A finishing method for the micro-middle wave shape of thin-gauge high-strength strip steel

Abstract

The present invention discloses a finishing method for the micro-middle wave shape of thin-specification high-strength strip steel, belonging to the field of steel plate production. It includes the following steps: 1) Uncoiling, the tension of the uncoiler is 150-180 kN; 2) Rough straightening, after uncoiling, the strip steel is subjected to rough straightening, the number of straightening rolls of the rough straightening machine is 5 rolls, and the roll diameter of the straightening rolls is Φ180-220 mm; 3) Temper rolling, the double-sided wave height of the strip steel entering the temper rolling mill is 5-20 mm / m, the work rolls of the temper rolling mill are convex rolls, the convexity is 30-70 μm, the temper rolling force is 4000-8000 kN, the bending roll force is 600-1080 kN, the temper rolling speed is 20-100 m / min, and the middle wave value of the strip steel after temper rolling is 2-5 mm / m; 4) Fine straightening, after temper rolling, the strip steel is subjected to fine straightening, the number of straightening rolls of the fine straightening machine is 13 rolls, and the roll diameter of the straightening rolls is Φ80-120 mm; 5) Coiling, after the strip steel exits the fine straightening machine, it is coiled, and the tension of the coiler is 250-300 kN. The present invention controls the strip steel after temper rolling to form a micro-middle wave within a certain range value, which can significantly improve the shape quality after leveling.

Description

Technical Field

[0001] The present invention belongs to the field of steel plate production, and more specifically, relates to a finishing method for the micro-middle wave shape of thin-gauge high-strength strip steel. Background Art

[0002] With the increasingly obvious trend of high strengthening and thin gauging of materials in industries such as special vehicles, passenger vehicles, construction machinery, and containers, economically and efficiently producing thin-gauge high-strength hot-rolled strip steel has become the main means for major steel enterprises to increase product added value and enhance market competitiveness. Therefore, alloy reduction type and phase transformation strengthening type hot-rolled high-strength steels with ultra-fast cooling technology as the core have emerged. The product tensile strength ≥ 980 MPa, and mainly adopts low-temperature rolling, segmented cooling, and low-temperature coiling processes. In order to improve the shape quality, this kind of thin-gauge hot-rolled high-strength steel often adds a tempering process, and tempering is also the key process determining its shape quality.

[0003] Due to factors such as the thin thickness specification, wide width specification, and large rolling pressure of high-strength hot-rolled strip steel, shape defects such as double-sided waves often occur after the strip steel exits the last finishing stand. After the strip steel with shape defects is cooled, due to factors such as fast cooling rate, multi-phase transformation during the cooling process, and low coiling temperature, the cooling non-uniformity in the width or length direction of the strip steel is further aggravated, resulting in the common existence of waviness problems in the cooled strip steel, mainly manifested as double-sided waves and different wave heights at different positions of the head, middle, and tail in the length direction of the hot-rolled strip steel. This poses a great challenge to the shape control in the subsequent tempering process. Existing tempering often adopts a constant rolling force mode or a constant elongation rate mode, such as two patents with publication numbers CN110624954B and CN107838199B.

[0004] However, the constant rolling force or constant elongation rate mode can basically meet the shape control requirements for plain carbon steel or HSLA steel with small and simple incoming waviness, but for high-strength steel with complex and large incoming waviness, adopting the constant rolling force mode in tempering often cannot completely eliminate the shape defects, and even cannot be eliminated by increasing the tempering times. When adopting the constant elongation rate mode in tempering, there is a possibility of large tempering rolling force exceeding the allowable limit value of the equipment, and the large rolling force will cause large roll deflection and low response efficiency of the work roll bending, which is instead not conducive to shape control. The thin-gauge high-strength hot-rolled strip steel with double-sided wave defects enters the next transverse cutting and tempering process. Due to its high deformation resistance, it is difficult to further improve the shape, and it is difficult to correct through conventional straightening processes, resulting in the still existence of shape defects in the transverse cut flat plate and low shape qualification rate.

