CN113695545B - Continuous casting method of small square billet meeting production requirement of large-specification wire rod cold heading steel - Google Patents

Continuous casting method of small square billet meeting production requirement of large-specification wire rod cold heading steel Download PDF

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Publication number
CN113695545B
CN113695545B CN202110947778.3A CN202110947778A CN113695545B CN 113695545 B CN113695545 B CN 113695545B CN 202110947778 A CN202110947778 A CN 202110947778A CN 113695545 B CN113695545 B CN 113695545B
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continuous casting
reduction
billet
rolling
wire rod
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CN113695545A (en
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王郢
徐建飞
王昆鹏
王立涛
沈艳
王向红
杨成威
蒋鲤平
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Zenith Steel Group Co Ltd
Changzhou Zenith Special Steel Co Ltd
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Zenith Steel Group Co Ltd
Changzhou Zenith Special Steel Co Ltd
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    • BPERFORMING OPERATIONS; TRANSPORTING
    • B22CASTING; POWDER METALLURGY
    • B22DCASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
    • B22D11/00Continuous casting of metals, i.e. casting in indefinite lengths
    • B22D11/16Controlling or regulating processes or operations
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B22CASTING; POWDER METALLURGY
    • B22DCASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
    • B22D11/00Continuous casting of metals, i.e. casting in indefinite lengths
    • B22D11/16Controlling or regulating processes or operations
    • B22D11/18Controlling or regulating processes or operations for pouring
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B22CASTING; POWDER METALLURGY
    • B22DCASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
    • B22D11/00Continuous casting of metals, i.e. casting in indefinite lengths
    • B22D11/16Controlling or regulating processes or operations
    • B22D11/22Controlling or regulating processes or operations for cooling cast stock or mould
    • B22D11/225Controlling or regulating processes or operations for cooling cast stock or mould for secondary cooling

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Metal Rolling (AREA)

Abstract

The invention relates to a continuous casting method of a small square billet meeting the requirement of producing large-specification wire rod cold forging steel, which selects a continuous casting billet with the section size of 160mm multiplied by 160mm, the drawing speed is 2.3-2.8 m/min, the superheat degree is controlled at 35-45 ℃, a straight-through submerged nozzle is adopted, and the secondary cooling specific water amount is 0.8-1.4L/kg; closing the electromagnetic stirring at the tail end, and equipping the continuous casting machine with 7 withdrawal straightening machines, wherein 4# to 7# withdrawal straightening rolls are adopted for reduction, the single-roll reduction is 5 to 12mm, the total reduction is 20 to 40mm, and the total deformation is 10 to 25 percent. The invention adopts high drawing speed, high superheat degree and high specific water content for casting, closes the electromagnetic stirring at the tail end, adopts large reduction of 20-40 mm to carry out reduction on the continuous casting billet so as to obtain columnar crystals with higher proportion, improves the central porosity and shrinkage cavity of the casting billet, ensures that the density of the continuous casting billet reaches the hot rolling state control level, and realizes the rolling of large-size wire rods under the condition of adopting small compression ratio, thereby realizing the production of replacing two hot rods by one hot rod, and finally achieving the purposes of reducing the production cost and improving the product quality.

