CN104195439B - Thick-specification hot-rolled dual-phase steel plate and manufacturing method thereof - Google Patents
Thick-specification hot-rolled dual-phase steel plate and manufacturing method thereof Download PDFInfo
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- CN104195439B CN104195439B CN201410414629.0A CN201410414629A CN104195439B CN 104195439 B CN104195439 B CN 104195439B CN 201410414629 A CN201410414629 A CN 201410414629A CN 104195439 B CN104195439 B CN 104195439B
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Abstract
The invention discloses a low-cost thick-specification uniform-structure hot-rolled dual-phase steel plate based on a post ultra-fast cooling technique and a manufacturing method thereof. The steel plate comprises the following chemical components in percentage by weight: 0.055-0.085% of C, 0.20-0.50% of Si, 1.20-1.50% of Mn, at most 0.40% of Cr, at most 0.012% of P, at most 0.002% of S, and the balance of Fe and inevitable impurities. The manufacturing method comprises the following steps: (1) heating a casting blank, and carrying out controlled rolling; (2) after hot rolling, cooling to a ferrite phase-change zone in a forepart centralized laminar cooling mode; and (3) cooling to martensitic phase-change temperature below by using a post ultra-fast cooling system, and coiling. The production mode, which uses the post ultra-fast cooling technique as the core, is utilized to lower the dependence of the thick-specification high-strength hot-rolled dual-phase steel on alloy elements; and the thick-specification high-strength hot-rolled dual-phase steel has the advantages of cheap components, uniform structure and excellent and stable performance, and is suitable for mass industrial production.
Description
Technical field
The present invention relates to metallurgical technology and technical field of steel rolling, particularly to a kind of low based on rear-mounted ultrafast refrigeration technique
The homogeneous hot rolling biphase plate of cost think gauge tissue and manufacture method.
Background technology
Increasingly strict with energy-saving and environmental protection and safety requirements, automotive light weight technology progress is rapid.High-strength steel and advanced
The consumption rapid growth of high-strength steel.Dual phase steel mates because of its low yield strength ratio, high initial manufacture hardening ratio, good strength plastic,
It is one of most AHSS of current application.
Hot-rolled dual-phase steel mainly passes through chemical composition and is distributed one on ferrite matrix with the acquisition of mating of rolling mill practice
Determine volume fraction and the duplex structure of shape characteristic martensite, thus possess good intensity combining with plasticity.In production process
In carry out organizational controls be characterized by obtain q.s ferrite, suppress not changing austenite to pearlite, bayesian simultaneously
Body changes, and does not then change austenite phase and is changed into martensite, ultimately forms the duplex structure of ferrite+martensite.
Produce hot-rolled dual-phase steel when, it is necessary to assure formed q.s ferrite after be cooled to soon again martensitic transformation point with
Under, and on hot-rolled strip production line, the last frame throwing steel speed of hot tandem is higher, based on traditional laminar flow cooling device
Cooling capacity is it is difficult to ensure, before batching, belt steel temperature is down to below martensitic transformation point.At present, for Thin Specs（≤
6mm）The production of hot-rolled dual-phase steel, it usually needs add the alloying elements such as Cr, Mo of higher amount in steel, or increase substantially
The constituent content that carbide is formed is stoped, such as Si, P etc. be not so that change during slow cooling after batching for the steel plate in steel
Austenite is changed into martensite；In addition the temperature that the mode increasing back segment cooled region improves steel plate also can be taken to reduce interval,
Guarantee the formation of martensite, but reduce process window.Refer in published patent and scientific and technical literature at present possesses
The hot-rolled dual-phase steel of mass production environment and production technology are all around above-mentioned thinking and are directed to Thin Specs（≤6mm）Product.As
" a kind of 600MPa level hot-rolled dual-phase steel and preparation method thereof " of Publication No. CN 102703815 A, the CN of Publication No.
" tensile strength 590MPa level hot-rolled dual-phase steel and its manufacture method " of 102912235A and Publication No. CN 100441724C
The technique of hot-rolled dual-phase steel " CSP produce " be using C-Mn-Cr component system, add in steel >=
The stability to improve austenite for the 0.4% Cr element.A kind of " tensile strength 540MPa of Publication No. CN 100357475C
Level dual phase sheet steel and manufacture method " and a kind of " tensile strength 600MPa level dual phase sheet steel of Publication No. CN 100357474C
And manufacture method " describe using C-Mn component system hot-rolled dual-phase steel and manufacture method, after hot rolling control rate of cooling be 25 ~
