A soft strip steel and a method of making the same

Abstract

The application provides a preparation method of soft strip steel, which comprises the following steps: hot metal pretreatment, converter deoxidization, secondary refining, hot rolling and coiling, wherein the coiling is roll lag trailing and is restrained by side dams and pinch rollers; the pressure of the side dams on the edge of the strip steel is 1.9-9.8 kN, specifically 7lambda / 1000+0.3, and lambda is the width-thickness ratio of the strip steel. The application also provides the soft strip steel prepared by the above method. When the strip steel is coiled, the pressure of the side dams is adjusted according to the width-thickness ratio and thickness of the strip steel, so that the wear of the side dams by the edge of the strip steel can be effectively reduced, the sparks can be prevented from splashing, the risk of foreign matter pressing in can be effectively reduced under the premise of ensuring the good coiling quality, the surface quality of the soft strip steel is improved, the wear of the side dams is reduced, the replacement frequency of the side dams is reduced, the production cost is saved for large-scale production, the product quality and the production efficiency can be greatly improved under the premise of not increasing the equipment modification cost, and the application has wide practicability.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of steel production, in particular to a soft strip steel and a preparation method thereof. BACKGROUND

[0002] The hot rolling and coiling process belongs to the hot continuous rolling process, and the purpose is to roll the hot rolled steel plate into a steel coil for packaging. When the hot rolling and coiling process is improper, the edge of the strip and the side guide plate and other components are prone to scratching, and the splashed debris is often rolled into the steel coil. Since the cold rolling base materials such as tinplate and IF steel have low hardness, hard foreign matters are easily pressed into the surface of the strip to form a bruise or inlay into the base, which is difficult to effectively remove in the pickling process. Due to the difference in plasticity between the pressed debris and the base, a willow leaf-shaped hole is formed during subsequent cold rolling. Especially when producing extremely thin specifications (≤0.3mm) of tinplate, the thickness of the cold rolling base material is about 1.3-2.0mm, and the shape control is difficult, and the risk of scratching between the strip and the equipment is increased. After the finishing rolling and steel throwing, the up-and-down jumping and left-and-right shaking of the tail of the strip increase the risk of scratching. The sparks generated by the shaking of the tail of the thin strip and the scratching of the side guide plate are difficult to be effectively washed by the side water spray, which eventually aggravates the pressing risk. In the subsequent cold rolling process, affected by the linear flow law of the metal, the defect is easily further expanded. Especially when cold rolling the extremely thin specification product, the slight bruise of the hot rolling may cause the cold rolling defect to be enlarged, and finally a large number of holes are formed.

[0003] In view of the foreign matter pressing defect, the hot rolling process increases the surface inspection intensity and removes the defect to avoid the defect flowing into the cold rolling process. This not only increases the labor intensity, but also reduces the yield. Some enterprises have achieved certain effect by using side guide plates with wear-resistant coating. However, there is no systematic method according to the size characteristics of the strip, and the equipment modification not only increases the cost, but also the effect is not obvious. SUMMARY

[0004] Therefore, the technical problem to be solved by the present application is the problem of foreign matter pressing defect in the existing hot rolling process, so as to provide a soft strip steel and a preparation method thereof.

[0005] To this end, the present application adopts the following technical scheme:

[0006] The present application provides a preparation method of a soft strip steel, which comprises molten iron pretreatment, converter deoxidization, secondary refining, hot rolling and coiling. The coiling is roll lag dragging, and is constrained by a side guide plate and a pinch roll.

[0007] The pressure of the side guide plate on the edge of the strip is 1.9-9.8kN;

[0008] The pressure of the side guide plate on the edge of the strip is specifically:

[0009] f=7λ / 1000+0.3;

[0010] Where f is the pressure of the side guide plate on the edge of the strip, λ is the width-to-thickness ratio of the strip, λ=L / d, L is the width of the strip in mm; d is the thickness of the strip in mm.

