CN111659734B - A kind of control method of surface pitting defect of thin-gauge pickling board - Google Patents
A kind of control method of surface pitting defect of thin-gauge pickling board Download PDFInfo
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- 238000000034 method Methods 0.000 title claims abstract description 37
- 230000007547 defect Effects 0.000 title claims abstract description 28
- 238000005554 pickling Methods 0.000 title claims abstract description 16
- 238000005096 rolling process Methods 0.000 claims abstract description 149
- 238000009749 continuous casting Methods 0.000 claims abstract description 36
- 238000004519 manufacturing process Methods 0.000 claims abstract description 18
- 229910000831 Steel Inorganic materials 0.000 claims description 44
- 239000010959 steel Substances 0.000 claims description 44
- 239000000498 cooling water Substances 0.000 claims description 43
- 238000010438 heat treatment Methods 0.000 claims description 30
- 230000009467 reduction Effects 0.000 claims description 13
- 238000003723 Smelting Methods 0.000 claims description 12
- 229910052785 arsenic Inorganic materials 0.000 claims description 11
- 229910052802 copper Inorganic materials 0.000 claims description 11
- 229910052718 tin Inorganic materials 0.000 claims description 11
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 claims description 9
- 229910052760 oxygen Inorganic materials 0.000 claims description 9
- 239000001301 oxygen Substances 0.000 claims description 9
- 230000008569 process Effects 0.000 abstract description 12
- 238000005098 hot rolling Methods 0.000 abstract description 7
- 230000000694 effects Effects 0.000 abstract description 6
- 230000033764 rhythmic process Effects 0.000 abstract description 4
- 230000000052 comparative effect Effects 0.000 description 36
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 description 18
- 230000003647 oxidation Effects 0.000 description 11
- 238000007254 oxidation reaction Methods 0.000 description 11
- 229910052742 iron Inorganic materials 0.000 description 9
- 230000003746 surface roughness Effects 0.000 description 6
- 238000012986 modification Methods 0.000 description 5
- 230000004048 modification Effects 0.000 description 5
- 241001062472 Stokellia anisodon Species 0.000 description 4
- 239000011159 matrix material Substances 0.000 description 4
- 239000002436 steel type Substances 0.000 description 4
- 230000015572 biosynthetic process Effects 0.000 description 3
- 238000005266 casting Methods 0.000 description 3
- 150000001247 metal acetylides Chemical class 0.000 description 3
- UQSXHKLRYXJYBZ-UHFFFAOYSA-N Iron oxide Chemical compound [Fe]=O UQSXHKLRYXJYBZ-UHFFFAOYSA-N 0.000 description 2
- 229910001209 Low-carbon steel Inorganic materials 0.000 description 2
- 238000007373 indentation Methods 0.000 description 2
- 230000014759 maintenance of location Effects 0.000 description 2
- 230000024121 nodulation Effects 0.000 description 2
- 230000000630 rising effect Effects 0.000 description 2
- 238000012360 testing method Methods 0.000 description 2
- 229910000997 High-speed steel Inorganic materials 0.000 description 1
- 241001622901 Scomberomorus commerson Species 0.000 description 1
- 239000002253 acid Substances 0.000 description 1
- 230000004075 alteration Effects 0.000 description 1
- 239000003153 chemical reaction reagent Substances 0.000 description 1
- 238000001816 cooling Methods 0.000 description 1
- 230000003247 decreasing effect Effects 0.000 description 1
- 238000009792 diffusion process Methods 0.000 description 1
- 229910000734 martensite Inorganic materials 0.000 description 1
- 230000001590 oxidative effect Effects 0.000 description 1
- 238000011056 performance test Methods 0.000 description 1
- 239000011148 porous material Substances 0.000 description 1
- 238000004321 preservation Methods 0.000 description 1
- 238000012545 processing Methods 0.000 description 1
- 238000003908 quality control method Methods 0.000 description 1
- 239000002994 raw material Substances 0.000 description 1
- 238000005406 washing Methods 0.000 description 1
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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
- B21B1/463—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 in a continuous process, i.e. the cast not being cut before rolling
-
- 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
- B21B1/22—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 plates, strips, bands or sheets of indefinite length
- B21B1/24—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 plates, strips, bands or sheets of indefinite length in a continuous or semi-continuous process
