CN105369134A - Hot rolled steel plate for 400MPa-level acid-pickling-free automobile structure and production method of hot rolled steel plate - Google Patents

Hot rolled steel plate for 400MPa-level acid-pickling-free automobile structure and production method of hot rolled steel plate Download PDF

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CN105369134A
CN105369134A CN201510778750.6A CN201510778750A CN105369134A CN 105369134 A CN105369134 A CN 105369134A CN 201510778750 A CN201510778750 A CN 201510778750A CN 105369134 A CN105369134 A CN 105369134A
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hot
rolled steel
steel sheet
400mpa
pickling
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CN105369134B (en
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刘庆春
郑之旺
李卫平
许哲峰
张功庭
方勇
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Pangang Group Panzhihua Iron and Steel Research Institute Co Ltd
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Pangang Group Panzhihua Iron and Steel Research Institute Co Ltd
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    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/04—Ferrous alloys, e.g. steel alloys containing manganese
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21C—PROCESSING OF PIG-IRON, e.g. REFINING, MANUFACTURE OF WROUGHT-IRON OR STEEL; TREATMENT IN MOLTEN STATE OF FERROUS ALLOYS
    • C21C7/00—Treating molten ferrous alloys, e.g. steel, not covered by groups C21C1/00 - C21C5/00
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D8/00—Modifying the physical properties by deformation combined with, or followed by, heat treatment
    • C21D8/02—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips
    • C21D8/0221—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips characterised by the working steps
    • C21D8/0226—Hot rolling
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/02—Ferrous alloys, e.g. steel alloys containing silicon
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/06—Ferrous alloys, e.g. steel alloys containing aluminium
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D2211/00—Microstructure comprising significant phases
    • C21D2211/005—Ferrite
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D2211/00—Microstructure comprising significant phases
    • C21D2211/009—Pearlite

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Materials Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Mechanical Engineering (AREA)
  • Physics & Mathematics (AREA)
  • Thermal Sciences (AREA)
  • Crystallography & Structural Chemistry (AREA)
  • Heat Treatment Of Sheet Steel (AREA)

Abstract

The invention belongs to the technical field of metallurgy and particularly relates to a production and preparation method of a hot rolled steel plate for a 400MPa-level acid-pickling-free automobile structure. Chemical components of the hot rolled steel plate for the 400MPa-level acid-pickling-free automobile structure include, by weight, 0.05-0.10% of C, 0.05-0.15% of Si, 0.7-1.00% of Mn, 0.002-0.006% of N, 0-0.025% of P, 0-0.015% of S, 0.02-0.06% of Al and the balance Fe. According to a finished steel strip obtained through the method, the yield strength is larger than or equal to 255 MPa, the tensile strength is larger than or equal to 400 MPa, the ductility is larger than or equal to 34%, and the cold bending property is good.

