150Mpa.

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