CN104017969A - Cold-rolled steel sheet, preparation method thereof, hot galvanized steel sheet and preparation method thereof - Google Patents
Cold-rolled steel sheet, preparation method thereof, hot galvanized steel sheet and preparation method thereof Download PDFInfo
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- CN104017969A CN104017969A CN201410271704.2A CN201410271704A CN104017969A CN 104017969 A CN104017969 A CN 104017969A CN 201410271704 A CN201410271704 A CN 201410271704A CN 104017969 A CN104017969 A CN 104017969A
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Abstract
The invention discloses a preparation method of a cold-rolled steel sheet. The method comprises the steps of sequentially carrying out hot rolling, reeling, cold rolling and annealing on a sheet blank, wherein the sheet blank is composed of 0.001-0.005wt% of C, 0.01-0.06wt% of Si, 0.1-0.6wt% of Mn, 0.02-0.08wt% of P, less than or equal to 0.02wt% of S, 0.01-0.08wt% of Al, 0.001-0.02wt% of Ti, 0.001-0.025wt% of Nb and the balance of Fe and unavoidable impurities. The invention also discloses a cold-rolled steel sheet prepared by using the method, a hot galvanized steel sheet and a preparation method thereof. According to the invention, the galvanized steel sheet with favorable strength (ReL is 200-270MPa, and Rm is 320-360MPa), forming property and surface quality can be obtained.
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 being made by this cold-rolled steel sheet and preparation method thereof.
Background technology
Along with the development of automobile industry, more and more higher for intensity and the formability performance requriements of the required hot dip cold-rolled steel sheet of vehicle body.
CN101036968A discloses a kind of production method of deep drawing skin-passed hot-dip galvanizing sheet steel.The method used by the carbon content control of substrate in the scope of 0.003-0.006 % by weight, Ti* content is controlled in the scope of 0.02-0.04 % by weight.Yet the yield strength of the deep drawing skin-passed hot-dip galvanizing sheet steel of the method gained is only below 190MPa, intensity is lower.
CN102839322A discloses hot-dip galvanizing sheet steel and production method thereof for a kind of automobile.The chemical component weight per-cent 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.Yet the yield strength of this steel plate is only below 170MPa, and tensile strength is also only below 300MPa.
Summary of the invention
The object of the invention is to overcome existing hot-dip galvanizing sheet steel can not have concurrently higher-strength and compared with high formability can defect, provide 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 the preparation of cold-rolled steel sheet of steel plate galvanized of the present invention and preparation method thereof.
To achieve these goals, the invention provides a kind of preparation method of cold-rolled steel sheet, the method comprises: by slab successively through hot rolling, batch, cold rolling and annealing, wherein,
After described hot rolling and before described batching, first the speed of cooling with 70-90 ℃/s is cooled to 750-810 ℃ by the intermediate slab obtaining after hot rolling, then is cooled to the temperature of batching with the speed of cooling of 15-25 ℃/s;
Described temperature of batching is 670-750 ℃;
Described cold rolling draft is 60-75%;
The condition of described annealing comprises: soaking temperature is 830-890 ℃, and soaking time is 40-70s;
Consisting of of described slab: C:0.001-0.005 % by weight, Si:0.01-0.06 % by weight, Mn:0.1-0.6 % by weight, P:0.02-0.08 % by weight, S :≤0.02 % by weight, Al:0.01-0.08 % by weight, Ti:0.001-0.02 % by weight, Nb:0.001-0.025 % by weight, surplus is Fe and inevitable impurity.
The present invention also provides the cold-rolled steel sheet being made by aforesaid method.
The present invention also provides a kind of preparation method of hot-dip galvanizing sheet steel, and wherein, the method comprises adheres to upper zinc coating by above-mentioned cold-rolled steel sheet through galvanizing.
The hot-dip galvanizing sheet steel that the present invention also provides the preparation method by above-mentioned hot-dip galvanizing sheet steel to make.
