CN107747042A - A kind of high reaming steel of the economical great surface quality of 690MPa levels and preparation method thereof - Google Patents
A kind of high reaming steel of the economical great surface quality of 690MPa levels and preparation method thereof Download PDFInfo
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- CN107747042A CN107747042A CN201711080428.1A CN201711080428A CN107747042A CN 107747042 A CN107747042 A CN 107747042A CN 201711080428 A CN201711080428 A CN 201711080428A CN 107747042 A CN107747042 A CN 107747042A
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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
- C22C38/02—Ferrous alloys, e.g. steel alloys containing silicon
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- 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
- C21D8/04—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips to produce plates or strips for deep-drawing
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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
- C22C38/002—Ferrous alloys, e.g. steel alloys containing In, Mg, or other elements not provided for in one single group C22C38/001 - C22C38/60
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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
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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
- C22C38/06—Ferrous alloys, e.g. steel alloys containing aluminium
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Abstract
The invention discloses a kind of high reaming steel of the economical great surface quality of 690MPa levels and preparation method thereof, belongs to Ferrous Metallurgy and calendering technical field.The high reaming steel of the economical great surface quality of 690MPa levels, by weight percentage, its chemical composition is [C], [Si], [Mn], [P], [S], [Alt], [Ca], [N] and [O], and remaining is Fe and inevitable impurity.Its preparation method comprises the following steps：Smelting procedure → continuous casting working procedure → heating process → roughing operation → Coil Box process → finishing rolling step → laminar flow cooling technology → batches → Slow cooling → pickling process → and batches packaging.The present invention makes high reaming steel have the characteristics of low great surface quality, cost, excellent performance, disclosure satisfy that the demand of automobile chassis and complicated stamping steel by the control to high reaming steel chemical composition and preparation method.
Description
Technical field
The invention belongs to Ferrous Metallurgy and calendering technical field, and in particular to a kind of economical great surface quality of 690MPa levels
High reaming steel and preparation method thereof.
Background technology
For automotive light weight technology, reduce oil consumption and improvement vehicle security etc., in recent years the research and development plan of many new steel grades
It is concentrated mainly on AHSS (Advanced High Strength Steel, letter of the exploitation with favorable forming property
Claim AHSS).The species of AHSS steel is a lot, such as ferrite/martensite two-phase (Ferrite/Martensite Dual Phase, letter
Claim FMDP) steel, ferrite/bainite two-phase (Ferrite/Bainite Dual Phase, abbreviation FBDP) steel, phase-change induced modeling
Property (Transformation Induced Plasticity, abbreviation TRIP) steel, twin crystal inducing plasticity (Twinning
Induced Plasicity, abbreviation TWIP) steel, complex phase (Complex Phase, abbreviation CP) steel, martensite (Martensite,
Abbreviation M) steel, quenching partition (Quenching andParitioning, abbreviation Q＆P) steel and hot forming (Hot Formed, referred to as
HF) steel etc..
The schedule of reinforcement of AHSS steel is in addition to the schedule of reinforcements such as solid solution, crystal grain refinement, precipitation, also phase transformation strengthening, and this is
It is one of main schedule of reinforcement of AHSS steel not available for common high-strength steel.Compared with rolled products of ordinary high-strength steel, the shaping of AHSS steel
Property it is good, S. E. A. is high, anticollision concavity can good, baking and hardening performance, yield strength, work hardening rate be high and fatigue behaviour
The advantages that good, its good application scenario is increasingly shown in automobile industry.
Hot-rolled high-strength steel plate is used to make the automobile traveling part such as automobile chassis, wheel, is the weight for realizing car body loss of weight
One of effective way wanted.Automotive chassis components are not exposed, though it is not very strict to plate surface quality requirement, due to its shape
Complexity, main shaping include：Stretch flanging, bending, reaming and spark-erosion sinking etc., shaping of these forming modes to steel plate
Property, especially Extending flange Perfor requires higher.
Traditional FMDP steel when shaping Complicated Automobile part (such as：Automobile chassis, rim for automobile wheel and spoke etc.), change be present
The very big two-phase of shape capacity variance (F+M) interface, easily ftractureed in forming process in osseotomy site, stretch flange formability forming property is not
Reach, especially after Flash Butt Welding, martenaging martempering softening easily occurs at heat affected area (HAZ), while fatigue strength is low, therefore nothing
Method meets shaping demand.
