CN102179407A - Method for preparing hot rolling strip steel capable of preventing edge crack of extremely thin rolled strip steel - Google Patents
Method for preparing hot rolling strip steel capable of preventing edge crack of extremely thin rolled strip steel Download PDFInfo
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Abstract
The invention relates to a method for preparing hot rolling strip steel capable of preventing edge crack of extremely thin rolled strip steel. The method comprises the following steps of: (1) smelting, namely desulfurizing molten iron, smelting by using a converter, blowing argon at an argon station, and performing continuous casting to form slabs; (2) performing hot rolling, namely heating the slabs to 1,210 to 1260 DEG C, wherein the temperature difference of the same slab is less than or equal to 30 DEG C; performing rough rolling, and finish rolling, wherein the side pressure delta B when the slab with the width B is subjected to rough rolling is controlled according to the following formula: delta B ranges from 35*B/1,250*(B-1,050)/(1,250-1,050)+35*B/1,050*(1,250-B)/(1,250-1,050) to 50; and finally reeling to obtain the hot rolling strip steel. The method is simple and practical, is stable in use and high in uniformity, reduces the alloy cost and shortens the production cycle; and the steel plate heat commercial (SPHC) hot rolling strip steel prepared by the method has the obvious effect of preventing the edge crack of extremely thin cold-rolled sheet.
Description
Technical field
The invention belongs to the band steel and be equipped with the field, particularly relate to a kind of preparation method who avoids the hot-strip that rolling strip edge as thin as a wafer splits.
Background technology
In China Yangtze River Delta Area, building trades such as household electrical appliances and colored steel are very flourishing, use low-carbon steel material, thickness of slab specification cold-reduced sheet as thin as a wafer, galvanized sheet, the Coil Coating Products below 0.5mm mostly.The cold rolling mill of this series products of domestic production mostly is medium-sized private enterprise, generally all adopt single chassis or the cold rolling unit of two-shipper stand reversible, using the low-carbon (LC) hot-continuous-rolling strip steel to make the thickness of slab specification is the cold-strip steel as thin as a wafer of 0.15～0.39mm, because its cold rolling tension force is very big, mill speed is fast and total reduction ratio is very high, be easy to occur narrow rule, limit portion breach, toothed edge defective, sometimes excessive even quality accidents such as broken belt, quick-fried roller take place because of raw edges, not only have a strong impact on user's ordinary production, and cause heavy economic losses.
It is a kind of crackle that comes across strip edge portion, is vertical curve or chevron distribution that the limit is split.Study carefully it and produce reason, cut Bian Yuanpan cutting edge wearing and tearing passivation or blade clearance during except that, burning overheated, coil of strip edge mechanical damage, cold-rolling pickling with the hot rolling slab edge, that cutting edge coincidence amount is adjusted is improper, too small, the cold rolling overall reduction of acid washing and edge cutting amount is excessive, the reduction ratio of each passage and tension force unreasonable distribution etc. relevant, also the inherent quality (as existing chemical composition segregation, rimhole and field trash on the high side) of mainly rolling up with incoming hot rolled slab is relevant; For this reason, each hot rolling supply of material producer all does one's utmost to improve the inherent degree of purity of hot rolled coil, for satisfying the requirement of the rolling cold-strip steel as thin as a wafer of cold rolling mill, all make great efforts to reduce S content, improve Mn content and Mn/S value, and with steel inclusion rank to 0.5 grade～below 1 grade, even do not stint and handle through the LF refining furnace, fully purify steel; These methods all can cause production cost obviously to increase.
In August, 2004, Seat etc. discloses a patent of invention " edge regions at cold-rolling of metal strips applies the method and apparatus that a kind of adjustable tensile-stress distributes " (patent publication No. CN 1845803A in China the Germany SMS H.P. of company, open day on October 11st, 2006), make the lubricated of working roll and cooling separately by being lubricated at cold rolling unit entrance side and cooling off at outlet side, use the section injection apparatus to spray rolled lubricating oil strip edge portion is applied methods such as added influence, its objective is and reduce the danger that generates too high pulling force and strip edge portion cracking with different temperatures scope.But if use at the medium and small cold rolling mill of China's numerous domestic, because of need at cold rolling unit newly added equipment, be subjected to the restriction of on-the-spot place, and increase production cost and everyday devices working service cost.