By technique scheme, the present invention can obtain at low cost a kind ofly to be had finished product mechanical property and reaches yield strength R
eLfor 200-270MPa, tensile strength R
mfor 320-360MPa, elongation after fracture A
80>=37%, plastic strain ratio r
90>=2, work hardening exponent n
90>=0.2, baking hardening value BH
2ferritic structure, the ferrite grain size that>=35MPa, surface quality feature FC level are above, microstructure is 100% is that 8 grades of above and ferrite grain sizes are the hot-dip galvanizing sheet steel of 12-20 μ m, it is a kind of good super low carbon microalloy baking hardening steel plate galvanized, be particularly suitable for, as the steel plate of manufacturing the complicated and exposed component of automobile and motorcycle (such as car seat reinforcing plate etc.), thering are good market outlook.
Other features and advantages of the present invention partly in detail are described the embodiment subsequently.
Accompanying drawing explanation
Accompanying drawing is to be used to provide a further understanding of the present invention, and forms a part for specification sheets, is used from explanation the present invention, but is not construed as limiting the invention with embodiment one below.In the accompanying drawings:
Fig. 1 is the microstructure picture of the hot-dip galvanizing sheet steel that makes of embodiment 1.
Fig. 2 is the microstructure picture of the hot-dip galvanizing sheet steel that makes of embodiment 2.
Fig. 3 is the microstructure picture of the hot-dip galvanizing sheet steel that makes of embodiment 3.
Fig. 4 is the microstructure picture of the hot-dip galvanizing sheet steel that makes of embodiment 4.
Fig. 5 is the microstructure picture of the hot-dip galvanizing sheet steel that makes of comparative example 1.
Fig. 6 is the microstructure picture of the hot-dip galvanizing sheet steel that makes of comparative example 2.
Fig. 7 is the microstructure picture of the hot-dip galvanizing sheet steel that makes of comparative example 3.
Fig. 8 is the microstructure picture of the hot-dip galvanizing sheet steel that makes of comparative example 4.
Fig. 9 is the microstructure picture of the hot-dip galvanizing sheet steel that makes of comparative example 5.
Embodiment
Below the specific embodiment of the present invention is elaborated.Should be understood that, embodiment described herein only, for description and interpretation the present invention, is not limited to the present invention.
The invention provides a kind of preparation method of cold-rolled steel sheet, the method comprises: by slab successively through hot rolling, batch, cold rolling and annealing, wherein, after described hot rolling and before described batching, first the speed of cooling with 70-90 ℃/s is cooled to 750-810 ℃ by the intermediate slab obtaining after hot rolling, then is cooled to the temperature of batching with the speed of cooling of 15-25 ℃/s; Described temperature of batching is 670-750 ℃; Described cold rolling draft is 60-75%; The condition of described annealing comprises: soaking temperature is 830-890 ℃, and soaking time is 40-70s; Consisting of of described slab: C:0.001-0.005 % by weight, Si:0.01-0.06 % by weight, Mn:0.1-0.6 % by weight, P:0.02-0.08 % by weight, S :≤0.02 % by weight, Al:0.01-0.08 % by weight, Ti:0.001-0.02 % by weight, Nb:0.001-0.025 % by weight, surplus is Fe and inevitable impurity.
In the present invention, although just can obtain the cold-rolled steel sheet of better intensity and better forming property and the hot-dip galvanizing sheet steel that is made good surface quality by this cold-rolled steel sheet when the composition of slab is in above-mentioned scope, but in order to strengthen the performance of obtained cold-rolled steel sheet and hot-dip galvanizing sheet steel, under preferable case, consisting of of described slab: C:0.001-0.004 % by weight, Si:0.01-0.055 % by weight, Mn:0.2-0.55 % by weight, P:0.025-0.065 % by weight, S:0.01-0.016 % by weight, Al:0.02-0.065 % by weight, Ti:0.005-0.017 % by weight, Nb:0.005-0.022 % by weight, surplus is Fe and inevitable impurity.More preferably, consisting of of described slab: C:0.002-0.004 % by weight, Si:0.01-0.05 % by weight, Mn:0.28-0.52 % by weight, P:0.032-0.06 % by weight, S:0.01-0.016 % by weight, Al:0.034-0.065 % by weight, Ti:0.008-0.017 % by weight, Nb:0.01-0.02 % by weight, surplus is Fe and inevitable impurity.