FBDP steel is also referred to as stretch flange formability (Stretch-Flangeable, abbreviation SF) steel or high reaming (High Hole-
Expansion, abbreviation HHE) steel, when bainite content is 10%~20%, it has very good forming property, especially
It is Extending flange Perfor.Relative to HSLA (Aldecor, High Strength LowAlloy Steel) and FMDP
Steel, the major advantage of FBDP steel are to improve sheared edge ductility, take into account the contradiction and balance of intensity and extensibility, and it is welded
Connect, fatigue and reaming it is functional, have general material it is incomparable the advantages of；FBDP steel heat affected area after Flash Butt Welding
Hardness be higher than parent metal, be not in ruckbildung during with post-processing, while the steel plate has good slight-fatigability
It can coordinate, compared with the HSLA steel of equality strength rank, FBDP steel strain hardening exponent (n values) and breaking elongation are higher, therefore
FBDP steel is higher similar to requirements such as automobile chassises more suitable for punching press, and the part that extension property is good.
In the 1990s, the U.S., Japan etc. develop the hot rolling FB steel of the high reaming performance of 440~780MPa levels in succession
Plate, its hole expansibility are 70%~131%, are mainly used in formability, the especially good automobile chassis of flange performance requirement, car
The parts such as wheel, because it contains more expensive alloying elements Cr, Nb, Ti, V and Mo etc., although can under conditions of cooling rate is relatively low
To obtain ferrite/bainite duplex structure, but its cost is higher.
The content of the invention
The technical problems to be solved by the invention are to provide a kind of high reaming steel of the economical great surface quality of 690MPa levels, should
The economical high reaming steel of great surface quality has good hole expandability without expensive alloying elements such as Cr, Nb, Ti, V and Mo
The advantages that energy, forming property, microstructure property, punching performance, isotropism.
Technical scheme is to provide a kind of economical high surface of 690MPa levels used by the present invention solves above-mentioned technical problem
The high reaming steel of quality, by weight percentage, its chemical composition is：[C]：0.055%~0.095%, [Si]：0.85%~
1.50%, [Mn]：1.30%~1.80%, [P]：0.010%~0.020%, [S]：≤ 0.003%, [Alt]：0.010%~
0.050%, [Ca]：0.0010%~0.0050%, [N]：≤ 0.0050%, [O]：≤ 0.0040%, remaining is Fe and can not
The impurity avoided, and [C] × [Mn] × 104≤ 0.15, { [P]+10 × [S] } × 102≤ 0.04, [Ca]/[S] >=0.3.
Wherein, in the high reaming steel of the economical great surface quality of 690MPa levels described above, the 690MPa levels are economical
The thickness specification of the high reaming steel of great surface quality is 1.4~6.0mm.
Wherein, in the high reaming steel of the economical great surface quality of 690MPa levels described above, the 690MPa levels are economical
The microstructure of the high reaming steel of great surface quality is made up of ferrite and bainite.
Wherein, the yield strength (R of the high reaming steel of the economical great surface quality of 690MPa levels described aboveel(or Pp0.2))
For 450~550MPa, tensile strength (Rm) it is >=690MPa, hole expansibility (λ) is >=75%, elongation after fracture (A80) for >=
19%, 180 ° of cold bending test D=0a are qualified；Wherein, the parallel-segment gauge length L of tensile sample0=80mm, parallel-segment width b=
20mm；D is Bend diameter in cold bending test, and a is thickness of strips.
Present invention also offers the preparation method of the above-mentioned high reaming steel of the economical great surface quality of 690MPa levels, including it is following
Step：Smelting procedure → continuous casting working procedure → heating process → roughing operation → Coil Box process → finishing rolling step → laminar flow cooling
Skill → batch → Slow cooling → pickling process → batches packaging.
Wherein, in the preparation method of the high reaming steel of the economical great surface quality of 690MPa levels described above, the smelting
Smelted in process according to the corresponding chemical composition of the high reaming steel of the economical great surface quality of 690MPa levels；At LF desulfurization
Reason, control S contents.
Wherein, in the preparation method of the high reaming steel of the economical great surface quality of 690MPa levels described above, the continuous casting
In process, cast using low overheat, the degree of superheat is controlled at 20~25 DEG C, using chamfer crystallizer, is casting continuously to form slab.
Wherein, in the preparation method of the high reaming steel of the economical great surface quality of 690MPa levels described above, the heating
Continuous casting steel billet tapping temperature is 1200 ± 30 DEG C in process.
