CN104017969B - Cold-rolled steel sheet and preparation method thereof and hot-dip galvanizing sheet steel and preparation method thereof - Google Patents
Cold-rolled steel sheet and preparation method thereof and hot-dip galvanizing sheet steel and preparation method thereof Download PDFInfo
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Abstract
The preparation method that the invention discloses a kind of cold-rolled steel sheet, the method includes: slab sequentially passes through hot rolling, batch, cold rolling and annealing, wherein, and consisting of of described slab: C:0.001-0.005 weight %, Si:0.01-0.06 weight %, Mn:0.1-0.6 weight %, P:0.02-0.08 weight %, S :≤0.02 weight %, Al:0.01-0.08 weight %, Ti:0.001-0.02 weight %, Nb:0.001-0.025 weight %, surplus is Fe and inevitable impurity.The invention also discloses the cold-rolled steel sheet prepared by said method, and hot-dip galvanizing sheet steel and preparation method thereof.The present invention can obtain ReLFor 200-270MPa, RmFor the hot-dip galvanizing sheet steel that the intensity of 320-360MPa and forming property, surface quality are good.
Description
Technical field
The present invention relates to a kind of cold-rolled steel sheet and preparation method thereof, and the hot-dip galvanizing sheet steel prepared by this cold-rolled steel sheet and preparation method thereof.
Background technology
Along with the development of automobile industry, intensity and mouldability performance requirement for the hot dip cold-rolled steel sheet needed for vehicle body are more and more higher.
CN101036968A discloses the production method of a kind of deep drawing skin-passed hot-dip galvanizing sheet steel.Used by the method by the carbon content control of substrate in the scope of 0.003-0.006 weight %, Ti* content is controlled in the scope of 0.02-0.04 weight %.But, the yield strength of the deep drawing skin-passed hot-dip galvanizing sheet steel of the method gained is only at below 190MPa, and intensity is relatively low.
CN102839322A discloses a kind of automobile hot-dip galvanizing sheet steel and production method thereof.The chemical component weight percentage ratio of this steel plate is: 0.001%≤C≤0.003%, 0.05%≤Mn≤0.15%, Si≤0.03%, P≤0.02%, 0.008%≤S≤0.015%, 0.02%≤Al≤0.07%, 0.05%≤Ti≤0.09%, 0.0002%≤B≤0.01%, N≤0.004%, surplus is Fe and trace element.But the yield strength of this steel plate is only at below 170MPa, tensile strength is also only at below 300MPa.
Summary of the invention
It is an object of the invention to overcome existing hot-dip galvanizing sheet steel can not have concurrently higher-strength and relatively high formability can defect, there is provided a kind of intensity and forming property all better and the hot-dip galvanizing sheet steel of excellent surface quality and preparation method thereof, and for cold-rolled steel sheet of galvanized steel plain sheet preparing the present invention and preparation method thereof.
To achieve these goals, the preparation method that the present invention provides a kind of cold-rolled steel sheet, the method includes: slab sequentially passes through hot rolling, batch, cold rolling and annealing, wherein,
After described hot rolling and before described batching, first with the rate of cooling of 70-90 DEG C/s, the intermediate slab obtained after hot rolling is cooled to 750-810 DEG C, then is cooled to the temperature batched with the rate of cooling of 15-25 DEG C/s；
The described temperature batched is 670-750 DEG C；
Described cold rolling reduction ratio is 60-75%；
The condition of described annealing includes: soaking temperature is 830-890 DEG C, and soaking time is 40-70s；
Consisting of of described slab: C:0.001-0.005 weight %, Si:0.01-0.06 weight %, Mn:0.1-0.6 weight %, P:0.02-0.08 weight %, S :≤0.02 weight %, Al:0.01-0.08 weight %, Ti:0.001-0.02 weight %, Nb:0.001-0.025 weight %, surplus is Fe and inevitable impurity.
The present invention also provides for the cold-rolled steel sheet prepared by said method.
The preparation method that the present invention also provides for a kind of hot-dip galvanizing sheet steel, wherein, the method includes above-mentioned cold-rolled steel sheet through the upper zinc coat of galvanizing by dipping attachment.
The present invention also provides for the hot-dip galvanizing sheet steel prepared by the preparation method of above-mentioned hot-dip galvanizing sheet steel.
