CN112355055A - Rolling method of corrosion-resistant steel plate for ship - Google Patents
Rolling method of corrosion-resistant steel plate for ship Download PDFInfo
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- CN112355055A CN112355055A CN202011169120.6A CN202011169120A CN112355055A CN 112355055 A CN112355055 A CN 112355055A CN 202011169120 A CN202011169120 A CN 202011169120A CN 112355055 A CN112355055 A CN 112355055A
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- rolling
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- descaling
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
- B21B—ROLLING OF METAL
- B21B1/00—Metal-rolling methods or mills for making semi-finished products of solid or profiled cross-section; Sequence of operations in milling trains; Layout of rolling-mill plant, e.g. grouping of stands; Succession of passes or of sectional pass alternations
- B21B1/46—Metal-rolling methods or mills for making semi-finished products of solid or profiled cross-section; Sequence of operations in milling trains; Layout of rolling-mill plant, e.g. grouping of stands; Succession of passes or of sectional pass alternations for rolling metal immediately subsequent to continuous casting
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
- B21B—ROLLING OF METAL
- B21B37/00—Control devices or methods specially adapted for metal-rolling mills or the work produced thereby
- B21B37/74—Temperature control, e.g. by cooling or heating the rolls or the product
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
- B21B—ROLLING OF METAL
- B21B45/00—Devices for surface or other treatment of work, specially combined with or arranged in, or specially adapted for use in connection with, metal-rolling mills
- B21B45/04—Devices for surface or other treatment of work, specially combined with or arranged in, or specially adapted for use in connection with, metal-rolling mills for de-scaling, e.g. by brushing
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
- B21B—ROLLING OF METAL
- B21B45/00—Devices for surface or other treatment of work, specially combined with or arranged in, or specially adapted for use in connection with, metal-rolling mills
- B21B45/04—Devices for surface or other treatment of work, specially combined with or arranged in, or specially adapted for use in connection with, metal-rolling mills for de-scaling, e.g. by brushing
- B21B45/08—Devices for surface or other treatment of work, specially combined with or arranged in, or specially adapted for use in connection with, metal-rolling mills for de-scaling, e.g. by brushing hydraulically
Abstract
The invention discloses a rolling method of a corrosion-resistant ship steel plate, which is mainly characterized in that secondary and tertiary oxidized iron scales generated in the rolling process are reserved by controlling the rolling temperature, descaling pass, rolling speed and other technical measures aiming at a wide and thick plate reversible rolling mill production line, so that a layer of compact oxide layer film is formed on the surface of the steel plate, the steel plate is prevented from rusting in the transportation, storage and use processes, and the corrosion resistance of the steel plate is improved. The invention does not need to modify the existing equipment, and improves the corrosion resistance of the steel plate by changing the oxide layer structure on the surface of the steel plate through process optimization on the basis of not increasing the production cost.
Description
Technical Field
The invention belongs to the technical field of metallurgy, and relates to a rolling method of a corrosion-resistant steel plate for a ship.
Technical Field
In recent years, the problem of surface quality defects of marine steel plates has been on the rise, and a large part of the problems is the surface corrosion pit defect. Such defects seriously impair the surface quality of the ship's board, are one of the important classes of surface defects that affect the appearance of the ship's board and the subsequent production process, and have long plagued steel mills and shipyards.
The pit defect on the surface of the ship plate generally occurs on the ship plate with a long storage period, and the steel plate is stored outdoors for a long time before being used, is in a coastal humid atmosphere environment or is wetted by rainwater, so that the surface of the steel plate is easy to generate point-like corrosion or crevice corrosion. The steel plate surface after shot blasting presents point-like pits with different sizes, and the depth is generally in the range of 0.1 mm-0.5 mm. For slight corrosion defects, a shipyard generally adopts a coping mode for treatment; and for more serious corrosion defects, steel plates are directly scrapped, so that steel mills and shipyards suffer great economic loss.
