阅读说明：本技术 一种薄规格冷轧hsla连退带钢的板形控制方法 (Plate shape control method for thin cold-rolled HSLA continuous annealing strip steel ) 是由 康华伟 孙卫华 汤化胜 李洪翠 侯晓英 尹翠兰 毕永杰 张磊 王鹏 许铭 于 2021-08-02 设计创作，主要内容包括：本发明公开了一种薄规格冷轧HSLA连退带钢的板形控制方法,带钢化学成分组成及质量百分含量为：C：0.060～0.090％,Si：0.03～0.40％,Mn：0.70～1.30％,P：0.015～0.025％,S≤0.010％,Als：0.025～0.060％,Nb：0.025～0.050％,N≤0.0050％,其余为Fe和不可避免的杂质；制造方法包括冶炼、连铸、热连轧、酸连轧、连续退火工序、平整和拉矫工序；通过控制温度、板型质量、冷轧压下率等生产工艺,在确证有良好的力学性能外,使带钢具有较好的板形质量：以满足汽车厂对板形质量的要求,显著提高冷轧HSLA带钢产品的品质,具有较好的推广应用价值。(The invention discloses a plate shape control method of thin cold-rolled HSLA continuous annealing strip steel, which comprises the following chemical components in percentage by mass: c: 0.060 to 0.090%, Si: 0.03 to 0.40%, Mn: 0.70-1.30%, P: 0.015-0.025%, S is less than or equal to 0.010%, Als: 0.025 to 0.060%, Nb: 0.025-0.050%, N is less than or equal to 0.0050%, and the balance of Fe and inevitable impurities; the manufacturing method comprises the working procedures of smelting, continuous casting, hot continuous rolling, acid continuous rolling, continuous annealing, leveling and straightening; by controlling the production processes such as temperature, plate shape quality, cold rolling reduction rate and the like, the strip steel has better plate shape quality besides ensuring good mechanical properties: the method meets the requirements of automobile factories on the plate shape quality, obviously improves the quality of the cold-rolled HSLA strip steel products, and has good popularization and application values.)

1. A plate shape control method of thin-gauge cold-rolled HSLA continuous annealing strip steel is characterized by comprising the following steps:

1) the steel comprises the following chemical components in percentage by mass: c: 0.060 to 0.090%, Si: 0.03 to 0.40%, Mn: 0.70-1.30%, P: 0.015-0.025%, S is less than or equal to 0.010%, Als: 0.025 to 0.060%, Nb: 0.025-0.050%, N is less than or equal to 0.0050%, and the balance of Fe and inevitable impurities;

2) smelting process;

3) a continuous casting process;

4) hot continuous rolling;

5) acid continuous rolling process;

6) a continuous annealing process;

7) leveling;

8) and (5) a withdrawal and straightening procedure.

2. The method for controlling the shape of the thin cold-rolled HSLA continuous annealing strip steel as claimed in claim 1, wherein the thickness of the strip steel produced in the steps 1) to 8) is 0.4-0.8 mm, and the width of the strip steel is 1000-1700 mm.

3. The method for controlling the strip shape of the thin cold-rolled HSLA continuously-annealed strip steel as claimed in claim 1, wherein the hot continuous rolling in the step 4) is performed at a finish rolling temperature of 870-910 ℃ by front-end laminar cooling at a coiling temperature of 550-610 ℃ and at a hot-rolled strip steel flatness of not more than 30I-Unit and crown C₄₀Is 40-60 μm and is wedge-shaped W₄₀Is within a range of + -25 μm.

4. The strip shape control method of thin gauge cold rolled HSLA continuous strip steel according to claim 1, wherein the acid continuous rolling process in step 5) adopts a five-stand tandem CVC⁺The six-roller cold continuous rolling mill has a cold rolling total reduction rate of 73-81% and a final stand reduction rate of 2-5%.

5. The method for controlling the shape of the thin cold-rolled HSLA continuous annealing strip steel according to claim 1, wherein the continuous annealing process in the step 6) adopts a vertical full radiant tube heating continuous annealing furnace, and the annealing soaking temperature is 750-790 ℃, the slow cooling temperature is 650-680 ℃, and the overaging temperature is 360-390 ℃.