By technique scheme, the present invention can obtain one at low cost to be had finished product mechanical property and reaches yield strength ReLFor 200-270MPa, tensile strength RmFor 320-360MPa, elongation after fracture A80>=37%, plastic strain ratio r90>=2, work hardening index n90>=0.2, baking hardening value BH2More than >=35MPa, surface quality characteristics FC level, microscopic structure be the ferritic structure of 100%, ferrite grain size is more than 8 grades and ferrite grain size is the hot-dip galvanizing sheet steel of 12-20 μm, it is a kind of excellent super low carbon microalloy baking hardening galvanized steel plain sheet, it is particularly suited for use as the steel plate (such as car seat reinforcing plate etc.) of the complicated and exposed parts manufacturing automobile and motorcycle, there is good market prospect.
Other features and advantages of the present invention will be described in detail in detailed description of the invention part subsequently.
Accompanying drawing explanation
Accompanying drawing is used to provide a further understanding of the present invention, and constitutes the part of description, is used for explaining the present invention, but is not intended that limitation of the present invention together with detailed description below.In the accompanying drawings:
Fig. 1 is the microstructure picture of the hot-dip galvanizing sheet steel that embodiment 1 prepares.
Fig. 2 is the microstructure picture of the hot-dip galvanizing sheet steel that embodiment 2 prepares.
Fig. 3 is the microstructure picture of the hot-dip galvanizing sheet steel that embodiment 3 prepares.
Fig. 4 is the microstructure picture of the hot-dip galvanizing sheet steel that embodiment 4 prepares.
Fig. 5 is the microstructure picture of the hot-dip galvanizing sheet steel that comparative example 1 prepares.
Fig. 6 is the microstructure picture of the hot-dip galvanizing sheet steel that comparative example 2 prepares.
Fig. 7 is the microstructure picture of the hot-dip galvanizing sheet steel that comparative example 3 prepares.
Fig. 8 is the microstructure picture of the hot-dip galvanizing sheet steel that comparative example 4 prepares.
Fig. 9 is the microstructure picture of the hot-dip galvanizing sheet steel that comparative example 5 prepares.
Detailed description of the invention
Hereinafter the specific embodiment of the present invention is described in detail.It should be appreciated that detailed description of the invention described herein is merely to illustrate and explains the present invention, it is not limited to the present invention.
The preparation method that the present invention provides a kind of cold-rolled steel sheet, the method includes: slab sequentially passes through hot rolling, batch, cold rolling and annealing, wherein, after described hot rolling and before described batching, first with the rate of cooling of 70-90 DEG C/s, the intermediate slab obtained after hot rolling is cooled to 750-810 DEG C, then is cooled to the temperature batched with the rate of cooling of 15-25 DEG C/s；The described temperature batched is 670-750 DEG C；Described cold rolling reduction ratio is 60-75%；The condition of described annealing includes: soaking temperature is 830-890 DEG C, and soaking time is 40-70s；Consisting of of described slab: C:0.001-0.005 weight %, Si:0.01-0.06 weight %, Mn:0.1-0.6 weight %, P:0.02-0.08 weight %, S :≤0.02 weight %, Al:0.01-0.08 weight %, Ti:0.001-0.02 weight %, Nb:0.001-0.025 weight %, surplus is Fe and inevitable impurity.
In the present invention, although be obtained with the cold-rolled steel sheet of better intensity and more excellent forming property when the composition of slab is in above-mentioned scope and is prepared the hot-dip galvanizing sheet steel of good surface quality by this cold-rolled steel sheet, but in order to strengthen the performance of cold-rolled steel sheet and the hot-dip galvanizing sheet steel obtained, under preferable case, consisting of of described slab: C:0.001-0.004 weight %, Si:0.01-0.055 weight %, Mn:0.2-0.55 weight %, P:0.025-0.065 weight %, S:0.01-0.016 weight %, Al:0.02-0.065 weight %, Ti:0.005-0.017 weight %, Nb:0.005-0.022 weight %, surplus is Fe and inevitable impurity.More preferably, consisting of of described slab: C:0.002-0.004 weight %, Si:0.01-0.05 weight %, Mn:0.28-0.52 weight %, P:0.032-0.06 weight %, S:0.01-0.016 weight %, Al:0.034-0.065 weight %, Ti:0.008-0.017 weight %, Nb:0.01-0.02 weight %, surplus is Fe and inevitable impurity.