Wherein, in the preparation method of the high reaming steel of the economical great surface quality of 690MPa levels described above, the roughing
De-scaling, de-scaling water pressure >=20MPa are carried out in process, dephosphorization nozzle angle is 40~50 °.
Wherein, in the preparation method of the high reaming steel of the economical great surface quality of 690MPa levels described above, the hot rolling
De-scaling, de-scaling water pressure >=20MPa are carried out in case process, dephosphorization nozzle angle is 40~50 °.
Wherein, in the preparation method of the high reaming steel of the economical great surface quality of 690MPa levels described above, the finish rolling
De-scaling, de-scaling water pressure >=20MPa are carried out in process, dephosphorization nozzle angle is 40~50 °.
Wherein, in the preparation method of the high reaming steel of the economical great surface quality of 690MPa levels described above, through roughing work
Sequence obtains middle base, into Coil Box, batches scale breading, using de-scaling water de-scaling, de-scaling water pressure >=20MPa, dephosphorization nozzle angle
For 40~50 °.
Wherein, in the preparation method of the high reaming steel of the economical great surface quality of 690MPa levels described above, the roughing
The workpiece thickness that roughing exports in process is 40 ± 3mm.
Wherein, in the preparation method of the high reaming steel of the economical great surface quality of 690MPa levels described above, the finish rolling
Entry temperature at finishing is 1080 ± 40 DEG C in process, and finishing temperature is 820~880 DEG C, and finish rolling exit thickness is 1~6mm.
Wherein, in the preparation method of the high reaming steel of the economical great surface quality of 690MPa levels described above, the laminar flow
Using double section types of cooling in cooling technique, with quickly 650~700 DEG C of the cooling of the cooling velocity not less than 26 DEG C/s, Ran Houkong
Cold 7~12s, then it is quickly cooled to 400~470 DEG C with the cooling velocity not less than 18 DEG C/s；The coiling temperature batched
For 400~470 DEG C；The Slow cooling is to slowly cool to 280~350 DEG C after batching, then naturally cools to less than 40 DEG C.
Wherein, in the preparation method of the high reaming steel of the economical great surface quality of 690MPa levels described above, the pickling
Straightening elongation percentage is 0.8~1.8% in process, and descaling bath HCl acid liquor temperatures are 55~85 DEG C, descaling bath free acid HCl concentration
For 50~160g/L, descaling bath Fe2+Concentration is 50~140g/L, and pickling speed is 60~120m/min, and potcher temperature is 50
± 10 DEG C, Drying unit stabilizes to 85 ± 5 DEG C.
The beneficial effects of the invention are as follows：
The high reaming steel of the economical great surface quality of 690MPa levels of the present invention using " low C+Si+Mn " Alloying Treatments technology,
The expensive alloying elements such as Cr, Nb, Ti, V and Mo are not added, are significantly reduced the cost of alloy of steel, are realized in terms of material
It is economical；The economical high reaming steel of great surface quality of the present invention is for cost is low, technique is simple, its yield strength (Rel(or
Pp0.2)) it is 450~550MPa, tensile strength (Rm) it is >=690MPa, hole expansibility (λ) is >=75%, elongation after fracture (A80) be
>=19%, 180 ° of cold bending test D=0a are qualified；With good reaming performance, forming property, microstructure property, stampability
The advantages that energy, isotropism, meets the needs of automobile chassis and complicated stamping steel.
The chemical composition of the present invention by controlling steel and preparation method thereof, has obtained a kind of economical high surface of 690MPa levels
The high reaming steel of quality：Chemical composition ranges reasonable in design, using thermomechanical control technique (Thermo Mechanical
Control Process, abbreviation TMCP) technology and Controlled Rolling And Controlled Cooling, it is equipped with rational quick cooldown rate and batches
Temperature range uses, on the one hand can effective fining ferrite grains, it is preferable on the other hand can to obtain moderate ratio, form and distribution
Bainite structure, realize the microstructure of steel band ferrite and bainite, technology controlling and process is simple, easily production, without after
Continuous heat treatment step, shortens production process, has saved process cost；It is mingled with by Design of Chemical Composition, smelting procedure steel
Thing is effectively controlled, the use of continuous casting working procedure chamfer crystallizer and low overheat are cast, and obtains the strand of high-quality；Hot-rolled process is adopted
With control de-scaling number and de-scaling water pressure, and pickling process scale breading technique and acid cleaning process, the production of great surface quality is obtained
Product.