Description

400MPa level exempts from pickling vehicle structure hot-rolled steel sheet and production method thereof
Technical field
The invention belongs to metallurgical technology field, particularly a kind of 400MPa level exempts from production method of pickled hot vehicle structure steel plate and preparation method thereof.
Background technology
Growing along with national economy, automobile industry has become the mainstay industry of China, the consumption of hot-rolled steel plates for automobiles increases year by year, according to Hyundai Motor " energy-saving and emission-reduction, environmental protection, safety etc. " demand, car manufactures proposes the requirement of developing the steel products can exempting from pickling or be easy to pickling to automobile component steel aspect.The iron scale form that this hot-strip product surface produces is Fe 3o 4+ Fe, instead of Fe 3o 4+ FeO type, even needs to generate multilayer Fe 3o 4oxide compound.Due to Fe 3o 4have lower hardness (HV350 ~ 500), preferably plasticity and good adhesion, therefore can not decortication occur because of bending and break in deep-processing process subsequently, simultaneous oxidation iron sheet can play the lubrication between instrument and workpiece.Like this, the acid cleaning process after even fully phasing out hot rolling can be simplified, contribute to the sticking power improving plating enamelled coating simultaneously.
At present, domestic have people based on the control climate in iron scale forming process, have developed the rust-preventive agent being sprayed at Surfaces of Hot Rolled Strip, makes can promote Fe in this way 3o 4generation, but need increase cooling apparatus, therefore need larger investment, meanwhile, this method can not produce Fe 3o 4the iron scale tissue that+Fe is easily deformable.The technology that the states such as Japan, Korea S, Australia adopt is type and the thickness of controlled oxidization iron sheet in hot rolling is produced, and only need course of hot rolling, particularly roller repairing process carries out careful control, and does not need to increase new equipment.The states such as Japan, Korea S and Australia have carried out a large amount of work all in this regard.NKK, NipponSteel and KawasakiSteel etc. of Japan maintain the leading position at exploitation hot-rolled black-skin steel technical elements.The exploitation of China's iron and steel bound pair hot-rolled black-skin steel is still in the exploratory stage at present, and the hot-rolled sheet users such as automobile production producer are to this existing strong requirement.Therefore, develop the easy pickling of hot rolling or exempt from pickling black rust steel and become an important technical research job.
For Miniature riding car material, 400MPa level hot rolled steel plate belongs under body structure mainly applies material, steel require to possess good obdurability, processability, enough structural rigidity and welding property, to meet the impact briquetting of auto parts, welding process requirement and loading process opposing local deformaton, at utmost apparatus with shock absorbing, guarantees vehicle body safety.The common mode of production mainly considers the obdurability coupling of steel, refined crystalline strengthening and solution strengthening is utilized to improve the performance of steel plate to greatest extent, later stage adopts acid cleaning process to remove surface oxide layer, and the phosphatize phosphate coat utilizing phosphating process to be formed improves the binding ability of steel plate and finish paint.In recent years, in order to adapt to the demand of vehicle lightness, partial automobile manufacturing concern proposing low cost when purchasing 400MPa level vehicle structure hot-rolled steel sheet, exempting from the service requirements of pickled surface quality, and it is mainly in table 1.
Table 1400MPa level hot-rolled structural steel mechanical property and processing performance requirement
400MPa level vehicle structure hot-rolled steel sheet chemical composition design adopts low C-Mn microalloying scheme both at home and abroad usually, Mn content is generally 1.0%, C content is generally about 0.10%, hot rolling technology adopts controlled rolling and controlled cooling, its technical characterstic is the effect more considering alloying element solid solution strength and refined crystalline strengthening, but need the later stage to increase pickling process, there is the higher and spent acid environmental protection treatment fringe cost of production cost.
Summary of the invention