- B21B1/26—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 plates, strips, bands or sheets of indefinite length in a continuous or semi-continuous process by hot-rolling, e.g. Steckel hot mill
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
- B22D11/00—Continuous casting of metals, i.e. casting in indefinite lengths
- B22D11/16—Controlling or regulating processes or operations
- B22D11/166—Controlling or regulating processes or operations for mould oscillation
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- Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- Metal Rolling (AREA)
Abstract
本发明公开了一种薄规格酸洗板表面麻点缺陷的控制方法，该酸洗板的规格为2mm以下，本发明通过酸洗板生产工序中全流程工艺调整，有效控制薄规格酸洗板表面麻点缺陷，提高酸洗板表面质量，方法简单，经济高效，适用性强，不需要额外增加设备，控制效果显著，有效提高酸洗板表面质量。本发明涉及成分控制、连铸坯表面振痕控制、热轧关键温度控制和轧制节奏控制等方面。
The invention discloses a method for controlling the surface pitting defects of a thin-gauge pickling board. The specification of the pickling board is less than 2 mm. The invention can effectively control the thin-gauge pickling board by adjusting the whole process process in the production process of the pickling board. Surface pitting defects, improve the surface quality of pickling board, the method is simple, cost-effective, strong applicability, no additional equipment is required, the control effect is remarkable, and the surface quality of pickling board is effectively improved. The invention relates to composition control, continuous casting slab surface vibration mark control, hot rolling key temperature control, rolling rhythm control and the like.
Description
Technical Field
The invention relates to an iron scale in a hot rolling production process of a pickled plate and a surface quality control method, in particular to a control method for surface pitting defects of a thin pickled plate. Belongs to the technical field of steel rolling.
Background
The higher surface quality requirements of thin pickled plates make their production more difficult than that of ordinary hot rolled sheets. In particular to a thin pickled plate with the yield strength of more than 400MPa, and the hot rolling production difficulty is outstanding. On one hand, the control difficulty of the iron scale is higher, and the iron scale defect which is difficult to eliminate can be generated due to the fact that the unit rolling force of the thin-specification pickling plate is higher, the roller is seriously abraded, and the roller surface falling phenomenon. On the other hand, the rolling stability of thin specifications is poor, the temperature of the tail of the plate is reduced greatly, the rising amplitude of the rolling force is large, the axial force is increased, the rolling of the strip steel in the rolling mill is unstable, the phenomena of sleeve rising, deviation and the like are easy to occur, the tail is damaged, and the roller surface is damaged to generate indentation. Meanwhile, the contradiction exists between the iron scale and the rolling stability control: the temperature is increased, the stability is improved, but the iron sheet defects are increased; the temperature is reduced, the rolling force fluctuation is obvious, and the iron sheet is easy to control. Therefore, the contradiction is solved to mass production of the thin pickled plates, the iron oxide scale defects are well controlled, and the surface quality after pickling is ensured.
Patent application CN101704026B (Nanjing Steel products Ltd.) discloses a method for controlling surface pockmarks of a medium plate steel, and proposes methods of reducing Si content, heating at low temperature, descaling at low temperature and rapidly cooling after rolling; the primary oxide scale on the surface of the steel plate can be basically cleaned, and the incidence rate of pockmarks on the surface of the steel plate is greatly reduced.
The production line of the Spanish mackerel ring 1580 hot-rolled pickled plate mainly comprises low-carbon steel, and relates to steel types SP221, SPHC, A420L, SAPH370 and the like, wherein the thickness range is 1.6-5.0mm, and the defects of oxidation pits and pores with different degrees exist when the steel types are rolled into thin specifications. The defects are distributed on the surface of the strip steel in a needle-shaped dense manner, and are in a block shape or a strip shape when serious, so that the defects cannot be thoroughly removed by acid washing.
The scale and indentation defects of the products with thin specifications of the pickled plates of the Bao steel products are frequent, the specifications are mainly below the thickness of 2.1mm, and the Bao steel products relate to steel types including BTC360R, SAPH440, QSTE420M and the like.
