CN1939610A - Continuous high-temperature cast-rolling technology of magnesium and aluminium alloy plates or strips - Google Patents

Abstract

A continuous casting-rolling technique for the Mg-Al alloy plate or band features that the continuous dual-roller casting-rolling technique is combined with the hot rolling technique for improving the deformed structure, surface finish quality and surface accuracy. After the Mg-Al alloy plate is continuously cast and rolled, it is immediately hot-rolled by a pair of hot rollers.

Description

Magnesium, aluminum alloy sheets and strips continuous high-temperature cast-rolling technology

Technical field:

The invention belongs to the production technology of a kind of magnesium, aluminium metal sheet band, especially belong to the technology that a kind of pair of roller continuous casting and rolling and Re Wen tandem rolling combine, can directly become strip material to liquid metals with plastic deformation tissue.

Background technology:

Magnesium, aluminum alloy plate materials are the materials in tool extensive use field, and sheet material is carried out various bulk formings and sheet forming processing, can obtain various machine parts, hardware and equipment etc.Metal with the form of sheet material as the intermediate products supply, greatly simplified the metal material deep processing production procedure, reduce production costs, enlarge range of application.But, when sheet material when further pressure processing becomes various part, wish that sheet material even tissue, grain size are tiny, reach the effect the most favourable to the subsequent production process.

At present magnesium alloy plate is to adopt hot extrusion and rolling method production substantially, mainly is limited to the alloy of low alloying such as AZ21, AZ31, Mg-Mn is an alloy etc., and the intensity index of the magnesium alloy of low alloying is also lower.Hot extrusion can only be produced narrow band-type product, because productivity ratio is low, production cost is also higher, can not produce very thin product simultaneously.The low temperature and the temperature-room type plasticity of magnesium alloy are relatively poor, and general rolling temperature is all being carried out more than 250 ℃.When the distortion finishing temperature was lower than 250 ℃, magnesium alloy had very strong resistance of deformation.In addition, the thermal capacity of magnesium is little, and is responsive especially to temperature, as: the necessary preheating of roll aborning, otherwise rolling performance is also very low; The breaker roll preheating also requires the preheating speed to be convenient to adjustment, roll internal and external temperature unanimity.The technological process of production of magnesium alloy rolling plates is very complicated, comprises the production of strand, and strand mills face, and strand heating makes even tissueization, be then hot rolling, roughing, in roll, finish rolling, ply rolling, between need constantly to shear, pickling, slab are heated once more etc.The tissue of hot rolling product and performance are also inadequately evenly, size inaccuracy, surface smoothness and dimensional discrepancy be bigger, general many as the blank of proceeding Rolling Production.Hot-rolled temperature is generally 350---and 500 ℃, working modulus is respectively at 28-60%.The plate of hot rolling heats and carries out roughing, and the thickness of base is rolled to 5.5 millimeters from 10 millimeters, and slab heats once more, and the secondary roughing is rolled to 3.0 millimeters by 5.5 millimeters.The roughing product heat once more through shearing, pickling, slab, roll in carrying out, in roll no strict boundary, roll in the rolling general designation of all genus half products.Increase with passage, temperature reduces, and flow of metal belongs to incomplete cold deformation, rolled piece can with the similar mechanical (intensity height, percentage elongation reduce) of cold rolling goods.Rolling pass is generally 20---and 40 passages can reach the 50-60 passage at most.Pass reduction is generally 5%, and maximum is no more than 10%.In also want finish rolling after rolling, in roll with the finishing pass working modulus and have only substantially about 5%, roll to 1.3 millimeters from 2.7 millimeters.Ply rolling can rolling thinner sheet material, and thickness can roll to 0.5 millimeter, is applicable to the product not high to surperficial quality requirement.The ply rolling plate thickness is controlled at below 1.5 millimeters; The ply rolling plate should not surpass two, and the plate thickness difference is not more than 0.02 millimeter, heating and reduction ratio with in roll with finish rolling identical.Last mill product also will be annealed, finishing (shear, align), oxidation colouring, oiling packing.Because complex manufacturing, the cycle of magnesium alloy sheet are long, cause production cost very expensive.

The production equipment broadly similar of continuous asynchronous rolling casting technology of two rollers and twin-roll continuous casting technology, the cast sturcture of the continuous asynchronous cast-rolled block of two rollers is through fully pyroplastic deformation, its tissue and performance change a lot, on the basis of compression, increase to rub with the hands and cut distortion, compression and rub the deformation extent that the stack cut distortion increases substantially the cast sturcture of initial formation with the hands promotes to have the formation of the thin plate band of plastic deformation tissue signature.The asynchronous casting of two rollers mainly is to produce magnesium, aluminium alloy sheet band, be not suitable for thick sheet material, the asynchronous casting and rolling machine of two in addition rollers is produced magnesium, the surface smoothness of aluminium alloy sheet band and the index that dimensional accuracy still can not satisfy high-quality sheet material, needs follow-up rolling processing.