[0011] Furthermore, during winding, when the 25m tail length passes through the side guide plate, the opening margin on one side is 15-50mm;

[0012] The take-up roller conveyor is divided into 3 sections for hysteresis rate control, with a hysteresis rate of 3% to 9%.

[0013] The pressure of the take-up pinch roll is 20-35 kN.

[0014] The strip width L is 800-1500mm; the strip thickness d is 1.0-5.0mm.

[0015] The relationship between the strip thickness d and the strip tail opening allowance is as follows:

[0016] When 1.0mm≤d<1.5mm, the tail opening margin is 50mm on one side;

[0017] When 1.5mm≤d<2.0mm, the tail opening margin is 40mm on one side;

[0018] When 2.0mm≤d<2.5mm, the tail opening margin is 30mm on one side;

[0019] When 2.5mm≤d<3.0mm, the tail opening margin is 20mm on one side;

[0020] When 3.0mm≤d<3.5mm, the tail opening margin is 10mm on one side;

[0021] When 3.5mm≤d, the tail opening margin is 10mm on one side.

[0022] The relationship between the strip thickness d and the coiling roller hysteresis rate is as follows:

[0023] When 1.0mm ≤ d < 1.5mm, R1 = 9%, R2 = 8%, R3 = 7%;

[0024] When 1.5mm ≤ d < 2.0mm, R1 = 8%, R2 = 7%, R3 = 6%;

[0025] When 2.0mm ≤ d < 2.5mm, R1 = 7%, R2 = 6%, R3 = 5%;

[0026] When 2.5mm ≤ d < 3.0mm, R1 = 6%, R2 = 5%, R3 = 4%;

[0027] When 3.0mm ≤ d < 3.5mm, R1 = 6%, R2 = 5%, R3 = 4%;

[0028] When 3.5mm≤d, R1=5%, R2=4%, R3=3%;

[0029] R1, R2, and R3 represent the hysteresis rates of the three winding roller sections, respectively.

[0030] The relationship between the strip thickness d and the coiler pinch roll pressure is as follows:

[0031] When 1.0mm≤d<1.5mm, the pressure of the winding machine's pinch roll is 20kN;

[0032] When 1.5mm≤d<2.0mm, the pressure of the winding machine's pinch rollers is 25kN;

[0033] When 2.0mm≤d<2.5mm, the pressure of the winding machine's pinch roll is 25kN;

[0034] When 2.5mm≤d<3.0mm, the pressure of the winding machine's pinch roll is 30kN;

[0035] When 3.0mm≤d<3.5mm, the pressure of the winding machine's pinch roll is 30kN;

[0036] When 3.5mm≤d, the pressure of the winding machine's pinch roller is 35kN.

[0037] The temperature range during coiling is 600–700℃, and the strip running speed on the roller conveyor is 8–14 m / s. -1 .

[0038] The present invention also provides a soft steel strip, which is prepared by the above-described preparation method.

[0039] The technical solution of this invention has the following advantages:

[0040] (1) In the preparation method of the present invention, different pressure values ​​and opening margins are set on the side guide plate according to the different width-to-thickness ratio and thickness of the strip during winding; the roller lag rate is set in sections according to the difference in strip thickness to control the tension of the strip in sections; the pressure of the pinch roller is adjusted to avoid residual debris from being pressed into the surface, thereby ensuring good coil quality and effectively reducing the risk of foreign matter being pressed in, and improving the surface quality of soft strip.

[0041] (2) The present invention adjusts the pressure of the side guide plate according to the width-to-thickness ratio of the strip, which can effectively reduce the wear between the strip edge and the side guide plate and avoid spark splashing; the strip tail opening is increased according to the strip thickness, which can avoid the strip tail from being severely scraped by the side guide plate due to loss of tension, strip shape defects and the side guide plate; the roller lag rate is set in sections to ensure that the strip maintains stable tension after finishing and avoids severe shaking after loss of tension; the pinch roll pressure is set according to the thickness, which is a supplement to the above process, avoids excessive pressure causing foreign objects to be pressed too deeply, and can also improve the strip being narrowed or thinned due to tension fluctuations.

