CN108941213B - Rolling method for controlling structural uniformity of high-strength hot-rolled steel plate - Google Patents

Rolling method for controlling structural uniformity of high-strength hot-rolled steel plate Download PDF

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Publication number
CN108941213B
CN108941213B CN201810661642.4A CN201810661642A CN108941213B CN 108941213 B CN108941213 B CN 108941213B CN 201810661642 A CN201810661642 A CN 201810661642A CN 108941213 B CN108941213 B CN 108941213B
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rolling
temperature
rolling mill
controlling
rough rolling
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CN108941213A (en
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李俊洪
罗许
刘序江
肖强
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Pangang Group Panzhihua Iron and Steel Research Institute Co Ltd
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Pangang Group Panzhihua Iron and Steel Research Institute Co Ltd
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    • BPERFORMING OPERATIONS; TRANSPORTING
    • B21MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
    • B21BROLLING OF METAL
    • B21B37/00Control devices or methods specially adapted for metal-rolling mills or the work produced thereby
    • B21B37/74Temperature control, e.g. by cooling or heating the rolls or the product
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B21MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
    • B21BROLLING OF METAL
    • B21B2201/00Special rolling modes
    • B21B2201/06Thermomechanical rolling

Abstract

The invention discloses a rolling method, particularly discloses a rolling method for controlling the structural uniformity of a high-strength hot-rolled steel plate, and belongs to the technical field of steel plate rolling processes. Provided is a rolling method capable of effectively controlling the structural uniformity of a high-strength hot-rolled steel sheet by improving the rolling process and the parameters thereof. The rolling method comprises the steps of discharging from a furnace by uniform temperature heating temperature control difference, rough rolling at a medium speed in a four-roller reversible rough rolling mill, finish rolling at a surface temperature control temperature in a seven-frame continuous rolling mill and cooling at a laminar flow cooling unit under the condition of controlling the internal temperature and the external temperature, wherein in the process of rough rolling at the medium speed in the four-roller reversible rough rolling mill, a high-pressure water descaling nozzle at an inlet of the four-roller reversible rolling mill is opened to descale and cool the surface of the strip steel, so that the surface temperature of the strip steel is reduced.