In the present invention, it is contemplated that the combination property of purity of steel and product, the carbon content in described slab needs to control in above-mentioned scope, if carbon (C) content is more than 0.005 weight %, then the plasticity of steel plate reduces, and forming property worsens；Furthermore, the content of silicon (Si) needs to control in relatively low scope, for instance 0.01-0.06 weight %；Manganese (Mn) can increase the intensity of described slab, and can be combined into MnS with sulfur (S), prevents because of the FeS fire check caused simultaneously, but Mn too high levels, the welding performance of steel can be affected, accordingly, it would be desirable to controlled in above-mentioned scope by the content of Mn.Additionally, phosphorus (P) is as intensified element, it is necessary to be added in above-mentioned scope.Consider the economy of steel making working procedure and the effect of Calcium treatment, S is controlled at below 0.02 weight %.Aluminum (Al) adds primarily as deoxidant element, realizing complete deoxidation, its content requirement is at more than 0.01 weight %, but too high aluminum will affect the welding performance of steel and coating adhesion and uneconomical, therefore, Al content is chosen as 0.01-0.08 weight % and is advisable.Niobium (Nb) main fixed interval (FI) C atom, titanium (Ti) is mainly fixed interval (FI) atom N, makes interstitial atom be removed, obtains pure ferrite matrix.In the present invention, the content of Nb and the Ti in described slab is relatively low, and this makes the substrate of the hot-dip galvanizing sheet steel formed by this slab more have stable interstitial carbon, at roasting procedure, it is possible to pinning crystal boundary, and the advantage improving intensity.
Described slab can adopt the known method preparing continuous casting billet of this area to be prepared, for instance obtains the continuous casting billet described slab as the present invention after can passing through blast furnace ironmaking, molten iron pretreatment, converter smelting, steel ladle deoxidation, alloying furnace rear refining, LF electrical heating, RH application of vacuum and sheet billet continuous casting.Its condition specifically prepared is well known in the art.
Additionally, in the present invention, the thickness of described slab can be about 190-205mm.
According to the present invention, described hot rolling includes roughing and finish rolling.The start rolling temperature of described roughing can be 1170-1220 DEG C, it is preferred to 1180-1215 DEG C；The finishing temperature of described roughing can be 1125-1175 DEG C, it is preferred to 1130-1170 DEG C, more preferably 1145-1160 DEG C.Additionally, the thickness of the intermediate slab after described roughing can be 35-39mm, it is preferred to 35.5-38mm.
Additionally, the start rolling temperature of described finish rolling can be 1100-1155 DEG C, it is preferred to 1110-1145 DEG C, more preferably 1118-1135 DEG C；The finishing temperature of described finish rolling can be 890-940 DEG C, it is preferred to 895-935 DEG C, more preferably 905-925 DEG C；The thickness of the intermediate slab after described finish rolling can be 2-5mm, it is preferred to 2.5-4.5mm.In order to reach hot rolling roughing required for open bundle temperature, it is possible to first continuous casting billet is heated in heater before roughing, heats and required open bundle temperature when carrying out roughing to continuous casting billet.The thickness of the intermediate slab obtained after described hot rolling is the thickness of the intermediate slab after described finish rolling here, and after namely referring to after described hot rolling that described finish rolling completes.
According to the present invention, after described hot rolling and before described batching, the intermediate slab obtained after hot rolling is carried out two step coolings, under preferable case, first with the rate of cooling of 73-88 DEG C/s, the intermediate slab obtained after hot rolling is cooled to 760-805 DEG C, then is cooled to the temperature batched with the rate of cooling of 17-23 DEG C/s；In preferred situation, first with the rate of cooling of 73-85 DEG C/s, the intermediate slab obtained after hot rolling is cooled to 765-795 DEG C, then is cooled to the temperature batched with the rate of cooling of 17-23 DEG C/s.
According to the invention it is preferred in situation, the type of cooling of the above-mentioned cooling first carried out is the cooling of ultrafast cold water or laminar flow of water cooling, then the type of cooling of the cooling carried out is air cooling or laminar flow of water cooling.
According to the invention it is preferred in situation, described in the temperature batched be 673-748 DEG C, more preferably 675-745 DEG C.
According to the invention it is preferred in situation, described cold rolling reduction ratio is 64-69%, more preferably 67-69%.
According to the invention it is preferred in situation, the condition of described annealing includes: soaking temperature is 845-885 DEG C, soaking time is 45-65s.It is highly preferred that the condition of described annealing includes: soaking temperature is 848-880 DEG C, soaking time is 47-65s.