6. The method for controlling the strip shape of the thin cold-rolled HSLA continuous strip steel as claimed in claim 1, wherein in the leveling step 7), the leveler rolls the small roll of a six-roll CVC wet leveler, the roll diameter of the working roll is 360-400 mm, the concentration of the leveling liquid is 3.0-4.0%, the leveling elongation is 0.7-1.2%, the working height of the anti-creasing roll is 180-210 mm, the working height of the anti-chattering roll is 190-220 mm, and the unit tension of the inlet is 75-90N/mm²The outlet unit tension is 80-95N/mm²。

7. The method for controlling the strip shape of the thin cold-rolled HSLA continuously-annealed strip steel as claimed in claim 1, wherein the withdrawal and straightening process in the step 8) adopts a two-bending and one-straightening process, the withdrawal and straightening elongation is 0.2-0.5%, the withdrawal and straightening tension is 50-80 KN, the insertion amount of the No. 1 bending roll is 6-8 mm, the insertion amount of the No. 2 bending roll is 5-7 mm, and the insertion amount of the No. 3 bending roll is 2-5 mm.

8. The method for controlling the strip shape of the thin-gauge cold-rolled HSLA continuous annealing strip steel as claimed in claim 1, wherein the mechanical properties of the strip steel meet the standard requirements and have better strip shape quality: the maximum wave height with the width more than or equal to 1500mm is not more than 6mm, the degree of urgency is not more than 1.5%, and the camber is not more than 2mm/2000 mm; the maximum wave height of the width of 1500mm is not more than 5mm, the degree of rigor is not more than 1.2%, and the camber is not more than 3mm/2000 mm.

Technical Field

The invention relates to the technical field of metallurgy, in particular to a method for controlling the shape of thin cold-rolled HSLA continuous annealing strip steel.

Background

With the development of light weight of automobiles, cold-rolled HSLA steel for automobiles is beneficial to stamping forming, welding and the like due to good strength and toughness and low carbon equivalent, is widely applied to automobile structural members and reinforcements, and thin and high-strength HSLA strip steel greatly contributes to light weight of automobiles, so that the cold-rolled HSLA steel is favored by a large number of users.

At present, cold-rolled HSLA steel is mainly produced through a continuous annealing line, and compared with cover annealing, the continuous annealing line has the advantages of high production efficiency, uniform mechanical property, good surface and plate shape quality and the like. However, for cold-rolled HSLA steel with a thickness of less than 0.8mm, the control difficulty of the strip shape of the strip steel after cold rolling and continuous annealing is large, even a small difference of rolling or heat treatment processes in the production process can cause rapid change of the strip shape of the strip steel, and the control difficulty of the strip shape is large when the width of the strip steel is large and the thickness of the strip steel is small, so that the quality requirement of automobile steel is difficult to meet.

CN 102632085A discloses a cold-rolled strip steel plate shape control system and method, which mainly solve the technical problem of outlet plate shape quality deterioration caused by actual factors such as incoming material convexity change, rolling force fluctuation and the like in the rolling process through the modes of on-line adjustment quantity calculation, plate shape precision prediction and the like. Compared with the invention, CN 102632085A only optimizes the control system of the rolling mill, and does not control the whole process from hot rolling to continuous annealing.

CN 105312359A discloses a strip shape control method for a low-temperature annealed steel strip, which mainly carries out parameter optimization control on a horizontal annealing furnace, a leveler and a tension leveler respectively, eliminates edge waves and meets the requirements of strip shape and elongation percentage. Compared with the invention, the control process of the horizontal annealing furnace adopted by CN 105312359A is different from that of the vertical continuous annealing furnace in the patent.

CN 109702020A discloses a control system and a control method for a thin strip steel plate shape of a cold rolling temper mill, which mainly improve the flatness of the strip steel by adjusting a rolling force and tension integrated model and the like flatly. Compared with the invention, CN 109702020A only optimizes the leveling control system and does not control the whole process from hot rolling to continuous annealing.

CN 111438189A discloses a cold-rolled sheet and a method for controlling the shape thereof, which mainly controls the parameters of the hot rolling process and applies the hot rolling flattening process to obtain better acid-rolled sheet shape quality. Compared with the method, the CN 111438189A is not optimized from the processes of cold rolling, continuous annealing, flattening, straightening and the like, so that the aim of controlling the plate shape quality is fulfilled.

Therefore, a plate shape control method of the thin-gauge cold-rolled HSLA continuous annealing strip steel below 0.8mm needs to be designed to solve the problems of high plate shape control difficulty and high defective rate of the existing strip steel production line.

Disclosure of Invention

Aiming at the problems in the prior art, the invention aims to provide a method for controlling the shape of thin-gauge cold-rolled HSLA continuous annealing strip steel.

The technical scheme adopted by the invention for solving the technical problems is as follows: a plate shape control method of thin-gauge cold-rolled HSLA continuous annealing strip steel comprises the following steps:

1) the steel comprises the following chemical components in percentage by mass: c: 0.060 to 0.090%, Si: 0.03 to 0.40%, Mn: 0.70-1.30%, P: 0.015-0.025%, S is less than or equal to 0.010%, Als: 0.025 to 0.060%, Nb: 0.025-0.050%, N is less than or equal to 0.0050%, and the balance of Fe and inevitable impurities;

2) smelting process;

3) a continuous casting process;

4) hot continuous rolling;

5) acid continuous rolling process;

6) a continuous annealing process;

7) leveling;

8) and (5) a withdrawal and straightening procedure.