[0005] At the same time, the existing judgment criteria for excellent shape in the tempering process are basically that the flatness is zero, such as two patents with publication numbers CN111215454A and CN111215455A. However, due to the extremely small order of magnitude of the shape (10 -5) The strip has a thin specification, and during the tempering process, the strip is under a large tension. It is difficult to measure the strip shape online, and the strip shape defects are masked to a certain extent, unable to accurately reflect the actual strip shape situation, resulting in potential strip shape defects in the strip. That is, the strip shape is good and the flatness is zero during tempering, but after transverse cutting and tempering, when in a tension-free state, the strip shape defects are exposed, and the cut-to-length strip still has strip shape problems, restricting its popularization and application.

[0006] In summary, for alloy-reduced and phase transformation-strengthened thin-specification high-strength hot-rolled strip steel, there is an urgent need to propose a strip shape finishing method to improve its flatness after final transverse cutting and tempering, increase its strip shape qualification rate, solve its strip shape problems, realize its mass popularization and application, and improve the satisfaction of downstream users with product use. Summary of the Invention

[0007] 1. Problems to be Solved

[0008] Aiming at the problems that it is difficult to completely eliminate the strip shape defects after tempering of thin-specification (≤6 mm) high-strength (tensile strength ≥980 MPa) hot-rolled strip steel and the existing potential strip shape defects, resulting in unevenness after final transverse cutting and tempering and a low strip shape qualification rate, the present invention provides a micro-middle-wave strip shape finishing method for thin-specification high-strength strip steel. A unique strip shape tempering method is designed for thin-specification high-strength hot-rolled strip steel of specific model sizes, controlling the strip steel after tempering to form a micro-middle wave within a certain range value, which can significantly improve the strip shape quality after cutting to length.

[0009] 2. Technical Solution

[0010] To solve the above problems, the present invention adopts the following technical solutions.

[0011] A micro-middle-wave strip shape finishing method for thin-specification high-strength strip steel includes the following steps:

[0012] 1) Uncoiling

[0013] The tension of the uncoiler is 150 - 180 kN;

[0014] 2) Rough leveling

[0015] After uncoiling, the strip steel is roughly leveled. The number of leveling rolls of the rough leveling machine is 5, and the roll diameter of the leveling rolls is Φ180 - 220 mm;

[0016] 3) Tempering

[0017] The double-sided wave height of the strip steel entering the tempering mill is 5 - 20 mm / m. The work rolls of the tempering mill are convex rolls with a convexity of 30 - 70 μm. The tempering force is 4000 - 8000 kN, the bending roll force is 600 - 1080 kN, the tempering speed is 20 - 100 m / min, and the middle-wave value of the strip steel after tempering is 2 - 5 mm / m;

[0018] 4) Precision straightening

[0019] After leveling, the strip steel is subjected to precision straightening. The number of straightening rolls of the precision straightening machine is 13, and the roll diameter of the straightening rolls is Φ80 - 120 mm;

[0020] 5) Coiling

[0021] After the strip steel exits the precision straightening machine, it is coiled. The tension of the coiling machine is 250 - 300 kN.

[0022] As a further improvement of the technical solution, for strip steel with a tensile strength of 980 MPa, the crown of the work roll of the leveling machine is 30 - 50 μm, the leveling force is 4000 - 7000 kN, the bending roll force is 600 - 1020 kN, the leveling speed is 30 - 100 m / min, the mid - wave value of the leveled strip steel is 2 - 4 mm / m, the tension of the uncoiler is 150 - 160 kN, and the tension of the coiling machine is 250 - 270 kN.

[0023] As a further improvement of the technical solution, for strip steel with a thickness ≥ 4.0 mm and < 6.0 mm, the crown of the work roll of the leveling machine is 30 - 45 μm, the leveling force is 4000 - 6500 kN, the bending roll force is 600 - 900 kN, the leveling speed is 40 - 100 m / min, and the mid - wave value of the leveled strip steel is 2 - 3 mm / m.