There is more excellent plastic deformation ability in Deformation structure than cast sturcture, and wherein, hot rolling is best to improving the material property effect.If the method with twin-roll continuous casting can once directly be produced the high performance strip material with Deformation structure, then is important breakthrough technically, practical significance is extremely great.Produce the technology of high performance magnesium, aluminium alloy sheet band with the method for twin-roll continuous casting, it is the forward position research and development problem of present world magnesium industry circle, the present both at home and abroad method of the twin-roll continuous casting of no use technology of producing this magnesium, aluminium alloy sheet band is not also more directly produced the technology of the thin plate with Deformation structure from liquid magnesium.

The purpose of invention is to realize the strip material of two roller continuous casting and rollings is implemented immediately the continuous high-temperature cast-rolling technology of hot rolling.

Summary of the invention

The inventor finds in production process, no matter be to adopt twin-roll continuous casting, and the still thin plate pair asynchronous continuous casting rolling technology productions of roller, when shaping sheet material leaves the casting roller, temperature is still higher, and temperature range is in higher mecystasis, satisfies the temperature conditions of hot rolling or warm-rolling substantially.Once used improved carry-over pinch rolls to board rolling for this reason, the effect of hot continuous rolling was arranged.Inference in view of the above, behind two roller continuous castings and hot-rolling mill be together in series, hot-rolling mill bear pyroplastic deformation in roll with finish rolling be fully possible, practice has also proved this point.

The advantage of the warm tandem rolling of heat is that rolling strip material has good Deformation structure's performance, owing to cancelled middle production link, avoids the damage of pilot process, has improved product quality; Once-forming, cost of equipment and production cost increase few, can give full play to the ability of equipment, significantly reduce energy consumption, improve yield rate and productivity ratio, reduce production costs, and can make metal carry out the transition to Deformation structure from cast sturcture, improve the processing performance of metal.

In order to realize magnesium, aluminium alloy continuous high-temperature cast-rolling, from the temperature changing regularity of strip, the basis of research magnesium, aluminium alloy continuous high-temperature cast-rolling.As long as provide necessary parameter, comprise diameter, heat transfer coefficient, linear resonance surface velocity, surface temperature, cooling water flow, environment temperature, radiating condition of molten metal temperature, specific heat, latent heat, hydrostatic head, density, surface tension, slab thickness, absolute draft amount, roll etc., just can calculate the temperature decline rule after shaped sheet leaves the casting roller theoretically.Because theoretical analytical Calculation is quite complicated loaded down with trivial details, and error is bigger, the temperature decline rule of actual measurement continuous casting and rolling process tabularium base is more convenient.Through a large amount of test, the casting base in the temperature in two rollers exit 500-300 ℃ of scope.Different working conditions, different slab thicknesses, temperature has bigger difference, generally is that slab is thick more, and temperature is high more.If suitably improve the linear resonance surface velocity of casting roller, temperature even higher.Along with strip blank leaves outlet, temperature continues to descend subsequently, and in 2 meters distances, temperature is still higher, partially overlaps with heat deformable regions in the diagram of forgeability behaviour, is in higher plastic range substantially.Therefore, realize that hot temperature tandem rolling is feasible.

Casting support back is that and then hot temperature tandem rolling support is installed, at a distance of certain distance two roller continuous castings and hot warm-rolling machine are being together in series, distance is wanted suitably, do not influencing under the operational hypothesis condition of two frames, the position of the warm tandem rolling support of heat should be positioned as close to the casting support, to reduce the heat radiation before the hot rolling.