Specifically, the thickness specification of the strip steel produced in the steps 1) to 8) is 0.4-0.8 mm, and the width specification is 1000-1700 mm.

In the hot continuous rolling process in the step 4), the final rolling temperature is 870-910 ℃, the front-section laminar cooling is adopted, the coiling temperature is 550-610 ℃, and the straightness of the hot-rolled strip steel is not more than 30I-Unit and the convexity C₄₀Is 40-60 μm and is wedge-shaped W₄₀Is within a range of + -25 μm.

Specifically, in the acid continuous rolling process in the step 5), a five-stand tandem CVC (continuous variable crown) is adopted⁺The six-roller cold continuous rolling mill has a cold rolling total reduction rate of 73-81% and a final stand reduction rate of 2-5%.

Specifically, in the continuous annealing process in the step 6), a vertical full radiant tube is adopted to heat the continuous annealing furnace, the annealing soaking temperature is 750-790 ℃, the slow cooling temperature is 650-680 ℃, and the overaging temperature is 360-390 ℃.

Specifically, in the leveling process in the step 7), the leveling machine adopts a small roller of a six-roller CVC wet type leveling machine for rolling, the roller diameter of a working roller is phi 360-400 mm, the concentration of a leveling liquid is 3.0-4.0%, the leveling elongation is 0.7-1.2%, the working height of a crease-resistant roller is 180-210 mm, the working height of an anti-vibration roller is 190-220 mm, and the unit tension of an inlet is 75-90N/mm²Unit sheet of exportThe force is 80-95N/mm²。

Specifically, in the withdrawal and straightening process in the step 8), a two-bending one-straightening process is adopted, the withdrawal and straightening elongation is 0.2-0.5%, the withdrawal and straightening tension is 50-80 KN, the insertion amount of the No. 1 bending roll is 6-8 mm, the insertion amount of the No. 2 bending roll is 5-7 mm, and the insertion amount of the No. 3 bending roll is 2-5 mm.

Specifically, the mechanical properties of the strip steel meet the standard requirements, and the strip steel has better strip shape quality: the maximum wave height with the width more than or equal to 1500mm is not more than 6mm, the degree of urgency is not more than 1.5%, and the camber is not more than 2mm/2000 mm; the maximum wave height of the width of 1500mm is not more than 5mm, the degree of rigor is not more than 1.2%, and the camber is not more than 3mm/2000 mm.

The invention has the following beneficial effects:

the invention discloses a method for controlling the shape of thin-gauge cold-rolled HSLA continuous annealing strip steel

1) The key processes such as the hot rolling finishing temperature and the like are controlled, so that the better strip shape quality of the hot rolled strip steel is ensured, and the strip shape, the defects and the surface quality of the hot rolled strip steel have important influence on the subsequent cold rolling annealing; the hot rolling finishing temperature is 870-910 ℃, so that the high-temperature finishing rolling above Ar3 is realized, the uniformity of the structure is facilitated, and the generation of deformation texture, anisotropy, edge mixed crystal and banded structure is prevented; adopting front-section laminar cooling, wherein the coiling temperature is 550-610 ℃, so that the microstructure of the finish-rolled cold-rolled substrate is ferrite and pearlite, the moderate mechanical property of the thin-gauge HSLA cold-rolled substrate is ensured, the good plate shape quality of the cold-rolled substrate is obtained, and good conditions are created for cold rolling and continuous annealing;

2) the five-frame tandem CVC + six-roller cold continuous rolling mill has strong rolling capacity and can realize the production of large reduction ratio of 73-81%; in addition, emulsion is adopted for process lubrication and strip high-tension rolling during cold continuous rolling, so that the rolling force can be effectively reduced, the strip steel can extend uniformly in the width direction, the strip shape is improved, and accidents such as deviation are avoided; meanwhile, through reasonable reduction rate distribution and rolling of the last stand by adopting a small reduction rate of 2-5%, the plate shape and thickness precision control of the cold-hard strip steel is facilitated, and good conditions are created for continuous annealing;

3) the vertical full radiant tube heating continuous annealing furnace is adopted, and the complete recrystallization of the strip steel is ensured by controlling parameters such as continuous annealing soaking temperature, slow cooling temperature, overaging temperature and the like, so that uniform equiaxial grain structure is obtained, and the control of the flatness, the tension and the leveling and the straightening of the strip shape is facilitated;

4) the finishing control with larger elongation can be realized by matching with manual regulation of a bending roll, inclination, roll shifting amount and the like through a six-roll CVC wet leveler and a six-fold two-bending one-straightening withdrawal straightener, and the final strip shape quality regulation and control of the strip steel are facilitated.