Hot-dip galvanizing sheet steel more superior in order to obtain surface quality in the present invention, it is preferable that before annealing, the cold-rolled steel sheet of gained is carried out.Described cleaning can adopt the cleaning method of the steel plate of this area routine, for instance alkali cleaning and/or electrolytic cleaned, and its purpose is to remove the greasy dirt of surface of cold-rolled steel plate, iron scale, iron powder etc. affects the impurity of plate surface quality.Preferably, the present invention first carries out alkali cleaning and electrolytic cleaned before being annealed by described cold-rolled steel sheet.The condition of described alkali cleaning preferably includes: the free alkalinity of cleanout fluid is 74-95Pt, and temperature is 70-95 DEG C, and the time is 60-80s.Preferably, the condition of described electrolytic cleaned preferably includes: the free alkalinity of cleanout fluid is 75-95Pt, and temperature is 75-90 DEG C, and electric current is 7100-7700A, and the time is 45-75s.It is highly preferred that the condition of described electrolytic cleaned preferably includes: the free alkalinity of cleanout fluid is 85-95Pt, and temperature is 80-90 DEG C, electric current is 7200-7500A, and the time is 45-75s.
The present invention also provides for the cold-rolled steel sheet prepared by above-mentioned preparation method.
The preparation method that the present invention also provides for a kind of hot-dip galvanizing sheet steel, wherein, the method includes above-mentioned cold-rolled steel sheet through the upper zinc coat of galvanizing by dipping attachment.
According to the present invention, described galvanizing by dipping can adopt continuous way hot dipping method, it would however also be possible to employ batch (-type) hot dipping method, but in order to improve productivity ratio and lumber recovery, present invention preferably employs continuous way hot dipping method.The condition of the preferred described galvanizing by dipping of the present invention includes: the temperature of zinc pot is 450-470 DEG C, more preferably 455-465 DEG C.
There is no particular limitation to the amount of the zinc coating of hot-dip galvanizing sheet steel for the present invention, can be adjusted according to the concrete requirement to galvanized steel plain sheet, preferably, on every square metre of described hot-dip galvanizing sheet steel, the weight of described zinc coat is 75-150g, being more preferably 85-130g, the zinc coat on the described hot-dip galvanizing sheet steel of every square metre here refers to the double-edged zinc coat of galvanized steel plain sheet.
According to the present invention, described preparation method also includes the zinc melt on the steel plate taken out from zinc pot is purged so that the zinc coating on steel plate is distributed more uniform, it is preferred to use air knife purges.The condition that described air knife purges preferably includes: pressure 15-25KPa, is highly 290-330mm, and the vertical dimension from steel plate is 24-29mm.
According to the present invention, described preparation method also includes the hot-dip galvanizing sheet steel after purging is carried out the method that finishing and straightening, described finishing and straightening can adopt this area conventional, it is preferable that described finishing elongation percentage is 0.4-0.8%.Preferably, described straightening elongation percentage is 0.1-0.5%.More preferably only the hot-dip galvanizing sheet steel after purging is carried out straightening process, when only the hot-dip galvanizing sheet steel after purging being carried out straightening process and do not carry out finishing process, it is possible to the intensity of steel plate this steel plate simultaneously obtaining good plate shape can be maintained at ReLFor 200-270MPa and RmFor in the scope of 320-360MPa.
According to the present invention, the preparation method of described hot-dip galvanizing sheet steel generally also includes the steel plate of gained is passivated, and present invention preferably employs chromium-free deactivation.The method of described passivation is not particularly limited, it is possible to for the passivating method that this area is conventional.Preferably, described passivation is for adopting environmental protection chromium-free passivation liquid, by roll coating model, strip steel is carried out surface treatment, the condition of described passivation includes: the roller speed ratio of roller coat application roll and dipping liquid roller is (130-140): (65-80), top roll roll-in is 85-90daN, and lower roll roll-in is 80-100daN (being preferably 82-85daN).Under this condition, it is ensured that uniform film thickness is stable, there is no obvious aberration.
The present invention also provides for the hot-dip galvanizing sheet steel prepared by said method.
The yield strength R that the hot-dip galvanizing sheet steel prepared by the method for the present invention is hadeLFor 200-270MPa, it is preferred to 210-260MPa；Tensile strength RmFor 320-360MPa, it is preferred to 330-360MPa；Elongation after fracture A80>=37%, it is preferred to 38-42%；Plastic strain ratio r90>=2, it is preferred to 2.1-2.5；Work hardening index n90>=0.2, it is preferred to 0.22-0.25；Baking hardening value BH2>=35MPa, it is preferred to 40-58；The surface quality characteristics having is more than FC level.And microscopic structure is the ferritic structure of 100%, ferrite grain size is more than 8 grades, it is preferably 8-9 level, ferrite grain size is 12-20 μm, it is preferably 13.5-18.5 μm and less costly, it is a kind of excellent super low carbon microalloy baking hardening galvanized steel plain sheet, is particularly suited for use as the steel plate (such as car seat reinforcing plate etc.) of the complicated and exposed parts manufacturing automobile and motorcycle, has excellent market prospect.