In the present invention, consider the over-all properties of purity of steel and product, the carbon content in described slab need to be controlled in above-mentioned scope, if carbon (C) content surpasses 0.005 % by weight, and the Plasticity Decreasing of steel plate, forming property worsens; For example, moreover the content of silicon (Si) need to be controlled at lower scope, 0.01-0.06 % by weight; Manganese (Mn) can increase the intensity of described slab, and can be combined into MnS with sulphur (S), prevents the thermal crack causing because of FeS simultaneously, but Mn too high levels, the welding property that can affect steel, therefore, need to be controlled at the content of Mn in above-mentioned scope.In addition, phosphorus (P), as strengthening element, need to be added in above-mentioned scope.Consider the economy of steel making working procedure and the effect that calcium is processed, S is controlled at below 0.02 % by weight.Aluminium (Al) mainly adds as deoxidant element, realize complete deoxidation, its content requirement is more than 0.01 % by weight, but too high aluminium will affect welding property and the coating adhesion and uneconomical of steel, therefore, Al content is chosen as 0.01-0.08 % by weight and is advisable.The main fixed interval (FI) of niobium (Nb) C atom, titanium (Ti) is mainly fixed interval (FI) N atom, and interstitial atom is removed, and obtains pure ferrite matrix.In the present invention, the Nb in described slab and the content of Ti are relatively low, and this makes the substrate of the hot-dip galvanizing sheet steel that formed by this slab more have stable interstitial carbon, at roasting procedure, can pinning crystal boundary, and put forward high-intensity advantage.
Described slab can adopt the known method of preparing continuously cast bloom of this area to be prepared, for example can be by obtaining continuously cast bloom after blast furnace ironmaking, hot metal pretreatment, converter smelting, steel ladle deoxidation, alloying furnace rear refining, LF electrically heated, RH vacuum-treat and sheet billet continuous casting as described slab of the present invention.The condition of its concrete preparation is well known in the art.
In addition, in the present invention, the thickness of described slab can be 190-205mm left and right.
According to the present invention, described hot rolling comprises roughing and finish rolling.The start rolling temperature of described roughing can be 1170-1220 ℃, is preferably 1180-1215 ℃; The finishing temperature of described roughing can be 1125-1175 ℃, is preferably 1130-1170 ℃, more preferably 1145-1160 ℃.In addition, the thickness of the intermediate slab after described roughing can be 35-39mm, is preferably 35.5-38mm.
In addition, the start rolling temperature of described finish rolling can be 1100-1155 ℃, is preferably 1110-1145 ℃, more preferably 1118-1135 ℃; The finishing temperature of described finish rolling can be 890-940 ℃, is preferably 895-935 ℃, more preferably 905-925 ℃; The thickness of the intermediate slab after described finish rolling can be 2-5mm, is preferably 2.5-4.5mm.In order to reach the needed bundle temperature of opening of roughing of hot rolling, can before roughing, first continuously cast bloom be heated in heater to the required bundle temperature of opening when being heated to continuously cast bloom and carrying out roughing.The thickness of the intermediate slab obtaining after described hot rolling is the thickness of the intermediate slab after the described finish rolling here, and after 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 obtaining after hot rolling is carried out to two steps cooling, under preferable case, first the speed of cooling with 73-88 ℃/s is cooled to 760-805 ℃ by the intermediate slab obtaining after hot rolling, then is cooled to the temperature of batching with the speed of cooling of 17-23 ℃/s; In preferred situation, first the speed of cooling with 73-85 ℃/s is cooled to 765-795 ℃ by the intermediate slab obtaining after hot rolling, then is cooled to the temperature of batching with the speed of cooling of 17-23 ℃/s.
According to the present invention, under preferable case, the above-mentioned cooling type of cooling of first carrying out is the cooling or laminar flow water cooling of ultrafast cold water, the more cooling type of cooling of carrying out is air cooling or laminar flow water cooling.
According to the present invention, under preferable case, described in the temperature of batching be 673-748 ℃, more preferably 675-745 ℃.
According to the present invention, under preferable case, described cold rolling draft is 64-69%, more preferably 67-69%.
According to the present invention, under preferable case, the condition of described annealing comprises: soaking temperature is 845-885 ℃, and soaking time is 45-65s.More preferably, the condition of described annealing comprises: soaking temperature is 848-880 ℃, and soaking time is 47-65s.
