CN104593665A - Method for manufacturing thick hot-rolled dual-phase steel based on CSP (Compact Strip Production) process - Google Patents
Method for manufacturing thick hot-rolled dual-phase steel based on CSP (Compact Strip Production) process Download PDFInfo
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Abstract
The invention discloses a method for manufacturing hot-rolled dual-phase steel based on a CSP (Compact Strip Production) process. The method comprises the following steps: (1) preparing a raw material comprising the following chemical compositions in percentage by weight: 0.055-0.070% of C, 0.40-0.50% of Si, 1.20-1.50% of Mn, less than or equal to 0.015% of P, less than or equal to 0.002% of S and the balance of Fe and unavoidable impurities; and (2) sequentially pretreating molten steel, carrying out converter top and bottom combined blowing, refining in an LF, continuously casting thin billet, soaking in a tunnel furnace, continuously rolling by virtue of an F1-F7 seven-stand hot continuous rolling mill group, cooling by virtue of a laminar cooling system, cooling by virtue of an ultra-fast cooling system and coiling. In the method, the out-of-furnace temperature of the continuous casting billet passing through the tunnel soaking furnace is equal to or greater than 1130 DEG C, the initial rolling temperature in the hot continuous rolling step is equal to or greater than 1010 DEG C, the reduction rate in an F1 stand is equal to or greater than 40%, the reduction rate in an F2 stand is equal to or greater than 33.3%, the temperature after the laminar cooling and air cooling is 600-690 DEG C, the temperature after ultra-fast cooling is 150-250 DEG C, the ultra-fast cooling speed is 70-150 DEG C/s. The microstructures of 11.0mm-thickness 590MPa-grade dual-phase steel in the thickness direction, which is produced from a simple low C-Mn-component system in an industrial mass manner, are ferrite and martensite duplex microstructures so that the dual-phase steel is excellent in comprehensive performance.
Description
Technical field
The present invention relates to a kind of production technique of hot-rolled steel sheet, particularly a kind of manufacture method of the low cost thickness specification 590MPa level hot-rolled dual-phase steel based on CSP technique.
Background technology
The advanced high-strength steel of a certain proportion of martensite duplex structure that distributes on ferrite matrix that hot-rolled dual-phase steel is mainly obtained by controlled rolling and Controlled cooling process by soft steel or low-carbon alloy steel, having excellent comprehensive mechanical property, is a kind of widely used automotive sheet.The 590MPa level hot-rolled dual-phase steel of 10.0 ~ 14.0mm thickness specification is mainly for the manufacture of wheel of truck and crossbeam etc., and demand is huge.
Relative to conventional hot continuous rolling machine production line, CSP(Compact Strip Production, also known as compact torrid zone production technique) production line production process is a stationary process, comparatively stable to the control of the processing parameters such as the control of the physical dimension such as steel plate thickness, plate shape and temperature in the operation of rolling, can be controlled on higher precision level, be beneficial to and produce the dual phase steel higher to transformation behavior control overflow.But be subject to the restriction of CSP production line cooled region and Technology at present, the hot-rolled dual-phase steel produced is mainly below 6.0mm specification, and alloy designs is by adding the content of Cr element or increase Mn, Si to alleviate the deficiency of cooling power.Mandate publication number is that the patent of invention " CSP produces the technique of hot-rolled dual-phase steel " of CN 100441724C have employed higher alloy designs (Si:0.6-1.0%, Mn:1.5-2.0%, the microstructure of the hot rolling biphase plate Cr:0.4-0.6%) obtained is based on ferrite+martensite (or bainite), simultaneously also may containing tissues such as a small amount of perlite.Authorize publication number to be " a kind of tensile strength 600MPa level dual phase sheet steel and the manufacture method " of CN100357474C and authorize publication number to be that " a kind of manufacture method of the economical hot-rolled dual-phase steel good based on the surface quality of CSP technique " of CN101906571B obtains hot-rolled dual-phase steel of good performance based on CSP technique, but described hot-rolled dual-phase steel thickness is only limitted to 6.0mm and following thickness.