30 DEG C/s, it is cooled to 100 ~ 200 DEG C and batches, described steel plate thickness is limited to 2.5 ~ 6.0mm.
For think gauge（≥9.0mm）Hot-rolled dual-phase steel especially high intensity levels then have higher difficulty.Although with
The raising of product thickness specification, last frame throws steel speed relative reduction, and then extends cool time, be conducive to acquisition higher
Temperature drop scope.But now thickness is more prominent to the adverse effect of cooling effect, is not only difficult to using conventional section cooling
Be cooled to below martensitic transformation temperature before batching, and steel plate thickness be larger with the temperature difference on surface, surface of steel plate temperature low and
Center portion temperature is high, and center portion temperature is even above martensite and starts phase transition temperature, and the temperature of thickness direction is inconsistent to ultimately result in product
The heterogeneity of product tissue.Therefore, think gauge hot-rolled dual-phase steel is because of the deficiency of conventional chilling ability, product thickness direction tissue odds
One, center portion bayesian body burden is higher it is difficult to the duplex structure of the preferable ferrite+martensite of acquisition or intensity rank are limited
System.Scientific and technical literature " Baogang CSP ' is ultrafast cold ' system and 590 MPa levels C-Mn low cost hot-rolled dual-phase steel exploitation "（《Iron and steel》
Volume 43 the 3rd phase P49-52 in 2008）The composition being adopted and technique obtain the hot-rolled dual-phase steel of 4.0 ~ 11.0mm, so
And it does not explicitly point out the processing parameter of hot-rolled dual-phase steel, do not refer to the tissue shape in think gauge product thickness direction yet
State, and the line and staff control being organized as ferrite+martensite+bainite of produced steel plate and the two-phase of non-ferrous+martensite
Tissue.Scientific and technical literature " CSP produces the production practices of line development C-Mn type hot-rolled dual-phase steel "（《Shanghai Metals》2010 the 32nd
Roll up the 1st phase P27-29）The hot-rolled dual-phase steel of the 11.0 ~ 13.0mm thickness specification obtaining under described composition and process conditions,
Its tensile strength is 550 ~ 585MPa, only meets the performance requirement of DP540.Therefore, under traditional roller repairing flow path conditions,
Limited by section cooling section length and strip steel muzzle velocity, for think gauge high-strength hot-rolled dual-phase steel it is difficult to realize chemistry
Composition, process window, the stable matching of structure property, constrain the industrialized production of such dual phase steel.
Content of the invention
The present invention cannot meet for prior art that think gauge high-strength hot-rolled dual-phase steel is stable, mass is industrial
Problem, provides a kind of homogeneous hot rolling biphase plate of low cost think gauge tissue and manufacture method.
Above-mentioned purpose is realized by following proposal：
A kind of think gauge hot rolling biphase plate is it is characterised in that the chemical composition of described steel plate is by weight percentage：
0.055 ~ 0.085% C, 0.20 ~ 0.50% Si, 1.20 ~ 1.50% Mn, Cr≤0.40%, P≤0.012%, S≤0.002%, surplus
For Fe and inevitable impurity.
According to above-mentioned steel plate it is characterised in that the thickness specification of described steel plate be 9.0 ~ 13.0mm, thickness direction tissue
For homogeneous duplex structure.
A kind of method preparing above-mentioned steel plate is it is characterised in that methods described comprises the steps of：
（1）Smelted by the chemical composition of described steel plate, obtained strand；
（2）By described heating strand to 1160 ~ 1240 DEG C, then adopt and include the rolling of austenite recrystallization area and austenite
The two-stage control rolling mill practice of Unhydrated cement rolling, the reduction ratio of previous stage is >=60%, the reduction ratio of the latter half >=
52%, finishing temperature is 820 ~ 850 DEG C, and the thickness controlling steel plate after hot rolling is 9.0 ~ 13.0mm；
（3）Through step（2）The steel plate obtaining after hot rolling is first cooled down using section cooling leading portion hubbed mode, cooling
Speed is 10 ~ 25 DEG C/s；
（4）Steel plate concentrates belt steel temperature after cooling using rear-mounted ultrafast cooling system through section cooling leading portion by 660 ~
700 DEG C are cooled to 150 ~ 300 DEG C and are batched, and wherein ultrafast cooling system hydraulic pressure is set as more than 0.6MPa, and jet density is 100
~240(m3/h)/m2, when temperature is cooled to 200 DEG C by 700 DEG C, cooldown rate is 80 ~ 120 DEG C/s.
Beneficial effects of the present invention：
（1）Using rear-mounted ultrafast cold high cooling capacity, obtain the hot-rolled dual-phase steel that thickness is 9.0 ~ 13mm, simultaneously
Achieve wider process window to control.Due to possessing wider process window, in ferrite, the ratio of martensite of best match
Under the conditions of, tensile strength rank can reach 590MPa level.