In January, 2008, the Qiao Lei of Anshan iron and steel plant joint-stock company etc. has applied for a utility model patent " a kind of hot continuous rolling unit prevents to produce the device that the limit is split with steel " (patent announcement CN 201183064Y, January 21 2009 Granted publication day), feature is at hot rolling unit flipper guide horn mouth and flipper guide passage intersection, transmission side and active side are installed guide wheel device respectively, and the hot-rolling oil nozzle is installed in guide wheel device body of roll both sides, spray hot-rolling oil in the operation of rolling and produce the limit to avoid strip edge portion scratching flipper guide and split.Its shortcoming is: 1. increase manufacturing facilities; 2. use hot-rolling oil, increase production cost, pollute the production site environment, cost of equipment maintenance increases; 3. can only partly solve the hot-strip limit and split problem, fail to solve in the cold-rolled process as thin as a wafer limit and split problem with steel.
In May, 2005, the Hu Hongxu of Angang Xinya company etc. has applied for a patent of invention " control method for acid washing and edge cutting of super low carbon soft steel " (patent publication No. CN 1858666A, open day on November 8th, 2006), what it is characterized in that the horizontal clearance value of circle shear and down suction value cuts the limit parameter value by calculating by process computer with the linear Mathematical Modeling of raw thickness, after the actual Test Application in scene, defect level such as split and descended about 55% than in the past because of cutting finished product cold-strip steel toothed edge, the limit of causing on the limit; But still problem is split on the limit of failing thoroughly to solve the finished product cold-strip steel.
Though domestic most of iron and steel enterprise produces when cold-strip steel is used hot rolled coil as thin as a wafer, produce horizontal micro-crack for suppressing steel plate limit portion, all require the Mn/S value in the steel is controlled at more than 20 (even 30), but in steel mills such as Ningbo iron company, for reducing production costs, the S content of smelting with steel scrap auxiliary material and molten iron remains high, and improve the Mn/S value, have to increase Mn content, the product smelting cost has the rising of certain amplitude like this.
Summary of the invention
Technical problem to be solved by this invention provides a kind of preparation method who avoids the hot-strip that rolling strip edge as thin as a wafer splits, and technology of the present invention is simple and easy to do, has the unique advantage of low-carbon (LC), green, environmental protection, is easy to large-scale promotion and uses; Method of the present invention had so both reduced cost of alloy, can shorten the production cycle again, and it is remarkable to prevent that cold rolling as thin as a wafer edges of boards from splitting effect.
A kind of preparation method who avoids the hot-strip that rolling strip edge as thin as a wafer splits of the present invention comprises:
(1) smelting process: adopt desulfurizing iron, converter smelting, the processing of argon station Argon, continuous casting to become slab, wherein pouring molten steel time control molten steel overheat is+15～+ 25 ℃ in the continuous casting, the strand pulling rate is controlled to be 1.30～1.45m/min, and the strand width is that (the mill product plate is wide by 1000～1260mm) for 1050～1300mm;
(2) hot rolling technology: slab is heated to 1210～1260 ℃, with the plate temperature difference≤30 ℃; Carry out roughing then, the roughing outlet temperature is 1060～1100 ℃, and the edger roll before the roughing mill adopts width automatic hydraulic control technology and short stroke control; Then carry out finish rolling, finishing temperature is 870～910 ℃, adopts the fast cold laminar flow type of cooling of leading portion that the band steel is cooled off, and cooling velocity is 15～30 ℃/s; Batch at last, promptly get this hot-strip, wherein coiling temperature is 640～680 ℃.
In the above-mentioned steps (1) during continuous casting, should establish the continuous casting operating procedure theory of " low temperature draws soon, anti-limit split ".
When slab is heated, even in the above-mentioned steps (2) for guaranteeing slab heating temperature, guarantee that heating-up temperature is higher than 20～30 ℃ of heating-up temperatures down; The control firing rate prevents that excessive velocities from causing steel material internal-external temperature difference excessive; Make board briquette even in this low-temperature heat stage of heating furnace preheating section, and then improve firing rate; Time inside furnace 150～200min, even to guarantee high-temperature region plate temperature.
In the above-mentioned steps (2), when carrying out roughing, the lower limit of lateral pressure amount Δ B is controlled to be that Δ B 〉=35 * B/1250 * (B-1050)/(1250-1050)+35 * B/1050 * (1250-B)/(1250-1050), wherein B is the continuous casting steel billet width; The higher limit of lateral pressure amount Δ B is controlled to be 50mm; In addition, width of plate slab through the roughing side pressure subtract narrow after, should meet finished product hot rolled coil order specification; Set roughing lateral pressure amount Δ B value thus.Adopt stay-warm case between second roughing mill and the finishing mill, effectively reduce the temperature drop of hot rolled plate on roller-way.
