CN103774060A - Production technology for 345MPa-level hot-rolled plate roll - Google Patents
Production technology for 345MPa-level hot-rolled plate roll Download PDFInfo
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- CN103774060A CN103774060A CN201310738709.7A CN201310738709A CN103774060A CN 103774060 A CN103774060 A CN 103774060A CN 201310738709 A CN201310738709 A CN 201310738709A CN 103774060 A CN103774060 A CN 103774060A
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Abstract
The invention discloses a production technology for a 345MPa-level hot-rolled plate roll. The 345MPa-level hot-rolled plate roll comprises the components in percentage by weight: 0.14-0.18 percent of C, 0.20-0.30 percent of Si, 1.35-1.50 percent of Mn, less than or equal to 0.10 percent of S, less than or equal to 0.20 percent of P, 0.015-0.045 percent of Als, 0.015-0.030 percent of Ti and the balance of iron and residual impurities. The production technology for the 345MPa-level hot-rolled plate roll comprises liquid iron pretreatment, RH refining, LF refining, continuous casting, heating through a heating furnace, rolling and coiling. According to the production technology for the 345MPa-level hot-rolled plate roll, the content of sulfide inclusions in the Q345B plate roll is reduced, the metallographic structure of the plate roll is improved, the matching property of the intensity and the extending rate performance is improved, the influence, which is caused by fluctuation of rolling parameters, on the performance of the Q345B plate roll is alleviated, and the stability of the quality of a product is guaranteed.
Description
Technical field
The present invention relates to a kind of production technique of 345MPa level hot-rolled sheet coil.
Background technology
The alloying constituent of existing Q345B steel only adopts C, Si, Mn, P, this five large element of S, and such alloying constituent has certain advantage on production cost, but the stability of rolling technology is relatively relied on.In the operation of rolling of the large production of industry, rolling parameter (finishing temperature, coiling temperature etc.) is to have variation to a certain extent, has under normal circumstances 50～150 ℃ of upper and lower temperature fluctuations, and in the time of special season, temperature has greatly and floats.
Finishing temperature in course of hot rolling, coiling temperature are that the impact of microstructure on steel and performance is than more sensitive parameter.Coiling temperature improves, and steel yield strength declines, and unit elongation promotes, and coiling temperature reduces, otherwise.Adopt the Q345B steel of conventional five large elements, susceptibility to rolling temperature is stronger, because the fluctuation of industrial production temperature is large, often occur that unit elongation is higher, intensity is lower, or unit elongation is lower, the phenomenon that intensity is higher, cause intensity not mated with unit elongation performance, always have a performance not reach standard-required.
What tradition adopted is that converter smelting, continuous casting, heat send, heat the technique of rear continuous steel rolling, and owing to not adopting the refining of LF stove, therefore S control of element is too high, causes steel medium sulphide content inclusion content too much, also can affect to some extent material unit elongation.Although production cost is lower, lower lumber recovery not only can cause the quality objection of part, also can damage the self-image of enterprise.
Summary of the invention
The object of the invention is to overcome the deficiencies in the prior art, provide one not to be subject to rolling technology stability influence, can guarantee the production technique of the 345MPa level hot-rolled sheet coil of quality product.
To achieve these goals, the technical solution used in the present invention is:
The production technique of this 345MPa level hot-rolled sheet coil, 345MPa level hot-rolled sheet coil composition proportion is by weight percentage: C:0.14～0.18, Si:0.20～0.30, Mn:1.35～1.50, S :≤0.10, P :≤0.20, Als:0.015～0.045, Ti:0.015～0.030, all the other are iron and residual impurity;
The production technique of 345MPa level hot-rolled sheet coil is: hot metal pretreatment → RH refining → LF refining → continuous casting → process furnace heating → rolling → batch;
Process furnace is heated to 1220～1280 ℃, is incubated 1.5～2.5 hours;
The control of roughing temperature is >=1150 ℃;
Finish rolling breaking down temperature is 1020～1080 ℃;
Finish rolling finishing temperature is 820 ℃～880 ℃, and the cooling rear coiling temperature of laminar flow is 590 ℃～650 ℃.