For above-mentioned defect, the 400MPa level that the invention provides a kind of high comprehensive performance exempts from pickled hot vehicle structure steel plate, and it has good room-temperature mechanical property and processing performance, Fe in finished surface iron scale 3o 4shared ratio is all more than 80%, and can adapt to automobile component enterprise and exempt from pickling production requirement, the cost performance of steel is high.
Technical scheme of the present invention:
First technical problem to be solved by this invention is to provide a kind of 400MPa level and exempts from pickling vehicle structure hot-rolled steel sheet, its chemical composition by weight percentage is counted: C:0.05 ~ 0.10, Si:0.05 ~ 0.15, Mn:0.7 ~ 1.00, N:0.002 ~ 0.006, P:0 ~ 0.025, S:0 ~ 0.015, Al:0.02 ~ 0.06, and all the other are Fe.
Further, the heterogeneous microstructure that described 400MPa level exempts from pickling vehicle structure hot-rolled steel sheet comprises ferrite and pearlite, with the cumulative volume of crystalline structure for benchmark, ferritic percent by volume is 88 ~ 90%, and pearlitic percent by volume is 10 ~ 12%.Ferrite and pearlitic percent by volume can adopt the method for well known to a person skilled in the art to record, such as GB/T6394 metallographic method.400MPa level vehicle structure hot-rolled steel sheet provided by the invention has good room-temperature mechanical property and processing performance, meets the requirement of technical indicator completely.
Further, the yield strength >=255MPa of described hot-rolled steel sheet, tensile strength >=400MPa, unit elongation >=34%.
Further, Fe in the iron scale of described hot rolled sheet metal surface 3o 4content>=80%.
Further, the iron scale thickness of described hot rolled sheet metal surface is 7 ~ 9 μm.
Second technical problem to be solved by this invention is to provide the preparation method that above-mentioned 400MPa level exempts from pickling vehicle structure hot-rolled steel sheet, comprises converter smelting, LF refining, continuous casting, continuously cast bloom reheat, hot rolling, cools and batch; Wherein,
It is 1210 ~ 1230 DEG C that continuously cast bloom reheats temperature, and heat-up time is 1.2 ~ 1.8 hours;
In hot-rolled process, roughing start rolling temperature is 1173 DEG C ~ 1200 DEG C, de-scaling water pressure >=21MPa; Finish rolling start rolling temperature≤1020 DEG C, open rolling speed >=1.5m/s, finish rolling finishing temperature is 860 ~ 890 DEG C, finish rolling finish to gauge roll speed >=7.8m/s;
Coiling temperature is 560 DEG C ~ 590 DEG C;
The chemical composition of steel billet is: C:0.05 ~ 0.10, Si:0.05 ~ 0.15, Mn:0.7 ~ 1.00, N:0.002 ~ 0.006, P:0 ~ 0.025, S:0 ~ 0.015, Al:0.02 ~ 0.06, and all the other are Fe.
Further, in hot-rolled process, roughing de-scaling water pressure >=21MPa; Finish rolling open rolling speed >=1.5m/s, finish rolling finish to gauge roll speed >=7.8m/s.
Further, in aforesaid method, refrigerating work procedure adopts the sparse type of cooling.
Further, in converter smelting operation, tapping temperature is 1660 ~ 1680 DEG C, the oxygen activity <80ppm of pre-deoxidation terminal during tapping.
Beneficial effect of the present invention:
1, the inventive method adopts in production process technological measures such as controlling chemical composition ranges, hot rolling Heating temperature, finishing temperature, coiling temperature, finished steel sheet yield strength >=the 255MPa obtained, tensile strength >=400MPa, unit elongation >=34%, cold-bending property is excellent.
2, low equivalent scheme is adopted during chemical composition design, Plate Welding excellent property.
3, external refining process adopts Si-Ca line to carry out sulfide denaturing treatment, sulfide exists with ribbon or corynebacterium usually at steel grade, be unfavorable for the punching performance of steel, thus sulfide denaturing treatment is adopted when external refining process, Ca:S >=2.0, improve molten steel cleanliness, and make residual nonmetal inclusion shape in steel abnormal, rolled by untreated front edge and become hammer-imitation type or spherical to the ribbon distributed or corynebacterium, improve the cold forming capability of steel plate.
4, Fe in finished surface iron scale 3o 4shared ratio, all more than 80%, effectively can adapt to user and exempt from pickling requirement.
5, compared with the same level hot-rolled steel sheet produced with low C-Mn-Si alloying, the production technique that the present invention adopts is simple, production cost is lower, effectively can substitute acid cleaning process, have higher cost performance, promote the use of and have good prospects.
Embodiment