[0024] As a further improvement of the technical solution,

[0025] For strip steel with a width ≥ 1200 mm and < 1500 mm, the crown of the work roll of the leveling machine is 30 - 40 μm, the leveling force is 4000 - 6000 kN, the bending roll force is 600 - 780 kN, and the leveling speed is 60 - 100 m / min;

[0026] For strip steel with a width ≥ 1500 mm and < 1800 mm, the crown of the work roll of the leveling machine is 35 - 45 μm, the leveling force is 4500 - 6500 kN, the bending roll force is 720 - 900 kN, and the leveling speed is 40 - 80 m / min.

[0027] As a further improvement of the technical solution, for strip steel with a thickness ≥ 3 mm and < 4 mm, the crown of the work roll of the leveling machine is 35 - 45 μm, the leveling force is 5000 - 7000 kN, the bending roll force is 720 - 1020 kN, the leveling speed is 30 - 90 m / min, and the mid - wave value of the leveled strip steel is 3 - 4 mm / m.

[0028] As a further improvement of the technical solution,

[0029] For strip steel with a width of ≥1200 mm and <1500 mm, the crown of the work roll of the temper mill is 35 - 45 μm, the tempering force is 5000 - 6500 kN, the roll bending force is 720 - 900 kN, and the tempering speed is 50 - 90 m / min;

[0030] For strip steel with a width of ≥1500 mm and <1800 mm, the crown of the work roll of the temper mill is 40 - 50 μm, the tempering force is 5500 - 7000 kN, the roll bending force is 840 - 1020 kN, and the tempering speed is 30 - 70 m / min.

[0031] As a further improvement of the technical solution, for strip steel with a tensile strength of 1180 MPa, the crown of the work roll of the temper mill is 50 - 70 μm, the tempering force is 5000 - 8000 kN, the roll bending force is 780 - 1080 kN, the tempering speed is 20 - 90 m / min, the center wave value of the tempered strip steel is 4 - 5 mm / m, the tension of the uncoiler is 170 - 180 kN, and the tension of the coiler is 280 - 300 kN.

[0032] As a further improvement of the technical solution, for strip steel with a thickness of ≥4.0 mm and <6.0 mm, the crown of the work roll of the temper mill is 50 - 65 μm, the tempering force is 5000 - 7000 kN, the roll bending force is 660 - 960 kN, the tempering speed is 30 - 90 m / min, and the center wave value of the tempered strip steel is 3 - 4 mm / m.

[0033] As a further improvement of the technical solution, for strip steel with a thickness of ≥3 mm and <4 mm, the crown of the work roll of the temper mill is 55 - 70 μm, the tempering force is 6000 - 8000 kN, the roll bending force is 780 - 1080 kN, the tempering speed is 20 - 80 m / min, and the center wave value of the tempered strip steel is 4 - 5 mm / m.

[0034] As a further improvement of the technical solution, for strip steel with the same tensile strength and specifications, the higher the double - side wave of the strip steel when entering the temper mill, the greater the crown, tempering force, and roll bending force of the work roll of the temper mill, and the smaller the tempering speed.

[0035] 3. Beneficial effects

[0036] (1) Compared with the prior art, the micro-middle-wave shape finishing method for thin-gauge high-strength strip steel of the present invention designs a detailed and unique shape leveling method for thin-gauge high-strength hot-rolled strip steel with specific model dimensions and a certain range of bilateral wave heights. The overall control method is perfect, which can control the strip steel after leveling to form a micro-middle wave within a certain range value, significantly improving the shape quality after slitting. The middle wave value of the strip steel after leveling is 2 - 6 mm / m. After transverse slitting and leveling, the shape of the slit sheet is significantly improved, and the flatness of the slit sheet is ≤ 6 mm / m, preferably reaching 0 mm / m, and the shape qualification rate is ≥ 88%, and the highest can reach 95%.