In the present invention, in order to obtain the hot-dip galvanizing sheet steel that surface quality is more superior, preferably before annealing, the cold-rolled steel sheet to gained cleans.Described cleaning can adopt the purging method of the steel plate of this area routine, and for example alkali cleaning and/or electrolytic cleaning its objective is that greasy dirt in order to remove surface of cold-rolled steel plate, iron scale, iron powder etc. affect the impurity of plate surface quality.Preferably, the present invention first carries out alkali cleaning and electrolytic cleaning before described cold-rolled steel sheet is annealed.The condition optimization of described alkali cleaning comprises: the free alkalinity of scavenging solution is 74-95Pt, and temperature is 70-95 ℃, and the time is 60-80s.Preferably, the condition optimization of described electrolytic cleaning comprises: the free alkalinity of scavenging solution is 75-95Pt, and temperature is 75-90 ℃, and electric current is 7100-7700A, and the time is 45-75s.More preferably, the condition optimization of described electrolytic cleaning comprises: the free alkalinity of scavenging solution is 85-95Pt, and temperature is 80-90 ℃, and electric current is 7200-7500A, and the time is 45-75s.
The present invention also provides the cold-rolled steel sheet being made by above-mentioned preparation method.
The present invention also provides a kind of preparation method of hot-dip galvanizing sheet steel, and wherein, the method comprises adheres to upper zinc coating by above-mentioned cold-rolled steel sheet through galvanizing.
According to the present invention, described galvanizing can adopt continous way hot dipping method, also can adopt intermittent type hot dipping method, but in order to boost productivity and lumber recovery, the present invention preferably adopts continous way hot dipping method.The condition of the preferred described galvanizing of the present invention comprises: the temperature of zinc pot is 450-470 ℃, more preferably 455-465 ℃.
The present invention there is no special restriction to the amount of the zinc coating of hot-dip galvanizing sheet steel, can adjust according to the concrete requirement to steel plate galvanized, preferably, on every square metre of described hot-dip galvanizing sheet steel, the weight of described zinc coating is 75-150g, 85-130g more preferably, the zinc coating on the described hot-dip galvanizing sheet steel of here every square metre refers to the double-edged zinc coating of steel plate galvanized.
According to the present invention, described preparation method also comprises that the zinc melt on the steel plate to taking out from zinc pot purges, and makes the zinc coating on steel plate distribute more evenly, preferably adopts air knife to purge.The condition optimization that described air knife purges comprises: pressure 15-25KPa is highly 290-330mm, apart from the vertical range of steel plate, is 24-29mm.
According to the present invention, described preparation method also comprises the hot-dip galvanizing sheet steel after purging carried out to polishing and straightening, and described polishing and straightening can adopt the method for this area routine, and preferably, described polishing unit elongation is 0.4-0.8%.Preferably, described straightening unit elongation is 0.1-0.5%.More preferably only the hot-dip galvanizing sheet steel after purging is carried out to straightening processing, when only the hot-dip galvanizing sheet steel after purging being carried out straightening processing and do not carry out polishing processing, the steel plate that can the obtain good plate shape simultaneously intensity of this steel plate can remain on R
eLfor 200-270MPa and R
min scope for 320-360MPa.
According to the present invention, the preparation method of described hot-dip galvanizing sheet steel conventionally also comprises the steel plate of gained carried out to passivation, and the present invention preferably adopts chromium-free deactivation.Method to described passivation is not particularly limited, and can be the passivating method of this area routine.Preferably, described passivation is for adopting environmental protection chromium-free passivation liquid, by roll coating model, band steel is carried out to surface treatment, the condition of described passivation comprises: roller coat application roll is (130-140) with the roller speed ratio that dips in liquid roller: (65-80), top roll roll-in is 85-90daN, and lower roll roll-in is 80-100daN (being preferably 82-85daN).Under this condition, can guarantee that uniform film thickness is stable, there is no obvious aberration.
The present invention also provides the hot-dip galvanizing sheet steel being made by aforesaid method.