In the above-mentioned steps (2) the band steel is carried out laminar flow when cooling, control side water injection valve winding-up angle makes it evenly purge belt steel surface along plate width direction, and strictness is avoided only strip edge portion being jetted.
When batching in the above-mentioned steps (2), control is with the steel camber to be≤15mm/5m, is not more than 15mm in promptly every 5m, in order to avoid strip edge portion scraping flipper guide clashes the spark that flashes, causes strip edge portion grain structure unusual.
The chemical composition of gained hot-strip is by weight percentage in the above-mentioned steps (2): 0＜C≤0.07%, 0＜Si≤0.030%, 0.09%≤Mn≤0.29%, 0＜P≤0.025%, 0＜S≤0.020%, 0.012%≤Als≤0.050%, 0＜N≤0.006%, all the other are iron and unavoidable impurities, wherein field trash rank≤3 grade.
The product grade of gained hot-strip is SPHC in the above-mentioned steps (2), chemical composition and mechanical property are carried out by existing commercial SPHC delivery technical conditions, thickness range is 2.5～3.0mm, the plate wide region is 1000～1260mm, wherein the hot-strip grain structure is ferrite and a small amount of pearlite, the steel plate grain size number is 8.0～9.5 grades, hot-strip limit portion grain structure mixed crystal rank≤0.5 grade, and the field trash rank can be 2.0～3.0 grades.
Because existing cold rolling plate as thin as a wafer manufacturing firm mainly produces the cold-strip steel of 1000mm, two kinds of width specifications of 1200mm, the main thickness specification of using of coils of hot-rolled steel is 2.5～3.0mm, consider that coils of hot-rolled steel cuts drawing down situation in limit and subsequently the cold rolling production process at the pickling unit, produce cold rolling steel band as thin as a wafer so the user mainly orders the SPHC coils of hot-rolled steel of 1015mm, two kinds of width specifications of 1215mm.
Operation principle
Split the smelting of formation because of mixed crystal causes the cold-rolled thin steel strip limit, the hot rolling technology reason has:
1) steel billet exists thick column crystal, subcrack, chink and a large amount of inherent quality problem such as be mingled with; 2) steel billet existing micro-crack before advancing heating furnace; 3) billet heating temperature is higher, and heating-up temperature inequality everywhere, causes tissue abnormalities, thereby causes that performance descends, and causes steel billet the limit to occur after rolling and splits.Solution mainly is: 1. rationally control the pulling rate and the cooling water ratio of conticaster, the cooling velocity of control steel billet prevents thick column crystal and crackle of steel billet; 2. strict control soaking pit firing rate and temperature avoid high temperature to descend long-time heating, and make regular check on the school inspection work of heating furnace and instrument.
Improve in the steel Mn/S value and can effectively suppress steel plate limit portion and produce horizontal micro-crack, this be because: S in the steel and Fe form FeS, and FeS and Fe formation low-melting-point eutectic form reticular membrane on crystal boundary, and in the later process operation of rolling the hot-short phenomenon of generation.By adding the Mn of capacity, because the affinity of manganese and sulphur is much larger than the affinity of sulphur and iron,, be present in crystal grain inside so can impel the sulphur MnS higher than FeS in the steel with its formation fusing point, offset the hot-short effect of the low-melting-point eutectic generation of FeS and Fe formation, reach the purpose that suppresses micro-crack.
Fall S owing to Mn/S value in the raising steel must increase Mn, cost increases obviously, and the present invention studies under the very low prerequisite of Mn/S value, suppresses the method that the cold-rolled thin steel strip limit is split.
Carrying out when hot rolling is produced is to guarantee that slab heating temperature is even, must accomplish:
When 1) heating, be called heating, be called heating down by the burner heat supply of steel billet bottom by the burner heat supply on steel billet top in the high-temperature region.Should guarantee that heating-up temperature is higher than 20～30 ℃ of heating-up temperatures down, to reduce the temperature difference of top and bottom.
2) strict control firing rate prevents that excessive velocities from causing steel material internal-external temperature difference excessive, and must make temperature even at low thermophase, and then improves firing rate.