[0042] (3) This invention improves the product qualification rate. It avoids the intrusion of foreign objects without affecting the mechanical properties and shape of the steel plate, solving problems such as excessive foreign object intrusion, holes, marks, and damaged rolls in existing coiling processes. This invention improves the surface quality of the strip steel while reducing side guide plate wear by 70% and halving the replacement frequency, thus saving production costs for large-scale production. The coiling process method, set according to the strip steel thickness, takes into account multiple factors such as product quality and production rhythm, and can greatly improve product quality and production efficiency without increasing equipment modification costs, making it widely applicable. Attached Figure Description

[0043] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0044] Figure 1 This is a photograph of a soft strip steel with a specification of 1.2×850, obtained by coiling according to the process in this embodiment of the invention, after cold rolling.

[0045] Figure 2 This is a photograph of the soft strip steel obtained by coiling the 1.2×850 strip steel in the comparative example of the present invention after cold rolling. Detailed Implementation

[0046] The following embodiments are provided to better understand the present invention and are not limited to the preferred embodiments described. They do not constitute a limitation on the content and scope of protection of the present invention. Any product that is the same as or similar to the present invention, derived by any person under the guidance of the present invention or by combining the features of the present invention with other prior art, falls within the protection scope of the present invention.

[0047] For any experimental steps or conditions not specified in the examples, the procedures or conditions described in the literature in this field can be followed. All reagents mentioned are commercially available standard reagents.

[0048] The following specific embodiments further illustrate the present invention. The examples given do not represent all embodiments of the present invention; only some embodiments are described as examples. Specific embodiments are as follows:

[0049] Example

[0050] This embodiment provides a soft strip steel. The raw materials used contain 0.03-0.05 wt% C, 0.17-0.23 wt% Mn, ≤0.010 wt% S, ≤0.015 wt% P, ≤0.02 wt% Si, 0.055-0.075 wt% Als, ≤0.030 N, and the remainder is Fe and unavoidable impurities.

[0051] The preparation method is as follows: After pretreatment of the raw material with molten iron, deoxidation in a converter, ladle refining, and hot rolling, strip steel with a thickness of 1-5 mm and a width of 800-1500 mm is obtained to be coiled. 100 strip steel pieces of each of five different specifications are taken and coiled according to the process shown in Table 1. The coiling is a delayed dragging process on a roller conveyor, constrained by side guide plates and pinch rolls. The coiling temperature is 600℃, and the strip steel runs at a speed of 10 m / s on the roller conveyor. -1 .

[0052] Table 1. Winding process parameters for the embodiment

[0053]

[0054] No foreign objects were pressed into the soft strip steel coiled using the parameters in the table above. A photograph of the soft strip steel after cold rolling is shown below, for example, a strip steel with a specification of 1.2×850. Figure 1 As shown, its shape is complete and there are no defects.

[0055] Comparative Example

[0056] This comparative example provides a soft steel strip, which uses the same steel strip to be wound as the embodiment. The difference between the two examples is the winding process used, and the specific process parameters are shown in Table 2:

[0057] Table 2 Comparative Example Winding Process Parameters

[0058]

[0059] The soft strip steel coiled using the parameters in the table above has foreign object indentation. A photograph of the soft strip steel with a specification of 1.2×850 after cold rolling is shown below.Figure 2 As shown, it has obvious cold-rolled defects—strip-shaped holes, which will seriously affect subsequent production and use.

[0060] Obviously, the above embodiments are merely illustrative examples for clear explanation and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here. However, obvious variations or modifications derived therefrom are still within the scope of protection of this invention.