The yield strength R that the hot-dip galvanizing sheet steel making by method of the present invention has
eLfor 200-270MPa, be preferably 210-260MPa; Tensile strength R
mfor 320-360MPa, be preferably 330-360MPa; Elongation after fracture A
80>=37%, be preferably 38-42%; Plastic strain ratio r
90>=2, be preferably 2.1-2.5; Work hardening exponent n
90>=0.2, be preferably 0.22-0.25; Baking hardening value BH
2>=35MPa, is preferably 40-58; More than the surface quality having is characterized as FC level.And the ferritic structure that microstructure is 100%, ferrite grain size is more than 8 grades, be preferably 8-9 level, ferrite grain size is 12-20 μ m, be preferably 13.5-18.5 μ m and cost lower, it is a kind of good super low carbon microalloy baking hardening steel plate galvanized, is particularly suitable for, as the steel plate of manufacturing the complicated and exposed component of automobile and motorcycle (such as car seat reinforcing plate etc.), having good market outlook.
Below will describe the present invention by embodiment.
Yield strength R in following examples and comparative example
eL, tensile strength R
m, elongation after fracture A
80testing method according to GBT228-2002 metallic substance tensile test at room temperature method, carry out; Plastic strain ratio r
90testing method according to the measuring method of GBT5027-2007 metal sheet and strip plastic strain ratio (r value), carry out; Work hardening exponent n
90testing method according to GBT5028-2008 metal sheet and strip tension strain hardenability value (n value) test method, carry out; Baking hardening value (BH
2) testing method 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, carry out; Adopt the method for stipulating in GB/T2518-2008 to judge the surface quality feature of hot-dip galvanizing sheet steel.
Embodiment 1
The present embodiment is used for illustrating cold-rolled steel sheet of the present invention and preparation method thereof and hot-dip galvanizing sheet steel and preparation method thereof.
At converter smelting, through LF stove Ca processing, RH decarburization and the thick slab of continuous casting acquisition 200mm, its moiety is in Table 1.This heating of plate blank to 1182 ℃ is carried out to roughing, the finishing temperature of roughing is 1145 ℃, the thickness of the intermediate slab after roughing is 36.8mm, again the intermediate slab after roughing is carried out to finish rolling again by Coil Box, the starting temperature of finish rolling is 1122 ℃, the finishing temperature of finish rolling is 923 ℃, and the thickness of the intermediate slab after finish rolling is 3.75mm; The type of cooling that first adopts subsequently ultrafast cold water is cooled to 791 ℃ with the speed of cooling of 73 ℃/s by the intermediate slab after hot rolling, then adopts the laminar flow type of cooling to be cooled to 748 ℃ to batch with the speed of cooling of 22 ℃/s; Again on cold-rolling mill with 68% draft, be cold-rolled to the thickness of 1.2mm.With being about to this cold-rolled steel sheet, carry out alkali cleaning and electrolytic cleaning, alkali cleaning condition is: free alkalinity is controlled at 85Pt, and temperature is 88 ℃, and the time is 71s; The condition of electrolytic cleaning is: free alkalinity is controlled at 90Pt, and temperature is 88 ℃, and Faradaic current is controlled at 7300A, and the time is 58s.Then anneal (under the soaking temperature of 879 ℃, carrying out soaking 55s), then enter the zinc pot of 460 ℃.Steel plate goes out the laggard promoting the circulation of qi cutter of zinc pot and purges, and the condition that air knife purges is: pressure 19KPa is highly 300mm, apart from the vertical range of steel plate, is 28mm.Carry out straightening and chromium-free deactivation, wherein, straightening unit elongation is 0.21% again; The condition of passivation comprises: roller coating machine is delivered to application roll by dipping in liquid roller by environment-friendly chromium-free passivating solution, then is rotated and be evenly coated in surface of steel plate by application roll.Roller coat application roll with dip in liquid roller roller speed ratio 135:70, top roll roll-in is 88daN, lower roll roll-in is 82daN.Obtain thus hot-dip galvanizing sheet steel, wherein, with respect to the cold-rolled steel sheet of 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 steel
eL, tensile strength R
m, elongation after fracture A
80, plastic strain ratio r
90, work hardening exponent n
90with baking hardening value BH
2in Table 2, the measurement result of microstructure and surface quality feature is in Table 3, and Fig. 1 is shown in by the photo of its microstructure.
Embodiment 2
The present embodiment is used for illustrating cold-rolled steel sheet of the present invention and preparation method thereof and hot-dip galvanizing sheet steel and preparation method thereof.