Brief description of the drawings
Fig. 1 is the pickling finished product metallographic structure of the experimental group 2 of the embodiment of the present invention 1；
Fig. 2 is the pickling finished product metallographic structure of the experimental group 5 of the embodiment of the present invention 1.
Embodiment
Specifically, a kind of tensile strength is the high reaming steel of the economical great surface quality of 690MPa levels, by weight percentage,
Its chemical composition is：[C]：0.055%~0.095%, [Si]：0.85%~1.50%, [Mn]：1.30%~1.80%,
[P]：0.010%~0.020%, [S]：≤ 0.003%, [Alt]：0.010%~0.050%, [Ca]：0.0010%~
0.0050%, [N]：≤ 0.0050%, [O]：≤ 0.0040%, remaining is Fe and inevitable impurity, and [C] × [Mn] ×
104≤ 0.15, { [P]+10 × [S] } × 102≤ 0.04, [Ca]/[S] >=0.3.
Must possess the C of certain content in the high reaming steel of the economical great surface quality of 690MPa levels of the present invention, to promote
The formation of carbide reinforced phase, and then ensure the intensity rank of steel band；When research finds that C content is too high, the carbide of precipitation
Grain increase, is unfavorable for steel plate reaming performance；When C content is too low, intensity does not reach design requirement；The present invention exists C content control
0.055%~0.095%.
Si has solution strengthening effect in steel, can improve the intensity and elongation percentage of steel band simultaneously, improve the shaping of steel band
Performance, it is 0.85%~1.50% that the present invention, which controls Si contents,；However, when Si contents are higher, steel strip surface is also easy to produce Fe2SiO4
Red rust, it is not easy to dispel in pickling, to improve steel strip surface quality, the present invention devises the de-scaling mode and acid of the suitable steel grade
Wash technique.
Mn belongs to solution strengthening element, and according to the intensity requirement of steel grade of the present invention, when Mn contents are too low, intensity will reach not
To design requirement；Mn too high levels, the ratio of pearlite will be increased, and easily cause strand Mn component segregations during high Mn, this is
Steel band is caused one of the main reason for banded structure occur, and banded structure will be such that the reaming performance of steel band drastically declines, because
This, it is 1.30%~1.80% that the present invention, which controls Mn contents,；Meanwhile for carbon manganese steel, C and Mn reciprocation, to pearly-lustre
The formation and distribution of body tissue have a certain impact, and during the two too high levels, the increase of [C] × [Mn] products, are also easy to produce pearlite
Thick and banded structure, therefore matching of the present invention to C, Mn content proposes control requirement, i.e. [C] × [Mn]≤0.15.
Element most strong as reinforced ferrite element P, there is very strong solution strengthening effect and flow harden to act on, make
For alloying element in use, the atmospheric corrosion resistance of its intensity and steel band can be improved, but during too high levels, the cold stamping of steel band
Performance will drastically decline, simultaneously, it may appear that continuous casting steel billet component segregation, cause uneven microstructure, increase temper brittleness, significantly drop
The plasticity and toughness of low steel band so that steel band occurs " cold short " phenomenon in cold working and embrittlement；In addition, P is in carbon manganese steel
Belong to impurity element, therefore its content is also unsuitable too high, usual content not should be greater than 0.030%~0.040%.The present invention is in order to abundant
Using P solution strengthening effect, reduce steel band Mechanical Fluctuation, while reduce P effect as far as possible, control the P content to be
0.010%~0.020%.
S is the impurity element in steel, the easily formation MnS in steel, and the sulfide quantity and form in steel directly affect steel band
Reaming performance, particularly strip sulphide inculsion is also easy to produce crackle in deformation process, therefore necessary in designing chemical composition
S contents are reduced, it is≤0.003% that the present invention, which controls S contents, and requires [P]+10 × [S]≤0.04.
As deoxidant element excellent in steel, the oxide that can be reduced in steel is mingled with Al elements, improves purity of steel, from
And the forming property of steel band is improved, most Al after deoxidation2O3Molten steel upper strata is floated up to as oxide covering slag, so as to
The oxygen content in steel is reduced, remaining simple substance Al is dissolved in steel, referred to as dissolved aluminum (Als), meanwhile, few Al2O3Also can be stagnant
Stay in and Al is formed in steel2O3Field trash, reduce the forming property of steel band, simple substance Al and Al2O3Content summation be referred to as total aluminium
(Alt), therefore the present invention is makes that a certain amount of Als must be contained in steel, while reduces Al2O3Inclusion content, Alt contents are not easy
Too high, it is 0.010%~0.050% that Alt is controlled in the economical high reaming steel of great surface quality of the present invention.