3) often observe Temperature Distribution situation in the stove, correctly adjust in the stove temperature and make along the temperature of the wide each point of stove and keep evenly can reducing along the temperature difference on the charge length.
4) soaking zone will have enough temperature retention times, to guarantee that temperature is even.
Slab is when hot rolling roughing unit is rolling, and the side pressure that must suit is rolling, is heated to the thick austenite crystal tissue that forms in the process of austenitizing with abundant fragmentation, refinement continuous casting billet limit portion column crystal in heating furnace.Producing the strand width B that cold-reduced sheet as thin as a wafer uses at present is that 1050～1300mm, mill product hot-strip width are 1000～1260mm, and the present invention draws, and during the hot rolling roughing, its suitable lateral pressure amount Δ B need satisfy following two requirements:
(1)50≥ΔB≥35×B/1250×(B-1050)/(1250-1050)+35×B/1050×(1250-B)/(1250-1050)；
(2) width of plate slab through the roughing side pressure subtract narrow after, meet finished product hot rolled coil order specification.
When the band steel was carried out the laminar flow cooling, strict control side water injection valve opened and closed sequential and winding-up angle, makes it evenly purge belt steel surface along plate width direction, and strictness is avoided only strip edge portion being jetted.In the coiling process, by control band steel camber, come strict control strip running deviation, the flipper guide in order to avoid strip edge portion acutely swipes, clash the spark that flashes, cause when batching band crystalline grain of steel tissue by austenite in the ferritic transformation process, limit portion grain structure takes place unusually because of the input of extraneous mechanical damage and additional heat energy, the colder zone of limit portion forms ferrite crystal grain in advance, engulf the ferrite crystal grain that the partial heat zone later stage forms and grow up, the ferrite crystal grain everywhere that the result forms is organized the thickness inequality, and causes mixed crystal to occur.
In a word, the thick column crystal in the steel plate, part be grain structure state such as crystallization and strain-induced crystal boundary migration again, can cause unusual coarse-grain, mixed grain structure occurring in the ferrite+pearlite of finished product hot-strip, must avoid as possible.
Because of mixed crystal causes the inherent mechanism that formation is split on the cold-rolled thin steel strip limit be:
The carbon that can influence between intracrystalline and the crystal boundary by change crystal boundary place's segregation source number and crystallite dimension distributes.Along with crystallite dimension increases, grain boundary area reduces, and the carbon total amount that is stored in the crystal boundary place then is lower than fine grained structure.Tiny grain structure can make YIELD STRENGTH and tensile strength improve.Crystal grain is more tiny, and crystal boundary just relatively the more; Because of crystal boundary can be limited to plastic deformation in certain scope, make the distortion homogenising, so crystal grain thinning can improve the plasticity of material; Crystal boundary is again the resistance of crackle expansion, so crystal grain thinning can also improve the toughness of material; Thick crystal grain is then opposite, and is less relatively because of its crystal boundary, is easy to take place non-homogeneousization distortion, and can not effectively hinder crackle expansion, thus mould, poor toughness; The hot-strip edging tissue is if having unusual coarse-grain, mixed crystal phenomenon to exist, and then certainly will when rolling cold rolling plate as thin as a wafer the limit take place very easily and split defective.
The invention provides and a kind ofly overcritically reducing S content (≤0.020% gets final product) in the steel, do not increasing under the prerequisite of Mn/S value (〉=4.5 get final product), not strict restriction steel inclusion rank (≤3.0 grades get final product), by control hot-strip limit portion grain structure, avoid occurring obvious mixed crystal, thereby prevent that flat cold-rolled sheet from producing the method that the limit is split.
Beneficial effect
Compared with prior art, the present invention has the following advantages:
1, the present invention is easy to operate: need not hardware facilities such as incoming what production equipment, do not have newly-increased technological process.
2, the present invention manipulates stable: this method can be guaranteed the stable use of existing rolling mill practice equipment, and satisfies the technological parameter requirement that sets easily, and is simple and easy to do, is easy to large-scale promotion and uses.
3, the present invention is because of going the refining furnace of field trash to handle to molten steel, allow field trash ranks such as sour molten aluminium to reach 2.0～3.0 grades, so not only can effectively reduce the auxilliary material consumption of steel-making, but also can significantly reduce power consumption, and shorten the heat, unique advantage with low-carbon (LC), green, environmental protection is applied in the iron and steel enterprise at home, is expected to obtain great economic benefit and social benefit.