At converter smelting, through LF stove Ca processing, RH decarburization and the thick slab of continuous casting acquisition 200mm, its moiety is in Table 1.This heating of plate blank to 1213 ℃ is carried out to roughing, the finishing temperature of roughing is 1154 ℃, the thickness of the intermediate slab after roughing is 35.5mm, again the intermediate slab after roughing is carried out to finish rolling again by Coil Box, the starting temperature of finish rolling is 1128 ℃, the finishing temperature of finish rolling is 909 ℃, and the thickness of the intermediate slab after finish rolling is 3mm; The type of cooling that first adopts subsequently ultrafast cold water is cooled to 773 ℃ with the speed of cooling of 79 ℃/s by the intermediate slab after hot rolling, then adopts the laminar flow type of cooling to be cooled to 722 ℃ to batch with the speed of cooling of 16 ℃/s; Again on cold-rolling mill with 67% draft, be cold-rolled to the thickness of 1mm.With being about to this cold-rolled steel sheet, carry out alkali cleaning and electrolytic cleaning, alkali cleaning condition is: free alkalinity is controlled at 74Pt, and temperature is 79 ℃, and the time is 79s; The condition of electrolytic cleaning is: free alkalinity is controlled at 85Pt, and temperature is 80 ℃, and Faradaic current is controlled at 7500A, and the time is 63s.Then anneal (under the soaking temperature of 851 ℃, carrying out soaking 65s), then enter the zinc pot of 455 ℃.Steel plate goes out the laggard promoting the circulation of qi cutter of zinc pot and purges, and the condition that air knife purges is: pressure 23KPa is highly 300mm, apart from the vertical range of steel plate, is 26mm.Carry out straightening and chromium-free deactivation, wherein, straightening unit elongation is 0.3% again; The condition of passivation comprises: roller coating machine is delivered to application roll by dipping in liquid roller by environment-friendly chromium-free passivating solution, then is rotated and be evenly coated in surface of steel plate by application roll.Roller coat application roll with dip in liquid roller roller speed ratio 130:67, top roll roll-in is 88daN, lower roll roll-in is 82daN.Obtain thus hot-dip galvanizing sheet steel, wherein, with respect to the cold-rolled steel sheet of 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 steel
eL, tensile strength R
m, elongation after fracture A
80, plastic strain ratio r
90, work hardening exponent n
90with baking hardening value BH
2in Table 2, the measurement result of microstructure and surface quality feature is in Table 3, and Fig. 2 is shown in by the photo of its microstructure.
Embodiment 3
The present embodiment is used for illustrating cold-rolled steel sheet of the present invention and preparation method thereof and hot-dip galvanizing sheet steel and preparation method thereof.
At converter smelting, through LF stove Ca processing, RH decarburization and the thick slab of continuous casting acquisition 200mm, its moiety is in Table 1.This heating of plate blank to 1204 ℃ is carried out to roughing, the finishing temperature of roughing is 1160 ℃, the thickness of the intermediate slab after roughing is 37.1mm, again the intermediate slab after roughing is carried out to finish rolling again by Coil Box, the starting temperature of finish rolling is 1135 ℃, the finishing temperature of finish rolling is 895 ℃, and the thickness of the intermediate slab after finish rolling is 4.5mm; The type of cooling that first adopts subsequently ultrafast cold water is cooled to 758 ℃ with the speed of cooling of 85 ℃/s by the intermediate slab after hot rolling, then adopts the laminar flow type of cooling to be cooled to 673 ℃ to batch with the speed of cooling of 23 ℃/s; Again on cold-rolling mill with 67% draft, be cold-rolled to the thickness of 1.5mm.With being about to this cold-rolled steel sheet, carry out alkali cleaning and electrolytic cleaning, alkali cleaning condition is: free alkalinity is controlled at 93Pt, and temperature is 92 ℃, and the time is 64s; The condition of electrolytic cleaning is: free alkalinity is controlled at 91Pt, and temperature is 89 ℃, and Faradaic current is controlled at 7100A, and the time is 58s.Then anneal (under the soaking temperature of 865 ℃, carrying out soaking 47s), then enter the zinc pot of 465 ℃.Steel plate goes out the laggard promoting the circulation of qi cutter of zinc pot and purges, and the condition that air knife purges is: pressure 22KPa is highly 310mm, apart from the vertical range of steel plate, is 27mm.Carry out straightening and chromium-free deactivation, wherein, straightening unit elongation is 0.42% again; The condition of passivation comprises: roller coating machine is delivered to application roll by dipping in liquid roller by environment-friendly chromium-free passivating solution, then is rotated and be evenly coated in surface of steel plate by application roll.Roller coat application roll with dip in liquid roller roller speed ratio 136:65, top roll roll-in is 82daN, lower roll roll-in is 85daN.Obtain thus hot-dip galvanizing sheet steel, wherein, with respect to the cold-rolled steel sheet of 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 steel
eL, tensile strength R
m, elongation after fracture A
80, plastic strain ratio r
90, work hardening exponent n
90with baking hardening value BH
2in Table 2, the measurement result of microstructure and surface quality feature is in Table 3, and Fig. 3 is shown in by the photo of its microstructure.