[0037] (2) The micro-middle-wave shape finishing method for thin-gauge high-strength strip steel of the present invention can expand the product variety types, thickness specification ranges, and strength levels of conventional transverse shears with insufficient slitting equipment capacity. Without new investment or equipment transformation, it can realize the production of slit sheets of thin-gauge high-strength steel with a strength of ≥ 980 MPa, high shape quality, and high shape qualification rate on conventional transverse shears. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 The shape of the slit sheet of hot-rolled strip steel after using the finishing method of the present invention (tensile strength 980 MPa, specification: 3.5 × 1700 mm);

[0039] Figure 2 The shape of the slit sheet of hot-rolled strip steel after using the finishing method of the present invention (tensile strength 1180 MPa, specification: 3.0 × 1300 mm). DETAILED DESCRIPTION OF THE INVENTION

[0040] The exemplary embodiments of the present invention are described in detail below. Although these exemplary embodiments are described in sufficient detail to enable those skilled in the art to implement the present invention, it should be understood that other embodiments can be realized and various changes can be made to the present invention without departing from the spirit and scope of the present invention. The following more detailed description of the embodiments of the present invention is not intended to limit the scope of the claimed present invention, but is merely for illustrative purposes and does not limit the description of the features and characteristics of the present invention, in order to present the best mode of implementing the present invention and to enable those skilled in the art to implement the present invention. Therefore, the scope of the present invention is only defined by the appended claims.

[0041] A micro-middle-wave shape finishing method for thin-gauge high-strength strip steel, for strip steel with a thickness ≤ 6 mm and a tensile strength R mThe transformation-strengthened ultra-high strength steel plate with a strength of ≥1000 MPa can significantly improve the shape quality of the coiled sheet after decoiling when the crosswise wave is within a certain range. The chemical composition and mass percentage of the steel plate are as follows: C: 0.10 - 0.20%, Si: 1.2 - 2.0%, Mn: 1.2 - 2.0%, P: ≤0.010%, S: ≤0.005%, Als: 0.30 - 0.50%, Ti: 0.015 - 0.050%, and the rest is Fe and inevitable inclusions. The process and principle will be described in detail below.

[0042] The method includes the following steps:

[0043] 1) Uncoiling

[0044] The tension of the uncoiler is 150 - 180 kN.

[0045] 2) Rough leveling

[0046] After the strip steel exits the uncoiler, it enters a 5-roll leveling machine for rough leveling. The roll diameter of the leveling machine is Φ180 - 220 mm.

[0047] 3) Skin pass rolling

[0048] The work rolls of the skin pass rolling mill are convex rolls. The convex rolls are dynamically selected according to the shape of the hot-rolled strip steel at the inlet of the skin pass rolling mill, and the rolling force, bending roll force, and skin pass rolling rate are adjusted.

[0049] 4) Fine leveling

[0050] After the strip steel exits the skin pass rolling mill, it undergoes fine leveling. The fine leveling machine is a 13-roll leveling machine, and the roll diameter of the leveling machine is Φ80 - 120 mm.

[0051] 5) Coiling

[0052] After the strip steel exits the fine leveling machine, it is coiled. The tension of the coiler is 250 - 300 kN.

[0053] Specifically, the detailed control strategy of this finishing method is shown in Table 1.

[0054] Table 1 Control Strategy for Strip Steel Slight Crosswise Wave Shape in Skin Pass Rolling Process

[0055]

[0056] In the uncoiling and recoiling processes of this method, a large-tension uncoiling - large-tension recoiling control strategy is adopted. This is because considering that the tensile strength of the strip steel targeted by this method is ≥980 MPa, large uncoiling tension and matching large recoiling tension are required to ensure the flatness stability of the strip steel and good coiling quality. Large tension is beneficial to reducing the temper rolling force, which can further improve the efficiency of work roll bending adjustment and is conducive to improving the shape quality of the strip. If the tension of the uncoiler and recoiler is too small, it will cause the strip to be loose and scratched. However, the tension of the uncoiler and recoiler should not be too large, as excessive tension is likely to cause interlayer slip of the strip, resulting in surface bruising of the strip, which is not conducive to surface quality control.