4, uniformity is good: but the present invention's all standard, unified utilizations in existing hot continuous rolling factory and single, double frame reversible cold-rolling factory.
5, the overcritical S content of hot-strip of the present invention＜0.01%, also overcritical Mn/S＞20 had so both reduced cost of alloy, can shorten the production cycle again, and obviously improved the smelting hit rate and count ratio with the qualified stove of steel-making.
6, the present invention significantly reduces accident rate, can prevent from significantly in the cold rolling of strip steel production as thin as a wafer to produce that the limit is split, the serious accident of broken belt, thereby significantly improves the quality of products, and improves the unit operation rate, reduces production costs.
Description of drawings
Fig. 1 is the hot-strip limit portion metallographic structure of embodiment 1.
Fig. 2 is the cold-strip steel limit portion shape appearance figure of embodiment 1.
Fig. 3 is the hot-strip limit portion metallographic structure of embodiment 2.
Fig. 4 is the cold-strip steel limit portion shape appearance figure of embodiment 2.
Fig. 5 is the hot-strip limit portion metallographic structure of comparative example 1.
Fig. 6 is the cold-strip steel limit portion breach defective shape appearance figure of comparative example 1.
Fig. 7 is the hot-strip limit portion metallographic structure of comparative example 2.
Fig. 8 is the cold-strip steel limit portion breach defective shape appearance figure of comparative example 2.
The specific embodiment
Below in conjunction with specific embodiment, further set forth the present invention.Should be understood that these embodiment only to be used to the present invention is described and be not used in and limit the scope of the invention.Should be understood that in addition those skilled in the art can make various changes or modifications the present invention after the content of having read the present invention's instruction, these equivalent form of values fall within the application's appended claims institute restricted portion equally.
Embodiment 1
The percentage by weight of slab chemical composition is:
C:0.06%, Si:0.015%, Mn:0.095%, P:0.019%, S:0.018%, Als:0.039%, N:0.0027%, all the other are Fe and unavoidable impurities.
Steel-making adopts desulfurizing iron, converter smelting, the processing of argon station Argon, continuous casting to become slab.The control molten steel overheat is+19 ℃ during pouring molten steel, and the strand pulling rate is pressed 1.40m/min～1.45m/min control, and the strand width is 1050mm, the wide 1015mm of mill product plate.
Hot rolling: the cold charge slab is heated to 1230 ℃, with the plate temperature difference≤30 ℃, time inside furnace 170min; Carry out roughing, the roughing outlet temperature is 1080 ℃, and the edger roll before the roughing mill R2 adopts width automatic hydraulic control technology and short stroke control.Width of plate slab B is 1050mm, and by the inventive method, lateral pressure amount Δ B must satisfy during roughing:
50≥ΔB≥35×1050/1250×(1050-1050)/(1250-1050)+35×1050/1050×(1250-1050)/(1250-1050)
I.e. 50 〉=Δ B 〉=35mm; In view of hot rolled coil order specification is 1015mm, it is 35mm that the roughing lateral pressure amount is chosen on the historical facts or anecdotes border.
Adopt stay-warm case between second roughing mill and the finishing mill, reduce the temperature drop of hot rolled plate on roller-way.
The finishing temperature of finish rolling is 885 ℃, and finished strip thickness is 2.50mm, adopts the fast cold laminar flow type of cooling of leading portion that the band steel is cooled off, and cooling velocity is 29 ℃/s; When the band steel was carried out the laminar flow cooling, control side water injection valve winding-up angle made it evenly purge belt steel surface along plate width direction, and strictness is avoided only strip edge portion being jetted.
It is 650 ℃ that hot-strip batches temperature, and in the coiling process, control band steel camber≤15mm/5m is in order to avoid strip edge portion scraping flipper guide clashes the spark that flashes.
The finished product hot rolled plate grain structure that obtains at last is ferrite and a small amount of pearlite; The molten aluminium field trash rank of acid is 3 grades, and its limit portion microcosmic metallographic structure as shown in Figure 1.
This hot-strip edging tissue is ferrite+a small amount of pearlite, and grain size number is 9.5 grades (according to GB/T6394-2002 metal material grain size grading standard testings, down with), and does not have mixed crystal phenomenon (mixed crystal rank≤0.5 grade).