The iron scale on the surface of the steel plate produced by the traditional process is too thin and loose, and is easy to fall off in the processes of storage, transportation and hoisting, so that the steel plate matrix is exposed, and the electrode potential of the steel plate matrix is lower than that of the iron scale, so that the steel plate matrix is easy to rust when corrosive media such as water films exist. The prior art methods for improving the corrosion resistance of steel sheets are generally divided into two methods, the first method is a method of adding high-phosphorus, copper, Ni-Cr series, Cr-Mn series and other high alloys to steel sheets. For example, CN 106498280B discloses a production method of "a high-strength corrosion-resistant steel" by adding P: 0.09-0.10%, Cu: 0.52 to 0.58%, Ni: 0.42-0.48%, although the corrosion resistance of the steel plate is improved, the high phosphorus brings low-temperature brittleness, the high copper strip brings hot rolling cracks, bending cracks and the like, namely, the plasticity and the toughness of the steel plate are reduced, and the high alloy content obviously improves the manufacturing cost of the steel plate. The second method is a method for coating the surface of the steel plate with an organic antirust coating. For example, CN 102002700 a discloses a "short-term rust prevention and film coating process method on the surface of a steel plate", which increases the rust prevention capability of the steel plate by coating the surface of the steel plate with an organic chemical reagent, but this method is only effective indoors, has an unsatisfactory outdoor effect, only achieves a short-term rust prevention effect, and is also ineffective for the steel plate stored for a long time, and some organic rust prevention coating reagents are flammable, explosive, toxic, harmful, difficult to remove, and not safe and environment-friendly.
Disclosure of Invention
The invention aims to provide a rolling method of a corrosion-resistant steel plate for a ship, which changes original iron oxide scales which have negative influence on the surface quality of the steel plate into a complete, compact and uniform oxide protective film through the adjustment of a rolling process under the condition of the existing equipment of a steel mill, and improves the corrosion resistance of the steel plate.
The technical scheme of the invention is as follows:
a rolling method of a corrosion-resistant marine steel plate comprises the following process steps:
(1) heating and descaling a continuous casting blank: the heating temperature is more than or equal to 1180 ℃; the descaling temperature is more than or equal to 1168 ℃; the pressure of the descaling water is more than or equal to 220 bar;
(2) rolling: the two-stage controlled rolling is adopted, the final rolling temperature in the rough rolling stage is more than or equal to 1050 ℃, the first pass, the first widening and the second pass of rolling in the rough rolling stage, the first pass after widening and the last pass of rough rolling need to be descaled; closing the cooling water of the roller way at the intermediate temperature waiting section from the outlet of the roughing mill to the inlet of the finishing mill, and not carrying out any descaling and water cooling operation at the intermediate billet temperature waiting section; in the finish rolling stage, cooling water of an input roller way and an output roller way of the rolling mill is closed, the total descaling pass cannot exceed 2, and only the first three passes remove scale; the finish rolling temperature is controlled to be 780-820 ℃, and the rolling speed is less than or equal to 4 m/s;
(3) and (3) cooling: and (3) after finish rolling, cooling the steel plate and closing water valves of all water cooling systems in direct contact with the steel plate without water cooling operation or water contact in the process of steel plate cooling and steel plate unloading.
The technical principle of the invention is as follows:
the invention adopts two-stage control rolling, descaling and rough rolling stages to remove primary scale generated in the heating process, the steel plate after rough rolling does not carry out any type of water cooling operation and does not contact water, and the invention is used for keeping secondary and tertiary scale generated on the surface of the steel plate in the rolling process and ensuring that the steel plate generates secondary and tertiary scale after rolling and coolingCompact and stable inner layer Fe3O4And an outer layer of Fe2O3The structure (red), this structure plays the protection film effect after the steel sheet cooling, blocks air and water, prevents that inside base member from rustting, plays the corrosion-resistant effect of steel sheet. If the steel sheet meets water and can destroy the oxide layer structure on surface when rolling and cooling, the reaction formula is: 4Fe +3O2+6H2O=4Fe(OH)3，Fe(OH)3Further dehydrating in air to form loose Fe2O3·xH2O (x is any positive real number and generally does not exceed 10), and the oxide layer is loose in structure and easy to fall off, namely the surface quality of the steel plate is damaged, and the steel plate is not corrosion-resistant.
The invention has the beneficial effects that: the steel plate produced by the traditional process has the surface generally made of cyan or black Fe3O4The oxide layer structure which is the main one has poorer performance of resisting the corrosion of the atmosphere and the seawater, and when the steel plate is exposed outdoors and is contacted with humid air or water, the steel plate is easy to rust, and the use of the steel plate is influenced. The invention breaks through the traditional concept, and the secondary and tertiary iron scales which have adverse effects on the surface of the steel plate are reserved and converted into a layer of complete, compact and uniform oxide protective film, so that the surface quality of the steel plate is improved, and the corrosion resistance of the steel plate is improved. The invention does not need to modify the existing equipment, and improves the corrosion resistance of the steel plate by changing the oxide layer structure on the surface of the steel plate through process optimization on the basis of not increasing the production cost.