Description

Rolling method for controlling structural uniformity of high-strength hot-rolled steel plate
Technical Field
The invention relates to a rolling method, in particular to a rolling method for controlling the structural uniformity of a high-strength hot-rolled steel plate, and belongs to the technical field of steel plate rolling processes.
Background
The hot rolled steel plate is an important raw material generally applied to national economic construction, and a hot continuous rolling mill group is usually adopted to roll hot rolled strip steel or a single-stand/double-stand reversible rolling mill to produce medium-thickness steel plates. Along with the improvement of the product quality requirements of downstream users, the requirements on the quality of hot rolled steel plates serving as raw materials are higher, and particularly the requirements on the structural uniformity of steel plates with the thickness of more than or equal to 10mm in the thickness direction are higher. It is known that when the uniformity of the structure in the thickness direction in the thick hot rolled steel plate is poor, impact damage may occur in the subsequent use process, which affects the service life of the product.
Currently, in order to control the uniformity of the structure in the thickness direction in the hot rolled steel sheet, a heat treatment process is generally used to texture-control the product after rolling. However, the heat treatment process is adopted to regulate and control the tissues, so that the workload and the production cost are inevitably increased.
Disclosure of Invention
The technical problem to be solved by the invention is as follows: provided is a rolling method capable of effectively controlling the structural uniformity of a high-strength hot-rolled steel sheet by improving the rolling process and the parameters thereof.
The technical scheme adopted for solving the technical problems is as follows: a rolling method for controlling the uniformity of the structure of a high-strength hot-rolled steel plate comprises the steps of uniform-temperature heating and temperature control difference discharging, medium-speed rough rolling of a four-roller reversible rough rolling mill, surface temperature control and finish rolling of a seven-stand continuous rolling mill and cooling of a laminar flow cooling unit under the condition of internal and external temperatures,
and opening a high-pressure water descaling nozzle at the inlet of the four-roller reversible roughing mill to descale and cool the surface of the strip steel in the medium-speed roughing process of the four-roller reversible roughing mill, so that the surface temperature of the strip steel is reduced by 80-120 ℃.
Furthermore, in the process of uniform-temperature heating and temperature-difference control discharging, the maximum temperature difference in the width direction, the length direction and the thickness direction of the plate blank is controlled below 20 ℃ during discharging.
In the preferable mode of the scheme, the maximum temperature difference in the width direction, the length direction and the thickness direction of the plate blank is controlled between 15 and 18 ℃ during discharging.
Further, in the intermediate speed rough rolling step of the four-high reversible rough rolling mill, the rolling speed of the four-high reversible rolling mill is 2.0m/S to 3.0 m/S.
Furthermore, in the surface temperature control finish rolling process of the seven-stand continuous rolling mill, the surface temperature of the rolled steel plate is subjected to water spray cooling on the inlet roll gap of each stand by adopting a water spray device special for the seven-stand continuous rolling mill, so that the surface temperature of the strip steel is reduced by 40-60 ℃.
Furthermore, in the cooling process of the laminar flow cooling unit under the condition of controlling the internal and external temperatures, the cooling nozzles are opened every three times, and the temperature difference between the surface and the center of the strip steel is controlled within 80 ℃.
The invention has the beneficial effects that: the rolling method provided by the application is based on controlling the temperature of steel plates of each procedure in the rolling process, and controls the grain size difference between the surface of the strip steel and the central structure within a specified level through the steps of temperature equalization heating and temperature control difference tapping, medium-speed rough rolling of a four-roller reversible rough rolling mill, surface temperature control finish rolling of a seven-frame continuous rolling mill, cooling of a laminar flow cooling unit under the condition of internal and external temperatures and the like. Particularly, in the middle-speed rough rolling process of the four-roller reversible rough rolling mill, the high-pressure water descaling nozzle at the inlet of the four-roller reversible rough rolling mill is opened to descale and cool the surface of the strip steel, so that the surface temperature of the strip steel is reduced by 80-120 ℃, and the purpose that the structural uniformity of the high-strength hot-rolled steel plate can be effectively controlled by improving the rolling process and parameters of the rolling process is achieved. Furthermore, in order to provide the strip steel with better controlled surface and central structure grain size difference, namely the surface and central structure grain size difference can be controlled within 0.5 grade, the application also accurately controls the heating before hot rolling, the rolling speed during rough rolling, the cooling range during finish rolling and the difference value of the internal temperature and the external temperature of the strip steel during laminar cooling, namely, the strip steel with the controlled surface and central structure grain size difference within 0.5 grade is provided through the effective combination of the heating, rolling and cooling methods, so as to meet the requirements of customers with high control requirement on the structure grain size difference, meanwhile, the rolling cost can be reduced through the control of the process, the length of the rolling flow is saved, the low-cost production of high-quality hot-rolled high-strength steel plates is realized, and the market competitiveness of products is improved.
Detailed Description
In order to solve the technical problems in the background art of the present application, the present invention provides a rolling method capable of effectively controlling the structural uniformity of a high-strength hot-rolled steel sheet by improving the rolling process and the parameters thereof. The rolling method comprises the steps of discharging from a furnace by uniform temperature heating temperature control difference, rough rolling at a medium speed in a four-roller reversible rough rolling mill, finish rolling at a surface temperature control temperature in a seven-frame continuous rolling mill and cooling at a laminar flow cooling unit under the condition of controlling the internal temperature and the external temperature, wherein in the process of rough rolling at the medium speed in the four-roller reversible rough rolling mill, a high-pressure water descaling nozzle at an inlet of the four-roller reversible rolling mill is opened to descale and cool the surface of the strip steel, so that the surface temperature of the strip steel is reduced. The rolling method provided by the application is based on controlling the temperature of steel plates of each procedure in the rolling process, and controls the grain size difference between the surface of the strip steel and the central structure within a specified level through the steps of temperature equalization heating and temperature control difference tapping, medium-speed rough rolling of a four-roller reversible rough rolling mill, surface temperature control finish rolling of a seven-frame continuous rolling mill, cooling of a laminar flow cooling unit under the condition of internal and external temperatures and the like. Particularly, in the middle-speed rough rolling process of the four-roller reversible rough rolling mill, the high-pressure water descaling nozzle at the inlet of the four-roller reversible rough rolling mill is opened to descale and cool the surface of the strip steel, so that the surface temperature of the strip steel is reduced by 80-120 ℃, and the purpose that the structural uniformity of the high-strength hot-rolled steel plate can be effectively controlled by improving the rolling process and parameters of the rolling process is achieved.