This hot rolled coil specification is 2.50mm * 1050mm * C, is rolled into the 0.28mm cold-rolled thin steel strip on 1450 single-stand cold-rolling machine groups, the boundless defective of splitting, as shown in Figure 2.
The percentage by weight of slab chemical composition is:
C:0.032%, Si:0.012%, Mn:0.19%, P:0.018%, S:0.0158%, Als:0.022%, N:0.0033%, all the other are Fe and unavoidable impurities.
Steel-making adopts desulfurizing iron, converter smelting, the processing of argon station Argon, continuous casting to become slab.The control molten steel overheat is+25 ℃ during pouring molten steel, and the strand pulling rate is pressed 1.30m/min～1.40m/min control, and the strand width is 1250mm, the wide 1215mm of mill product plate.
Hot rolling: the cold charge slab is heated to 1240 ℃, with the plate temperature difference≤30 ℃, time inside furnace 155min; Carry out roughing, the roughing outlet temperature is 1085 ℃, and the edger roll before the roughing mill adopts width automatic hydraulic control technology and short stroke control.Width of plate slab B is 1250mm, and by the inventive method, lateral pressure amount Δ B must satisfy during roughing:
50≥ΔB≥35×1250/1250×(1250-1050)/(1250-1050)+35×1250/1050×(1250-1250)/(1250-1050)
I.e. 50 〉=Δ B 〉=35mm; In view of hot rolled coil order specification is 1215mm, it is 35mm that the roughing lateral pressure amount is chosen on the historical facts or anecdotes border.
Adopt stay-warm case between second roughing mill and the finishing mill, reduce the temperature drop of hot rolled plate on roller-way.
The finishing temperature of finish rolling is 882 ℃, and finished strip thickness is 2.75mm, adopts the fast cold laminar flow type of cooling of leading portion that the band steel is cooled off, and cooling velocity is 21 ℃/s; When the band steel was carried out the laminar flow cooling, control side water injection valve winding-up angle made it evenly purge belt steel surface along plate width direction, and strictness is avoided only strip edge portion being jetted.
It is 655 ℃ that hot-strip batches temperature, and in the coiling process, control band steel camber≤15mm/5m is in order to avoid strip edge portion scraping flipper guide clashes the spark that flashes.
The finished product hot rolled plate grain structure that obtains at last is ferrite and a small amount of pearlite; Its limit portion microcosmic metallographic structure as shown in Figure 3.
This hot-strip edging tissue is ferrite+a small amount of pearlite, and sour molten aluminium field trash rank is 2.5 grades, and grain size number is 9.0 grades, and does not have mixed crystal phenomenon (mixed crystal rank≤0.5 grade), as shown in Figure 3.
This hot rolled coil specification is 2.75mm * 1250mm * C, is rolled into the 0.29mm cold-rolled thin steel strip on 1450 single-stand cold-rolling machine groups, the boundless defective of splitting, as shown in Figure 4.
Embodiment 3
The percentage by weight of slab chemical composition is:
C:0.07%, Si:0.030%, Mn:0.29%, P:0.025%, S:0.008%, Als:0.049%, N:0.006%, all the other are Fe and unavoidable impurities.
Steel-making adopts desulfurizing iron, converter smelting, the processing of argon station Argon, continuous casting to become slab.The control molten steel overheat is+15 ℃ during pouring molten steel, and the strand pulling rate is pressed 1.40m/min～1.45m/min control, and the strand width is 1300mm, the wide 1260mm of mill product plate.
Hot rolling: the cold charge slab is heated to 1255 ℃, with the plate temperature difference≤20 ℃, time inside furnace 180min; Carry out roughing, the roughing outlet temperature is 1090 ℃, and the edger roll before the roughing mill R2 adopts width automatic hydraulic control technology and short stroke control.Width of plate slab B is 1300mm, and by the inventive method, lateral pressure amount Δ B must satisfy during roughing:
50≥ΔB≥35×1300/1250×(1300-1050)/(1250-1050)+35×1300/1050×(1250-1300)/(1250-1050)
I.e. 50 〉=Δ B 〉=34.66mm; In view of hot rolled coil order specification is 1260mm, it is 40mm that the roughing lateral pressure amount is chosen on the historical facts or anecdotes border.
Adopt stay-warm case between second roughing mill and the finishing mill, reduce the temperature drop of hot rolled plate on roller-way.