Ca can change these as the important element that sulfide-based, oxide-based and silicates etc. are mingled with modified steel
The shape and composition of field trash, promote it is block, enter chain and strip sulfide transformation glomeration, so as to improve the plasticity of steel band and tough
Property, and then improve the fatigue performance of steel band；In addition, inventor has found in practice：Ca can improve the anisotropy of steel band, promote
Enter the equal orientation performance of steel band, as [Ca]/[S] rise, the equal orientation performance of steel band are in rising trend；When [Ca]/[S]=0.2
When, the ratio between horizontal and vertical notched bar impact strength of steel band is 0.85；When [Ca]/[S] >=0.3, steel band is horizontal and vertical to be rushed
The ratio between toughness value is hit close to 1, therefore it is 0.0010%~0.0050% that the present invention, which controls Ca contents, and requirement [Ca]/[S] >=
0.3。
N can be combined production nonmetal inclusion with alloying element, reduced alloys producing, be considered as harmful element,
Therefore it is≤0.0050% that the present invention, which controls N content,；Remaining oxygen in steel band, or the oxygen of steel strip surface is diffused into, easily make crystalline substance
Boundary's oxide forms brittle interlayer oxide, causes intercrystalline crack in subsequent deformation processing, so as to cause workpiece to ftracture,
Therefore the oxygen content in steel band should be as far as possible low, it is≤0.0040% that the present invention, which controls O content,.
On the one hand the high reaming steel of the economical great surface quality of 690MPa levels of the present invention uses " low C+Si+Mn " Alloying Treatments
Technology, the expensive alloying elements such as Cr, Nb, Ti, V and Mo are not added, significantly reduce the cost of alloy of steel, it is real in terms of material
Show economical；On the other hand, the yield strength (R of the economical high reaming steel of great surface quality of the present inventionel(or Pp0.2)) it is 450
~550MPa, tensile strength (Rm) it is >=690MPa, hole expansibility (λ) is >=75%, elongation after fracture (A80) be >=19%, 180 °
Cold bending test D=0a is qualified；With good reaming performance, forming property, microstructure property, punching performance, isotropism
The advantages that, meet the needs of automobile chassis and complicated stamping steel.
Wherein, tensile strength described above is the economy in the high reaming steel of the economical great surface quality of 690MPa levels
The thickness specification of the high reaming steel of type great surface quality is 1.4~6.0mm.
Present invention also offers the preparation side that above-mentioned tensile strength is the high reaming steel of the economical great surface quality of 690MPa levels
Method, comprise the following steps：Smelt and continuous casting working procedure → heating process → roughing operation → Coil Box process → finishing rolling step → layer
Stream cooling technique → pickling process → batches packaging.
In smelting procedure, it should be smelted according to following chemical composition ranges, its chemical component weight percentage is as follows,
[C]：0.055%~0.095%, [Si]：0.85%~1.50%, [Mn]：1.30%~1.80%, [P]：0.010%~
0.020%, [S]：≤ 0.003%, [Alt]：0.010%~0.050%, [Ca]：0.0010%~0.0050%, [N]：≤
0.0050%, [O]：≤ 0.0040%, remaining is Fe and inevitable impurity, and [C] × [Mn] × 104≤ 0.15, [P]+
10×[S]}×102≤ 0.04, [Ca]/[S] >=0.3.
The chemical composition of the high reaming steel of economical great surface quality designed for the present invention, inventor is to its preparation method
In each technological operation and parameter largely attempted.
The present invention uses LF desulfurization process in smelting procedure, finished product [S]≤0.003%, ensure that S contents are sufficiently low；
Cast in casting process using low overheat, the degree of superheat is controlled at 20~25 DEG C, can be reduced strand center portion component segregation, be adopted simultaneously
With chamfer crystallizer, the cracked risk in strand corner can be greatly reduced, avoids follow-up peeling.
In heating process, it is 1200 ± 30 DEG C to control continuous casting steel billet tapping temperature.