Under existing CSP technical qualification, when producing this kind of think gauge hot-rolled dual-phase steel, relatively reduce although last frame throws steel speed, and then extend cooling time, be conducive to obtaining larger temperature drop scope, but now thickness is more outstanding to the disadvantageous effect of cooling performance, causes being difficult to obtain desirable ferrite+martensitic duplex structure, steel plate center is easy to form bainite structure, the tissue odds one on thickness direction.Existing document " Baogang CSP ' is ultrafast cold ' system and the exploitation of 590 MPa level C-Mn low cost hot-rolled dual-phase steels " (" iron and steel " the 43rd volume the 3rd phase P49-52 in 2008) composition of adopting of delivering and technique obtain the hot-rolled dual-phase steel of 4.0 ~ 11.0mm, but it does not explicitly point out the processing parameter of hot-rolled dual-phase steel, also the tissue morphology in not mentioned think gauge product thickness direction, and produce the mixed structure being organized as ferrite+martensite+bainite of steel plate and non-ferrous+martensitic duplex structure.The hot-rolled dual-phase steel of the 11.0 ~ 13.0mm thickness specification obtained under the composition of document " production practice of CSP production line exploitation C-Mn type hot-rolled dual-phase steel " described in (" Shanghai Metals " the 32nd volume the 1st phase P27-29 in 2010) and processing condition, its tensile strength is 550 ~ 585MPa, only meets the performance requriements of DP540.Therefore, under existing CSP technical process condition, by the restriction of cooling equipment and process technology, for think gauge high-strength hot-rolled dual-phase steel, be difficult to the stable matching realizing chemical composition-process window-structure property, suitability for industrialized production and the application of such dual phase steel cannot be realized.
Patent of the present invention by setting up rear-mounted ultrafast cooling system on CSP production line, solve very well cause because cooling power is not enough in industrial production 11.0mm thickness specification 590MPa level hot-rolled dual-phase steel thickness direction tissue odds one, there is the problems such as too much bainite and unstable properties in tissue.The present invention relies on rearmounted super formula fast-cooling technology, by the overall-in-one control schema (mainly comprising the continuous casting of thin slab, heating, rolling and process of cooling) of CSP full-flow process, adopt the low cost low C-Mn component system steel without the need to adding hardening capacity element Cr, Mo, obtain thickness direction is polygonal ferrite matrix and the tissue of the island-like martensite of Dispersed precipitate therebetween dual phase steel by surface to center, and excellent performance is stablized, achieve the low cost of think gauge high-strength hot-rolled dual-phase steel, the suitability for industrialized production of high stability.
Summary of the invention
The object of the invention is for prior art Problems existing, a kind of hot-rolled dual-phase steel manufacture method based on CSP technique is provided.
Above-mentioned purpose is realized by following proposal:
Based on a hot-rolled dual-phase steel manufacture method for CSP technique, it is characterized in that, said method comprising the steps of:
(1) configure raw material: chemical composition is 0.055 ~ 0.070%C, 0.40 ~ 0.50%Si by weight percentage, 1.20 ~ 1.50%Mn, P≤0.015%, S≤0.002%, surplus is Fe and inevitable impurity;
(2) carry out molten steel pre-treatment → converter top bottom blowing → LF refining treatment → sheet blank continuous casting → continuous tunnel furnace soaking → F1 ~ F7 seven frame hot tandem tandem rolling → laminar cooling system cooling → ultrafast cooling system successively to cool → batch.
According to above-mentioned manufacture method, it is characterized in that, in described continuous tunnel furnace soak step, time inside furnace is 10 ~ 25min, and tapping temperature controls as>=1130 DEG C; In F1 ~ F7 seven frame hot tandem tandem rolling step, start rolling temperature>=1010 DEG C, F1 roll housing draft>=40%, F2 roll housing draft>=33.3%, control finishing temperature 840 ~ 860 DEG C, last frame rolls speed control in the scope of 1.3 ~ 2.8m/s, and finish to gauge thickness is 11.0 ~ 14.0mm; In section cooling step, cooling mode is that leading portion collector concentrates unlatching, back segment collector is closed and carried out air cooling, and after air cooling, temperature controls within the scope of 600 ~ 690 DEG C; In ultra-rapid cooling step, be cooled to 150 ~ 250 DEG C and batch, the water yield of ultrafast cooling system is set as 3300 ~ 4500m
3/ s, rate of cooling controls within the scope of 70 ~ 150 DEG C/s.
Beneficial effect of the present invention:
(1) manufacture method that the present invention relates to, by the full-range technology controlling and process of CSP being core with ultrafast refrigeration technique, adopts the C-Mn component system of low cost, can produce 10.0 ~ 14.0mm thickness specification 590MPa level hot-rolled dual-phase steel.
