CN103757531B - The high-strength tie of thin strap continuous casting economy of tensile strength >=1000MPa and manufacture method thereof - Google Patents

The high-strength tie of thin strap continuous casting economy of tensile strength >=1000MPa and manufacture method thereof Download PDF

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CN103757531B
CN103757531B CN201410035069.8A CN201410035069A CN103757531B CN 103757531 B CN103757531 B CN 103757531B CN 201410035069 A CN201410035069 A CN 201410035069A CN 103757531 B CN103757531 B CN 103757531B
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tie
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1000mpa
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CN103757531A (en
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王秀芳
方园
秦波
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Baoshan Iron and Steel Co Ltd
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Abstract

The high-strength tie of thin strap continuous casting economy of tensile strength >=1000MPa and manufacture method thereof, it comprises the steps: 1) use double roller continuous casting cast thickness to be the Cast Strip of 1.0 4.5mm, its chemical component weight percentage is: C0.25 0.40%, Si0.15 0.40%, Mn1.3 2.0%, P≤0.015%, S≤0.01%, N≤0.012%, remaining is Fe and inevitable impurity;2) Cast Strip cooling;3) the online hot rolling in Cast Strip;4) hot-rolled strip cooling;5) batch;6) cold rolling;7) blue annealing.The high-strength tie that the present invention is produced by the economy technique carrying out recovery annealing after thin strap continuous casting+cold rolling, tensile strength >=1000MPa, elongation percentage >=12%.

Description

The high-strength tie of thin strap continuous casting economy of tensile strength >=1000MPa and manufacture method thereof
Technical field
The present invention relates to high strength steel tie and manufacture method thereof, particularly relate to a kind of tensile strength The thin strap continuous casting economy high strength steel tie of >=1000MPa and manufacture method thereof.
Background technology
Steel tie is a kind of thin ribbon shaped deep processed product of steel, be mainly used to tie up steel, non-ferrous metal, Light textile goods, building materials, paper roll (plate) and wool and other items.In order to ensure safe handling of cargo and fortune Defeated, it is desirable to tie has higher tensile strength and certain elongation percentage.Further, since tie is long-term Use in outdoor environment, it is also desirable to have certain corrosion resistance.
Steel tie divides according to intensity, can be divided into low strong, in strong, high-strength and strong four classes of superelevation.Wherein High-strength tie, be mainly used in tying up in iron and steel enterprise coils of hot-rolled steel, round steel, shaped steel, steel pipe, The product such as wire rod and pipe line steel, it is in great demand.
With developing rapidly of metallurgy industry, high-quality, the steel products output of high intensity grade are got over Coming bigger, the coil diameter of coil of strip is also increasing, and monovolume reaches 30 tons, even 40 tons, strong for tie The requirement of degree improves constantly, and consumption also increases continuous.Therefore, the height that low cost process produces is used Strength steel tie has boundless market prospects.
But, owing to high strength steel tie requires have higher intensity and elongation percentage simultaneously, therefore give birth to Produce difficulty bigger.At present, the production technology of high strength steel tie mainly has three kinds:
First, the technique carrying out recovery annealing process after cold rolling
This technique generally includes following steps: 1) utilize tradition continuous casting+slab reheating+hot continuous rolling Technique produces hot-rolled strip;2) by cold rolling thickness hot-rolled strip being thinned to required for high-strength tie;3) Blue annealing process is carried out to cold rolling strap.
Hot rolled strip intensity after cold rolling is largely increased, but elongation percentage falls too low.By replying After annealing, steel band intensity decreases, but elongation percentage is improved, so that steel band reaches one Fixed strong plasticity coupling, forms blue layer oxide-film in steel strip surface simultaneously, plays oxidation resistant work With.The final microscopic structure of steel band is usually cold working recovery annealing ferrite matrix and spreads all over matrix more Dissipate carbide.This technological operation is simple, with low cost, energy resource consumption is few, environmental pollution is little.
Owing to first tensile strength and the elongation percentage of tie are to be affected by hot rolling material performance, then pass through Cold rolling power rate and annealing treating process are regulated.Do not produce special in the market for high-strength tie The hot rolling raw material of design, high-strength tie produces and generally selects the alloy being mainly composed of C, Si, Mn Structural steel.The organization type of this kind of hot-rolled product of the market supply of material and various composition phase content fluctuate relatively Greatly, determining that its tensile property changes greatly, so it will ripple to the influence degree of high-strength tie performance Dynamic bigger;The thickness specification of this kind of hot-rolled product of the other market supply of material compares limitation, if different thick The high-strength tie of degree uses the hot rolled plate of similar thickness to produce, then the change model of cold rolling reduction ratio Enclosing just relatively big, the Hot Rolling Plate Production thickness for example with 2.8mm is respectively 1.0mm's and 0.5mm High-strength tie, cold rolling reduction ratio is respectively 64% and 82%, its performance impact degree to high-strength tie Will fluctuate bigger.Two above fluctuation determines for different hot rolling raw materials, it is necessary to use difference Annealing process carry out the last adjustment of tie performance, otherwise tie performance can be very different.Moving back During ignition technique adjusts, tie performance is very sensitive to parameter and annealing, when tie tensile strength When higher, elongation percentage is generally relatively low;And when the elongation percentage of tie is higher, tensile strength is generally relatively low, Tie to be made has higher intensity and elongation percentage simultaneously, relatively difficult.Above-mentioned reason causes, and utilizes Carrying out recovery annealing after cold rolling and processing the steel tie that technique produces, its tensile strength and elongation percentage are difficult to prominent Broken 980MPa and 12%.This technique seems simple, must with production tensile strength and elongation percentage have The more preferably high-strength tie of coupling, difficulty is bigger.