[0057] The main purpose of rough leveling before tempering is to reduce the residual stress generated during the rolling and cooling process of the strip by repeated bending, reduce the waviness of the incoming hot-rolled strip, and improve the stability of the strip tempering process. The main purpose of fine leveling after tempering is to further reduce the residual stress of the strip after tempering and improve the shape quality of the strip.

[0058] The tempering process emphasizes the control strategy of the strip with a slightly middle-wave shape, and coordinates the control of the temper rolling force, work roll bending force, work roll profile, and speed according to the strength level, thickness specification, width specification, and waviness of the hot-rolled strip. The main reason for the micro-middle-wave shape control of the strip after tempering is that the shape detected after tempering is in a large-tension state, and the bilateral wave shape defects of the strip are covered to a certain extent, unable to accurately reflect the actual shape of the strip. Therefore, to ensure that the strip after tempering does not have bilateral waves, micro-middle-wave compensation control is carried out on the strip shape during tempering. The middle-wave value of the strip after tempering is 2 - 6 mm / m. The specific middle-wave value is controlled in grades according to the strength level, thickness specification, and width specification of the strip. The overall control principle is that as the strength level of the strip increases and the thickness specification thins, the middle-wave value of the strip after tempering increases.

[0059] It should be noted that the middle-wave value of the strip after tempering should not be too small. If the middle-wave value < 1 mm / m, there will be some positions where the bilateral waves cannot be completely eliminated. However, the middle-wave value should not be too large either. If the middle-wave value > 6 mm / m, it will cause the middle-wave value to not be eliminated during subsequent slitting and straightening, which is instead not conducive to shape control.

[0060] In order to control the micro-middle wave of the strip after tempering, the present invention emphasizes the coordinated matching control of temper rolling force, bending roll force, work roll profile and speed according to the strength level, thickness specification, width specification and wave shape of the hot-rolled strip. The overall control principle is that as the material strength level increases, the bilateral wave height value increases, the tempering force, bending roll force and convexity of the tempering work roll increase, and the tempering speed slows down. Under the condition of ensuring the strip shape, a control strategy of using a small tempering force and a large bending roll force is preferred. The main purpose is to avoid the aggravation of work hardening of the strip, which is not conducive to the performance uniformity in the width direction of the strip. At the same time, in order to control the strip shape stability during the tempering process, the strip tempering speed should not be too fast, and the tempering speed is controlled below 100 m / min.

[0061] In summary, the micro-middle wave strip shape finishing method for this thin-gauge high-strength strip is different from the traditional flatness opening control method. A detailed and unique strip shape tempering method is designed for thin-gauge high-strength hot-rolled strips with specific model sizes and a certain range of bilateral wave heights. The overall control method is perfect, which can control the strip after tempering to form a micro-middle wave within a certain range value, and can significantly improve the strip shape quality after slitting. The middle wave value of the strip after tempering is 2 - 6 mm / m. After transverse slitting and tempering, the shape of the tempered plate is significantly improved, the flatness of the tempered plate is ≤ 6 mm / m, and it can preferably reach 0 mm / m. The strip shape qualification rate is ≥ 88%, and the highest can reach 95%.

[0062] The technical solutions of the present invention will be described below through specific examples and comparative examples.

[0063] For Examples 1 - 4 and Comparative Examples 1 - 4, the yield strength level of the strip is 980 MPa, and its chemical composition and weight percentage content are: 0.14% C, 1.20% Si, 1.65% Mn, 0.010% P, 0.002% S, 0.42% Als, 0.028% Ti, and the rest is Fe and inevitable inclusions.

[0064] For Examples 5 - 8 and Comparative Examples 5 - 8, the yield strength level of the strip is 1180 MPa, and its chemical composition and weight percentage content are: 0.17% C, 1.10% Si, 1.80% Mn, 0.30% Cr, 0.012% P, 0.003% S, 0.40% Als, 0.025% Ti, and the rest is Fe and inevitable inclusions.