Hereinafter will be described the present invention by embodiment.
Yield strength R in following example and comparative exampleeL, tensile strength Rm, elongation after fracture A80Method of testing carry out according to GBT228-2002 metal material tensile testing at ambient temperature；Plastic strain ratio r90Method of testing carry out according to the assay method of GBT5027-2007 metal sheet and strip plastic strain ratio (r value)；Work hardening index n90Method of testing carry out according to GBT5028-2008 sheet metal and strip elongation strain hardenability value (n value) test method；Baking hardening value (BH2) method of testing carry out according to the part 1 baking hardened steel test method of GBT20564.1-2007 automobile high-strength cold continuous rolling steel plate and steel band；Adopt the method for regulation in GB/T2518-2008 that the surface quality characteristics of hot-dip galvanizing sheet steel is judged.
Embodiment 1
The present embodiment is for cold-rolled steel sheet that the present invention is described and preparation method thereof and hot-dip galvanizing sheet steel and preparation method thereof.
At converter smelting, obtaining the thick slab of 200mm through LF stove Ca process, RH decarburization and continuous casting, its constituent is in Table 1.This heating of plate blank to 1182 DEG C is carried out roughing, the finishing temperature of roughing is 1145 DEG C, the thickness of the intermediate slab after roughing is 36.8mm, again the intermediate slab after roughing is carried out finish rolling again by Coil Box, the initial temperature of finish rolling is 1122 DEG C, the finishing temperature of finish rolling is 923 DEG C, and the thickness of the intermediate slab after finish rolling is 3.75mm；Intermediate slab after hot rolling is cooled to 791 DEG C with the rate of cooling of 73 DEG C/s by the type of cooling first adopting ultrafast cold water subsequently, then adopts section cooling mode to be cooled to 748 DEG C with the rate of cooling of 22 DEG C/s to batch；Again with the reduction ratio of 68% on cold-rolling mill, it is cold-rolled to the thickness of 1.2mm.With carrying out alkali cleaning and electrolytic cleaned by this cold-rolled steel sheet, alkali cleaning condition is: free alkalinity controls at 85Pt, and temperature is 88 DEG C, and the time is 71s；The condition of electrolytic cleaned is: free alkalinity controls at 90Pt, and temperature is 88 DEG C, and Faradaic current controls at 7300A, and the time is 58s.Then it is annealed (under the soaking temperature of 879 DEG C, carrying out soaking 55s), enters back into the zinc pot of 460 DEG C.Steel plate goes out the laggard circulation of qi promoting cutter of zinc pot and purges, and the condition that air knife purges is: pressure 19KPa, is highly 300mm, and the vertical dimension from steel plate is 28mm.Carrying out straightening and chromium-free deactivation again, wherein, straightening elongation percentage is 0.21%；The condition of passivation includes: environment-friendly chromium-free passivating solution is delivered to application roll by dipping liquid roller by roll coater, rotates again through application roll and is evenly coated in surface of steel plate.Roller coat application roll and dipping liquid roller roller speed ratio 135:70, top roll roll-in is 88daN, and lower roll roll-in is 82daN.Thus obtaining hot-dip galvanizing sheet steel, wherein, the cold-rolled steel sheet relative to every square metre, the weight of described zinc coating is 130g (two sides zinc coating).The strong R of surrender of gained hot-dip galvanizing sheet steeleL, tensile strength Rm, elongation after fracture A80, plastic strain ratio r90, work hardening index n90With baking hardening value BH2In the measurement result of Table 2, microscopic structure and surface quality characteristics in Table 3, Fig. 1 is shown in by the photo of its microscopic structure.
Embodiment 2
The present embodiment is for cold-rolled steel sheet that the present invention is described and preparation method thereof and hot-dip galvanizing sheet steel and preparation method thereof.