Description

Continuous casting method of small square billet meeting production requirement of large-specification wire rod cold heading steel
Technical Field
The invention relates to the technical field of continuous casting, in particular to a small square billet continuous casting method for producing large-specification wire rod cold heading steel.
Background
Cold heading steel is mainly used for machining and manufacturing fasteners and connecting pieces (such as bolts, nuts, screws, rivets and the like). Cold heading properties are one of the important properties of cold heading steel. At present, cold forging steel wires with the specification of less than phi 25 are mainly rolled by small square billets domestically, and the section size of the casting billet is basically 140-180 mm in width and 140-180 mm in thickness. For a cold forging steel wire rod with larger specification such as phi 30-phi 50, because a designed rolling mill cannot directly roll a large-section casting blank, and the direct rolling of a small-section casting blank has the problem of low compression ratio, so that the center of the wire rod is loose, the shrinkage cavity and the like are difficult to meet the quality control requirements, usually, only two-hot-material production process can be adopted, namely, the large-section casting blank is firstly blanked into the small-section casting blank, and then the small-section casting blank is rolled, and the method has the problems of high production cost, low production efficiency and about 400-600 yuan increase in average steel cost per ton.
Disclosure of Invention
The technical problem to be solved by the invention is as follows: in order to overcome the defects in the prior art, the invention provides a small square billet continuous casting method for producing large-specification wire rod cold heading steel, which optimizes the continuous casting process parameters to ensure that the density of a continuous casting billet before rolling reaches or approaches the hot rolling state control level, thereby ensuring that indexes such as center porosity, segregation and the like of large-specification wire rods completely meet the quality requirements for producing large-specification wire rod cold heading steel under the production condition of a small compression ratio.
The technical scheme adopted by the invention for solving the technical problems is as follows: a small square billet continuous casting method for producing large-specification wire rod cold heading steel comprises the following steps:
(1) The section size of the continuous casting billet is 160 multiplied by 160mm 2
(2) The drawing speed of the continuous casting billet is 2.3-2.8 m/min;
(3) Controlling the superheat degree of the molten steel to be 35-45 ℃ before casting, and closing the electromagnetic stirring at the tail end;
(4) Adopting a straight-through type submerged nozzle, wherein the secondary cooling specific water amount is 0.8-1.4L/kg;
(5) The continuous casting machine is provided with 7 straightening machines, 1# to 3# straightening rollers do not conduct reduction, 4# to 7# straightening rollers conduct reduction, and the reduction amount of a single roller can be 5-12 mm, the total reduction amount of the casting blank thickness is 20-40 mm, and the total deformation amount of the casting blank thickness is 10-25% by applying pressure to the thickness direction of the casting blank.
The rolling specification of the wire rod is phi 30-phi 50.
The continuous casting billet adopts a large coil rolling process, the rolling parameters are obtained according to a conventional process, the rolling parameters do not need to be adjusted or optimized intentionally, the rolling process is that the continuous casting billet is subjected to high-pressure water descaling after passing through a heating furnace, and then is subjected to rough rolling, medium rolling, pre-finish rolling, three-roller kocks rolling, curling, packaging and warehousing in sequence.
Through the research on the reduction effect, the center of the casting blank is columnar crystal, and the reduction process is adopted to more easily press the central shrinkage cavity due to the directivity of the columnar crystal; when the center is isometric crystal, as the isometric crystal has no directionality, the pressing process is adopted, the center loosening and shrinkage cavity control effects are not obvious without columnar crystal, and a typical schematic diagram is shown in figure 1.
Therefore, in order to obtain more columnar crystals, the method abandons the traditional casting process with low superheat degree, low pulling speed and low specific water content, adopts high superheat degree, high pulling speed and high specific water content for casting, and closes the electromagnetic stirring at the tail end so as to maximally improve the proportion of the columnar crystals and reduce the proportion of equiaxed crystals. Meanwhile, the central shrinkage cavity is pressed and combined with a large reduction process, and the obtained continuous casting billet can meet the requirement of producing large-specification wire cold heading steel by adopting a hot material production process.
The invention has the beneficial effects that: the invention adopts high drawing speed, high superheat degree and high specific water content for casting, closes the electromagnetic stirring at the tail end, adopts large reduction of 20-40 mm to carry out reduction on the continuous casting billet so as to obtain columnar crystals with higher proportion, improves the central porosity and shrinkage cavity of the casting billet, ensures that the density of the continuous casting billet reaches or approaches the hot rolling state control level, realizes the rolling of large-size wire rods under the condition of adopting small compression ratio, thereby realizing the production of replacing two hot rods by one hot rod, and finally achieving the purposes of reducing the production cost and improving the product quality.
Drawings
The invention is further illustrated with reference to the following figures and examples.
FIG. 1 is a schematic view of the light pressure effect of columnar crystal and equiaxed crystal.
FIG. 2 is a photograph of a longitudinal cut of a cast slab of example 1 after pickling of a low-magnification sample.
FIG. 3 is a photograph of a longitudinal cut of a cast slab obtained in example 2 after pickling of a low-magnification sample.
Detailed Description
The present invention will now be described in further detail with reference to examples.
Example 1:
the embodiment provides a small square billet continuous casting method for producing large-specification wire rod cold heading steel.
And (3) continuous casting process: adopting a 160X 160 section continuous casting machine for production, controlling the drawing speed to be 2.5m/min, controlling the superheat degree to be 42 ℃, adopting a straight-through submerged nozzle, controlling the secondary cooling specific water amount to be 1.2L/kg, and closing the electromagnetic stirring at the tail end; and 4# to 7# withdrawal and straightening rollers are adopted for pressing, the pressing amount is 6 mm, 8 mm and 5mm respectively, and the total pressing amount is 25mm.
And a steel rolling process, namely, a large coil rolling process is adopted, rolling parameters are obtained according to a conventional process, the rolling parameters do not need to be adjusted or optimized intentionally, the rolling process is that the temperature of a casting blank in a heating section is 1020 ℃, the temperature of a soaking section is 1075 ℃, the rolling temperature is 1030 ℃, the total heating time is 125min, the casting blank is descaled by high pressure water after passing through a heating furnace, and then the casting blank is subjected to rough rolling, medium rolling, pre-finish rolling, three-roll kocks rolling mill, curling, packaging and warehousing sequentially.
And (3) detection results: the picture of the acid-washed longitudinal section of the continuous casting blank is shown in figure 2, the central shrinkage cavity is completely pressed, the central segregation and the porosity are 0.5 grade, and the central shrinkage cavity is 0 grade; the specification of the hot-rolled wire rod is phi 38, the center of the wire rod is segregated and loosened by 0.5 grade, and the quality requirement is completely met.
Example 2:
the embodiment provides a small square billet continuous casting method for producing large-specification wire rod cold heading steel.
And (3) continuous casting process: adopting a 160X 160 section continuous casting machine for production, controlling the drawing speed to be 2.6m/min, controlling the superheat degree to be 39 ℃, adopting a straight-through submerged nozzle, controlling the secondary cooling specific water amount to be 1.2L/kg, and closing the electromagnetic stirring at the tail end; and 4# to 7# withdrawal and straightening rollers are adopted for pressing, the pressing amount is 6 mm, 7 mm, 8 mm and 9mm respectively, and the total pressing amount is 30mm.
The steel rolling process adopts a large coil rolling process, rolling parameters are obtained according to a conventional process, the rolling parameters do not need to be adjusted or optimized intentionally, the rolling process is that the temperature of a casting blank in a heating section is 1043 ℃, the temperature of a soaking section is 1085 ℃, the rolling temperature is 1042 ℃, the total heating time is 138min, the casting blank is descaled by high pressure water after passing through a heating furnace, and then the casting blank is subjected to rough rolling, medium rolling, pre-finish rolling, three-roll kocks rolling mill, curling, packaging and warehousing in sequence.
And (3) detection results: the picture of the acid-washed longitudinal section of the continuous casting blank is shown in figure 3, the central shrinkage cavity is completely pressed, the central segregation and the porosity are 0.5 grade, and the central shrinkage cavity is 0 grade; the specification of the hot-rolled wire rod is phi 42, the center of the wire rod is segregated and loosened by 0.5 grade, and the quality requirement is completely met.
In light of the foregoing description of the preferred embodiment of the present invention, many modifications and variations will be apparent to those skilled in the art without departing from the spirit and scope of the invention. The technical scope of the present invention is not limited to the content of the specification, and must be determined according to the scope of the claims.