The finishing temperature of finish rolling is 905 ℃, and finished strip thickness is 3.0mm, adopts the fast cold laminar flow type of cooling of leading portion that the band steel is cooled off, and cooling velocity is 15 ℃/s; When the band steel was carried out the laminar flow cooling, control side water injection valve winding-up angle made it evenly purge belt steel surface along plate width direction, and strictness is avoided only strip edge portion being jetted.
It is 680 ℃ that hot-strip batches temperature, and in the coiling process, control band steel camber≤15mm/5m is in order to avoid strip edge portion scraping flipper guide clashes the spark that flashes.
The finished product hot rolled plate grain structure that obtains at last is ferrite and a small amount of pearlite; The molten aluminium field trash rank of acid is 2 grades.
This hot-strip edging tissue is ferrite+a small amount of pearlite, and grain size number is 8.0 grades, and does not have mixed crystal phenomenon (mixed crystal rank≤0.5 grade).
This hot rolled coil specification is 3.0mm * 1260mm * C, is rolled into the 0.30mm cold-rolled thin steel strip on 1450 single-stand cold-rolling machine groups, the boundless defective of splitting.
Comparative example 1
The percentage by weight of slab chemical composition is:
C:0.036%, Si:0.010%, Mn:0.29%, P:0.016%, S:0.011%, Als:0.042%, N:0.0035%, all the other are Fe and unavoidable impurities.
Steel-making adopts desulfurizing iron, converter smelting, the processing of argon station Argon, continuous casting to become slab.The control molten steel overheat is+29 ℃ during pouring molten steel, and the strand pulling rate is pressed 1.05m/min～1.15m/min control, and the strand width is 1050mm, the wide 1050mm of mill product plate.
Hot rolling: the cold charge slab is heated to 1230 ℃, with the plate temperature difference≤30 ℃, time inside furnace 170min; Carry out roughing, the roughing outlet temperature is 1080 ℃, and the edger roll before the roughing mill R2 adopts width automatic hydraulic control technology and short stroke control, lateral pressure amount Δ B=0 during roughing.
Adopt stay-warm case between second roughing mill and the finishing mill, reduce the temperature drop of hot rolled plate on roller-way.
The finishing temperature of finish rolling is 885 ℃, and finished strip thickness is 2.50mm, adopts the fast cold laminar flow type of cooling of leading portion that the band steel is cooled off, and cooling velocity is 20 ℃/s.
It is 680 ℃ that hot-strip batches temperature, and in the coiling process, strip edge portion scraping flipper guide is more serious.
The limit portion microcosmic metallographic structure of the finished product hot rolled plate that obtains at last as shown in Figure 5.
This hot-strip edging tissue is ferrite+pearlite, and sour molten aluminium field trash rank is 2.5 grades, and obvious mixed crystal phenomenon is arranged, the mixed crystal situation: 9.5 grades account for 50%; 12 grades account for 50%.
This hot rolled coil specification is 2.50mm * 1050mm * C, is rolled into the 0.28mm cold-rolled thin steel strip on certain 1450 single-stand cold-rolling machine group, obvious limit portion breach defective is arranged, as shown in Figure 6.
Comparative example 2
The percentage by weight of slab chemical composition is:
C:0.031%, Si:0.011%, Mn:0.31%, P:0.017%, S:0.010%, Als:0.041%, N:0.0037%, all the other are Fe and unavoidable impurities.
Steel-making adopts desulfurizing iron, converter smelting, the processing of argon station Argon, continuous casting to become slab.The control molten steel overheat is+34 ℃ during pouring molten steel, and the strand pulling rate is pressed 1.00m/min～1.05m/min control, and the strand width is 1250mm, the wide 1250mm of mill product plate.
Hot rolling: the cold charge slab is heated to 1240 ℃, with the plate temperature difference≤30 ℃, time inside furnace 180min; Carry out roughing, the roughing outlet temperature is 1080 ℃, and the edger roll before the roughing mill R2 adopts width automatic hydraulic control technology and short stroke control.Lateral pressure amount Δ B=0 during roughing.
Adopt stay-warm case between second roughing mill and the finishing mill, reduce the temperature drop of hot rolled plate on roller-way.
The finishing temperature of finish rolling is 885 ℃, and finished strip thickness is 2.75mm, adopts the fast cold laminar flow type of cooling of leading portion that the band steel is cooled off, and cooling velocity is 20 ℃/s.
It is 680 ℃ that hot-strip batches temperature, and in the coiling process, strip edge portion scraping flipper guide is more serious.