Drawings
FIG. 1 is a photograph showing a rolled steel sheet of example 1.
FIG. 2 is a photograph showing a rolled surface of a steel sheet in comparative example 1.
FIG. 3 is a microscopic structural diagram of the cross-sectional morphology of the oxide film of the steel plate in example 1.
FIG. 4 is a microscopic structure diagram showing the cross-sectional morphology of the oxide film of the steel plate of comparative example 1.
Detailed Description
The present invention will be further described with reference to the following drawings by way of examples and comparative examples.
The steel of the example 1 and the steel of the comparative example 1 are high-strength boat deck AH36, and the chemical components of the steel are the same, and the steel comprises the following components in percentage by weight: c = 0.15%, Si = 0.24%, Mn = 1.18%, Nb = 0.016%, Ti =0.012%, Al =0.025%, and the balance Fe and unavoidable impurity elements. Plates with the thickness of 25mm multiplied by 3000mm are rolled by adopting a continuous casting billet with the thickness of 260mm multiplied by 2080mm, the specific rolling is carried out on a plate rolling line with the width of 5 meters, and the main production equipment comprises a walking beam type heating furnace; the system pressure of the high-pressure water descaling box is 250bar, and the pressure drop in the descaling process is controlled to be less than or equal to 5 bar; the four-roll reversible roughing mill with the vertical rolls has the working rolls of 900-1000 mm in diameter and the horizontal rolls of 1110-1210 mm in diameter; a four high reversing finishing mill with bending rolls and shifting rolls; and an accelerated cooling system.
Example 1
The heating temperature of the continuous casting billet is 1201 ℃; the descaling temperature is 1178 ℃; the average descaling pressure is 225 bar; the rolling is controlled in two stages, the initial rolling temperature of the rough rolling stage is 1132 ℃, the rolling is carried out for 5 times after 2 times of broadening, the intermediate billet is 85mm, the final rolling temperature is 1105 ℃, and the descaling passes are the first pass, the second pass and the first pass, the third pass and the fifth pass after broadening; closing the cooling water of the roller way at the intermediate temperature waiting section from the outlet of the roughing mill to the inlet of the finishing mill, and not carrying out any descaling and water cooling operation at the intermediate billet temperature waiting section; rolling for 9 times in the finish rolling stage, wherein the initial rolling temperature is 884 ℃, the rolling speed is 3.2-3.6 m/s, and the final rolling temperature is 796 ℃; closing cooling water of an input roller way and an output roller way of the finishing mill, wherein the descaling pass is the first pass of rolling; and after finish rolling, the steel plate is not subjected to any water cooling operation and does not contact water in the processes of cooling and discharging, and all water cooling system water valves in direct contact with the steel plate, such as ACC, roller way cooling water, a straightener and the like, are ensured to be closed.
And rolling the steel plate into a steel plate with the thickness of 25mm, wherein the steel plate performance meets the requirements according to the inspection result, the steel plate offline physical picture is shown in figure 1, the thickness of the oxide film on the surface of the steel plate is 35-45 mu m, the steel plate is complete and uniform, and the microstructure of the section appearance is shown in figure 3.
Comparative example 1
Heating the continuous casting slab at 1200 ℃; the descaling temperature is 1181 ℃; the average descaling pressure is 228 bar; the rolling is controlled in two stages, the initial rolling temperature of the rough rolling stage is 1136 ℃, the rolling is carried out for 5 times after 2 times of broadening, the intermediate billet is 85mm, the final rolling temperature is 1108 ℃, and the descaling passes are the first pass, the second pass and the first pass, the third pass and the fifth pass after broadening; the roller bed cooling water of the middle temperature waiting section from the outlet of the roughing mill to the inlet of the finishing mill is normally opened; rolling 9 times in the finish rolling stage, wherein the initial rolling temperature is 888 ℃, the rolling speed is 3.2-3.6 m/s, and the final rolling temperature is 789 ℃; closing the cooling water of the input and output roller ways of the finishing mill, wherein the descaling passes are the first, second, fifth and ninth passes; and (3) cooling the steel plate after finish rolling, and using all water cooling systems in direct contact with the steel plate, such as roller cooling water, a straightener and the like in the offline process.
Rolling the steel plate into a steel plate with the thickness of 25mm, and obtaining a steel plate with the performance meeting the requirements according to the inspection result, wherein an offline physical photograph of the steel plate is shown in figure 2, the thickness of an oxide film on the surface of the steel plate is less than 20 mu m, the steel plate is seriously crushed, and a microstructure of the section appearance is shown in figure 4.