Typical everything morphology of thin gauge oxide pitting defects is shown in figure 1. The surface is distributed with small pit-shaped appearance discretely. Once the pitting defects on the surface of the pickled plate flow into a user, the pitting defects cannot be eliminated in the subsequent use process, and can be further aggravated along with stamping deformation, so that the appearance is attractive, the use performance is affected, and even the processing equipment can be seriously damaged, for example, fig. 2 shows the pitting physical appearance.
Disclosure of Invention
In view of the above problems, the present invention is provided to provide a method for controlling pitting defects on a surface of a thin pickled plate, which can effectively reduce pitting defects on the surface of the thin pickled plate, and has the advantages of simple method, strong applicability and significant effect.
The embodiment of the invention provides a method for controlling pitting defects on a surface of a thin pickled plate, wherein the pickled plate has a specification of less than 2mm, and the production process comprises the following steps: smelting steel, continuous casting, heating plate blanks, rough rolling, finish rolling and coiling; wherein, the residual elements of the steel grade used for smelting the steel grade meet the condition that the sum of the weight contents of As, Sn and Cu is less than 0.01 percent; in the continuous casting step, the casting speed is controlled to be 1.3-1.5 m/min, the superheat degree is 10-15 ℃, and the basic amplitude of a continuous casting crystallizer is 2-4 mm; the rough rolling step adopts a combination of 1R 1 rough rolling and 5R 2 rough rolling or a combination of 3R 1 rough rolling and 3R 2 rough rolling; the temperature of a finish rolling inlet is controlled to be 1000-1030 ℃, the opening amount of cooling water among the racks of the first three racks in the finish rolling step is 50-100%, and the finish rolling speed is 9-12 m/s; the pressure of cooling water is 10-15 MPa when the roller is rolled, and the temperature of the roller surface of the roller is 30-40 ℃.
Preferably, the rolling gap is controlled to be 60-70 s.
Preferably, the basic amplitude of the continuous casting mold is 3 mm. If the vibration mark depth on the surface of the plate blank is too deep, the rolling mill vibrates in the hot rolling process, and the rolling mill vibrates to cause the oxide film on the surface of the roller to fall off to form a pockmark defect, so that the basic amplitude of the rolling process is controlled.
Preferably, the specific method for heating the slab is as follows: the heating temperature of the plate blank is 1180-1200 ℃, the residual oxygen content of the heating furnace is below 1%, and the retention time of the high-temperature section in the heating process of the plate blank is 20-30 minutes.
Preferably, in the rough rolling step, the rough rolling reduction ratio is increased, the reduction ratio is controlled to be 25-30%, and the thickness of the intermediate billet at the finish rolling inlet is reduced to be less than 38 mm.
Preferably, in the rolling step, the roll gap cooling water is opened, and meanwhile, a trapezoidal roll cooling water amount control mode is adopted, so that the central cooling water amount is 10% higher than the edge portion.
Preferably, the pickled plate production process comprises the following specific steps:
(1) smelting of steel grades: adopting high-quality scrap steel to smelt steel grades, and detecting that the residual elements of the steel grades meet the condition that the sum of the weight contents of As, Sn and Cu is less than 0.01 percent;
(2) continuous casting: controlling the drawing speed to be 1.3-1.5 m/min, controlling the superheat degree to be 10-15 ℃, adjusting the vibration parameters of the continuous casting crystallizer, and controlling the basic amplitude to be 2-4 mm so as to reduce the depth of the vibration mark on the surface in the continuous casting process;
(3) heating the plate blank: the heating temperature of the plate blank is 1180-1200 ℃, the residual oxygen content of the heating furnace is below 1%, and the retention time of the high-temperature section in the heating process of the plate blank is 20-30 minutes;
(4) rough rolling: the combination of 1R 1 rough rolling and 5R 2 rough rolling or the combination of 3R 1 rough rolling and 3R 2 rough rolling is adopted, the rough rolling reduction ratio is increased, and the thickness of the intermediate billet at the finish rolling inlet is reduced to be less than 38 mm;
(5) finish rolling: the temperature of a finish rolling inlet is controlled to be 1000-1030 ℃, the opening amount of cooling water among the racks of the first three racks in the finish rolling step is 50-100%, the finish rolling speed is 9-12 m/s, and the vibration of a rolling mill is avoided;
(6) and (3) rolling: and (3) opening the roll gap cooling water, and simultaneously adopting a trapezoidal roll cooling water quantity control mode to ensure that the cooling water quantity in the middle part is 10% higher than that in the edge part, the cooling water pressure is 10-15 MPa during rolling, and the roll surface temperature of the roll is 30-40 ℃.