Drawings

FIG. 1 is a schematic diagram of evaluation of the strip shape.

FIG. 2 is a schematic diagram of evaluation of camber of a strip steel.

In the figure: 1-strip steel; b-strip width, delta-wave height, lambda-wave length, severity ═ delta/lambda) × 100%; h-camber value.

Detailed Description

The technical solutions in the embodiments of the present invention will be described in further detail in the following clearly and completely with reference to the accompanying drawings in the embodiments of the present invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

As shown in the figure 1-2, the plate shape control method of the cold-rolled HSLA continuous annealing strip steel with the thin specification of less than 0.8mm is used for producing the strip steel with the thickness specification of 0.4-0.8 mm and the width specification of 1000-1700 mm; the method comprises the following steps:

1) the steel comprises the following chemical components in percentage by mass: c: 0.060 to 0.090%, Si: 0.03 to 0.40%, Mn: 0.70-1.30%, P: 0.015-0.025%, S is less than or equal to 0.010%, Als: 0.025 to 0.060%, Nb: 0.025-0.050%, N is less than or equal to 0.0050%, and the balance of Fe and inevitable impurities;

2) smelting process;

3) a continuous casting process;

4) hot continuous rolling, wherein the final rolling temperature is 870-910 ℃, the front-section laminar cooling is adopted, the coiling temperature is 550-610 ℃, and the straightness of the hot-rolled strip steel is not more than 30IUnit, convexity C₄₀Is 40-60 μm and is wedge-shaped W₄₀Is in the range of +/-25 mu m;

5) acid continuous rolling process, which adopts a five-stand tandem CVC⁺A six-roller cold continuous rolling mill, wherein the total cold rolling reduction rate is 73-81%, and the final frame reduction rate is 2-5%;

6) a continuous annealing process, namely heating the continuous annealing furnace by adopting a vertical full radiant tube, wherein the annealing soaking temperature is 750-790 ℃, the slow cooling temperature is 650-680 ℃, and the overaging temperature is 360-390 ℃;

7) the leveling process comprises the steps that the leveling machine adopts a small roller of a six-roller CVC wet type leveling machine for rolling, the roller diameter of a working roller is phi 360-400 mm, the concentration of a leveling liquid is 3.0-4.0%, the leveling elongation is 0.7-1.2%, the working height of a crease-resistant roller is 180-210 mm, the working height of a flutter-proof roller is 190-220 mm, and the unit tension of an inlet is 75-90N/mm²The outlet unit tension is 80-95N/mm²；

8) And a pulling-straightening process, wherein a two-bending one-straightening process is adopted, the pulling-straightening elongation is 0.2-0.5%, the pulling-straightening tension is 50-80 KN, the insertion amount of the 1# bending roller is 6-8 mm, the insertion amount of the 2# bending roller is 5-7 mm, and the insertion amount of the 3# straightening roller is 2-5 mm.

The mechanical property of the strip steel meets the standard requirement, and the strip steel has better strip shape quality: the maximum wave height with the width more than or equal to 1500mm is not more than 6mm, the degree of urgency is not more than 1.5%, and the camber is not more than 2mm/2000 mm; the maximum wave height of the width of 1500mm is not more than 5mm, the degree of rigor is not more than 1.2%, and the camber is not more than 3mm/2000 mm.

The implementation of the invention is carried out on a continuous casting and rolling production line and a cold rolling continuous annealing line, the chemical components of the embodiment are shown in table 1, the control of hot rolling process parameters and plate shape quality is shown in table 2, the control of cold rolling reduction rate and continuous annealing temperature is shown in table 3, the leveling process parameters are shown in table 4, and the withdrawal and straightening process parameters are shown in table 5. The plate-shape quality of the finished strip steel obtained in the example is shown in Table 6.

Table 1 mass percentage of chemical composition of cold rolled steel strip (%)

TABLE 2 Hot Rolling Process parameters and strip quality

TABLE 3 examples Cold Rolling reduction and continuous annealing temperature

TABLE 4 examples smoothing Process parameters

TABLE 5 examples withdrawal straightening process parameters

TABLE 6 quality of finished strip shape

The present invention is not limited to the above embodiments, and any structural changes made under the teaching of the present invention shall fall within the scope of the present invention, which is similar or similar to the technical solutions of the present invention.

The techniques, shapes, and configurations not described in detail in the present invention are all known techniques.