For reducing rolling drag, the hot roll diameter is unsuitable excessive.For cut deal, with hot rolling system, form good deformation processing tissue than heavy reduction, small diameter roller is favourable greatly to drafts.Roll hardness needn't be very big, but need anti-chilling and shock heating.Thin plate band for the asynchronous continuous casting and rolling of two rollers, the strip material of plastic deformation tissue is preferably arranged, rolling under lower middle temperature, main purpose is further to improve Deformation structure, improve the surface smoothness and the surface accuracy of strip material, because drafts is little, roll hardness height, strip material surface smoothness height.The hot continuous rolling process system will guarantee to obtain the product of high-quality, must make full use of the plasticity of metal, give full play to equipment usefulness and boost productivity.For this reason, need be according to the temperature and the diagram of forgeability behaviour of the phasor of alloy, hot warm-rolling system, finishing temperature should not make strip break, and volume under pressure is not the maximum of crackle to occur.Finishing temperature is determining the tissue and the performance of product, the finishing temperature height, and except that the percentage elongation height, intensity index generally descends, and crystallization degree also improves with finishing temperature again.For example, during 260 ℃ of MB8 finishing temperatures, sheet material inside is in substantially and returns to form, and is crystalline state more completely.For stablizing the mechanical performance of sheet material, must strict control finishing temperature.Must according to second class again crystallization figure determine finishing temperature.The warm tandem rolling temperature schedule of heat comprises start rolling temperature and finishing temperature, and start rolling temperature should be selected the temperature range that plasticity is the highest, intensity is minimum according to alloy phase diagram and diagram of forgeability behaviour theoretically, and for most magnesium alloys, roughly temperature range is at 300 ℃ to 450 ℃.For the hot temperature tandem rolling that utilizes the casting waste heat, not necessarily satisfy above-mentioned condition fully.But as long as the control volume under pressure is no more than the permissible value under the relevant temperature, even the temperature departure optimum value is still feasible.Be steady production, temperature need be controlled at certain limit, and promptly start rolling temperature and finishing temperature generally are no more than the plasticity allowed band, and drafts will reduce heat radiation less than 30%, if must be able to be provided with the preheating of strip material.Except that the temperature of strip, hot warm-rolling roll temperature also is important process conditions, and it is the key of production high-quality sheet material.The thermal capacity of magnesium is little, and responsive especially to temperature, if the not preheating of hot aborning warm-rolling roller, its rolling performance is very low.To the preheat requirements of hot warm-rolling roller: the preheating speed should be convenient to adjust, hot warm-rolling roller internal and external temperature should be consistent, hot warm-rolling roll temperature maintains 200---and 250 ℃, cross low rolling performance and descend, cross high product organize thick, performance is low, roll banding, curling round the roll, surface quality is poor.The temperature of hot warm-rolling roller is high more, and the volume under pressure of permission is big more, and volume under pressure is big more, and hot temperature roll temperature rises fast more.Hot warm-rolling roller pre-heating mean can adopt methods such as gas preheating surface, inner logical steam, to reach the life-span of all even prolongation roller of internal and external temperature.New roller or shutdown are surpassed the diel person, and the beginning preheating speed wants slow, increase firing rate after 2 hours.Because the radiating condition difference of roller, the flame on both sides should be than broad in the middle.The preheat temperature of roll is wanted strict control, the plate that thickness is big, and temperature is got height, and the temperature of thin plate is got low.Practice shows, during rolling slab below 1.4 millimeters, hot warm-rolling roll temperature maintains 100---170 ℃ scope.

The control of the warm tandem rolling of heat mainly is the necessary and two roller continuous casting and rolling speeds match of hot temperature tandem rolling speed.Hot rolling drafts control generally is pressed onto the goods predetermined thickness according to the thickness of casting and rolling machine ejection, so roll gap numerical value preestablishes, and the machine run duration does not change.As running into the performance that rapid cooling will reduce alloy, plank is thinner more responsive when rolling for magnesium, aluminium alloy, so magnesium alloy do not adopt cooling and lubricating usually when rolling, and it is lubricated often to utilize the oxide-film of metal self to do, but can not solve the problem of adhesion.Roll adhesion in order to reduce when rolling is can be antiseized to the requirement of magnesium alloy lubricant, does not reduce the rolling performance (not influencing nipping of metal) of alloy again; Can firm attachment on the surface that is rolled deformable metal, can smear equably, high-temperature stable, not pollution metal, can remove from the metal surface easily, economical and easy to use.

The specific embodiment

The two roll sleeves of casting and rolling machine adopt the good gun-steel of performances, and water-cooling groove is arranged in the roller, the water flowing cooling rapidly, 650 millimeters of the diameters of roller, roller surface of revolution linear velocity be 2-30 rice/minute, adjustable, make a machine can produce multiple kind metal plate and belt.The two rollers employings of the warm tandem mill of heat satisfy bending resistance, antitorque, intensity is high, resistance to elevated temperatures and chilling and shock heating is good, wearability is good real core 60CrMnMo forged steel, 500 millimeters of the diameters of roller, roller surface of revolution linear velocity roller surface of revolution linear velocity automatic and casting and rolling machine is mated.Twin-roll cast-rolling mill and hot warm-rolling machine adopt disjunctor support or independent support, 2 meters of the centre-to-centre spacing of two kinds of rolls.To magnesium alloy plate continuous high-temperature cast-rolling production experiment, operations is functional, index up to specification.Experimental result shows that the present invention has design productivity ratio height, security performance is good, and the magnesium alloy plate surface quality is good, and interior tissue is a Deformation structure, and punching performance is better.

Claims (3)

1, a kind of magnesium, aluminum alloy sheets and strips continuous high-temperature cast-rolling technology of being used for, it is characterized in that: two roller continuous castings and hot warm-rolling machine closely are together in series, and then carry out hot rolling to being in hot sheet material behind two roller continuous casting and rollings, make cast sturcture become the deformation processing tissue, improve the surface smoothness and the surface accuracy of strip material simultaneously.

2, magnesium according to claim 1, aluminum alloy sheets and strips continuous high-temperature cast-rolling technology, it is characterized in that: two roller continuous castings and hot-rolling mill both can adopt separately independently support, also can adopt the disjunctor support, distance between casting roller and the hot roll is in 2m, to obtain minimum hot rolling drag.

3, magnesium according to claim 1, aluminum alloy sheets and strips continuous high-temperature cast-rolling technology, it is characterized in that: the strip material of two roller continuous casting and rollings carries out the hot rolling system than heavy reduction immediately under high as far as possible temperature, volume under pressure is 5～30% of a casting thickness of slab, makes it have better deformation processing tissue and performance and surface accuracy.