At converter smelting, obtaining the thick slab of 200mm through LF stove Ca process, RH decarburization and continuous casting, its constituent is in Table 1.This heating of plate blank to 1213 DEG C is carried out roughing, the finishing temperature of roughing is 1154 DEG C, the thickness of the intermediate slab after roughing is 35.5mm, again the intermediate slab after roughing is carried out finish rolling again by Coil Box, the initial temperature of finish rolling is 1128 DEG C, the finishing temperature of finish rolling is 909 DEG C, and the thickness of the intermediate slab after finish rolling is 3mm；Intermediate slab after hot rolling is cooled to 773 DEG C with the rate of cooling of 79 DEG C/s by the type of cooling first adopting ultrafast cold water subsequently, then adopts section cooling mode to be cooled to 722 DEG C with the rate of cooling of 16 DEG C/s to batch；Again with the reduction ratio of 67% on cold-rolling mill, it is cold-rolled to the thickness of 1mm.With carrying out alkali cleaning and electrolytic cleaned by this cold-rolled steel sheet, alkali cleaning condition is: free alkalinity controls at 74Pt, and temperature is 79 DEG C, and the time is 79s；The condition of electrolytic cleaned is: free alkalinity controls at 85Pt, and temperature is 80 DEG C, and Faradaic current controls at 7500A, and the time is 63s.Then it is annealed (under the soaking temperature of 851 DEG C, carrying out soaking 65s), enters back into the zinc pot of 455 DEG C.Steel plate goes out the laggard circulation of qi promoting cutter of zinc pot and purges, and the condition that air knife purges is: pressure 23KPa, is highly 300mm, and the vertical dimension from steel plate is 26mm.Carrying out straightening and chromium-free deactivation again, wherein, straightening elongation percentage is 0.3%；The condition of passivation includes: environment-friendly chromium-free passivating solution is delivered to application roll by dipping liquid roller by roll coater, rotates again through application roll and is evenly coated in surface of steel plate.Roller coat application roll and dipping liquid roller roller speed ratio 130:67, top roll roll-in is 88daN, and lower roll roll-in is 82daN.Thus obtaining hot-dip galvanizing sheet steel, wherein, the cold-rolled steel sheet relative to every square metre, the weight of described zinc coating is 85g (two sides zinc coating).The strong R of surrender of gained hot-dip galvanizing sheet steeleL, tensile strength Rm, elongation after fracture A80, plastic strain ratio r90, work hardening index n90With baking hardening value BH2In the measurement result of Table 2, microscopic structure and surface quality characteristics in Table 3, Fig. 2 is shown in by the photo of its microscopic structure.
Embodiment 3
The present embodiment is for cold-rolled steel sheet that the present invention is described and preparation method thereof and hot-dip galvanizing sheet steel and preparation method thereof.
At converter smelting, obtaining the thick slab of 200mm through LF stove Ca process, RH decarburization and continuous casting, its constituent is in Table 1.This heating of plate blank to 1204 DEG C is carried out roughing, the finishing temperature of roughing is 1160 DEG C, the thickness of the intermediate slab after roughing is 37.1mm, again the intermediate slab after roughing is carried out finish rolling again by Coil Box, the initial temperature of finish rolling is 1135 DEG C, the finishing temperature of finish rolling is 895 DEG C, and the thickness of the intermediate slab after finish rolling is 4.5mm；Intermediate slab after hot rolling is cooled to 758 DEG C with the rate of cooling of 85 DEG C/s by the type of cooling first adopting ultrafast cold water subsequently, then adopts section cooling mode to be cooled to 673 DEG C with the rate of cooling of 23 DEG C/s to batch；Again with the reduction ratio of 67% on cold-rolling mill, it is cold-rolled to the thickness of 1.5mm.With carrying out alkali cleaning and electrolytic cleaned by this cold-rolled steel sheet, alkali cleaning condition is: free alkalinity controls at 93Pt, and temperature is 92 DEG C, and the time is 64s；The condition of electrolytic cleaned is: free alkalinity controls at 91Pt, and temperature is 89 DEG C, and Faradaic current controls at 7100A, and the time is 58s.Then it is annealed (under the soaking temperature of 865 DEG C, carrying out soaking 47s), enters back into the zinc pot of 465 DEG C.Steel plate goes out the laggard circulation of qi promoting cutter of zinc pot and purges, and the condition that air knife purges is: pressure 22KPa, is highly 310mm, and the vertical dimension from steel plate is 27mm.Carrying out straightening and chromium-free deactivation again, wherein, straightening elongation percentage is 0.42%；The condition of passivation includes: environment-friendly chromium-free passivating solution is delivered to application roll by dipping liquid roller by roll coater, rotates again through application roll and is evenly coated in surface of steel plate.Roller coat application roll and dipping liquid roller roller speed ratio 136:65, top roll roll-in is 82daN, and lower roll roll-in is 85daN.Thus obtaining hot-dip galvanizing sheet steel, wherein, the cold-rolled steel sheet relative to every square metre, the weight of described zinc coating is 110g (two sides zinc coating).The strong R of surrender of gained hot-dip galvanizing sheet steeleL, tensile strength Rm, elongation after fracture A80, plastic strain ratio r90, work hardening index n90With baking hardening value BH2In the measurement result of Table 2, microscopic structure and surface quality characteristics in Table 3, Fig. 3 is shown in by the photo of its microscopic structure.