One or more technical solutions in the embodiments of the present invention have at least the following technical effects or advantages:
the method effectively controls the pitting defects on the surface of the pickling plate with thin specification (less than 2 mm) by adjusting the whole process in the production process of the pickling plate, improves the surface quality of the pickling plate, is simple, economic and efficient, has strong applicability, does not need to additionally increase equipment, has obvious control effect, and effectively improves the surface quality of the pickling plate. The invention relates to the aspects of component control, continuous casting billet surface vibration mark control, hot rolling key temperature control, rolling rhythm control and the like, and the specific analysis is as follows:
1. influence of residual elements on steel:
from thermodynamic data, it is known that residual elements are concentrated on the surface of the steel sheet as a result of selective oxidation when heated in a suitable oxidizing atmosphere. Mainly due to the oxidation of iron and the diffusion process of oxygen, residual elements which are not oxidized are gradually deposited at the junction of the matrix and the iron scale, and the surface residual elements are gradually increased along with the extension of the heat preservation time. Because the surface of the residual element is enriched, a low-melting-point enriched phase is formed on the surface of the steel plate, the bonding force of a grain boundary is rapidly reduced due to the formation of a liquefied phase, and fine surface defects are formed in the continuous casting and hot rolling processes. It is proposed to control the residual elements of the steel grade to ensure that the sum of the contents of As, Sn and Cu is less than 0.01%, because several residual elements of As, Sn and Cu affect the formation of primary scales, the lower the sum of their contents, the better. 2. Vibration problem of rolling mill
When rolling thin (below 2 mm) products, the rolling mill vibrates frequently. The resonance phenomenon of F2\ F3 rack with unknown reasons also appears in the production line, and the specific reasons cannot be found for a long time, as shown in FIG. 3. The vibration of the rolling mill causes the large-scale falling of the F2\ F3 frame oxide film, and causes frequent defects of thin pickled sheet iron skins. Two solutions are provided for the vibration problem of the rolling mill: 1) controlling the vibration mark of the crystallizer in the continuous casting process, controlling the drawing speed to be 1.3-1.5 m/min, controlling the superheat degree to be 10-15 ℃, adjusting the vibration parameters of the continuous casting crystallizer, and ensuring the basic amplitude to be 3mm so as to reduce the depth of the vibration mark on the surface in the continuous casting process; 2) the rolling rhythm of the hot rolling process is controlled, the rolling load is moved forward, the finish rolling load is reduced, and meanwhile, cooling water in the finish rolling process is started, so that the surface temperature of the strip steel is reduced, and the rolling speed is increased. The concrete measures are as follows: the combination of 1R 1 rough rolling and 5R 2 rough rolling or the combination of 3R 1 rough rolling and 3R 2 rough rolling is adopted in the rough rolling process, the rough rolling reduction ratio is increased, and the thickness of an intermediate billet at a finish rolling inlet is reduced to be below 38 mm; the inlet temperature of finish rolling is controlled below 1030 ℃, the opening amount of cooling water between the three racks before the finish rolling process is not less than 50%, the finish rolling speed is increased to be more than 9m/s, and the vibration of the rolling mill is avoided.