Chinese patent 02109635.X open " a kind of high-intensity packing steel belt and Technology for Heating Processing ", its Composition is used to be C0.22-0.29%, Si0.015%, Mn1.30-1.50%, P≤0.015%, S≤ 0.010%, Als0.015%, Nb0.012%, the hot rolled plate raw material of balance of Fe, cold rolling after carry out Electrical heating blue annealing process, annealing furnace temperature is 550-650 DEG C, and steel belt operating speed is Its speed of 2.5-3.5m/min(is directly proportional to furnace temperature and body of heater length).Utilize the steel that this patent produces Tie tensile strength reaches 920MPa, and elongation percentage reaches 11%.
Chinese patent 200410031162.8 disclosure " high-intensity packing steel belt and manufacturing process thereof ", uses Composition is C0.25-0.28%, Si0.02-0.06%, Mn1.30-1.50%, P0.01-0.02%, S 0.001-0.012%, Als0.03-0.06%, the hot rolled plate raw material of balance of Fe, hot rolled plate thickness is 1.8-3.75mm, through 68-83% cold rolling after, obtaining thickness is 0.3-1.2mm steel band, utilizes continous way Heating furnace makes annealing treatment, and steel band heating-up temperature is 450-550 DEG C.Utilize the steel that this patent produces Tie tensile strength >=930MPa, elongation percentage >=8%.
Chinese patent 201210232927.9 disclosure " production method of high intensity blue steel strip ", uses C 0.19-0.21%, Mn1.62-1.71%, Si0.02-0.028%, P0.014-0.018%, S 0.0042-0.006%, Als0.033-0.05%, the composition design of balance of Fe, through smelting, even The processing steps such as casting, hot rolling, cold rolling, blue annealing carry out steel tie production.Cold rolling reduction ratio is 70%, Blue annealing temperature is 580-700 DEG C, and the time of turning blue is 100-160s.Utilize the steel that this patent produces Tie tensile strength is 950-960MPa, and elongation percentage is 11.5-12%.
2nd, the technique of cold rolling laggard quadrat bath means of isothermal quenching
This technique generally includes following steps: 1) utilize tradition continuous casting+slab reheating+hot continuous rolling Technique produces hot-rolled strip;2) by cold rolling thickness hot-rolled strip being thinned to required for high-strength tie;3) Carry out heating austenitizing to the steel band after cold rolling;4) lead patenting.
Pass through lead patenting, it is thus achieved that bainite structure, thus obtain steel band intensity to be wanted and Plasticity.The greatest problem utilizing this technique to produce is to produce device structure complexity, expensive, equipment Cost is high;Lead bath cooling capacity is limited, needs time enough to complete austenite to bainite transformation, Production efficiency is low;Serious environmental pollution can be caused;Production cost is high.Some countries have started to limit Use.And, although the steel tie intensity utilizing this technique to produce is higher, but elongation percentage is relatively low, It is susceptible to brittle failure during use.
United States Patent (USP) US6814817 is disclosed " Steel Strap Composition ", is C by composition The cold-rolled strip of 0.30-0.36%, Mn0.90-1.25%, Si0.75-1.10%, is initially pre-heated to It 370-510 DEG C, is then heated to 815-900 DEG C and carries out Ovshinsky, then carry out 370-510 DEG C of lead bath etc. Temperature Quenching Treatment.Utilize steel tie tensile strength >=1170MPa that this technique produces, elongation percentage >=6.5%.
Chinese patent 200810200449.7 disclosure " heat treatment method of a kind of steel belt for packages ", uses Composition is C0.29-0.35%, Si0.15-0.35%, Mn1.20-1.55%, P0.030%, S0.030%, The hot rolled plate of balance of Fe, cold rolling after first in lead bath, be preheating to 355-365 DEG C, preheating time 6.75-9s, is then heated to 860 ± 20 DEG C, and insulation 30-40s carries out austenitizing, then carries out 355-365 DEG C of lead patenting process, isothermal quenching time is 21-28s.This technique is utilized to produce Steel tie tensile strength >=1350MPa, elongation percentage >=6%.