（2）Being organized as of the homogeneous hot-rolled dual-phase steel thickness direction of the inexpensive think gauge tissue of the present invention is equally distributed
The duplex structure of the polygonal ferrite and volume fraction island-like martensite of small and dispersed distribution for 10 ~ 25%, thickness direction group
Knit homogeneous.
（3）Based on the overall-in-one control schema of chemical composition, rolling condition and cooling path, reduce hot-rolled dual-phase steel to alloy
The dependence of element is it is achieved that the composition of minimizing, low cost of alloy.
（4）The homogeneous hot rolling biphase plate of low cost think gauge tissue according to the present invention is it is achieved that China's industrialization is criticized
Amount produces, and structure property is stable.Simultaneously with the rear-mounted ultrafast cold popularization and application in steel enterprise of China, steel plate according to the present invention
And manufacture method possesses extensive popularizing application prospect it is adaptable to conventional hot continuous rolling machine production line and short route CSP production line.
Brief description
Fig. 1 is that the inexpensive think gauge of the present invention organizes homogeneous hot rolling biphase plate cooling process figure；
Fig. 2 is that the center metallographic of the hot-rolled dual-phase steel plate thickness direction of inexpensive 9.0mm thickness specification of the present invention shows
Micro-assembly robot；
Fig. 3 is metallography microscope at the 1/4 of the hot-rolled dual-phase steel plate thickness direction of inexpensive 9.0mm thickness specification of the present invention
Tissue；
Fig. 4 is gold at the near surface of hot-rolled dual-phase steel plate thickness direction of inexpensive 9.0mm thickness specification of the present invention
Phase microscopic structure；
Fig. 5 is that the center metallographic of the hot-rolled dual-phase steel plate thickness direction of inexpensive 13.0mm thickness specification of the present invention shows
Micro-assembly robot；
Fig. 6 is that at the 1/4 of the hot-rolled dual-phase steel plate thickness direction of inexpensive 13.0mm thickness specification of the present invention, metallographic shows
Micro-assembly robot；
Fig. 7 is gold at the near surface of hot-rolled dual-phase steel plate thickness direction of inexpensive 13.0mm thickness specification of the present invention
Phase microscopic structure.
Specific embodiment
The following is the specific embodiment of the present invention, this embodiment is used for explaining the present invention, is not intended to limit the present invention's
Scope.
The homogeneous hot rolling biphase plate of the inexpensive think gauge tissue based on rear-mounted ultrafast refrigeration technique of the present invention, by setting
Determine composition smelting molten steel and cast strand, composition is by weight percentage：0.055 ~ 0.085%C, 0.20 ~ 0.50%Si, 1.20 ~
1.50%Mn, Cr≤0.40%, P≤0.012%, S≤0.002%, balance of Fe and inevitable impurity.
Table 1 is the actual measurement chemical composition of the specific embodiment of the invention（By weight percentage, balance of Fe and inevitably
Impurity）.
Table 1 specific embodiment of the invention chemical composition（Wt.%）
Embodiment technique：The blank of composition shown in embodiment 1 ~ 4 is placed in heating furnace and is heated to 1160 ~ 1240 DEG C, adopt
With including the rolling of austenite recrystallization area（Reduction ratio >=60%）With the rolling of austenite Unhydrated cement（Reduction ratio >=52%）Two
Stage control rolling mill practice, in the range of 820 ~ 850 DEG C, after hot rolling, the thickness of steel plate is 9.0 ~ 13.0mm to finishing temperature control.
Referring to Fig. 1, the steel plate after hot rolling first adopts laminar cooling system 1 leading portion hubbed mode to be cooled to the cooldown rate of 10 ~ 25 DEG C/s
620 ~ 700 DEG C, convert the austenite to as polygonal ferrite, ferrite content is 75 ~ 90%.Before steel plate is through section cooling
It is cooled to after 150 ~ 300 DEG C using rear-mounted ultrafast cooling system 2 after Duan Jizhong cooling and is batched, ultrafast cooling system hydraulic pressure sets
For more than 0.6MPa, jet density is 100 ~ 240 (m3/h)/m2, cooldown rate controls in the range of 80 ~ 120 DEG C/s, to obtain
10 ~ 25% martensite, is finally organized as polygonal ferrite+disperse island-like martensite.
Table 2 is the actual measurement technological parameter of the specific embodiment of the invention and corresponding mechanical property parameters.