Roughing workpiece thickness is not less than 50mm.
Finish rolling adopts 7 passage rollings, and except extreme trace is inferior, other percentage pass reduction is 20-30%, and last percentage pass reduction is not less than 12%.
As preferred implementation, in 345MPa level hot-rolled sheet coil, the content of C, Si, Mn, S, P, Als and Ti is: C:0.16, Si:0.25, Mn:1.40, S :≤0.005, P :≤0.015, Als:0.030, Ti:0.020; In each production process of 345MPa level hot-rolled sheet coil, process furnace is heated to 1250 ℃, is incubated 2 hours; Roughing temperature objectives value is >=1150 ℃; Finish rolling breaking down temperature objectives value is 1050 ℃; Finish rolling adopts 7 passages, except extreme trace is inferior, and each percentage pass reduction 25%, last percentage pass reduction is not less than 12%; Roughing workpiece thickness is more than 50mm; Finish rolling finish to gauge target temperature is by 850 ℃ of controls, and after laminar flow is cooling, batching target temperature is 620 ℃.
The invention has the advantages that: the production technique of this 345MPa level hot-rolled sheet coil, reduce the content of the Sulfide inclusion in Q345B coiled sheet, improve coiled sheet metallographic structure, promoted the matching of intensity, unit elongation performance, reduced the impact that rolling parameter fluctuates on Q345B coiled sheet performance.
According to the Q345B coiled sheet of above-mentioned technique rolling, in tensile property check, the Sulfide inclusion in stretching fracture obviously reduces, and yield strength remains on that 390Mpa, tensile strength remain on 550Mpa, unit elongation remains on 25% mean level (ML), each Performance Match, balance is better.
Accompanying drawing explanation
Mark in content and the figure below each width accompanying drawing of specification sheets of the present invention being expressed is briefly described:
Fig. 1 is the metallographic structure figure of heart portion of the 345MPa level hot-rolled sheet coil of the production technique production of 345MPa level hot-rolled sheet coil of the present invention.
Fig. 2 is the structural representation of the 345MPa level hot-rolled sheet coil stretching fracture of the production technique production of 345MPa level hot-rolled sheet coil of the present invention.
Fig. 3 is the metallographic structure figure of heart portion of the 345MPa level hot-rolled sheet coil of the production technique production of 345MPa level hot-rolled sheet coil in prior art.
Fig. 4 is the structural representation of the 345MPa level hot-rolled sheet coil stretching fracture of the production technique production of 345MPa level hot-rolled sheet coil in prior art.
Embodiment
Contrast accompanying drawing below, by the description to optimum embodiment, the specific embodiment of the present invention is described in further detail.
The production technique of this 345MPa level hot-rolled sheet coil, 345MPa level hot-rolled sheet coil composition proportion is by weight percentage: C:0.14～0.18, Si:0.20～0.30, Mn:1.35～1.50, S :≤0.10, P :≤0.20, Als:0.015～0.045, Ti:0.015～0.030, all the other are iron and residual impurity;
The production technique of 345MPa level hot-rolled sheet coil is: hot metal pretreatment → RH refining → LF refining → continuous casting → process furnace heating → rolling → batch;
Process furnace is heated to 1220～1280 ℃, is incubated 1.5～2.5 hours;
The control of roughing temperature is >=1150 ℃;
Finish rolling breaking down temperature is 1020～1080 ℃;
Finish rolling finishing temperature is 820 ℃～880 ℃, and the cooling rear coiling temperature of laminar flow is 590 ℃～650 ℃.
Roughing workpiece thickness is not less than 50mm.
Finish rolling adopts 7 passage rollings, and except extreme trace is inferior, other percentage pass reduction is 20-30%, and last percentage pass reduction is not less than 12%.