The production method technical process that the 400MPa level that the present invention relates to exempts from pickling vehicle structure hot-rolled steel sheet is as follows:
Converter smelting → LF refining → electrically heated → continuous casting → hot rolling → cool → batch → finishing → packaging warehouse-in; In the present invention, steel billet can adopt the method for well known to a person skilled in the art to be obtained through converter smelting, LF refining, electrically heated, continuous casting working procedure by blast-melted.
Converter smelting is specially blast-melted and smelting furnace material to smelt in converter and obtains molten steel, then deoxidation of molten steel carried out alloying; In alloying step, carbonaceous material, aluminum-manganese-iron alloy and aluminum shot are joined in the molten steel after deoxidation, obtain molten steel (with molten steel gross weight for benchmark, in simple substance) be C:0.05 ~ 0.10, Si:0.05 ~ 0.15, Mn:0.7 ~ 1.00, N:0.002 ~ 0.006, P:0 ~ 0.025, S:0 ~ 0.015, Al:0.02 ~ 0.06, all the other are Fe.In order to make the content of S in feed stock for blast furnace be less than or equal to into stove molten iron gross weight 0.015%, low-sulfur molten iron or semisteel smelting can be adopted.In order to prevent the scaling loss of metallic element especially manganese element, strictly will control oxygen activity when smelting process temperature and tapping, smelting condition is tapping temperature 1660 ~ 1680 DEG C, and during tapping, the oxygen activity condition of pre-deoxidation terminal is [a 0] <80ppm.The carbonaceous material that smelting process is added is carbonaceous material well known in the art, is preferably one or more in pitch coke, hard coal and carbon dust.The time of smelting is the time of conventional smelting, is preferably 35 ~ 45 minutes.
The object of deoxidation of molten steel be reduce molten steel oxygen activity to improve yield of alloy, described reductor is ferro-aluminum, and the add-on of reductor is preferably 400 ~ 550Kg/ stove.
The mode of alloying step batch charging, external refining adopt and well known to a person skilled in the art method.Alloying step after deoxidation comprises and joins in the molten steel after deoxidation by ferro-aluminum, carbonaceous material, silicomanganese, ferro-niobium, obtain molten steel (with described molten steel gross weight for benchmark, in simple substance) C:0.05 ~ 0.10, Si:0.05 ~ 0.15, Mn:0.7 ~ 1.00, N:0.002 ~ 0.006, P:0 ~ 0.025, S:0 ~ 0.015, Al:0.02 ~ 0.06, all the other are Fe.
Even in order to ensure the chemical composition of steel, after alloying, argon bottom-blowing process is carried out to ladle.The condition of described argon bottom-blowing process is temperature 1600 ~ 1650 DEG C, pressure 200 ~ 400 handkerchief, 4 ~ 8 minutes time.
LF refinement step is finely tuned the oxygen activity of molten steel, purity and temperature, the oxygen activity utilizing secondary to feed Al line final deoxygenation control molten steel is 20 ~ 40ppm, the argon gas 4 ~ 6 minutes of pressure 200 ~ 400Pa is passed into bottom ladle, argon flow amount does not turn over as condition with molten steel very much, molten steel can be avoided to occur, and secondary oxidation and temperature decline too fast, steel inclusion is fully floated, improves steel degree of cleaning further.Ca Si wire feeding (containing Ca >=24%, specification: φ 10mm) process is carried out, add-on 1000 ~ 1200m/ stove after Al line is fed in electrically heated and benefit.
Electrically heated step is operation steel billet being reached be suitable for pouring temperature, is the basic working procedure that continuous casting steel is produced.Carry out heating to steel billet can adopt and well known to a person skilled in the art various heating installation and heating means.
Continuous casting step can adopt the method for well known to a person skilled in the art, the inventive method is by the molten steel casting after refining to the tundish roasted in advance, and the continuous casting machine through whole process protection is cast into slab.After casting, can conventionally cool, as at room temperature naturally cooling.
Hot-rolled step is rolled after heating by the slab of casting.The object of rolling makes the continuous casting steel billet of 400MPa level automobile structural steel reach required thickness.The rolling pass of hot-rolled sheet steel band of the present invention is roughing 6, finish rolling 5 ~ 6, and every frame frame rolling together every time rolling makes the thickness of hot rolling material base reduce 3 ~ 9 millimeters.