(2) manufacture method by the present invention relates to, 10.0 ~ 14.0mm thickness specification 590MPa level the hot-rolled dual-phase steel obtained, the center of its thickness direction, 1/4 place and surface tissue are polygonal ferrite matrix and the island-like martensite duplex structure that distributes of even dispersion therebetween.
(3) manufacture method by the present invention relates to, 10.0 ~ 14.0mm thickness specification 590MPa level hot-rolled dual-phase steel excellent in mechanical performance of acquisition, stable, meet DP590 performance requriements.
(4) the rear-mounted ultrafast cooling system that the present invention relates to, for the hot-rolled steel sheet of 10.0 ~ 14.0mm thickness specification, can realize the stability contorting of final cooling temperature at 100 DEG C ~ 300 DEG C scopes, rate of cooling 70 ~ 200 DEG C/s, process window is wider, ensure that the stability of industrialized mass production.
(5) manufacture method that the present invention relates to, being similar to license notification number for the low finishing temperature of 800 ~ 820 DEG C described in CN 101906571 B patent of invention without the need to adopting, alleviating the load of milling train.
(6) manufacture method that the present invention relates to, pass through technology controlling and process, adopt C-Mn component system steel billet can produce the hot-rolled dual-phase steel of 10.0 ~ 14.0mm thickness specification, without the need to adding austenitic stabilizing element Cr, Mo etc. again, composition be simple, alleviate smelt difficulty, cost is lower.
Accompanying drawing explanation
Fig. 1 is the think gauge 590MPa level hot-rolled dual-phase steel thickness direction center microstructure that method of the present invention is produced;
Fig. 2 is the think gauge 590MPa level hot-rolled dual-phase steel thickness direction 1/4 place microstructure that method of the present invention is produced;
Fig. 3 is the think gauge 590MPa level hot-rolled dual-phase steel surface microstructure that method of the present invention is produced.
Embodiment
Be below specific embodiments of the invention, this embodiment, for explaining the present invention, is not for limiting the scope of the invention.
The composition of the actual melting molten steel of embodiment by mass percentage content in table 1.
The molten steel of table 1 illustrated embodiment 1 ~ 3 composition is carried out pre-treatment → converter top bottom blowing → LF refining treatment → sheet blank continuous casting → continuous tunnel furnace soaking → F1 ~ F7 seven frame hot tandem tandem rolling → laminar cooling system → ultrafast cooling system → batch.
Table 1 specific embodiment of the invention chemical composition (Wt.%)
Continuously cast bloom is 10 ~ 25min in the time that continuous tunnel furnace is all hankered, control tapping temperature >=1130 DEG C, start rolling temperature >=1010 DEG C, F1 roll housing draft >=40%, F2 frame draft >=33.3%, control finishing temperature 840 ~ 860 DEG C, last frame rolls speed control in the scope of 1.3 ~ 2.8m/s, and finish to gauge thickness is 10.0 ~ 14.0mm.Band steel after hot rolling first adopts leading portion collector to concentrate the cold but system cools of the laminar flow of unlatching, and then carry out air cooling, after air cooling, temperature controls within the scope of 600 ~ 690 DEG C, makes the polygonal ferrite matrix of formation q.s.Steel plate adopts ultrafast cooling system to be cooled to 150 ~ 250 DEG C and batches after air cooling, and ultrafast cooling system collector is evenly opened, and the water yield is set as 3300 ~ 4500m
3/ s, controlled cooling model speed is within the scope of 70 ~ 150 DEG C/s, make not change austenite and all change martensite into, avoid and do not change the transformation of austenite to bainite, the final thickness direction that obtains is polygonal ferrite matrix and equally distributed island-like martensite two-phase steel organization therebetween.
Table 2 is depicted as the process tracking processing parameter in embodiment production process.
The process tracking processing parameter of table 2 embodiment production process
Table 3 is depicted as the mechanical property of product prepared by embodiment, and the tensile strength of the steel plate produced is 598 ~ 625MPa, yield tensile ratio 0.62 ~ 0.65, unit elongation 28 ~ 35%, 180
ocold-bending property is all qualified, the stable performance of embodiment gained steel plate, and different plate performance is within 27MPa.