3rd, the technique carrying out two-phase section Quenching Treatment after cold rolling
This technique generally includes following steps: 1) utilize tradition continuous casting+slab reheating+hot continuous rolling Technique produces hot-rolled strip;2) by cold rolling thickness hot-rolled strip being thinned to required for high-strength tie;3) Steel band after cold rolling is heated to ferrite and austenite two-phase section;4) rapid quenching.
Quenched by two-phase section, it is thus achieved that microscopic structure be martensite+cold working recovery annealing ferrite Matrix and the diffusion carbide spreading all over matrix, thus obtain steel band intensity to be wanted and plasticity.Utilize The steel tie that this technique produces, intensity and elongation percentage are all higher.But this technique Structure of need complexity Electromagnetic induction rapid-heating device and strength water cooling equipment, equipment cost is high;Production process is more complicated, Production cost is higher;And thin plate is often not ideal enough in two-phase section quenching back plate shape.
United States Patent (USP) US6635127 is disclosed " Steel strapping and method of making ", Composition is used to be C≤0.2%, Mn≤2.0%, Si0.2-0.4%, Ti0.025-0.045%, V 0.05-0.07%, Cr≤0.25%, Ni≤0.30%, Mo≤0.10%, Cu≤0.20%, Al≤0.08%, Nb≤0.005%, N≤0.005%, P≤0.035%, S≤0.02%, the steel billet warp of balance of Fe Hot rolling, cold rolling after, quick sensing is heated to 750 DEG C, is incubated 2s, is then rapidly quenched to room temperature.Utilize The steel tie tensile strength that this technique produces is 970-1070MPa, and elongation percentage is 10-14%.
Disclosed " the high intensity bundle higher than 1100MPa for the tensile strength of Chinese patent 200910046229.8 Band steel and manufacture method thereof ", employing C0.25-0.35%, Mn1.24-2.0%, Si≤0.45%, S≤ The composition design of 0.04%, P≤0.04%, through smelting, continuous casting, hot rolling, cold rolling, ferrite+ The processing steps such as the quenching of austenite two-phase section, tempering carry out steel tie production.Hardening heat is 730-790 DEG C, quenching velocity >=100 DEG C/s, temperature is 430-530 DEG C.This technique is utilized to produce Steel tie tensile strength >=1100MPa, elongation percentage >=10%.
In above-mentioned patent, produce the hot-rolled strip raw material that high-strength tie is used, be all to utilize tradition even Casting+hot rolling technology flow process produces.Due to the specification of hot-rolled strip raw material own, tissue, the limit of aspect of performance System, and the restriction of the operation such as follow-up cold rolling, heat treatment itself so that utilize above-mentioned technique to produce High-strength tie production cost or performance are difficult to obtain and break through.
At present, some emerging technologies, such as CSP, thin strap continuous casting etc., it is also possible to use Produce hot-rolled strip.Wherein, strip continuous casting technology is metallurgical and a forward position in investigation of materials field Technology, its steel and iron industry that appears as brings a revolution, and it changes tradition and controls hot rolling in metal working industry Casting, rolling, even heat treatment etc. continuously are integrated, make production by the production process of steel band Strip base form thin steel strip through the online hot rolling of a time is just disposable, enormously simplify production work Sequence, shortens the production cycle.Equipment investment also reduces accordingly, and product cost significantly reduces.
It about the patent of thin strap continuous casting product and manufacturing process thereof, is concentrated mainly on mild steel and low-carbon (LC) is micro- Alloy steel product and manufacturing process thereof, the aspect such as product surface quality improvement, such as Chinese patent 201080008606.X " hot rolled thin cast steel strip product and manufacture method thereof ";Chinese patent 201080017436.1 " high strength thin cast strip product and preparation method thereof ", Chinese patent 200880109715.3 " thin strip slab that micro-crack is reduced " etc..
The steel band being manufactured by above-mentioned thin strap continuous casting patent, is not to design for high-strength tie produces, Have not yet to see and the steel band that thin band continuous casting technique produces is used for the precedent that high-strength tie produces.Actual On, the final performance of high-strength tie is by the specification of hot rolling carrying raw material, and hot-rolled strip tissue and performance shadow Ring relatively big, during in particular by the first technique of relatively inexpensive high-strength tie production.Therefore, Want that the steel band using thin band continuous casting technique to produce, as raw material, produces to economy the height of excellent performance Strong tie, carries out specialized designs and manufacture to thin strap continuous casting steel band, most important.
Content of the invention
The thin strap continuous casting economy that it is an object of the invention to provide a kind of tensile strength >=1000MPa is high Strong tie and manufacture method thereof, by the design of rational composition design and processes, solve prior art The problem that environmental pollution is serious, production efficiency is relatively low, production cost is high existing, and utilize existing The strong plasticity of high-strength tie that economy technology produces mates undesirable problem.