The start rolling temperature of hot rolling refers to that steel billet enters the temperature of milling train, heats at such a temperature, can abundant solid solution microalloy element, eliminates the effect because continuous casting steel billet dendritic segregation, microalloy element skewness in steel causes performance not good.The finishing temperature of hot rolling refers to that steel band goes out the temperature of finishing train, in order to make the thickness of finished product and mechanical property even, adopt hot-rolled intermediate billet Coil Box Technology, make the hot-rolled intermediate billet stub bar before finish rolling, in, afterbody keeps specific finishing temperature.Hot rolling Heating temperature of the present invention is 1210 ~ 1230 DEG C, time is 1.2 ~ 1.8 hours, the breaking down temperature of hot-rolled step is 1130 ~ 1200 DEG C, de-scaling water pressure >=21MPa, finish rolling start rolling temperature≤1020 DEG C, open rolling speed >=1.5m/s, finishing temperature is 860 ~ 890 DEG C, finish to gauge outlet roll speed >=7.8m/s; Finishing temperature is 860 ~ 890 DEG C; Temperature in course of hot rolling controls to make steel be in complete austenite structure before finish rolling outlet; And avoid austenite structure too thick, being conducive to controlling hot-rolled finished product ferrite grain size is 5.6 ~ 7.9 microns, improves refined crystalline strengthening effect.
Cooling step adopts the sparse type of cooling, and object reduces the thermal stresses of surface oxide layer, avoids the too fast surface oxide layer of speed of cooling to form microcrack, causes zone of oxidation and basic bonding force to decline.For sheet steel band, the thin plate steel band comprised through rolling have adjusted the structural state of steel inside after cooling, then carries out batching rolling.In order to meet the structure and properties requirement of hot-rolled sheet, must in a short period of time, under very high speed of cooling, coiling temperature be cooled to batch from milling train steel band out.Such as, the speed of described cooling is 10 ~ 30 DEG C/sec, is cooled to 560 ~ 590 DEG C.
In the present invention, the detection method of chemical composition is respectively carbon steel and middle-low alloy steel spark source atomic emission spectrometry analytical procedure, and national standard is GB/T4336.
The present invention adopts low C-Mn-Si alloying scheme and controlled rolling and controlled cooling mode to produce, external refining measure is targetedly adopted after smelting, reduce inclusion to the impact of cold roll forming performance, hot rolling adopts the method for controlled rolling and controlled cooling model, obtains a certain amount of ferrite, pearlitic structure.Assay shows that the 400MPa level vehicle structure hot-rolled steel sheet produced by the method has good room-temperature mechanical property and processing performance, Fe in finished surface iron scale 3o 4shared ratio is all more than 80%, and can adapt to automobile component enterprise and exempt from pickling production requirement, the cost performance of steel is high, promotes the use of and has good prospects.
Below in conjunction with embodiment, the invention will be further elaborated.Embodiment only for illustration of the present invention, instead of limits the present invention by any way.
Embodiment 1
A, smelting molten steel: smelting equipment is 220 tons of combined blown converters, blast-melted as raw material, blast-melted temperature 1365 DEG C, add steelmaking ingredient melting to 1680 DEG C tapping to ladle, tap 1/3 time add 1000Kg ferroaluminium (Anyang Jia Xinnai material company limited) pre-deoxidation, then in the molten steel after deoxidation, add pitch coke (Flos Bombacis Malabarici Yangcheng metallurgic auxiliary materials company limited) and silicomanganese (Dechang iron alloy company limited), the content of each composition in molten steel is made to be (with the gross weight of molten steel for benchmark, wt%) C:0.07, Si:0.10, Mn:0.90, P:0.014, S:0.006, Al:0.05, N:0.0040, all the other are Fe.Carry out argon bottom-blowing process to ladle, argon pressure 200 ~ 400Pa at the outer chain-wales of stove subsequently, the time is 4 minutes.
The steel oxygen content in water after deoxidation is made to be 10ppm ~ 50ppm by the addition controlling reductor, manganese is prevented to be oxidized as far as possible, thus ensure that manganese exists with simple substance in the hot-rolled structural steel of preparation, instead of exist in the form of an oxide, to give full play to the function of simple substance manganese.