Embodiment 4
According to the method for embodiment 1, difference is, the steel plate after air knife is purged also will carry out polishing processing before carrying out straightening, and polishing elongation control is 0.65%, the strong R of surrender of gained hot-dip galvanizing sheet steel
eL, tensile strength R
m, elongation after fracture A
80, plastic strain ratio r
90, work hardening exponent n
90with baking hardening value BH
2in Table 2, the measurement result of microstructure and surface quality feature is in Table 3, and Fig. 4 is shown in by the photo of its microstructure.
Comparative example 1
According to the method for embodiment 1, difference is that the moiety of slab is different, is specifically shown in Table 1 the strong R of surrender of gained hot-dip galvanizing sheet steel
eL, tensile strength R
m, elongation after fracture A
80, plastic strain ratio r
90, work hardening exponent n
90with baking hardening value BH
2in Table 2, the measurement result of microstructure and surface quality feature is in Table 3, and Fig. 5 is shown in by the photo of its microstructure.
Comparative example 2
According to the method for embodiment 1, difference is that first the speed of cooling with 50 ℃/s is cooled to 791 ℃ by the intermediate slab after hot rolling, the strong R of surrender of gained hot-dip galvanizing sheet steel
eL, tensile strength R
m, elongation after fracture A
80, plastic strain ratio r
90, work hardening exponent n
90with baking hardening value BH
2in Table 2, the measurement result of microstructure and surface quality feature is in Table 3, and Fig. 6 is shown in by the photo of its microstructure.
Comparative example 3
According to the method for embodiment 1, difference is that coiling temperature is 620 ℃, the strong R of surrender of gained hot-dip galvanizing sheet steel
eL, tensile strength R
m, elongation after fracture A
80, plastic strain ratio r
90, work hardening exponent n
90with baking hardening value BH
2in Table 2, the measurement result of microstructure and surface quality feature is in Table 3, and Fig. 7 is shown in by the photo of its microstructure.
Comparative example 4
According to the method described in embodiment 1, difference is that cold rolling draft is 50%, the strong R of surrender of gained hot-dip galvanizing sheet steel
eL, tensile strength R
m, elongation after fracture A
80, plastic strain ratio r
90, work hardening exponent n
90with baking hardening value BH
2in Table 2, the measurement result of microstructure and surface quality feature is in Table 3, and Fig. 8 is shown in by the photo of its microstructure.
Comparative example 5
According to the method described in embodiment 1, difference is that the soaking temperature of described annealing is 780 ℃, the strong R of surrender of gained hot-dip galvanizing sheet steel
eL, tensile strength R
m, elongation after fracture A
80, plastic strain ratio r
90, work hardening exponent n
90with baking hardening value BH
2in Table 2, the measurement result of microstructure and surface quality feature is in Table 3, and Fig. 9 is shown in by the photo of its microstructure.
Table 1
Table 2
Note: "---" in table represents not perfect recrystallization of steel plate, during tension test, sample is disconnected in advance, cannot measure n, r value.
Table 3
Note: " cannot measure " refers to not perfect recrystallization of microstructure, cannot pass judgment on according to metallographic structure standard.