3. Roll oxide film control:
the high-speed steel roll structure mainly comprises a martensite matrix and various carbides, the V-rich MC type carbides have the lowest oxidation resistance, and the oxidation speed is the fastest in the rolling process. The second is Cr-rich M7C3 type carbide, which has higher oxidation rate than the matrix. And Mo-rich M2C type carbide has weak binding capacity with oxygen and is rarely involved in oxidation. The root cause of nodulation oxide film formation is the selective oxidation of different similar carbides: the oxidation resistance of the V-rich MC type carbide and the Cr-rich M7C3 type carbide is the lowest, and the oxidation is most easy to occur, so that the oxide films in the areas grow faster and gradually become convex, the difference of the oxidation rates of different types of carbide and steel matrix is further increased along with the increase of the temperature, the nodulation oxide film is more convex, and the surface of the roller is rougher. The control method for the roller oxide film comprises the following steps: opening the cooling water of the roll gap, and simultaneously adopting a trapezoidal roll cooling water quantity control mode to ensure that the cooling water quantity of the middle part is higher than 10 percent of the edge part, the cooling water pressure of the roll is controlled to be higher than 10Mpa, and the roll surface temperature of the roll is controlled to be 30-40 ℃; the rolling rhythm is controlled, the pure rolling time of thin product strips is long, and the rolling gap is controlled within 60-70 s. Drawings
In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings needed to be used in the description of the embodiments are briefly introduced below, and it is obvious that the drawings in the following description are some embodiments of the present invention, and it is obvious for those skilled in the art to obtain other drawings based on the drawings without creative efforts.
FIG. 1 is a table check of the appearance of an oxidized pockmark;
FIG. 2 shows the morphology of the oxidized pits;
FIG. 3 vibration of the mill causes the oxide film to peel off.
Detailed Description
The present invention will be described in detail below with reference to specific embodiments and examples, and the advantages and various effects of the present invention will be more clearly apparent therefrom. It will be understood by those skilled in the art that these specific embodiments and examples are for the purpose of illustrating the invention and are not to be construed as limiting the invention.
Throughout the specification, unless otherwise specifically noted, terms used herein should be understood as having meanings as commonly used in the art. Accordingly, unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. If there is a conflict, the present specification will control.
Unless otherwise specifically stated, various raw materials, reagents, instruments, equipment and the like used in the present invention are commercially available or can be prepared by existing methods.
Fig. 1 to 3 respectively show the surface appearance of the oxidized pits, the physical appearance of the oxidized pits, and the falling off of the oxide film caused by the vibration of the rolling mill.
Example 1:
a control method for pitting defects on the surface of a thin pickled plate is disclosed, the pickled plate has a specification of less than 2mm, and the production process comprises the following steps:
(1) smelting of steel grades: adopting high-quality scrap steel to smelt steel grades, and detecting that the residual elements of the steel grades meet the condition that the sum of the weight contents of As, Sn and Cu is less than 0.01 percent;
(2) continuous casting: controlling the drawing speed to be 1.3 m/min, controlling the superheat degree to be 15 ℃, adjusting the vibration parameters of the continuous casting crystallizer, and controlling the basic amplitude to be 2mm so as to reduce the depth of the surface vibration mark in the continuous casting process;
(3) heating the plate blank: the heating temperature of the plate blank is 1180 ℃, the residual oxygen content of the heating furnace is below 1 percent, and the residence time of the high-temperature section in the heating process of the plate blank is 20 minutes;
(4) rough rolling: the combination of 1R 1 rough rolling and 5R 2 rough rolling is adopted, the rough rolling reduction ratio is increased, the reduction ratio is controlled to be 25%, and the thickness of the intermediate billet at the finish rolling inlet is reduced to be below 38 mm;
(5) finish rolling: the inlet temperature of the finish rolling is controlled to be 1000 ℃, the opening amount of cooling water among the racks of the first three racks in the finish rolling step is 50%, the finish rolling speed is 9m/s, and the vibration of a rolling mill is avoided;
(6) and (3) rolling: and (3) opening the roll gap cooling water, and simultaneously adopting a trapezoidal roll cooling water quantity control mode to ensure that the cooling water quantity in the middle part is 10% higher than that in the edge part, the cooling water pressure is 10MPa when the roll is rolled, and the roll surface temperature of the roll is 40 ℃.
During the production process, the rolling gap is controlled to be 60 s.