For reaching above-mentioned purpose, the technical scheme is that
The present invention use cold rolling after carry out the processing technology routine of recovery annealing process to produce high-strength bundle Band.Taking this process route to produce high-strength tie, its performance design mainly considers three aspects: one is By the proper property of the produced Cast Strip of thin band continuous casting technique, mainly determined by composition and tissue morphology; Two is cold rolling working hardening, is mainly determined by cold rolling reduction ratio;Three be recovery annealing soften, mainly by Annealing process after cold rolling determines.Closely, each side is required in contact between these three aspect Stability contorting, and the stability contorting of a rear step must obtain the basis of stability contorting at back Upper just can be achieved, thus realize the ideal coupling of the strong plasticity of high-strength tie, it is achieved the present invention is imitated Really.
The present invention passes through chemical composition and thin band continuous casting technique design, the microscopic structure type to hot-rolled strip Carry out fixing quantity, and then the mechanical property of stability contorting hot-rolled strip with composition phase content, and to height The impact of strong tie mechanical property.Designed by thin band continuous casting technique, the thickness specification of hot-rolled strip is entered Row accurately control, and then the cold rolling reduction ratio that the production of stability contorting different-thickness high-strength tie is used, And the impact on high-strength tie mechanical property.And design is suitable for thin strap continuous casting hot-rolled strip microscopic structure The blue annealing technological parameter of type and cold rolling reduction ratio.Replied by after thin strap continuous casting+cold rolling The economic production technique of annealing, it is achieved the more excellent coupling of high-strength tie tensile strength and elongation percentage.
Concrete, the high-strength tie of thin strap continuous casting economy of tensile strength >=1000MPa of the present invention, its Chemical component weight percentage is: C0.25-0.40%, Si0.15-0.40%, Mn1.3-2.0%, P≤ 0.015%, S≤0.01%, N≤0.012%, remaining is Fe and inevitable impurity.
In the Design of Chemical Composition of the present invention:
C:C is intensified element most economical, most basic in steel, by solution strengthening and precipitation strength Improve the intensity of steel.C can be dissolved in ferrite formation interstitial solid solution, but at room temperature it is at iron Solubility in ferritic is extremely limited, and therefore its solution strengthening effect is restricted.At present invention process Under the conditions of, C mainly separates out with cementite form, as the part of pearlite.Containing of pearlite Measuring closely related with C content, when C content increases, content of pearlite in alloy increases, the intensity of steel, hard Degree improves therewith, and plasticity, toughness reduce accordingly.Therefore C content can not be too high, and the present invention uses C content scope be 0.25-0.40%.
Preferably, C content scope is 0.28-0.38%, and steel band can obtain more suitably content of pearlite in alloy, Can have more excellent tensile strength and elongation percentage coupling.
Si:Si plays solution strengthening effect in steel.When Si content is suitable, the intensity of steel is not only made to obtain Improve, and little on plasticity impact.The Si content range that the present invention uses is 0.15-0.4%.
Preferably, Si content range is 0.25-0.35%, and steel band can have more excellent tensile strength and prolong Stretch rate coupling.
Mn:Mn is one of generally the least expensive alloying element of price, and it has sizable solid solution in steel Degree, is improved the intensity of steel by solution strengthening, and when its content is suitable, to the plasticity of steel substantially without Infringement, is the topmost intensified element of intensity improving steel in the case of reducing C content.The present invention adopts Mn content range be 1.3-2.0%.
Preferably, Mn content range is 1.5-1.8%, and steel band can have more excellent tensile strength and prolong Stretch rate coupling.
P:P solubility in α-Fe is very big.Compared with other elements, P is caused in α-Fe Solid solution strengthening effect is bigger.But when P content is higher, as the intensity of steel improves, its plasticity is obvious Reduce.In the case of particularly segregation occurs in P in steel, bigger cold brittleness will be caused.In the present invention, P is to control as impurity element, its content≤0.015%.
Solubility in Fe for the S:S is minimum, and the mostly chemical combination of the S in steel is FeS, its harm be The red brittleness of steel can be caused when carrying out hot-working, reduce ductility and the toughness of steel, cause when rolling Crackle.In the present invention, S is to control as impurity element, its content≤0.01%.
N: similar with C element, N element can be improved the intensity of steel by gap solid solution, but, N Plasticity and toughness to steel for the gap solid solution have bigger harm, therefore N content can not be too high.The present invention N content≤0.012% using.