[0065] After the strip is rolled and cooled, it is tempered. The specifications, tempering process parameters and middle wave values of the strips after tempering for Examples 1 - 8 and Comparative Examples 1 - 8 are shown in Table 2.

[0066] After the flattened strip steel is cut and leveled transversely, the flatness of the cut-to-length sheet and the pass rate of the sheet shape are shown in Table 3. Among them, the flatness of the cut-to-length sheet ≤ 8 mm / m is a qualified finished product, and the pass rate of the sheet shape = the weight of the qualified finished product of the cut-to-length sheet / the weight of the hot coil.

[0067] Table 2 Flattening process parameters of the examples and comparative examples and the mid-wave value of the strip steel after flattening

[0068]

[0069]

[0070] Table 3 Flatness of the cut-to-length sheet and pass rate of the sheet shape corresponding to the examples and comparative examples

[0071] Number Flatness of the slit coil (mm / m) Qualified rate of strip shape (%) Example 1 1～5 88.80 Example 2 0～4 94.66 Example 3 0～3 92.35 Example 4 0～5 93.47 Example 5 2～6 88.09 Example 6 1～4 92.35 Example 7 3～5 90.01 Example 8 2～4 89.65 Comparative Example 1 7～16 61.49 Comparative Example 2 6～14 68.67 Comparative Example 3 6～13 65.22 Comparative Example 4 8～15 64.70 Comparative Example 5 8～20 59.49 Comparative Example 6 8～15 65.60 Comparative Example 7 7～17 64.24 Comparative Example 8 6～14 63.83

[0072] The examples described in the present invention are only descriptions of the preferred embodiments of the present invention, and do not limit the concept and scope of the present invention. Without departing from the design concept of the present invention, various deformations and improvements made by those skilled in the art to the technical solutions of the present invention shall fall within the protection scope of the present invention.

Claims

1. A finishing method for the micro-middle wave shape of thin-gauge high-strength strip steel, characterized in that: It includes the following steps: 1) Uncoiling The tension of the uncoiler is 150 - 180 kN; 2) Rough leveling After uncoiling, the strip steel is roughly leveled. The number of leveling rolls of the rough leveler is 5, and the roll diameter of the leveling rolls is Φ180 - 220 mm; 3) Skin pass rolling The double - edge wave height of the strip steel entering the skin pass mill is 5 - 20 mm / m. The work rolls of the skin pass mill are convex rolls with a convexity of 30 - 70 μm, the skin pass rolling force is 4000 - 8000 kN, the bending roll force is 600 - 1080 kN, the skin pass rolling speed is 20 - 100 m / min, and the center - wave value of the strip steel after skin pass rolling is 2 - 5 mm / m; 4) Fine leveling After skin pass rolling, the strip steel is finely leveled. The number of leveling rolls of the fine leveler is 13, and the roll diameter of the leveling rolls is Φ80 - 120 mm; 5) Coiling After the strip steel exits the fine leveler, it is coiled. The tension of the coiler is 250 - 300 kN; For strip steel with a tensile strength of 980 MPa, the convexity of the work rolls of the skin pass mill is 30 - 50 μm, the skin pass rolling force is 4000 - 7000 kN, the bending roll force is 600 - 1020 kN, the skin pass rolling speed is 30 - 100 m / min, the center - wave value of the strip steel after skin pass rolling is 2 - 4 mm / m, the tension of the uncoiler is 150 - 160 kN, and the tension of the coiler is 250 - 270 kN; For strip steel with a tensile strength of 1180 MPa, the convexity of the work rolls of the skin pass mill is 50 - 70 μm, the skin pass rolling force is 5000 - 8000 kN, the bending roll force is 780 - 1080 kN, the skin pass rolling speed is 20 - 90 m / min, the center - wave value of the strip steel after skin pass rolling is 4 - 5 mm / m, the tension of the uncoiler is 170 - 180 kN, and the tension of the coiler is 280 - 300 kN.