Example 2:
a control method for pitting defects on the surface of a thin pickled plate is disclosed, the pickled plate has a specification of less than 2mm, and the production process comprises the following steps:
(1) smelting of steel grades: adopting high-quality scrap steel to smelt steel grades, and detecting that the residual elements of the steel grades meet the condition that the sum of the weight contents of As, Sn and Cu is less than 0.01 percent;
(2) continuous casting: controlling the drawing speed to be 1.5m/min, controlling the superheat degree to be 10 ℃, adjusting the vibration parameters of the continuous casting crystallizer, and controlling the basic amplitude to be 4mm so as to reduce the depth of the surface vibration mark in the continuous casting process;
(3) heating the plate blank: the heating temperature of the plate blank is 1200 ℃, the residual oxygen content of the heating furnace is below 1 percent, and the residence time of the high-temperature section in the heating process of the plate blank is 30 minutes;
(4) rough rolling: the combination of 3 times of R1 rough rolling and 3 times of R2 rough rolling is adopted, the rough rolling reduction ratio is increased, the reduction ratio is controlled to be 30%, and the thickness of the intermediate billet at the finish rolling inlet is reduced to be below 38 mm;
(5) finish rolling: the inlet temperature of the finish rolling is controlled to be 1030 ℃, the opening amount of cooling water among the racks of the first three racks in the finish rolling step is 100%, the finish rolling speed is 12m/s, and the vibration of a rolling mill is avoided;
(6) and (3) rolling: and (3) opening the roll gap cooling water, and simultaneously adopting a trapezoidal roll cooling water quantity control mode to ensure that the cooling water quantity in the middle part is higher than 10% of the edge part, the cooling water pressure is more than 15MPa when the roll is rolled, and the roll surface temperature of the roll is 30 ℃.
During the production process, the rolling gap was controlled to 70 s.
Example 3:
a control method for pitting defects on the surface of a thin pickled plate is disclosed, the pickled plate has a specification of less than 2mm, and the production process comprises the following steps:
(1) smelting of steel grades: adopting high-quality scrap steel to smelt steel grades, and detecting that the residual elements of the steel grades meet the condition that the sum of the weight contents of As, Sn and Cu is less than 0.01 percent;
(2) continuous casting: controlling the drawing speed to be 1.4 m/min, controlling the superheat degree to be 12 ℃, adjusting the vibration parameters of the continuous casting crystallizer, and controlling the basic amplitude to be 3mm so as to reduce the depth of the surface vibration mark in the continuous casting process;
(3) heating the plate blank: the heating temperature of the plate blank is 1190 ℃, the residual oxygen content of the heating furnace is below 1 percent, and the residence time of the high-temperature section in the heating process of the plate blank is 25 minutes;
(4) rough rolling: the combination of 1R 1 rough rolling and 5R 2 rough rolling is adopted, the rough rolling reduction ratio is increased, the reduction ratio is controlled to be 28 percent, and the thickness of the intermediate billet at the finish rolling inlet is reduced to be below 38 mm;
(5) finish rolling: the inlet temperature of finish rolling is controlled below 1030 ℃, the opening amount of cooling water among the racks of the first three racks in the finish rolling step is 70 percent, the finish rolling speed is 11m/s, and the vibration of a rolling mill is avoided;
(6) and (3) rolling: and (3) opening the roll gap cooling water, and simultaneously adopting a trapezoidal roll cooling water quantity control mode to ensure that the cooling water quantity in the middle part is higher than 10% of the edge part, the cooling water pressure is more than 12MPa when the roll is rolled, and the roll surface temperature of the roll is 35 ℃.
During the production process, the rolling gap was controlled to 65 s.
Comparative example 1:
the steel scrap used in the steel type smelting had As, Sn and Cu contents in total of 0.015% by weight, and the rest was the same As in example 1.
Comparative example 2:
in the continuous casting step, the casting speed was 1.2 m/min, as in example 1.
Comparative example 3:
in the continuous casting step, the casting speed was 1.6 m/min, as in example 1.
Comparative example 4:
the same as in example 1 was applied to the continuous casting step, wherein the degree of superheat was 9 ℃.
Comparative example 5:
the degree of superheat in the continuous casting step was 16 ℃ as in example 1.
Comparative example 6:
the rough rolling step used a combination of 2R 1 rough rolls and 4R 2 rough rolls, as in example 1.
Comparative example 7:
the finish rolling inlet temperature was 1040 ℃ as in example 1.
Comparative example 8:
the finish rolling speed was 8m/s, and the same as in example 1.
Comparative example 9:
the cooling water pressure was 9MPa at the time of rolling, as in example 1.