The limit portion microcosmic metallographic structure of the finished product hot rolled plate that obtains at last as shown in Figure 7.
This hot-strip edging tissue is ferrite+pearlite, and sour molten aluminium field trash rank is 2.5 grades, and obvious mixed crystal phenomenon is arranged, the mixed crystal situation: 9 grades account for 50%; 11.5 level accounts for 50%.
This hot rolled coil specification is 2.75mm * 1250mm * C, is rolled into the 0.29mm cold-rolled thin steel strip on certain 1450 single-stand cold-rolling machine group, obvious limit portion breach defective is arranged, as shown in Figure 8.
Claims (7)
1. preparation method that can avoid the hot-strip that rolling strip edge as thin as a wafer splits comprises:
(1) adopt that desulfurizing iron, converter smelting, argon station Argon are handled, continuous casting becomes slab, wherein in the continuous casting during pouring molten steel control molten steel overheat be+15～+ 25 ℃, the strand pulling rate is controlled to be 1.30～1.45m/min, the strand width is 1050～1300mm;
(2) slab is heated to 1210～1260 ℃, with the plate temperature difference≤30 ℃; Carry out roughing then, the roughing outlet temperature is 1060～1100 ℃, and the edger roll before the roughing mill adopts width automatic hydraulic control technology and short stroke control; Then carry out finish rolling, finishing temperature is 870～910 ℃, adopts the fast cold laminar flow type of cooling of leading portion that the band steel is cooled off, and cooling velocity is 15～30 ℃/s; Batch at last, promptly get this hot-strip, wherein coiling temperature is 640～680 ℃.
2. a kind of preparation method who avoids the hot-strip that rolling strip edge as thin as a wafer splits according to claim 1, it is characterized in that: when slab was heated, following heating-up temperature was higher than 20～30 ℃ of heating-up temperatures, time inside furnace 150～200min in the step (2).
3. a kind of preparation method who avoids the hot-strip that rolling strip edge as thin as a wafer splits according to claim 1, it is characterized in that: when carrying out roughing in the step (2), lateral pressure amount Δ B value is controlled to be 50 〉=Δ B 〉=35 * B/1250 * (B-1050)/(1250-1050)+35 * B/1050 * (1250-B)/(1250-1050), wherein B is the continuous casting steel billet width, and the unit of Δ B is mm.
4. a kind of preparation method who avoids the hot-strip that rolling strip edge as thin as a wafer splits according to claim 1 is characterized in that: when carrying out roughing in the step (2), adopt stay-warm case between second roughing mill and the finishing mill.
5. a kind of preparation method who avoids the hot-strip that rolling strip edge as thin as a wafer splits according to claim 1 is characterized in that: when batching in the step (2), control band steel camber is 0mm/5m～15mm/5m.
6. a kind of preparation method who avoids the hot-strip that rolling strip edge as thin as a wafer splits according to claim 1, it is characterized in that: the chemical composition of gained hot-strip is by weight percentage in the step (2): 0＜C≤0.07%, 0＜Si≤0.030%, 0.09%≤Mn≤0.29%, 0＜P≤0.025%, 0＜S≤0.020%, 0.012%≤Als≤0.050%, 0＜N≤0.006%, all the other are iron and unavoidable impurities, wherein the field trash rank is 0.5～3 grade.
7. a kind of preparation method who avoids the hot-strip that rolling strip edge as thin as a wafer splits according to claim 1, it is characterized in that: the gained hot-strip is the SPHC hot-strip in the step (2), thickness range is 2.5～3.0mm, the plate wide region is 1000～1260mm, wherein the hot-strip grain structure is ferrite and a small amount of pearlite, the steel plate grain size number is 8.0～9.5 grades, hot-strip limit portion grain structure mixed crystal rank≤0.5 grade, and 2.0～3.0 grades of field trash ranks.
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| CN102416404A (en) * | 2011-09-21 | 2012-04-18 | 首钢总公司 | Method for producing cold-rolled steel strips |
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| CN104946969A (en) * | 2014-03-31 | 2015-09-30 | 上海梅山钢铁股份有限公司 | Hot-rolled pickled steel plate for air conditioner compressor housings and manufacturing method thereof |
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| CN112296097B (en) * | 2020-09-30 | 2022-08-02 | 江苏沙钢集团有限公司 | Method for controlling edge crack of strip steel through roller shape of crystallization roller |
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