Claims (1)
1. A rolling method of a corrosion-resistant steel plate for a ship is characterized by comprising the following process steps:
(1) heating and descaling a continuous casting blank: the heating temperature is more than or equal to 1180 ℃; the descaling temperature is more than or equal to 1168 ℃; the pressure of the descaling water is more than or equal to 220 bar;
(2) rolling: the two-stage controlled rolling is adopted, the final rolling temperature in the rough rolling stage is more than or equal to 1050 ℃, the first pass, the first widening and the second pass of rolling in the rough rolling stage, the first pass after widening and the last pass of rough rolling need to be descaled; closing the cooling water of the roller way at the intermediate temperature waiting section from the outlet of the roughing mill to the inlet of the finishing mill, and not carrying out any descaling and water cooling operation at the intermediate billet temperature waiting section; in the finish rolling stage, cooling water of an input roller way and an output roller way of the rolling mill is closed, the total descaling pass cannot exceed 2, and only the first three passes remove scale; the finish rolling temperature is controlled to be 780-820 ℃, and the rolling speed is less than or equal to 4 m/s;
(3) and (3) cooling: and (3) after finish rolling, cooling the steel plate and closing water valves of all water cooling systems in direct contact with the steel plate without water cooling operation or water contact in the process of steel plate cooling and steel plate unloading.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202011169120.6A CN112355055A (en) | 2020-10-28 | 2020-10-28 | Rolling method of corrosion-resistant steel plate for ship |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202011169120.6A CN112355055A (en) | 2020-10-28 | 2020-10-28 | Rolling method of corrosion-resistant steel plate for ship |
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| CN112355055A true CN112355055A (en) | 2021-02-12 |
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| CN202011169120.6A Pending CN112355055A (en) | 2020-10-28 | 2020-10-28 | Rolling method of corrosion-resistant steel plate for ship |
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Citations (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102671941A (en) * | 2012-06-11 | 2012-09-19 | 南京钢铁股份有限公司 | Process for producing thin gauge pipeline steel by using double-stand medium and heavy plate mill |
| CN103212571A (en) * | 2013-04-18 | 2013-07-24 | 湖南华菱湘潭钢铁有限公司 | Method for producing oxide scale capable of preventing steel plate surface from getting rusty |
| CN103769424A (en) * | 2014-01-08 | 2014-05-07 | 南京钢铁股份有限公司 | Method for controlling red oxide scale on surface of steckel mill steel plate |
| CN108435794A (en) * | 2018-04-10 | 2018-08-24 | 中冶赛迪工程技术股份有限公司 | A kind of process of continuous casting and rolling |
| JP2019081198A (en) * | 2017-10-30 | 2019-05-30 | Ｊｆｅスチール株式会社 | Manufacturing method and manufacturing equipment of steel material |
| CN110394363A (en) * | 2019-08-02 | 2019-11-01 | 武汉钢铁集团鄂城钢铁有限责任公司 | It is a kind of to utilize Wide and Thick Slab finishing mill differential temperature rolling thickness >=60mm carbon constructional quality steel production method |
-
2020
- 2020-10-28 CN CN202011169120.6A patent/CN112355055A/en active Pending
Patent Citations (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102671941A (en) * | 2012-06-11 | 2012-09-19 | 南京钢铁股份有限公司 | Process for producing thin gauge pipeline steel by using double-stand medium and heavy plate mill |
| CN103212571A (en) * | 2013-04-18 | 2013-07-24 | 湖南华菱湘潭钢铁有限公司 | Method for producing oxide scale capable of preventing steel plate surface from getting rusty |
| CN103769424A (en) * | 2014-01-08 | 2014-05-07 | 南京钢铁股份有限公司 | Method for controlling red oxide scale on surface of steckel mill steel plate |
| JP2019081198A (en) * | 2017-10-30 | 2019-05-30 | Ｊｆｅスチール株式会社 | Manufacturing method and manufacturing equipment of steel material |
| CN108435794A (en) * | 2018-04-10 | 2018-08-24 | 中冶赛迪工程技术股份有限公司 | A kind of process of continuous casting and rolling |
| CN110394363A (en) * | 2019-08-02 | 2019-11-01 | 武汉钢铁集团鄂城钢铁有限责任公司 | It is a kind of to utilize Wide and Thick Slab finishing mill differential temperature rolling thickness >=60mm carbon constructional quality steel production method |
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Application publication date: 20210212 |