B, LF electrically heated: secondary feeds Al line final deoxygenation, the argon gas 6 minutes of certain pressure (200Pa ~ 400Pa) is passed into bottom ladle, argon flow amount does not turn over as condition with molten steel very much, the backward Si-Ca line being added 1000m by wire feeder to ladle of blowing argon gas, LF process final temperature 1590 DEG C.
C, continuous casting: ladle is transported to casting position, the basal sliding mouth of a river of ladle adopts aluminium matter stopper (Anyang Ye Fu company limited), and molten steel flows into tundish automatically, through aluminium matter stopper, is drained to crystallizer and carries out continuous casting; Whole process adopts covering slag to carry out protective casting, is cooled to slab after casting.
D, hot rolling: it is 1226 DEG C (eliminate dendritic segregation, control original austenite grains size) that continuous casting steel billet reheats temperature, and the time is 1.6 hours; Roughing temperature is 1140 DEG C, de-scaling water pressure 22MPa, finish rolling start rolling temperature 1010 DEG C, open rolling speed 1.8m/s; Finish rolling finishing temperature is 872 DEG C, finish rolling finish to gauge outlet roll speed 8.5m/s; Cooling step adopts the sparse type of cooling; Coiling temperature 570 DEG C.The rolling pass of finish rolling is 7, and every time rolling makes the thickness of intermediate blank be respectively 38 ~ 21 millimeters, 21 ~ 13 millimeters, 13 ~ 9 millimeters, 9 ~ 6.7 millimeters, 6.7 ~ 5.6 millimeters and 5.6 ~ 5 millimeters.
E, finishing: steel band is packaging warehouse-in after skin pass mill group separately volume.
The coiled sheet of preparation is carried out measuring mechanical property, detects the yield strength Rel of room temperature, tensile strength Rm and elongation A respectively 200mm, tensile property carries out according to GB/T228 metallic substance tensile testing at ambient temperature.Finished product yield strength (Rel) is 311MPa, and tensile strength (Rm) is 425MPa, unit elongation (A 50mm) be 38%, cold bending process experimental performance is qualified, and the thickness of the iron scale of gained hot-rolled steel sheet finished surface is 8.5 μm, Fe in scale on surface 3o 4ratio reach 85%, meet the technical qualification requirement that 400MPa exempts from pickled hot vehicle structure steel plate.
Embodiment 2
Preparation method is substantially the same manner as Example 1, and the molten steel composition obtained unlike converter smelting is C:0.07, Si:0.11, Mn:0.87, P:0.015, S:0.007, Al:0.04, N:0.0036, and all the other are Fe; And with the hot-rolled steel sheet that aforementioned molten steel is produced, slab tapping temperature 1220 DEG C, finish rolling open rolling speed 1.88m/s, finish to gauge outlet roll speed 8.7m/s; Finishing temperature is 878 DEG C, and coiling temperature is 565 DEG C, hot-rolled finished product thickness 4.5mm.
The coiled sheet of preparation is carried out measuring mechanical property, detects tensile strength Rm and the elongation A of room temperature respectively 200mm, tensile property carries out according to GB/T228 metallic substance tensile testing at ambient temperature.Finished product yield strength (Rel) is 310MPa, and tensile strength (Rm) is 420MPa, unit elongation (A 50mm) be 39%, cold bending process experimental performance is qualified, finished product oxygen thickness of scale 7.9 μm, Fe in scale on surface 3o 4ratio reach 86%, meet the technical qualification requirement that 400MPa exempts from pickled hot vehicle structure steel plate.
Comparative example 1
Preparation method is substantially the same manner as Example 1, the molten steel composition obtained unlike converter smelting is C:0.09%, Si:0.19%, Mn:0.90%, P:0.016%, S:0.007%, Al:0.056%, all the other are Fe, and with the hot-rolled steel sheet that aforementioned molten steel is produced, slab tapping temperature 1200 DEG C, finish rolling open rolling speed 1.30m/s, finish to gauge outlet roll speed 6.0m/s; Finishing temperature is 890 DEG C, and coiling temperature is 620 DEG C, hot-rolled finished product thickness 5.0mm.
The coiled sheet of preparation is carried out measuring mechanical property, detects tensile strength Rm and the elongation A of room temperature respectively 50mm, tensile property carries out according to GB/T228 metallic substance tensile testing at ambient temperature.Finished product yield strength (Rel) is 330MPa, and tensile strength (Rm) is 430MPa, unit elongation (A 50mm) be 34%, cold bending process experimental performance is qualified, and finished surface iron scale thickness is 12 μm, Fe in scale on surface 3o 4ratio be 60%, visible, the thickness of gained surface of steel plate iron scale and scale structure do not meet the technical qualification requirement that 400MPa exempts from pickled hot vehicle structure steel plate.