The thin strap continuous casting economy high-strength tie manufacture method of the tensile strength >=1000MPa of the present invention, Comprise the steps:
1) Cast Strip using twin-roll thin strip continuous casting cast thickness to be 1.0-4.5mm, its chemistry becomes Point percentage by weight is: C0.25-0.40%, Si0.15-0.40%, Mn1.3-2.0%, P ≤ 0.015%, S≤0.01%, N≤0.012%, remaining is Fe and inevitable impurity;
2) cooling down Cast Strip, cooldown rate is 20-80 DEG C/s;
3) online hot rolling, finishing temperature >=900 DEG C, hot rolling reduction ratio≤10%, hot rolling are carried out to Cast Strip The thickness of rear steel band is 0.9-4.0mm;
4) cooling down hot-rolled strip, cooldown rate is 10-50 DEG C/s;
5) batching hot-rolled strip, coiling temperature is 530-630 DEG C;Hot-rolled strip microscopic structure by 65-80% pearlite, 20-35% acicular ferrite, and a small amount of polygonal ferrite are constituted, And cemetite lamellae layer thickness is nanometer scale in pearlite, cemetite lamellae interlamellar spacing is nanometer Or sub-micrometer scale.
6) carrying out cold rolling to hot-rolled strip, cold rolling reduction ratio is 60-70%, and cold rolling rear thickness of strips is 0.3-1.2mm;
7) carrying out blue annealing to cold rolling strap, annealing temperature is 475-525 DEG C, and annealing time is 120-180s;Microscopic structure after cold rolling strap annealing, is the ferrite matrix of recovery annealing And the cementite being distributed on ferrite matrix, part cementite generation nodularization, part is oozed Carbon body still keeps the strip after deforming, and its diameter is nanometer scale;High-strength tie Tensile strength >=1000MPa, elongation percentage >=12%.
Further, in described step 1), the content range of C is 0.28-0.38%, with percentage by weight Meter.
In described step 1), the content range of Mn is 1.5-1.8%, by weight percentage.
In described step 1), the content range of Si is 0.25-0.35%, by weight percentage.
Also, described step 2) in, Cast Strip cooldown rate is 30-60 DEG C/s.
In described step 3), hot rolling reduction ratio is 5-10%.
In described step 4), hot-rolled strip cooldown rate is 10-40 DEG C/s.
In described step 5), the tensile strength of hot-rolled strip is 700-750MPa, elongation percentage >=15%.
In addition, in manufacture method of the present invention, step 8) can also be increased as required to steel band Carry out painting or the subsequent treatment such as zinc-plated.
In the manufacturing process of the present invention:
1) thin strap continuous casting
Molten steel is introduced in a pair and rotates against and that the crystallization roll of internal water cooling and side seal board are formed is molten Within pond, direct pouring after rapid solidification goes out the Cast Strip that thickness is 1.0-4.5mm.This finger gauge Lattice pass through high-strength tie finished product thickness, and the online hot rolling reduction ratio of subsequent design and cold rolling strengthening institute Reduction ratio inverse is needed to obtain.
2) Cast Strip cooling
Cast Strip from crystallization roll continuous casting out after, through confined chamber, cool down in confined chamber.In order to Inside, control Cast Strip and surface quality, prevent austenite crystal from high temperature growing up too fast simultaneously, control The cooldown rate of Cast Strip is 20-80 DEG C/s.Preferably, the cooldown rate of Cast Strip is 30-60 DEG C/s.Casting Band cooling uses air cooling mode, and pressure, the gentle nozzle location of flow of cooling gas can be regulated and control System.Cooling gas can be the inert gases such as argon gas, nitrogen, helium, or several gas is mixed And gas.By between the type of control cooling gas, pressure, flow, and nozzle to Cast Strip Distance etc., it is achieved the control to Cast Strip cooldown rate.
3) the online hot rolling in Cast Strip, cool down and batch
The performance to high-strength tie for the tensile property of hot-rolled strip has a significant impact.Produce same intensity rank High-strength tie, the performance of hot-rolled strip used should not change too big, otherwise cannot realize to high-strength bundle Stability contorting with performance.The performance of hot-rolled strip is determined by composition and organization type.Hot-rolled strip to be controlled Stable performance, its organization type and composition phase content should be stablized as far as possible.Because organization type is cold to steel band The ability resisting recrystallization after rolling also has considerable influence, and therefore tissue stabilization is also beneficial to cold rolled annealed work Skill designs.
The control of organization type and tissue phase content is mainly realized by hot rolling reeling process.
The present invention controls temperature >=900 DEG C processed eventually, makes hot rolling carry out in austenitic area.
The present invention controls hot rolling reduction ratio≤10%, it is preferred that hot rolling reduction ratio is 5-10%.After hot rolling The thickness range of steel band is 0.9-4.0mm.In actual production, the thickness of hot-rolled strip passes through to be produced High-strength tie thickness specification, and the required reduction ratio of cold rolling processing carries out inverse.For example, thickness is produced The high-strength tie that degree is 0.5mm, required cold rolling reduction ratio is 65%, then the thickness of hot-rolled strip should For 1.43mm.Can realize that product thickness specification changes flexibly by adjusting thin band continuous casting technique parameter, This is a big advantage of strip continuous casting technology.