Embodiment 4
Method according to embodiment 1, institute the difference is that, by air knife purge after steel plate be also performed to before carrying out straightening finishing process, finishing elongation control is 0.65%, the strong R of surrender of gained hot-dip galvanizing sheet steeleL, tensile strength Rm, elongation after fracture A80, plastic strain ratio r90, work hardening index n90With baking hardening value BH2In the measurement result of Table 2, microscopic structure and surface quality characteristics in Table 3, Fig. 4 is shown in by the photo of its microscopic structure.
Comparative example 1
Method according to embodiment 1, institute is different the difference is that the constituent of, slab, is specifically shown in Table 1, the strong R of surrender of gained hot-dip galvanizing sheet steeleL, tensile strength Rm, elongation after fracture A80, plastic strain ratio r90, work hardening index n90With baking hardening value BH2In the measurement result of Table 2, microscopic structure and surface quality characteristics in Table 3, Fig. 5 is shown in by the photo of its microscopic structure.
Comparative example 2
Method according to embodiment 1, institute the difference is that, first with the rate of cooling of 50 DEG C/s, the intermediate slab after hot rolling is cooled to 791 DEG C, the strong R of surrender of gained hot-dip galvanizing sheet steeleL, tensile strength Rm, elongation after fracture A80, plastic strain ratio r90, work hardening index n90With baking hardening value BH2In the measurement result of Table 2, microscopic structure and surface quality characteristics in Table 3, Fig. 6 is shown in by the photo of its microscopic structure.
Comparative example 3
Method according to embodiment 1, institute the difference is that, coiling temperature is 620 DEG C, the strong R of surrender of gained hot-dip galvanizing sheet steeleL, tensile strength Rm, elongation after fracture A80, plastic strain ratio r90, work hardening index n90With baking hardening value BH2In the measurement result of Table 2, microscopic structure and surface quality characteristics in Table 3, Fig. 7 is shown in by the photo of its microscopic structure.
Comparative example 4
According to the method described in embodiment 1, institute the difference is that, cold rolling reduction ratio is 50%, the strong R of surrender of gained hot-dip galvanizing sheet steeleL, tensile strength Rm, elongation after fracture A80, plastic strain ratio r90, work hardening index n90With baking hardening value BH2In the measurement result of Table 2, microscopic structure and surface quality characteristics in Table 3, Fig. 8 is shown in by the photo of its microscopic structure.
Comparative example 5
According to the method described in embodiment 1, institute the difference is that, the soaking temperature of described annealing is 780 DEG C, the strong R of surrender of gained hot-dip galvanizing sheet steeleL, tensile strength Rm, elongation after fracture A80, plastic strain ratio r90, work hardening index n90With baking hardening value BH2In the measurement result of Table 2, microscopic structure and surface quality characteristics in Table 3, Fig. 9 is shown in by the photo of its microscopic structure.
Table 1
Table 2
Note: "---" in table represents the non-perfect recrystallization of steel plate, and during tension test, sample breaks in advance, it is impossible to measure n, r value.
Table 3
Note: " cannot measure " refers to the non-perfect recrystallization of microscopic structure, it is impossible to pass judgment on according to metallographic structure standard.
By the data in table 1-3 it can be seen that adopt the present invention preparation method, it is possible to obtain there is finished product mechanical property and reach yield strength ReLFor 200-270MPa, tensile strength RmFor 320-360MPa, elongation after fracture A80>=37%, plastic strain ratio r90>=2, work hardening index n90>=0.2, baking hardening value BH2More than >=35MPa, surface quality characteristics FC level, microscopic structure be the ferritic structure of 100%, ferrite grain size is more than 8 grades and ferrite grain size is the hot-dip galvanizing sheet steel of 12-20 μm.