2. The micro-middle wave shape finishing method for thin-gauge high-strength strip steel according to claim 1, characterized in that: For strip steel with a tensile strength of 980 MPa, a thickness of ≥4.0 mm and <6.0 mm, the convexity of the work rolls of the skin pass mill is 30 - 45 μm, the skin pass rolling force is 4000 - 6500 kN, the bending roll force is 600 - 900 kN, the skin pass rolling speed is 40 - 100 m / min, and the center - wave value of the strip steel after skin pass rolling is 2 - 3 mm / m.

3. A method for precision finishing of the micro - center - wave shape of thin - gauge high - strength strip steel according to claim 2, characterized in that: For strip steel with a tensile strength of 980 MPa, a width of ≥1200 mm and <1500 mm, the convexity of the work rolls of the skin pass mill is 30 - 40 μm, the skin pass rolling force is 4000 - 6000 kN, the bending roll force is 600 - 780 kN, and the skin pass rolling speed is 60 - 100 m / min; For strip steel with a tensile strength of 980 MPa, a width of ≥1500 mm and <1800 mm, the convexity of the work rolls of the skin pass mill is 35 - 45 μm, the skin pass rolling force is 4500 - 6500 kN, the bending roll force is 720 - 900 kN, and the skin pass rolling speed is 4 -> 80 m / min.

4. The micro-middle wave shape finishing method for a thin-specification high-strength strip steel according to claim 1, characterized in that: For strip steel with a tensile strength of 980 MPa, a thickness of ≥3 mm and <4 mm, the convexity of the work rolls of the skin pass mill is 35 - 45 μm, the skin pass rolling force is 5000 - 7000 kN, the bending roll force is 720 - 1020 kN, the skin pass rolling speed is 30 - 90 m / min, and the center - wave value of the strip steel after skin pass rolling is 3 - 4 mm / m.

5. A finishing method for the micro-middle wave shape of thin-specification high-strength strip steel according to claim 4, characterized in that: For strip steel with a tensile strength of 980 MPa, a width of ≥1200 mm and <1500 mm, the crown of the work roll of the temper mill is 35 - 45 μm, the tempering force is 5000 - 6500 kN, the roll bending force is 720 - 900 kN, and the tempering speed is 50 - 90 m / min; For strip steel with a tensile strength of 980 MPa, a width of ≥1500 mm and <1800 mm, the crown of the work roll of the temper mill is 40 - 50 μm, the tempering force is 5500 - 7000 kN, the roll bending force is 840 - 1020 kN, and the tempering speed is 30 - 70 m / min.

6. The micro-middle wave shape finishing method for thin specification high-strength strip steel according to claim 1, characterized in that: For strip steel with a tensile strength of 1180 MPa, a thickness of ≥4.0 mm and <6.0 mm, the crown of the work roll of the temper mill is 50 - 65 μm, the tempering force is 5000 - 7000 kN, the roll bending force is 660 - 960 kN, the tempering speed is 30 - 90 m / min, and the middle wave value of the tempered strip steel is 3 - 4 mm / m.

7. The fine finishing method for the micro-middle wave shape of a thin-specification high-strength strip steel according to claim 1, characterized in that: For strip steel with a tensile strength of 1180 MPa, a thickness of ≥3 mm and <4 mm, the crown of the work roll of the temper mill is 55 - 70 μm, the tempering force is 6000 - 8000 kN, the roll bending force is 780 - 1080 kN, the tempering speed is 20 - 80 m / min, and the middle wave value of the tempered strip steel is 4 - 5 mm / m.

8. A micro-middle wave shape finishing method for thin specification high-strength strip steel according to any one of claims 1-7, characterized in that: For strip steel with the same tensile strength and specifications, the higher the double-sided wave of the strip steel when entering the temper mill, the greater the crown of the work roll, the tempering force and the roll bending force of the temper mill, and the smaller the tempering speed.

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