Controlling hot rolling reduction ratio in such scope, reason has three: first, by a small amount of hot rolling Inside, Cast Strip and surface quality can be improved further;Second, in order to make austenite not send out after hot rolling Raw recrystallization, hot rolling drafts can not be too big.Deformation is the basis that recrystallization occurs, and is recrystallization Driving force deformation stores the source of energy, just can occur after must be over certain driving force Recrystallization, therefore recrystallization just can occur after only having more than certain deformation quantity.Deformation quantity is bigger, shape Becoming storage can be bigger, and deformation storage can be bigger, and Recrystallization nucleation and growth rate are all bigger, even if Also can sufficiently rapidly start at a lower temperature and complete recrystallization.Once austenite is sent out after hot rolling Raw recrystallization, austenite structure stability is difficult to control, in turn result in by the follow-up cooling of control and Pearlite that coiling technique parameter is obtained and acicular ferrite content generation larger fluctuation, thus affect The stability contorting of steel band tensile property.3rd, make that hot-rolled strip thickness will not subtract is too thin.Because producing High-strength tie also needs to ensure certain reduction ratio in follow-up cold rolling step, the control thinking of reduction ratio As detailed below.
The modes such as aerosol cooling, section cooling or spraying cooling are used to cool down hot-rolled strip.Cold But the flow of water, flow velocity, and delivery port position etc. can be regulated, thus realize cooling down hot-rolled strip The control of speed.The cooldown rate that the present invention controls hot-rolled strip is 10-50 DEG C/s, it is preferred that hot-rolled strip Cooldown rate be 10-40 DEG C/s.The speed of cooldown rate determines last coiling temperature.Technical process In, different cooldown rates need to be taked according to the difference of thin strap continuous casting steel band pulling rate and tape thickness, will Oiler temperature control is in desired scope.
The coiling temperature that the present invention controls hot-rolled strip is 530-630 DEG C, in the range of this coiling temperature, The microscopic structure of hot-rolled strip can be controlled by 65-80% pearlite, 20-35% acicular ferrite, and A small amount of polygonal ferrite is constituted.And cemetite lamellae layer thickness is nanometer scale in pearlite, cementite Sheet interlayer spacing is nanometer or sub-micrometer scale.Having the hot-rolled strip of this microscopic structure, its tensile strength is 700-750MPa, elongation percentage >=15%.
4) hot-rolled strip is carried out cold rolling
The cold rolling reduction ratio of hot-rolled strip is very big to the performance impact of high-strength tie, is to improve tie performance Important parameter, the performance of tie can increase with the increase of cold rolling reduction ratio.Produce same intensity level Other high-strength tie, cold rolling reduction ratio should not change too big, otherwise cannot realize to high-strength tie The stability contorting of energy.And the change of cold rolling reduction ratio is too greatly to the ability resisting recrystallization after cold rolling band steel Also having considerable influence, thus having influence on the selection of parameter and annealing, this also can affect to high-strength tie The stability contorting of performance.In addition, the design of cold rolling reduction ratio total amount, high-strength tie performance should be met and set Meter requires, guarantees that material does not ftractures in cold-rolled process again, can not be formed at material internal Micro-crack.The hot-rolled strip that the present invention obtains, in microscopic structure, 65-80% is pearlite, cemetite lamellae Layer thickness is nanometer scale, can elongate, the deformation of the form such as bending in cold-rolled process, no Easily occur broken, thus will not cause defect at material internal.Based on above-mentioned consideration, control of the present invention It is 60-70% that refrigeration rolls reduction ratio, changes in the range of 10%.
5) cold rolling strap blue annealing
The selection of parameter and annealing is most important.In annealing process, matrix is replied, and causes steel Band strength reduces, and elongation percentage improves.Temperature can not too high or time can not be long, otherwise can cause steel Band strength declines too many, and temperature can not be too low or the time is too short, and elongation percentage otherwise can be caused to go up not Enough.Also to simultaneously take account of, the height of annealing temperature with under hot-rolled strip microscopic structure type and cold rolling Rate relation is very big.The hot-rolled strip that the present invention obtains, in microscopic structure, 65-80% is pearlite, carburizing Body lamellar spacing is nanometer scale, and cemetite lamellae interlamellar spacing is nanometer or sub-micrometer scale, makes material exist Annealing process is relatively strong to Recovery and recrystallization resistivity, therefore can properly increase annealing temperature And/or annealing time.
In view of above-mentioned, it is 475-525 DEG C that the present invention controls annealing temperature, and annealing time is 120-180s. Under the conditions of this annealing process, the microscopic structure of steel band is that on the ferrite matrix of recovery annealing, disperse divides Cementite particle or cementite bar, the rod of a diameter of nanometer scale by cloth.Tie finally obtains more Preferable tensile strength and the coupling of elongation percentage.
6) japanning or the subsequent treatment such as zinc-plated
According to the application target of high-strength tie and use environment etc., the steel band after blue annealing can be entered Row japanning or the subsequent treatment such as zinc-plated.