In the above embodiments, in order to further control the uniformity of the structure of the high-strength hot-rolled steel sheet and provide a steel strip with better control of the grain size difference between the surface and the central structure, i.e., a high-strength hot-rolled steel sheet with a grain size difference between the surface and the central structure within 0.5 grade, which is described in the beneficial effects, the present application also precisely controls the heating before hot rolling, the rolling speed during rough rolling, the cooling range during finish rolling, and the difference between the inside and outside temperatures of the steel strip during laminar cooling, i.e., the purpose is achieved by effectively combining the heating, rolling and cooling methods, i.e., the grain size difference between the surface and the central structure is controlled within 0.5 grade. Specifically, in the process of discharging the plate blank from the furnace by uniform-temperature heating and temperature difference control, the maximum temperature difference in the width direction, the length direction and the thickness direction of the plate blank is controlled below 20 ℃ during discharging. At the moment, the optimal control range of the maximum temperature difference during discharging is that the maximum temperature difference in the width, length and thickness directions of the plate blank is controlled between 15 ℃ and 18 ℃. In the intermediate speed rough rolling procedure of the four-roller reversible rough rolling mill, the rolling speed of the four-roller reversible rolling mill is 2.0 m/S-3.0 m/S. In the surface temperature control finish rolling process of the seven-stand continuous rolling mill, a water spraying device special for the seven-stand continuous rolling mill is adopted to spray water to cool the inlet roll gap of each stand so as to reduce the surface temperature of the strip steel by 40-60 ℃. In the cooling process under the condition of controlling the internal and external temperatures of the laminar flow cooling unit, the cooling nozzles are opened with water every three nozzles, and the temperature difference between the surface and the center of the strip steel is controlled within 80 ℃.
In conclusion, the rolling method provided by the application also has the following advantages that aiming at the defects of the existing control method for the structural uniformity of the thick hot-rolled high-strength steel plate, the high-level control of the structural uniformity of the thick hot-rolled high-strength steel with the tensile strength of 500MPa or above is realized through the effective combination of the heating, rolling and cooling methods, and the grain size difference between the surface and the central structure of the strip steel is controlled within 0.5 grade, so that the requirements of customers with high control requirements for the structural grain size difference are met. Meanwhile, the rolling cost can be reduced through the control of the process, the length of the rolling process is saved, and the low-cost production of the high-quality hot-rolled high-strength steel plate is realized, so that the market competitiveness of the product is improved.
The first embodiment is as follows:
the hot-rolled high-strength steel with the tensile strength of 560MPa is rolled by a 230.0mm slab hot-rolled raw material, the thickness of the product is 16.0mm, and the structure uniformity control method comprises the following steps:
① heating the plate blank for producing hot-rolled high-strength steel in a combined heating furnace, controlling the heating temperature uniformity of the plate blank, and controlling the maximum temperature difference in the width, length and thickness directions of the plate blank to be below 18 ℃ when the plate blank is discharged from the furnace;
② A method for controlling the uniformity of hot rolled high-strength steel plate structure comprises rough rolling the plate blank with a four-roller reversible rough rolling mill at a rolling speed of 2.0 m/S.
③ A method for controlling the texture uniformity of hot-rolled high-strength steel plate comprises rough rolling the plate blank with a four-roller reversible rough rolling mill, and descaling and cooling the surface of the steel strip with a high-pressure water descaling nozzle at the inlet of the four-roller reversible rolling mill to reduce the surface temperature by 95 deg.C.
④ A method for controlling the uniformity of hot rolled high-strength steel plate structure includes such steps as rolling by seven-stand continuous rolling mill, and cooling by water spray to the roll gap at entrance of each stand to reduce the surface temp of steel plate by 55 deg.C.
⑤ A method for controlling the uniformity of hot rolled high-strength steel plate structure comprises rolling high-temperature steel strip by a seven-stand finishing mill, and cooling by a laminar flow cooling unit, wherein the water boiling state of the cooling nozzles is one every three, so that the temperature difference between the surface and the center of the steel strip is controlled within 40 deg.C.
By adopting the process technology, the grain size difference between the surface and the central structure of the hot-rolled high-strength steel with the thickness of 16.0mm and the tensile strength of 560MPa can be controlled to be 0.5 grade.
Example two:
the method comprises the following steps of rolling a hot-rolled high-strength steel with the tensile strength of 700MPa by using a 230.0mm slab hot-rolling raw material, wherein the thickness of the product is 12.0mm, and the residual stress control method comprises the following steps:
① heating the plate blank for producing hot-rolled high-strength steel in a combined heating furnace, controlling the heating temperature uniformity of the plate blank, and controlling the maximum temperature difference in the width, length and thickness directions of the plate blank to be below 15 ℃ when the plate blank is discharged from the furnace;
② A method for controlling the uniformity of hot rolled high-strength steel plate structure comprises rough rolling the plate blank with a four-roller reversible rough rolling mill at a rolling speed of 2.5 m/S.
③ A method for controlling the texture uniformity of hot-rolled high-strength steel plate comprises rough rolling the plate blank with a four-roller reversible rough rolling mill, and descaling and cooling the surface of the steel strip with a high-pressure water descaling nozzle at the inlet of the four-roller reversible rolling mill to reduce the surface temperature by 115 deg.C.
④ A method for controlling the uniformity of hot rolled high-strength steel plate structure includes such steps as rolling by seven-stand continuous rolling mill, and cooling by water spray to the roll gap at entrance of each stand to lower the surface temp of steel plate by 45 deg.C.
⑤ A method for controlling the uniformity of hot rolled high-strength steel plate structure comprises rolling high-temperature steel strip by a seven-stand finishing mill, and cooling by a laminar flow cooling unit, wherein the water boiling state of the cooling nozzles is one every three, so that the temperature difference between the surface and the center of the steel strip is controlled within 30 deg.C.
By adopting the process technology, the grain size difference between the surface and the central structure of the hot-rolled high-strength steel with the thickness of 12.0mm and the tensile strength of 700MPa can be controlled to be 0.4 grade.