Data by table in 1-3 can be found out, adopt preparation method of the present invention, can obtain to have finished product mechanical property and reach yield strength R
eLfor 200-270MPa, tensile strength R
mfor 320-360MPa, elongation after fracture A
80>=37%, plastic strain ratio r
90>=2, work hardening exponent n
90>=0.2, baking hardening value BH
2ferritic structure, the ferrite grain size that>=35MPa, surface quality feature FC level are above, microstructure is 100% is that 8 grades of above and ferrite grain sizes are the hot-dip galvanizing sheet steel of 12-20 μ m.
More than describe the preferred embodiment of the present invention in detail; but the present invention is not limited to the detail in above-mentioned embodiment, within the scope of technical conceive of the present invention; can carry out multiple simple variant to technical scheme of the present invention, these simple variant all belong to protection scope of the present invention.
It should be noted that in addition, each concrete technical characterictic described in above-mentioned embodiment, in reconcilable situation, can combine by any suitable mode, for fear of unnecessary repetition, the present invention is to the explanation no longer separately of various possible array modes.
In addition, between various embodiment of the present invention, also can carry out arbitrary combination, as long as it is without prejudice to 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 comprises: by slab successively through hot rolling, batch, cold rolling and annealing, it is characterized in that,
After described hot rolling and before described batching, first the speed of cooling with 70-90 ℃/s is cooled to 750-810 ℃ by the intermediate slab obtaining after hot rolling, then is cooled to the temperature of batching with the speed of cooling of 15-25 ℃/s;
Described temperature of batching is 670-750 ℃;
Described cold rolling draft is 60-75%;
The condition of described annealing comprises: soaking temperature is 830-890 ℃, and soaking time is 40-70s;
Consisting of of described slab: C:0.001-0.005 % by weight, Si:0.01-0.06 % by weight, Mn:0.1-0.6 % by weight, P:0.02-0.08 % by weight, S :≤0.02 % by weight, Al:0.01-0.08 % by weight, Ti:0.001-0.02 % by weight, Nb:0.001-0.025 % by weight, surplus is Fe and inevitable impurity.
2. method according to claim 1, wherein, consisting of of described slab: C:0.001-0.004 % by weight, Si:0.01-0.055 % by weight, Mn:0.2-0.55 % by weight, P:0.025-0.065 % by weight, S:0.01-0.016 % by weight, Al:0.02-0.065 % by weight, Ti:0.005-0.017 % by weight, Nb:0.005-0.022 % by weight, surplus is Fe and inevitable impurity.
3. method according to claim 1, wherein, after described hot rolling and before described batching, first the speed of cooling with 73-88 ℃/s is cooled to 760-805 ℃ by the intermediate slab obtaining after hot rolling, then is cooled to the temperature of batching with the speed of cooling of 17-23 ℃/s.
4. according to the method described in claim 1 or 3, wherein, described in the temperature of batching be 673-748 ℃.
5. method according to claim 1, wherein, described cold rolling draft is 64-69%.
6. method according to claim 1, wherein, the condition of described annealing comprises: soaking temperature is 845-885 ℃, soaking time is 45-65s.
7. method according to claim 1, wherein, described hot rolling comprises roughing and finish rolling, and the start rolling temperature of described roughing is 1170-1220 ℃, and the finishing temperature of described roughing is 1125-1175 ℃; The start rolling temperature 1100-1155 ℃ of described finish rolling, the finishing temperature of described finish rolling is 890-940 ℃.
8. the cold-rolled steel sheet that the method described in any one makes in claim 1-7.
9. a preparation method for hot-dip galvanizing sheet steel, is characterized in that, the method comprises adheres to upper zinc coating by cold-rolled steel sheet claimed in claim 8 through galvanizing.
10. preparation method according to claim 9, wherein, on every square metre of described hot-dip galvanizing sheet steel, the weight of described zinc coating is 75-150g.
11. the hot-dip galvanizing sheet steel being made by the preparation method described in claim 9 or 10.
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| CN106834937A (en) * | 2017-01-05 | 2017-06-13 | 河钢股份有限公司邯郸分公司 | A kind of 530MPa grades of Thin Specs galvanized steel and its production method |
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| CN106834937B (en) * | 2017-01-05 | 2018-02-06 | 河钢股份有限公司邯郸分公司 | A kind of 530MPa levels Thin Specs galvanized steel and its production method |
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