Claims (2)

1. A continuous casting method of small square billets for producing large-specification wire cold heading steel is characterized by comprising the following steps: the method comprises the following steps:
(1) The section size of the continuous casting billet is 160 multiplied by 160mm 2
(2) The drawing speed of the continuous casting billet is 2.3-2.8 m/min;
(3) Controlling the superheat degree of the molten steel to be 35-45 ℃ before casting, and closing the electromagnetic stirring at the tail end;
(4) A straight-through type submerged nozzle is adopted, and the secondary cooling specific water amount is 0.8-1.4L/kg;
(5) The continuous casting machine is provided with 7 withdrawal and straightening machines, the 1# to 3# withdrawal and straightening rollers do not conduct reduction, the 4# to 7# withdrawal and straightening rollers conduct reduction, and pressure is applied to the thickness direction of a casting blank, so that the reduction of a single roller is 5-12 mm, the total reduction of the thickness of the casting blank is 20-40 mm, and the total deformation of the thickness of the casting blank is 10-25%.
2. The small square billet continuous casting method for producing large-specification wire cold heading steel according to claim 1, which is characterized in that: the rolling specification of the wire rod is phi 30-phi 50.
CN202110947778.3A 2021-08-18 2021-08-18 Continuous casting method of small square billet meeting production requirement of large-specification wire rod cold heading steel Active CN113695545B (en)

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CN114657444A (en) * 2022-03-25 2022-06-24 中天钢铁集团有限公司 Method for producing steel QD08 for claw pole of motor by using small square billet with 160mm multiplied by 160mm section

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CN101147966A (en) * 2007-10-29 2008-03-26 江苏沙钢集团淮钢特钢有限公司 Continuous casting columnar crystallizer small square blank and its columnar crystal control method

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CN103506586B (en) * 2012-06-20 2016-01-20 鞍钢股份有限公司 Continuous casting method for improving central shrinkage cavity of high-carbon steel billet
US10307819B2 (en) * 2014-03-27 2019-06-04 Primetals Technologies Austria GmbH Semi-continuous casting of a steel strip
CN104874758B (en) * 2015-05-11 2017-11-17 中冶连铸技术工程有限责任公司 Continuous casting weight pressing control method
CN109622904B (en) * 2019-02-01 2020-06-02 东北大学 Device and method for realizing core pressing process in continuous casting round billet solidification process
CN109732049A (en) * 2019-02-21 2019-05-10 东北大学 A kind of vertical throwing conticaster of small billet and soft reduction process device

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CN101147966A (en) * 2007-10-29 2008-03-26 江苏沙钢集团淮钢特钢有限公司 Continuous casting columnar crystallizer small square blank and its columnar crystal control method

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