Claims (4)

1. A rolling method for controlling the structural uniformity of a high-strength hot-rolled steel plate is characterized by comprising the following steps: the rolling method comprises the steps of discharging from a furnace with uniform temperature heating and temperature control difference, medium-speed rough rolling of a four-roller reversible rough rolling mill, surface temperature control finish rolling of a seven-stand continuous rolling mill and cooling under the condition of internal and external temperature controlled by a laminar flow cooling unit,
wherein in the process of medium-speed rough rolling of the four-roller reversible rough rolling mill, a high-pressure water descaling nozzle at the inlet of the four-roller reversible rough rolling mill is opened to descale and cool the surface of the strip steel so as to reduce the surface temperature of the strip steel by 80-120 ℃,
in the process of uniform temperature heating and temperature difference control discharging, the maximum temperature difference in the width, length and thickness directions of the plate blank is controlled below 20 ℃ during discharging,
in the cooling process under the condition of controlling the internal and external temperatures of the laminar flow cooling unit, the cooling nozzles are opened with water every three nozzles, and the temperature difference between the surface and the center of the strip steel is controlled within 80 ℃.
2. The rolling method for controlling the structure uniformity of a high-strength hot-rolled steel sheet according to claim 1, wherein: and when the plate blank is discharged, the maximum temperature difference in the width direction, the length direction and the thickness direction of the plate blank is controlled to be 15-18 ℃.
3. The rolling method for controlling the structure uniformity of a high-strength hot-rolled steel sheet according to claim 1, wherein: in the intermediate speed rough rolling procedure of the four-roller reversible rough rolling mill, the rolling speed of the four-roller reversible rough rolling mill is 2.0 m/s-3.0 m/s.
4. The rolling method for controlling the structure uniformity of a high-strength hot-rolled steel sheet according to claim 1, wherein: in the surface temperature control finish rolling process of the seven-stand continuous rolling mill, a water spraying device special for the seven-stand continuous rolling mill is adopted to spray water to cool the inlet roll gap of each stand so as to reduce the surface temperature of the strip steel by 40-60 ℃.
CN201810661642.4A 2018-06-25 2018-06-25 Rolling method for controlling structural uniformity of high-strength hot-rolled steel plate Active CN108941213B (en)

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CN110527809B (en) * 2019-08-26 2020-12-22 武汉科技大学 Preparation method of hot-rolled high-strength strip steel capable of reducing residual stress
CN110586663A (en) * 2019-09-04 2019-12-20 鞍钢股份有限公司 Production method for reducing temperature drop of hot-rolled intermediate billet

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CN100438997C (en) * 2005-05-20 2008-12-03 中冶东方工程技术有限公司 Compact medium-width strip steel production process
CN102671992A (en) * 2012-05-29 2012-09-19 东北大学 Method for making easy-to-pickle steel plate
CN102699030B (en) * 2012-05-30 2014-05-14 东北大学 Preparation method of sheet billet continuous casting and rolling easy-acid washing hot rolling strip steel
CN103920729B (en) * 2013-11-07 2017-02-08 首钢总公司 Method for removing red rust defects of high-silicon type high-strength automobile plate
CN104826872B (en) * 2015-05-15 2016-10-19 东北大学 A kind of controlled rolling method eliminating Surfaces of Hot Rolled Strip chromatic aberration defect
CN105274430B (en) * 2015-09-30 2017-10-10 唐山钢铁集团有限责任公司 A kind of production method of the ultra-thin size hot-rolled Punching Steel of 510MPa grades of tensile strength 390
CN106282801B (en) * 2016-09-09 2019-06-25 武汉钢铁有限公司 A kind of hot rolling large roughness surface weathering steel and its manufacturing method

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