The production technique of this 345MPa level hot-rolled sheet coil is added suitable Al, Ti element in the composition system of former C, Si, Mn, S, P, and in technical process, adds LF stove refinery practice, effectively controls the content of S element in material.
One of major function of LF stove refining is exactly desulfurization, and desulfurization degree can reach 50%～70%, if the treatment time fully can reach the level of weight percent≤0.005% of S.The advantage of LF stove desulfurization is: the reducing atmosphere that (1) is good, (2) can make Al
2o
3high basicity slag, (3) bag Bottom Argon Stirring, slag is abundant, desulfurization kinetics is with favourable conditions, (4) temperature is high.
Adopt above chemical composition to make steel, in technique, add the refining of LF stove, effectively control S element, reach and reduce steel medium sulphide content inclusion, improved the effect of toughness of material.
Added Ti element, titanium is strong reductor in steel, and it can make the dense internal organization of steel, effectively thinning microstructure crystal grain, and intensity, toughness to material all have raising to a certain extent.
In steel, add a small amount of Al, can crystal grain thinning, crystal grain thinning can improve the strength and toughness of steel.
Preferred implementation one
345MPa level hot-rolled sheet coil composition proportion is by weight percentage: C:0.16, and Si:0.25, Mn:1.40, S :≤0.005, P :≤0.015, Als:0.030, Ti:0.020, all the other are iron and residual impurity;
The production technique of 345MPa level hot-rolled sheet coil is: hot metal pretreatment → RH refining → LF refining → continuous casting → process furnace heating → rolling → batch;
Process furnace is heated to 1250 ℃, is incubated 2 hours;
Roughing temperature objectives value is >=1150 ℃;
Finish rolling breaking down temperature objectives value is 1050 ℃, and finish rolling adopts 7 passages, except extreme trace is inferior, and each percentage pass reduction 25%, last percentage pass reduction is not less than 12%;
Roughing workpiece thickness is more than 50mm;
Finish rolling finish to gauge target temperature is by 850 ℃ of controls, and after laminar flow is cooling, batching target temperature is 620 ℃.
345MPa level rolling hot rolled coils technique, adopts above target component, considers rolling and batches 50～150 ℃ of upper and lower temperature fluctuations; Get the rear tapping temperature of process furnace heating, finish rolling finish to gauge temperature out and coiling temperature value in actual production technique, verify the product performance of the 345MPa level hot-rolled sheet coil of this 345MPa level rolling hot rolled coils explained hereafter, following two tables of verification msg.
Adopt above target value to control, the actual process parameter value that records is in table 1.
Table 1 actual process parameter
| Numbering | Tapping temperature ℃ | Finish rolling temperature out ℃ | Coiling temperature ℃ |
| 1 | 1167 | 834 | 610 |
| 2 | 1072 | 856 | 620 |
| 3 | 1160 | 836 | 550 |
| 4 | 1176 | 824 | 597 |
| 5 | 1160 | 874 | 690 |
| 6 | 1088 | 830 | 590 |
| 7 | 1140 | 866 | 670 |
| 8 | 1120 | 840 | 605 |
Table 2 mechanical property
| Numbering | Yield strength (MPa) | Tensile strength (MPa) | Unit elongation (%) |
| 1 | 420 | 562 | 27.5 |
| 2 | 418 | 557 | 25.0 |
| 3 | 415 | 574 | 24.5 |
| 4 | 380 | 555 | 24.0 |
| 5 | 385 | 532 | 28.5 |
| 6 | 423 | 605 | 23.5 |
| 7 | 390 | 562 | 24.0 |
| 8 | 415 | 609 | 25.0 |
Shown in table 1 and table 2, chemical composition adopts hello aluminium to add Ti element and crosses the technique of LF stove refining, and in process of the test, rolling temperature parameter all has certain fluctuation, and coiling temperature fluctuation maximum reaches 140 ℃.Although having certain temperature wave understands, mechanical property, the fluctuation of mechanical property is less, there is not underproof phenomenon in material, yield strength maximum disparity is at 43Mpa, unit elongation maximum disparity is 5%, has certain surplus capacity in performance, and there is no the appearance of performance inconsistency lattice product.