The preferred embodiment of the present invention described in detail above; but, the present invention is not limited to the detail in above-mentioned embodiment, in the technology concept of the present invention; technical scheme can being carried out multiple simple variant, these simple variant belong to protection scope of the present invention.
It is further to note that, each concrete technical characteristic described in above-mentioned detailed description of the invention, in reconcilable situation, it is possible to be combined by any suitable mode, in order to avoid unnecessary repetition, various possible compound modes are no longer illustrated by the present invention separately.
Additionally, can also carry out combination in any between the various different embodiment of the present invention, as long as it is without prejudice to the thought of the present invention, it should be considered as content disclosed in this invention equally.
Claims (11)
1. a preparation method for cold-rolled steel sheet, the method includes: slab sequentially passes through hot rolling, batch, cold rolling and annealing, it is characterised in that
After described hot rolling and before described batching, first with the rate of cooling of 70-90 DEG C/s, the intermediate slab obtained after hot rolling is cooled to 750-810 DEG C, then is cooled to the temperature batched with the rate of cooling of 15-25 DEG C/s；
The described temperature batched is 670-750 DEG C；
Described cold rolling reduction ratio is 60-75%；
The condition of described annealing includes: soaking temperature is 830-890 DEG C, and soaking time is 40-70s；
Described hot rolling includes roughing and finish rolling, and the start rolling temperature of described finish rolling is 1100-1155 DEG C, and the finishing temperature of described finish rolling is 890-925 DEG C；
Consisting of of described slab: C:0.001-0.005 weight %, Si:0.01-0.06 weight %, Mn:0.1-0.6 weight %, P:0.02-0.08 weight %, S :≤0.02 weight %, Al:0.01-0.08 weight %, Ti:0.001-0.02 weight %, Nb:0.001-0.025 weight %, surplus is Fe and inevitable impurity.
2. method according to claim 1, wherein, consisting of of described slab: C:0.001-0.004 weight %, Si:0.01-0.055 weight %, Mn:0.2-0.55 weight %, P:0.025-0.065 weight %, S:0.01-0.016 weight %, Al:0.02-0.065 weight %, Ti:0.005-0.017 weight %, Nb:0.005-0.022 weight %, surplus is Fe and inevitable impurity.
3. method according to claim 1, wherein, after described hot rolling and before described batching, first with the rate of cooling of 73-88 DEG C/s, the intermediate slab obtained after hot rolling is cooled to 760-805 DEG C, then is cooled to the temperature batched with the rate of cooling of 17-23 DEG C/s.
4. the method according to claim 1 or 3, wherein, described in the temperature batched be 673-748 DEG C.
5. method according to claim 1, wherein, described cold rolling reduction ratio is 64-69%.
6. method according to claim 1, wherein, the condition of described annealing includes: soaking temperature is 845-885 DEG C, and soaking time is 45-65s.
7. method according to claim 1, wherein, the start rolling temperature of described roughing is 1170-1220 DEG C, and the finishing temperature of described roughing is 1125-1175 DEG C；The start rolling temperature of described finish rolling is 1110-1145 DEG C, and the finishing temperature of described finish rolling is 905-925 DEG C.
8. the cold-rolled steel sheet that the method described in any one in claim 1-7 prepares.
9. the preparation method of a hot-dip galvanizing sheet steel, it is characterised in that the method includes the cold-rolled steel sheet described in claim 8 through the upper zinc coat of galvanizing by dipping attachment.
10. preparation method according to claim 9, wherein, on every square metre of described hot-dip galvanizing sheet steel, the weight of described zinc coat is 75-150g.
11. the hot-dip galvanizing sheet steel that the preparation method described in claim 9 or 10 prepares.
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| CN101736195A (en) * | 2008-11-24 | 2010-06-16 | 攀钢集团研究院有限公司 | Hot-dip coating aluminium-zinc alloy steel plate and production method thereof |
| CN103045833A (en) * | 2011-10-11 | 2013-04-17 | 攀钢集团攀枝花钢铁研究院有限公司 | Steel plate and galvanizing steel plate, and preparation method thereof |
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| CN101736195A (en) * | 2008-11-24 | 2010-06-16 | 攀钢集团研究院有限公司 | Hot-dip coating aluminium-zinc alloy steel plate and production method thereof |
| CN103045833A (en) * | 2011-10-11 | 2013-04-17 | 攀钢集团攀枝花钢铁研究院有限公司 | Steel plate and galvanizing steel plate, and preparation method thereof |
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