De-scaling is carried out in roughing operation and finishing rolling step, including：In roughing operation, it is desirable to whole de-scaling, de-scaling water
Pressure >=20Mpa, dephosphorization nozzle angle are 40~50 °；Middle base is obtained through roughing operation, it is middle into Coil Box process
Base batches scale breading, it is desirable to which whole process uses de-scaling water de-scaling, de-scaling water pressure >=20MPa, and dephosphorization nozzle angle is 40~50 °；So
Enter finishing rolling step afterwards, steel band, which goes out, carries out de-scaling, de-scaling water pressure >=20MPa in finish rolling exit, and dephosphorization nozzle angle is 40
~50 °.
In addition, the workpiece thickness that the present invention also controls roughing to export is 40 ± 3mm；In finishing rolling step, finish rolling entrance temperature
Spend for 1080 ± 40 DEG C, finishing temperature is 820~880 DEG C, and finish rolling exit thickness is 1~6mm.
In laminar flow cooling technology, steel band is used using double section types of cooling in laminar flow cooling technology, with not low after finish rolling
650~700 DEG C are quickly cooled down in 26 DEG C/s cooling velocity, then 7~12s of air cooling, then with the cooling not less than 18 DEG C/s
Speed is quickly cooled to 400~470 DEG C, is batched in rolls in the temperature section, stacking slowly cools to 280~350 DEG C after curling, so
After naturally cool to less than 40 DEG C；It is equipped with rational quick cooldown rate and coiling temperature section uses, on the one hand can be effectively thin
Change ferrite crystal grain, on the other hand can obtain moderate ratio, form and the preferable bainite structure of distribution, realize steel band ferrite
With the microstructure of bainite, technology controlling and process is simple, easily production, without subsequent heat treatment process, shortens production process, section
About process cost.
In pickling process, less than 40 DEG C of hot rolled strip promotes to aoxidize by rotoblasting unit and straightening scale breading unit
Iron sheet crushes, then carries out pickling through shallow slot turbulent flow type pickling unit, rinses, extracts, dries；The present invention controls the straightening elongation percentage to be
0.8~1.8%, descaling bath acid liquor temperature is 55~85 DEG C, and descaling bath free acid concentration is 50~160g/L, descaling bath Fe2+It is dense
To spend for 50~140g/L, pickling speed is 60~120m/min, and potcher temperature is 50 ± 10 DEG C, Drying unit stabilizes to 85 ±
5℃。
Hot-rolled process of the present invention is using control de-scaling number and de-scaling water pressure, and pickling process scale breading technique and pickling
Technique, when rolled surface is delivered goods, steel strip surface uniform color, between 5~15 μm, nothing is mingled with, aoxidized iron scale thickness
The surface defects such as iron sheet press-in, pit, peeling, roll marks and deformed steel strip；When pickled surface is delivered goods, except being lacked without above-mentioned surface
Fall into it is outer, be also not present owe pickling, overpickling with, scroll is bad the defects of；Rolled surface and pickled surface, which are administered, reaches advanced
Surface quality requirements.
By the trial of the chemical composition to the high reaming steel of economical great surface quality and preparation method thereof, the present invention obtains
A kind of high reaming steel of the economical great surface quality of 690MPa levels, its microscopic structure are made up of ferrite (F) and bainite (B)；
Yield strength (Rel(or Pp0.2)) it is 450~550MPa, tensile strength (Rm) it is >=690MPa, hole expansibility (λ) is >=75%, is broken
Elongation percentage (A afterwards80) it is >=19%, 180 ° of cold bending test D=0a are qualified；Wherein, the parallel-segment gauge length L of tensile sample0=80mm,
Parallel-segment width b=20mm；D is Bend diameter in cold bending test, and a is thickness of strips；The economical great surface quality of the present invention is high
Reaming steel has the advantages that good reaming performance, forming property, microstructure property, punching performance, isotropism, main to use
In the shaping of automobile chassis complicated shape part.
The present invention is described in further detail below by embodiment, but therefore not limited the scope of the present invention
Among described scope of embodiments.
In the embodiment of the present invention：
1st, hole expansibility evaluation method is as follows：Hole expansibility symbol is：λ, unit are：%；Taken in hot rolling or pickling steel bandRound pie sample preparation, and opened in centerHole, as initial apertures, labeled as d1；It is using drift angle
60 ° of circular cone drift expands the initial apertures；Determine aperture during crackle insertion thickness of strips direction caused by Punches, mark
For d2；
Hole expansibility (λ) calculation formula：λ=[(d2- d1)÷d1] × 100%；
In the present invention, during λ >=100%, it is qualified to be just considered as.