The difference of the present invention and prior art and beneficial effect:
1) existing produce high-strength tie cold rolling after carry out the technique of recovery annealing process, not to hot rolling Composition phase content in raw material microscopic structure and hot rolling raw thickness specification are controlled, and cause steel band Tensile strength and elongation percentage coupling are undesirable, are difficult to break through 980MPa and 12%.By the present invention's Thin band continuous casting technique designs, the microscopic structure type of control thin strap continuous casting hot-rolled strip, and fixing quantity shows Micro-assembly robot mainly comprises the content of phase;According to high-strength tie thickness specification inverse strip to be produced The thickness of continuous casting hot-rolled strip simultaneously accurately controls, and then the mechanical property of stability contorting hot-rolled strip and cold Roll the impact on high-strength tie mechanical property for the reduction ratio.Design is suitable for micro-group of thin strap continuous casting hot-rolled strip Knit the blue annealing technological parameter of type and cold rolling reduction ratio, it is achieved that high-strength tie tensile strength and prolonging Stretch the more excellent coupling of rate, tensile strength >=1000MPa, elongation percentage >=12%.
2) technique that prior art produces high-strength tie is: tradition continuous casting+slab reheating+heat is even Roll+cold rolling+recovery annealing or lead patenting or two-phase section quenching.The present invention produces high-strength tie Technique be: carry out recovery annealing after thin strap continuous casting+online hot rolling+cold rolling, shorten technological process, Simplify processing step, after the high-strength tie performance being produced is better than utilizing existing tradition continuous casting+cold rolling Carry out the high-strength tie of recovery annealing technique production, be better than or close to utilizing existing lead patenting The high-strength tie that technique and two-phase section isothermal quenching technique produce.
3) present invention produces the technology of high-strength tie, flow process is short, technological operation is simple, with low cost, Energy resource consumption is few, discharge less, environmental pollution little.Solve the environmental pollution that prior art exists serious, The problem that production efficiency is relatively low, production cost is high, and utilize that existing economy technology produces high-strength The undesirable problem of tie strong plasticity coupling.
Brief description
Fig. 1 is the microscopic structure of thin strap continuous casting hot-rolled strip in the embodiment of the present invention 1.
Fig. 2 is the cementite of thin strap continuous casting hot-rolled strip microscopic structure medium pearlite in the embodiment of the present invention 1 Lamella.
Fig. 3 is microscopic structure after cold rolling for the thin strap continuous casting hot-rolled strip in the embodiment of the present invention 1.
Fig. 4 is the microscopic structure in the embodiment of the present invention 1 after cold rolling strap annealing.
Detailed description of the invention
Below in conjunction with embodiment and accompanying drawing, the present invention will be further described.
The molten steel of embodiment of the present invention 1-5 all uses electric furnace smelting to obtain, specific chemical composition such as table 1 Shown in.The Cast Strip thickness obtaining after thin strap continuous casting, Cast Strip cooldown rate, hot rolling finishing temperature, hot rolling Reduction ratio, hot-rolled strip thickness, hot-rolled strip cooldown rate, coiling temperature, cold rolling reduction ratio, annealing temperature Degree, the technological parameter such as annealing time is shown in Table 2, and the tensile property of hot-rolled strip and high-strength tie is shown in Table 3.
Fig. 1 show the microscopic structure of thin strap continuous casting hot-rolled strip in embodiment 1, by the pearlite of 77%, 20% acicular ferrite, and a small amount of polygonal ferrite composition, do not occur for after typical hot rolling again The microstructure characteristic obtaining after the austenite phase transformation of crystallization.
Fig. 2 is the cementite lamella of thin strap continuous casting hot-rolled strip microscopic structure medium pearlite in embodiment 1, Cemetite lamellae layer thickness is nanometer scale, and cemetite lamellae interlamellar spacing is sub-micrometer scale.
Fig. 3 is microscopic structure after cold rolling for the hot-rolled strip in embodiment 1, can be at ferrite and pearlite Observing Zona transformans in crystal grain, crystal grain, along rolling to substantially being elongated, is distributed in threadiness.Pearlite In cementite also there occurs plastic deformation, be parallel to roll to cementite be elongated, be perpendicular to roll to Cementite bend.Having no any micro-crack inside cold rolling strap, quality is fine.
Fig. 4 is the microscopic structure in embodiment 1 after cold rolling strap annealing, is the ferrite base of recovery annealing The cementite of distribution on body and ferrite matrix, part cementite generation nodularization, part cementite is still Keeping the strip after deformation, its diameter is nanometer scale, so that high-strength tie has excellent Strong plasticity coupling.From table 3 it can be seen that the tensile strength >=1000MPa of the high-strength tie of the present invention, Elongation percentage >=12%.