Claims (9)

1.400MPa level exempts from pickling vehicle structure hot-rolled steel sheet, it is characterized in that, its chemical composition by weight percentage meter comprises: C:0.05 ~ 0.10, Si:0.05 ~ 0.15, Mn:0.7 ~ 1.00, N:0.002 ~ 0.006, P:0 ~ 0.025, S:0 ~ 0.015, Al:0.02 ~ 0.06, and all the other are Fe.
2. 400MPa level exempts from pickling vehicle structure hot-rolled steel sheet according to claim 1, it is characterized in that, the heterogeneous microstructure of described hot-rolled steel sheet comprises ferrite and pearlite, with the cumulative volume of crystalline structure for benchmark, ferritic percent by volume is 88 ~ 90%, and pearlitic percent by volume is 10 ~ 12%.
3. according to claim 1 or 2,400MPa level exempts from pickling vehicle structure hot-rolled steel sheet, it is characterized in that, the yield strength >=255MPa of described hot-rolled steel sheet, tensile strength >=400MPa, unit elongation >=34%.
4. according to any one of claims 1 to 3,400MPa level exempts from pickling vehicle structure hot-rolled steel sheet, it is characterized in that, Fe in the iron scale of described hot rolled sheet metal surface 3o 4content>=80%.
5. according to any one of Claims 1 to 4,400MPa level exempts from pickling vehicle structure hot-rolled steel sheet, it is characterized in that, the iron scale thickness of described hot rolled sheet metal surface is 7 ~ 9 μm.
6. described in any one of Claims 1 to 5,400MPa level exempts from the preparation method of pickling vehicle structure hot-rolled steel sheet, comprises converter smelting, LF refining, continuous casting, continuously cast bloom reheat, hot rolling, cools and batch; It is characterized in that,
It is 1210 ~ 1230 DEG C that continuously cast bloom reheats temperature, and heat-up time is 1.2 ~ 1.8 hours;
In hot-rolled process, roughing start rolling temperature is 1173 DEG C ~ 1200 DEG C, finish rolling start rolling temperature≤1020 DEG C, and finish rolling finishing temperature is 860 ~ 890 DEG C;
Coiling temperature is 560 DEG C ~ 590 DEG C.
7. 400MPa level exempts from the preparation method of pickling vehicle structure hot-rolled steel sheet according to claim 6, it is characterized in that, in converter smelting operation, tapping temperature is 1660 ~ 1680 DEG C, the oxygen activity <80ppm of pre-deoxidation terminal during tapping.
8. according to claim 6 or 7,400MPa level exempts from the preparation method of pickling vehicle structure hot-rolled steel sheet, it is characterized in that, in hot-rolled process, and de-scaling water pressure >=21MPa, finish rolling open rolling speed >=1.5m/s, finish rolling finish to gauge roll speed >=7.8m/s.
9. according to any one of claim 6 ~ 8,400MPa level exempts from the preparation method of pickling vehicle structure hot-rolled steel sheet, it is characterized in that, refrigerating work procedure adopts the sparse type of cooling.
CN201510778750.6A 2015-11-12 2015-11-12 400MPa grades is exempted from pickling vehicle structure hot rolled steel plate and its production method Active CN105369134B (en)