2nd, microstructure evaluation, yield strength, tensile strength, elongation percentage, hole expansibility, assay method by country
Standard is measured.
Embodiment 1
The present embodiment uses six experimental groups, the high reaming steel of the economical great surface quality of 690MPa levels of experimental group 1~6
Chemical composition is shown in Table 1；
The high reaming steel of the economical great surface quality of 690MPa levels of experimental group 1~6 is prepared by following methods：
Comprise the following steps：Smelting procedure → continuous casting working procedure → heating process → roughing operation → Coil Box process → finish rolling
Process → laminar flow cooling technology → batches → Slow cooling → pickling process → and batches packaging；Technological parameter is shown in Table 2 in each operation
With table 3；
The chemical composition of 1 embodiment of table, 1 each experimental group steel
In smelting procedure, smelted according to corresponding chemical composition range, using LF desulfurization process, control S contents；Even
Cast during casting using low overheat, the degree of superheat is controlled at 20~25 DEG C, using chamfer crystallizer, is casting continuously to form slab；In layer
Flow in cooling technique, steel band uses double section types of cooling using laminar flow cooling technology after finish rolling, with the cooling not less than 26 DEG C/s
Speed (i.e. in table 2 before laminar flow cooling velocity) quickly cools down 650~700 DEG C, then 7~12s of air cooling, then with not less than 18
DEG C/s (i.e. in table 2 after laminar flow cooling velocity) cooling velocity is quickly cooled to 400~470 DEG C, batches coiled, stacking is slowly cold
But to 280~350 DEG C, less than 40 DEG C are then naturally cooled to；
The hot rolling technology of the steel of experimental group 1~6 is shown in Table 2 in the present embodiment；
The hot rolling technology of 2 embodiment of table, 1 each experimental group
The acid cleaning process of the steel of experimental group 1~6 is shown in Table 3 in the present embodiment；
The acid cleaning process of 3 embodiment of table, 1 each experimental group
The performance of the steel of experimental group 1~6 is shown in Table 4 in the present embodiment；
The performance of 4 embodiment of table, 1 each experimental group steel
From the present embodiment, the high reaming steel of the economical great surface quality of the present invention is using " at low C+Si+Mn " alloyings
Reason technology, the expensive alloying elements such as Cr, Nb, Ti, V and Mo are not added, the cost of alloy of steel is significantly reduced, in terms of material
Realize economical；Chemical composition by controlling steel and preparation method thereof, a kind of economical high surface of 690MPa levels is obtained
The high reaming steel of quality：Using TMCP technologies and Controlled Rolling And Controlled Cooling, rational quick cooldown rate and coiling temperature are equipped with
Section uses, and realizes the microstructure of steel band ferrite and bainite, technology controlling and process is simple, easily production, without subsequent thermal
Treatment process, shorten production process, saved process cost；Have by the field trash of Design of Chemical Composition, smelting procedure steel
Effect control, the use of continuous casting working procedure chamfer crystallizer and low overheat casting, obtain the strand of high-quality；Hot-rolled process is using control
De-scaling number processed and de-scaling water pressure, and pickling process scale breading technique and acid cleaning process, obtain high gloss, low coarse
The product of the good great surface quality of degree, finish.
The economical high reaming steel of the economical great surface quality of great surface quality obtained by the present embodiment, its microscopic structure is by iron element
Body (F) and bainite (B) composition；Yield strength (Rel(or Pp0.2)) it is 360~450MPa, tensile strength (Rm) for >=
690MPa, hole expansibility (λ) are >=85%, elongation after fracture (A80) it is >=22%, 180 ° of cold bending test D=0a are qualified；Wherein, draw
Stretch the parallel-segment gauge length L of sample0=80mm, parallel-segment width b=20mm；D is Bend diameter in cold bending test, and a is that steel band is thick
Degree；There is good reaming performance, forming property, microstructure property, punching performance, isotropism, available for vapour
The shaping of chassis complicated shape part.