Claims

1. A method for producing a soft strip steel, comprising molten iron pretreatment, converter deoxidation, secondary refining, hot rolling, and coiling, characterized by, The coiling is roll lag drag, and is restrained by side guide plates and pinch rollers; The pressure of the side guide plates on the strip edge is 1.9-9.8 kN; The pressure of the side guide plates on the strip edge is specifically: f = 7 λ / 1000 +0.3； wherein f is the pressure of the side guide plate on the strip edge, λ is the width-to-thickness ratio of the strip, λ = 0.5 L / d , L is the strip width in mm; d is the strip thickness in mm; The coiling table is divided into three sections for lag rate control, and the lag rate is 3%-9%; The strip steel thickness d and the strip tail opening allowance is related as When 1.0 mm ≤ d When <1.5 mm, the tail opening allowance is 50 mm on one side. When 1.5 mm ≤ d When <2.0 mm, the tail opening allowance is 40 mm on one side. When 2.0 mm ≤ d When <2.5 mm, the tail opening allowance is 30 mm on one side. When 2.5 mm ≤ d When < 3.0 mm, the tail opening allowance is 20 mm on one side. When 3.0 mm ≤ d When < 3.5 mm, the tail opening allowance is 10 mm on one side. When 3.5 mm ≤ d When 3.5 mm ≤ d When 3.5 mm ≤ The relationship between the strip thickness d and the coiling table lag rate is: When 1.0 mm < d < 2.0 mm, d < 1.5 mm, R 1 = 9%, R 2 = 8%, R 3 = 7%; when 1.5 mm < d < 2.0 mm, d when 1.5 mm < d < 2.0 mm, R 1 = 8%, R 2 = 7%, R 3 = 6%; When 2.0 mm < d < 3.0 mm, d < 2.5 mm, R 1 = 7%, R 2 = 6%, R 3 = 5%; when 2.5 mm < d < 3.0 mm, d when 2.5 mm < d < 3.0 mm, R 1 = 6%, R 2 = 5%, R 3 = 4%; when 3.0 mm < d < 3.5 mm, d when 3.0 mm < d < 3.5 mm, R 1 = 6%, R 2 = 5%, R 3 = 4%; When 3.5 mm < d < 4.5 mm d When 3.5 mm < d < 4.5 mm R 1 = 5%, R 2 = 4%, R 3 = 3%; Wherein, R1, R2 and R3 are the lag rates of the three sections of the coiling table respectively; The relationship between the strip thickness d and the coiling machine pinch roller pressure is: when 1.0 mm ≤ d when <1.5 mm, the coiler pinch roll pressure is 20 kN; when 1.5 mm < d < 2.0 mm, the pressure of the coiler pinch roll is 25 kN; and d when 1.5 mm < d < 2.0 mm, the pressure of the coiler pinch roll is 25 kN; and when 1 when 2.0 mm < d < 3.0 mm, the coiler pinch roll pressure is 20 kN; d when d < 2.5 mm, the coiler pinch roll pressure is 25 kN; when 2.5 mm < d < 3.0 mm, the pressure of the coiler pinch roll is 30 kN; and d when 2.5 mm < d < 3.0 mm, the pressure of the coiler pinch roll is 30 kN; and when 3.0 mm < d < 3.5 mm, the pressure of the coiler pinch roll is 30 kN; and d when 3.0 mm < d < 3.5 mm, the pressure of the coiler pinch roll is 30 kN; and When 3.5 mm < L < 4.5 mm d The coiler pinch roll pressure is 35 kN.

2. The production method according to claim 1, characterized by, When coiling, the opening degree margin of one side of the 25 m length of the strip tail passing through the side guide plate is 15-50 mm; The coiling pinch roller pressure is 20-35 kN.

3. The preparation method according to claim 1, characterized in that, Strip width L is 800-1500 mm; strip thickness d is 1.0-5.0 mm.

4. The preparation method according to claim 1, characterized in that, The temperature range is 600-700 ℃ when coiling, and the running speed of the strip steel on the roller is 8-14 m / s -1 .

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