The ladle chemistry (wt.%) of table 1 embodiment 1-5
Embodiment C Si Mn P S N
1 0.37 0.36 2.00 0.014 0.008 0.0060
2 0.28 0.24 1.30 0.011 0.007 0.012
3 0.34 0.34 1.45 0.012 0.003 0.0097
4 0.40 0.15 1.76 0.014 0.006 0.0058
5 0.25 0.39 1.68 0.015 0.002 0.0074
Table 2
Table 3

Claims (13)

1. the high-strength tie of thin strap continuous casting economy of tensile strength >=1000MPa, its chemical component weight percentage Ratio is: C 0.25-0.40%, Si 0.15-0.40%, Mn 1.3-2.0%, P≤0.015%, S≤ 0.01%, N≤0.012%, remaining is Fe and inevitable impurity, resisting of described high-strength tie Tensile strength >=1000MPa, elongation percentage >=12%, its microscopic structure is the ferrite matrix of recovery annealing Upper Dispersed precipitate cementite particle or cementite bar, the rod of a diameter of nanometer scale.
2. the high-strength tie of thin strap continuous casting economy of tensile strength >=1000MPa as claimed in claim 1, It is characterized in that: the content range of C is 0.28-0.38%, by weight percentage.
3. the high-strength tie of thin strap continuous casting economy of tensile strength >=1000MPa as claimed in claim 1, It is characterized in that: the content range of Mn is 1.5-1.8%, by weight percentage.
4. the high-strength tie of thin strap continuous casting economy of tensile strength >=1000MPa as claimed in claim 1, It is characterized in that: the content range of Si is 0.25-0.35%, by weight percentage.
5. the thin strap continuous casting economy high-strength tie manufacture method of tensile strength >=1000MPa, including walk as follows Rapid:
1) Cast Strip using twin-roll thin strip continuous casting cast thickness to be 1.0-4.5mm, its chemical composition Percentage by weight is: C 0.25-0.40%, Si 0.15-0.40%, Mn 1.3-2.0%, P≤ 0.015%, S≤0.01%, N≤0.012%, remaining is Fe and inevitable impurity;
2) cooling down Cast Strip, cooldown rate is 20-80 DEG C/s;
3) online hot rolling, finishing temperature >=900 DEG C, hot rolling reduction ratio≤10%, hot rolling are carried out to Cast Strip The thickness of rear steel band is 0.9-4.0mm;
4) cooling down hot-rolled strip, cooldown rate is 10-50 DEG C/s;
5) batching hot-rolled strip, coiling temperature is 530-630 DEG C, hot-rolled strip microscopic structure by 65-80% pearlite, 20-35% acicular ferrite, and a small amount of polygonal ferrite are constituted, And cemetite lamellae layer thickness is nanometer scale in pearlite, cemetite lamellae interlamellar spacing be nanometer or Sub-micrometer scale;
6) carrying out cold rolling to hot-rolled strip, cold rolling reduction ratio is 60-70%, and cold rolling rear thickness of strips is 0.3-1.2mm;
7) carrying out blue annealing to cold rolling strap, annealing temperature is 475-525 DEG C, and annealing time is 120-180s, the microscopic structure after cold rolling strap annealing, is on the ferrite matrix of recovery annealing Dispersed precipitate cementite particle or cementite bar, the rod of a diameter of nanometer scale;High-strength Tensile strength >=the 1000MPa of tie, elongation percentage >=12%.
6. the high-strength tie system of thin strap continuous casting economy of tensile strength >=1000MPa as claimed in claim 5 Make method, it is characterised in that: in described composition, the content range of C is 0.28-0.38%, with weight Amount percentages.
7. the high-strength tie system of thin strap continuous casting economy of tensile strength >=1000MPa as claimed in claim 5 Make method, it is characterised in that: in described composition, the content range of Mn is 1.5-1.8%, with weight Percentages.
8. the high-strength tie system of thin strap continuous casting economy of tensile strength >=1000MPa as claimed in claim 5 Make method, it is characterised in that: in described composition, the content range of Si is 0.25-0.35%, with weight Amount percentages.
9. the high-strength tie system of thin strap continuous casting economy of tensile strength >=1000MPa as claimed in claim 5 Make method, it is characterised in that: described step 2) in, Cast Strip cooldown rate is 30-60 DEG C/s.
10. the high-strength tie system of thin strap continuous casting economy of tensile strength >=1000MPa as claimed in claim 5 Make method, it is characterised in that: described step 3) in, hot rolling reduction ratio is 5-10%.
The high-strength tie system of thin strap continuous casting economy of 11. tensile strength >=1000MPa as claimed in claim 5 Make method, it is characterised in that: described step 4) in, hot-rolled strip cooldown rate is 10-40 DEG C/s.
The high-strength tie system of thin strap continuous casting economy of 12. tensile strength >=1000MPa as claimed in claim 5 Make method, it is characterised in that: described step 5) in, the tensile strength of the hot-rolled strip after batching is 700-750MPa, elongation percentage >=15%.
13. the high-strength tie system of thin strap continuous casting economy of tensile strength >=1000MPa as claimed in claim 5 Make method, it is characterised in that: increase step 8 as required) carry out painting or zinc-plated to steel band Subsequent treatment.
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