Table 3 embodiment product mechanical property
Claims (2)
1., based on a hot-rolled dual-phase steel manufacture method for CSP technique, it is characterized in that, said method comprising the steps of:
(1) configure raw material: chemical composition is 0.055 ~ 0.070%C, 0.40 ~ 0.50%Si by weight percentage, 1.20 ~ 1.50%Mn, P≤0.015%, S≤0.002%, surplus is Fe and inevitable impurity;
(2) carry out molten steel pre-treatment → converter top bottom blowing → LF refining treatment → sheet blank continuous casting → continuous tunnel furnace soaking → F1 ~ F7 seven frame hot tandem tandem rolling → laminar cooling system cooling → ultrafast cooling system successively to cool → batch.
2. manufacture method according to claim 1, is characterized in that, in described continuous tunnel furnace soak step, time inside furnace is 10 ~ 25min, and tapping temperature controls as>=1130 DEG C; In F1 ~ F7 seven frame hot tandem tandem rolling step, start rolling temperature>=1010 DEG C, F1 roll housing draft>=40%, F2 roll housing draft>=33.3%, control finishing temperature 840 ~ 860 DEG C, last frame rolls speed control in the scope of 1.3 ~ 2.8m/s, and finish to gauge thickness is 10.0 ~ 14.0mm; In section cooling step, cooling mode is that leading portion collector concentrates unlatching, back segment collector is closed and carried out air cooling, and after air cooling, temperature controls within the scope of 600 ~ 690 DEG C; In ultrafast cooling step, but to 150 ~ 250 DEG C are batched, and the water yield of ultrafast cooling system is set as 3300 ~ 4500m
3/ s, rate of cooling controls within the scope of 70 ~ 150 DEG C/s.
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Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN106011618A (en) * | 2016-06-06 | 2016-10-12 | 日照宝华新材料有限公司 | Method for producing DP780 steel based on ESP sheet billet continuous casting and rolling flow |
| CN108754104A (en) * | 2018-06-20 | 2018-11-06 | 北京首钢股份有限公司 | A method of eliminating the flat volume defect of 590Mpa rank dual phase steel hot rollings |
| CN113926892A (en) * | 2020-06-29 | 2022-01-14 | 宝山钢铁股份有限公司 | Stamping forming process and application of hot-rolled ultrahigh-strength dual-phase steel part with tensile strength of more than or equal to 980MPa |
| CN115852240A (en) * | 2021-09-24 | 2023-03-28 | 宝山钢铁股份有限公司 | Steel for flexible pipe with yield strength of 750MPa and manufacturing method thereof |
| CN113926892B (en) * | 2020-06-29 | 2024-07-12 | 宝山钢铁股份有限公司 | Stamping forming process and application of hot-rolled ultra-high strength dual-phase steel part with tensile strength of more than or equal to 980MPa |
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| CN102732784A (en) * | 2012-06-15 | 2012-10-17 | 甘肃酒钢集团宏兴钢铁股份有限公司 | 590L automobile crossbeam steel and CSP preparation method thereof |
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Cited By (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN106011618A (en) * | 2016-06-06 | 2016-10-12 | 日照宝华新材料有限公司 | Method for producing DP780 steel based on ESP sheet billet continuous casting and rolling flow |
| CN106011618B (en) * | 2016-06-06 | 2018-07-03 | 日照宝华新材料有限公司 | Method based on ESP bar strip continuous casting and rolling flow paths production DP780 steel |
| CN108754104A (en) * | 2018-06-20 | 2018-11-06 | 北京首钢股份有限公司 | A method of eliminating the flat volume defect of 590Mpa rank dual phase steel hot rollings |
| CN113926892A (en) * | 2020-06-29 | 2022-01-14 | 宝山钢铁股份有限公司 | Stamping forming process and application of hot-rolled ultrahigh-strength dual-phase steel part with tensile strength of more than or equal to 980MPa |
| CN113926892B (en) * | 2020-06-29 | 2024-07-12 | 宝山钢铁股份有限公司 | Stamping forming process and application of hot-rolled ultra-high strength dual-phase steel part with tensile strength of more than or equal to 980MPa |
| CN115852240A (en) * | 2021-09-24 | 2023-03-28 | 宝山钢铁股份有限公司 | Steel for flexible pipe with yield strength of 750MPa and manufacturing method thereof |
| CN115852240B (en) * | 2021-09-24 | 2024-03-08 | 宝山钢铁股份有限公司 | Steel with yield strength of 750MPa for flexible pipe and manufacturing method thereof |
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Application publication date: 20150506 |