The production technique of this 345MPa level hot-rolled sheet coil, not only reduce the content of the Sulfide inclusion in Q345B coiled sheet, improve coiled sheet metallographic structure, promote the matching of intensity, unit elongation performance, and reduce the impact that rolling parameter fluctuates on Q345B coiled sheet performance, guaranteed Q345B coiled sheet quality conformance.
Accompanying drawing 1 is the core structure figure of the 345MPa level hot-rolled sheet coil of this preferred implementation acquisition, and 345MPa level hot-rolled sheet coil core structure is ferrite+bainite, and ferrite can reduce hardness and improve the mechanical properties such as toughness plasticity, and bainite improves strength property.
Obviously specific implementation of the present invention is not subject to the restrictions described above, as long as adopted the improvement of the various unsubstantialities that method design of the present invention and technical scheme carry out, all within protection scope of the present invention.
Claims (4)
1. the production technique of a 345MPa level hot-rolled sheet coil, it is characterized in that: 345MPa level hot-rolled sheet coil composition proportion is by weight percentage: C:0.14～0.18, Si:0.20～0.30, Mn:1.35～1.50, S :≤0.10, P :≤0.20, Als:0.015～0.045, Ti:0.015～0.030, all the other are iron and residual impurity;
The production technique of 345MPa level hot-rolled sheet coil is: hot metal pretreatment → RH refining → LF refining → continuous casting → process furnace heating → rolling → batch;
Process furnace is heated to 1220～1280 ℃, is incubated 1.5～2.5 hours;
The control of roughing temperature is >=1150 ℃;
Finish rolling breaking down temperature is 1020～1080 ℃;
Finish rolling finishing temperature is 820 ℃～880 ℃, and the cooling rear coiling temperature of laminar flow is 590 ℃～650 ℃.
2. the production technique of 345MPa level hot-rolled sheet coil as claimed in claim 1, is characterized in that: roughing workpiece thickness is not less than 50mm.
3. the production technique of 345MPa level hot-rolled sheet coil as claimed in claim 2, is characterized in that: finish rolling adopts 7 passage rollings, and except extreme trace is inferior, other percentage pass reduction is 20-30%, and last percentage pass reduction is not less than 12%.
4. the production technique of 345MPa level hot-rolled sheet coil as claimed in claim 3, it is characterized in that: in 345MPa level hot-rolled sheet coil, the content of C, Si, Mn, S, P, Als and Ti is: C:0.16, Si:0.25, Mn:1.40, S :≤0.005, P :≤0.015, Als:0.030, Ti:0.020; In each production process of 345MPa level hot-rolled sheet coil, process furnace is heated to 1250 ℃, is incubated 2 hours; Roughing temperature objectives value is >=1150 ℃; Finish rolling breaking down temperature objectives value is 1050 ℃; Finish rolling adopts 7 passages, except extreme trace is inferior, and each percentage pass reduction 25%, last percentage pass reduction is not less than 12%; Roughing workpiece thickness is more than 50mm; Finish rolling finishing temperature is by 850 ℃ of controls, and the cooling rear coiling temperature of laminar flow is 620 ℃.
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN106498293A (en) * | 2016-11-08 | 2017-03-15 | 攀钢集团攀枝花钢铁研究院有限公司 | A kind of preparation method of hot forming with high-carbon hot continuous rolling pickling steel band |
| CN107475622A (en) * | 2017-09-05 | 2017-12-15 | 武汉钢铁有限公司 | Steel plate and its manufacture method with good thermal processability energy |
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Cited By (3)
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| CN107475622A (en) * | 2017-09-05 | 2017-12-15 | 武汉钢铁有限公司 | Steel plate and its manufacture method with good thermal processability energy |
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