Claims (9)
- The high reaming steel of the economical great surface quality of 1.690MPa levels, it is characterised in that：By weight percentage, its chemical composition For：[C]：0.055%~0.095%, [Si]：0.85%~1.50%, [Mn]：1.30%~1.80%, [P]：0.010%~ 0.020%, [S]：≤ 0.003%, [Alt]：0.010%~0.050%, [Ca]：0.0010%~0.0050%, [N]：≤ 0.0050%, [O]：≤ 0.0040%, remaining is Fe and inevitable impurity, and [C] × [Mn] × 104≤ 0.15, [P]+ 10×[S]}×102≤ 0.04, [Ca]/[S] >=0.3.
- 2. the high reaming steel of the economical great surface quality of 690MPa levels according to claim 1, it is characterised in that：It is described The thickness specification of the high reaming steel of the economical great surface quality of 690MPa levels is 1.4~6.0mm.
- 3. the high reaming steel of the economical great surface quality of 690MPa levels according to claim 1 or 2, it is characterised in that：It is described The microstructure of the high reaming steel of the economical great surface quality of 690MPa levels is made up of ferrite and bainite.
- 4. the high reaming steel of the economical great surface quality of 690MPa levels according to claim 1 or 2, it is characterised in that：It is described The yield strength of the high reaming steel of the economical great surface quality of 690MPa levels is 450~550MPa, and tensile strength is >=690MPa, is expanded Porosity is >=75%, and elongation after fracture is >=19%, and 180 ° of cold bending test D=0a are qualified.
- 5. the preparation method of the high reaming steel of the economical great surface quality of 690MPa levels described in any one of Claims 1 to 4, it is special Sign is：Comprise the following steps：Smelting procedure → continuous casting working procedure → heating process → roughing operation → Coil Box process → finish rolling Process → laminar flow cooling technology → batches → Slow cooling → pickling process → and batches packaging.
- 6. the preparation method of the high reaming steel of the economical great surface quality of 690MPa levels according to claim 5, its feature exist In：De-scaling, de-scaling water pressure >=20MPa, dephosphorization nozzle angle are carried out in the roughing operation, Coil Box process and finishing rolling step For 40~50 °.
- 7. the preparation method of the high reaming steel of the economical great surface quality of 690MPa levels according to any one of claim 5~6, It is characterized in that：The workpiece thickness that roughing exports in the roughing operation is 40 ± 3mm；Finish rolling entrance in the finishing rolling step Temperature is 1080 ± 40 DEG C, and finishing temperature is 820~880 DEG C, and finish rolling exit thickness is 1~6mm.
- 8. the preparation method of the high reaming steel of the economical great surface quality of 690MPa levels according to claim 5, its feature exist In：Using double section types of cooling in the laminar flow cooling technology, with the cooling velocity not less than 26 DEG C/s quickly cooling 650~ 700 DEG C, then 7~12s of air cooling, is then quickly cooled to 400~470 DEG C with the cooling velocity not less than 18 DEG C/s；The volume The coiling temperature taken is 400~470 DEG C；The Slow cooling is to slowly cool to 280~350 DEG C, then natural cooling after batching To less than 40 DEG C.
- 9. the preparation method of the high reaming steel of the economical great surface quality of 690MPa levels according to any one of claim 5~8, It is characterized in that：Straightening elongation percentage is 0.8~1.8% in the pickling process, and descaling bath HCl acid liquor temperatures are 55~85 DEG C, Descaling bath free acid HCl concentration is 50~160g/L, descaling bath Fe2+Concentration is 50~140g/L, and pickling speed is 60~120m/ Min, potcher temperature are 50 ± 10 DEG C, and Drying unit stabilizes to 85 ± 5 DEG C.
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| CN109161791A (en) * | 2018-08-29 | 2019-01-08 | 宝山钢铁股份有限公司 | 690MPa rank ship and Marine Engineering Steel and its manufacturing method with superior low-temperature toughness |
| CN109706401A (en) * | 2019-02-13 | 2019-05-03 | 唐山不锈钢有限责任公司 | A kind of production technology of 690MPa high reaming steel band |
| CN113201691A (en) * | 2021-04-28 | 2021-08-03 | 攀钢集团攀枝花钢铁研究院有限公司 | Hot rolled steel plate for 590 MPa-level hydraulic bulging and preparation method thereof |
| CN113549823A (en) * | 2021-06-29 | 2021-10-26 | 鞍钢股份有限公司 | 900 MPa-grade hot-rolled and pickled multiphase steel with low yield ratio and high hole expansion rate and production method thereof |
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Application publication date: 20180302 |