The actual measurement technological parameter of table 2 specific embodiment of the invention and mechanical property parameters
Accompanying drawing 2 ~ 7 is the optics metallographic microstructure of the embodiment of the present invention, and sample adopts 4% nitric acid ethanol corrosion, by scheming
Understand, the center of DP590 hot-rolled dual-phase steel thickness direction of the present invention, the tissue at the 1/4 and attached place in surface are by polygon
The island-like martensite of ferrite and small and dispersed distribution is constituted, and that is, the organization type of thickness direction, distributional pattern are more consistent.
Claims (1)
1. a kind of method of think gauge hot rolling biphase plate, the chemical composition of described steel plate is by weight percentage：0.055~
0.085% C, 0.20 ~ 0.50% Si, 1.20 ~ 1.50% Mn, Cr≤0.40%, P≤0.012%, S≤0.002%, balance of Fe and
Inevitably impurity；The thickness specification of described steel plate is 9.0 ~ 13.0mm, and thickness direction is organized as homogeneous duplex structure, institute
Stating dual phase sheet steel duplex structure is polygonal ferrite and disperse island-like martensite, and described polygonal ferrite volume fraction is
75% ~ 90%, described disperse island-like martensite volume fraction is 10 ~ 25% it is characterised in that methods described comprises the steps of：
（1）Smelted by the chemical composition of described steel plate, obtained strand；
（2）By described heating strand to 1160 ~ 1240 DEG C, then adopt and include the rolling of austenite recrystallization area with austenite not again
The two-stage control rolling mill practice of crystal region rolling, the reduction ratio of previous stage is >=60%, reduction ratio >=52% of the latter half,
Finishing temperature is 820 ~ 850 DEG C, and the thickness controlling steel plate after hot rolling is 9.0 ~ 13.0mm；
（3）Through step（2）The steel plate obtaining after hot rolling is first cooled down using section cooling leading portion hubbed mode, cooldown rate
For 10 ~ 25 DEG C/s；
（4）Steel plate is concentrated belt steel temperature after cooling using rear-mounted ultrafast cooling system by 660 ~ 700 DEG C through section cooling leading portion
It is cooled to 150 ~ 300 DEG C to be batched, wherein ultrafast cooling system hydraulic pressure is set as more than 0.6MPa, jet density is 100 ~ 240
(m3/h)/m2, when temperature is cooled to 200 DEG C by 700 DEG C, cooldown rate is 80 ~ 120 DEG C/s.
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| CN104195439B true CN104195439B (en) | 2017-02-22 |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN104593665A (en) * | 2015-02-03 | 2015-05-06 | 东北大学 | Method for manufacturing thick hot-rolled dual-phase steel based on CSP (Compact Strip Production) process |
| CN107674954B (en) * | 2017-09-20 | 2019-04-09 | 武汉科技大学 | The method for improving multi-phase Steels comprehensive performance using deformation Substructure after hot rolling |
| CN110669913B (en) * | 2019-09-30 | 2021-05-28 | 鞍钢股份有限公司 | Hot-rolled and acid-washed dual-phase steel for high-strength automobile wheels and production method thereof |
| CN113441556B (en) * | 2020-03-25 | 2022-09-09 | 上海梅山钢铁股份有限公司 | Laminar cooling process control method of low-temperature coiled hot-rolled dual-phase steel |
Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1807669A (en) * | 2006-02-17 | 2006-07-26 | 东北大学 | Tensile strength 600Mpa grade dual phase steel plate and its production method |
| CN102321845A (en) * | 2011-09-21 | 2012-01-18 | 首钢总公司 | A kind of high-strength hot-rolled dual-phase steel and method of manufacture thereof |
| CN102703815A (en) * | 2012-06-19 | 2012-10-03 | 东北大学 | 600 Mpa grade hot-rolling dual-phase steel and preparation method thereof |
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Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1807669A (en) * | 2006-02-17 | 2006-07-26 | 东北大学 | Tensile strength 600Mpa grade dual phase steel plate and its production method |
| CN102321845A (en) * | 2011-09-21 | 2012-01-18 | 首钢总公司 | A kind of high-strength hot-rolled dual-phase steel and method of manufacture thereof |
| CN102703815A (en) * | 2012-06-19 | 2012-10-03 | 东北大学 | 600 Mpa grade hot-rolling dual-phase steel and preparation method thereof |
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Application publication date: 20141210 Assignee: Xi'an Heavy Technology Co.,Ltd. Assignor: Northeastern University Contract record no.: X2023210000017 Denomination of invention: A thick gauge hot-rolled dual-phase steel plate and its manufacturing method Granted publication date: 20170222 License type: Common License Record date: 20230301 |
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