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CN105369134B CN105369134B (en) 2017-07-04

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Cited By (4)

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Publication number Priority date Publication date Assignee Title
CN106636924A (en) * 2016-12-30 2017-05-10 武钢集团昆明钢铁股份有限公司 235 MPa level shock-proof hot-rolled steel plate and steel strip for building structure and preparation method thereof
CN107904503A (en) * 2017-11-24 2018-04-13 攀钢集团攀枝花钢铁研究院有限公司 Pickling vehicle structure steel plate and its production method are exempted from 510MPa grades of hot rollings
CN109440005A (en) * 2018-11-14 2019-03-08 河钢股份有限公司承德分公司 A kind of SAPH440 crystal grain refinement steel and its production method
CN114752725A (en) * 2022-04-02 2022-07-15 湖南华菱涟源钢铁有限公司 Pickled plate and production method thereof

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CN101935802A (en) * 2010-09-30 2011-01-05 攀钢集团钢铁钒钛股份有限公司 Method for producing 490MPa level acid-washing-free hot rolled steel plate
CN102086495A (en) * 2010-12-22 2011-06-08 山西太钢不锈钢股份有限公司 Production method of oxide film hot-rolled strip steel with high adhesion
CN102719754A (en) * 2012-05-31 2012-10-10 攀钢集团攀枝花钢铁研究院有限公司 Hot-rolled deep-punched pickled plate for automobile structures and production method thereof

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JP2004043888A (en) * 2002-07-11 2004-02-12 Jfe Steel Kk Hot-rolled steel sheet with mill scale having superior blackness, and manufacturing method therefor
CN101935802A (en) * 2010-09-30 2011-01-05 攀钢集团钢铁钒钛股份有限公司 Method for producing 490MPa level acid-washing-free hot rolled steel plate
CN102086495A (en) * 2010-12-22 2011-06-08 山西太钢不锈钢股份有限公司 Production method of oxide film hot-rolled strip steel with high adhesion
CN102719754A (en) * 2012-05-31 2012-10-10 攀钢集团攀枝花钢铁研究院有限公司 Hot-rolled deep-punched pickled plate for automobile structures and production method thereof

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN106636924A (en) * 2016-12-30 2017-05-10 武钢集团昆明钢铁股份有限公司 235 MPa level shock-proof hot-rolled steel plate and steel strip for building structure and preparation method thereof
CN106636924B (en) * 2016-12-30 2018-04-03 武钢集团昆明钢铁股份有限公司 A kind of building structure of 235MPa ranks earthquake-resistant hot rolled steel plate, steel band and preparation method thereof
CN107904503A (en) * 2017-11-24 2018-04-13 攀钢集团攀枝花钢铁研究院有限公司 Pickling vehicle structure steel plate and its production method are exempted from 510MPa grades of hot rollings
CN109440005A (en) * 2018-11-14 2019-03-08 河钢股份有限公司承德分公司 A kind of SAPH440 crystal grain refinement steel and its production method
CN114752725A (en) * 2022-04-02 2022-07-15 湖南华菱涟源钢铁有限公司 Pickled plate and production method thereof
CN114752725B (en) * 2022-04-02 2023-11-17 湖南华菱涟源钢铁有限公司 Pickle sheet and production method thereof

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