Comparative example 10:
the roll surface temperature was 28 ℃ during rolling, as in example 1.
Comparative example 11:
the surface temperature of the rolls was 42 ℃ during rolling, as in example 1.
Test example:
the effect of the properties of the pickled sheets obtained in the present application will be described in detail below with reference to examples, comparative examples and experimental data.
Property tests including surface roughness, tensile strength and elongation were performed on the pickled sheets (1.5mm) obtained in examples 1 to 3 and comparative examples 1 to 11, and the results are shown in Table 1.
Wherein, the surface roughness is detected by a surface roughness measuring instrument of Lantai SRT-6100; examination of tensile strength and elongation was conducted in accordance with JIS G3131-1996 (Japanese Industrial Standard, Hot-rolled Low carbon Steel sheet and Steel strip, trade name SPHC).
TABLE 1 pickled plate Performance test results
| Surface roughness (Ra, mum) | Tensile strength (MPa) | Elongation (%) | |
| Example 1 | 0.90 | 305 | 33 |
| Example 2 | 0.89 | 306 | 34 |
| Example 3 | 0.85 | 310 | 36 |
| Comparative example 1 | 1.13 | 255 | 26 |
| Comparative example 2 | 1.15 | 250 | 21 |
| Comparative example 3 | 1.12 | 265 | 27 |
| Comparative example 4 | 1.16 | 261 | 26 |
| Comparative example 5 | 1.21 | 250 | 22 |
| Comparative example 6 | 1.06 | 269 | 29 |
| Comparative example 7 | 1.25 | 246 | 20 |
| Comparative example 8 | 1.28 | 240 | 15 |
| Comparative example 9 | 1.11 | 266 | 27 |
| Comparative example 10 | 1.14 | 252 | 23 |
| Comparative example 11 | 1.26 | 244 | 19 |
As can be seen from Table 1, the pickled plates obtained in examples 1 to 3 have low surface roughness, few pockmark defects, high tensile strength and elongation, and good mechanical properties, and meet the relevant standards. Comparative example 1 the sum of the contents by weight of As, Sn and Cu in the scrap steel used in the steel kind smelting was 0.015%, comparative example 2 was a drawing rate of 1.2 m/min in the continuous casting step, comparative example 3 was a drawing rate of 1.6 m/min in the continuous casting step, comparative example 4 was a drawing rate of 9 ℃ in the continuous casting step, comparative example 5 was a drawing rate of 16 ℃ in the continuous casting step, the rough rolling step of comparative example 6 was a combination of 2R 1 rough rolling and 4R 2 rough rolling, comparative example 7 was a finish rolling inlet temperature of 1040 ℃, comparative example 8 was a finish rolling speed of 8m/s, comparative example 9 was a cooling water pressure of 9MPa at the time of rolling, comparative example 10 was a roll surface temperature of 28 ℃ at the time of rolling, comparative example 11 was a roll surface temperature of 42 ℃ at the time of rolling, pickled sheets obtained in comparative examples 1 to 11 had significantly increased surface roughness, had many pock defects and significantly decreased tensile strength and elongation, the mechanical properties are significantly deteriorated.
Finally, it should also be noted that the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus.
While preferred embodiments of the present invention have been described, additional variations and modifications in those embodiments may occur to those skilled in the art once they learn of the basic inventive concepts. Therefore, it is intended that the appended claims be interpreted as including preferred embodiments and all such alterations and modifications as fall within the scope of the invention.
It will be apparent to those skilled in the art that various changes and modifications may be made in the present invention without departing from the spirit and scope of the invention. Thus, if such modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention is also intended to include such modifications and variations.
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| CN105251779A (en) * | 2015-10-23 | 2016-01-20 | 首钢总公司 | Control method for surface oxidation pocking defects of hot-rolled pickled plate |
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| JPS57121806A (en) * | 1981-01-22 | 1982-07-29 | Nippon Steel Corp | Direct feed rolling device train |
| CN105316579A (en) * | 2014-07-29 | 2016-02-10 | 上海梅山钢铁股份有限公司 | Thin hot rolled pickled steel plate and fabrication method thereof for water heater enamel liner |
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