Strip steel, method of cold rolling and use thereof

Abstract

The application relates to the technical field of carbon steel cold rolling, in particular to a strip steel, a cold rolling method and application thereof. The cold rolling method of the strip steel comprises the following steps: subjecting a strip steel raw material to steps of middle wave rolling and double-side wave rolling to obtain a cold-rolled strip steel. The cold rolling method of the strip steel adopts the middle wave rolling combined with the double-side wave rolling, and effectively solves the technical problem of the turtle-back defect of the carbon steel in the cold rolling. The turtle-back height of the strip steel rolled by the cold rolling method is below 13 mm.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of carbon steel cold rolling, in particular to a strip steel and a cold rolling method and application thereof. BACKGROUND

[0002] In the production process of carbon steel, the strip steel is continuously deformed and work-hardened in one direction during cold rolling. The cold hard coil after being rolled by an eighteen-roller mill usually has the quality defect of buckling and tortoise back. When the steel coil needs to be cut into steel plates and then processed into required parts by laser cutting, if the steel plates have buckling and tortoise back defects, the steel plates or parts will be damaged due to collision with the laser head during processing; and the processed parts will also be deformed and cannot be used. Especially for medium and high strength strip steel, buckling and tortoise back plate defects are likely to occur after cold rolling and cannot be reversed, that is, once the buckling and tortoise back plate defects of the medium and high strength strip steel are rolled into shape, they cannot be reduced or eliminated.

[0003] Currently, there are two main ways to improve the buckling defects of the strip steel: the first way is to additionally increase straightening equipment or buckling correction devices, which will increase the cost of strip steel production; the second way is to improve the buckling defects of the strip steel during hot rolling heating, which is not suitable for rolling of medium and high strength strip steel. SUMMARY

[0004] To solve the above problems, the present application provides a strip steel and a cold rolling method and application thereof. The cold rolling method of the strip steel can not only effectively improve the technical problem of buckling defects of carbon steel during cold rolling, but also reduce the thickness difference between the edge and the center of the strip steel. The buckling height of the strip steel rolled by the cold rolling method is below 13 mm.

[0005] The present application is achieved by the following technical solutions:

[0006] One of the purposes of the present application is to provide a cold rolling method of a strip steel, which comprises the following steps:

[0007] The strip steel raw material is subjected to a step of middle wave rolling and a step of double-side wave rolling to obtain a cold-rolled strip steel.

[0008] The total rolling pass is 3-10 passes, and the pass ratio of the middle wave rolling is 10%-90%.

[0009] The cold rolling method of the strip steel provided by the present application adopts middle wave rolling combined with double-side wave rolling to improve the buckling (C-buckling) of the strip steel in the width direction.

[0010] In some possible implementation manners, in the step of middle wave rolling, the single-pass reduction is 10%-30%. In this case, the strip steel can have high thickness control precision.

[0011] In some possible implementation manners, the ratio of the middle wave rolling pass is 10% to 50%. In this case, the strip thickness accuracy can be maintained and the rolling pass can be reserved for the profile control.

[0012] In some possible implementation manners, the rolling temperature of the middle wave rolling is 50°C to 200°C. In this case, the rolling heat can be effectively transferred.

[0013] In some possible implementation manners, in the double-side wave rolling step, the single pass reduction is 1% to 30%. In this case, the strip profile can be effectively controlled.

[0014] In some possible implementation manners, the rolling temperature of the double-side wave rolling is 50°C to 200°C. In this case, the rolling heat can be effectively transferred.

[0015] In some possible implementation manners, the strength of the double-side wave rolling is 1 IU to 20 IU. In the strength range, the turtleback height can be effectively reduced to within 10 mm.

[0016] In some possible implementation manners, in the strip cold rolling method, the final pass reduction is 2% to 15%. In this case, the final pass reduction is small reduction, and the small reduction rolling can control the length direction warping (L warping) of the strip.

[0017] In some possible implementation manners, the strip cold rolling method further includes the following steps:

[0018] The strip after the middle wave rolling and the double-side wave rolling is subjected to straightening treatment.

[0019] In some possible implementation manners, the straightening treatment includes: applying an action force opposite to the deformation direction of the strip during rolling to the strip, and the depth of the action force pressed into the strip is 10 mm to 80 mm.

[0020] In the above strip straightening treatment, the action force opposite to the deformation direction of the strip during rolling is applied to the strip to straighten the strip, thereby effectively improving the turtleback warping problem of the strip. In combination with the small reduction of the final pass, the turtleback warping problem of the strip is significantly improved.

[0021] In some possible implementation manners, the straightening treatment adopts three-roller straightening, and in the three-roller straightening, the three rollers are rubber pressure rollers, profile rollers and steering rollers.

[0022] In some possible implementation manners, the rubber compression roller, the plate-shaped roller and the deflection roller are combined into a three-roller straightening device, and the plate-shaped roller, the rubber compression roller and the deflection roller are sequentially arranged from the outlet of the cold rolling mill. In this case, when the strip after rolling passes through the plate-shaped roller and the deflection roller, the compression roller downwardly applies an action force opposite to the deformation direction of the strip during rolling, thereby playing a reverse correction role on the turtleback condition.

[0023] In some possible implementation manners, the strip obtained by the strip cold rolling method has a turtleback height of 13 mm or less, preferably 6 mm to 13 mm; and the thickness difference between the edge portion of the strip 30 mm away from the edge and the center of the strip is 40 μm or less, preferably 25 μm to 40 μm.

[0024] The second purpose of the present application is to provide a strip, which comprises iron and the following components in mass fraction:

[0025] 0.1%≤C≤1.5%, 0.1%≤Si≤0.50%, 0.1≤Mn≤1.4%, P≤0.03%, S≤0.03%, W (Cr+Ni+Mo) ≤2.0%, Al≤0.06%.

[0026] The strip provided by the present application is used as the raw material of the strip cold rolling method provided by the present application, and the yield strength of the strip is 500 MPa or more, which belongs to a medium-high strength steel type that needs to improve the turtleback defect in the cold rolling process.

[0027] W (Cr+Ni+Mo) Refers to the mass fraction of the total content of Cr, Ni and Mo, and the content of one or two metals can infinitely approach 0 and cannot be counted.

[0028] In some possible implementation manners, the thickness of the cold rolled strip is 0.3 mm to 10 mm, and the width is 900 mm to 2250 mm.

[0029] In some possible implementation manners, the strip is composed of the following components in mass fraction: 0.1%≤C≤1.5%, 0.1%≤Si≤0.50%, 0.1≤Mn≤1.4%, P≤0.03%, S≤0.03%, W (Cr+Ni+Mo) ≤2.0%, Al≤0.06%, and the rest is Fe and inevitable impurities.

[0030] In some possible implementation manners, the strip is composed of the following components in mass fraction:

[0031] 0.41%≤C≤0.68%, 0.17%≤Si≤0.23%, 0.43≤Mn≤0.65%, 0.015%≤P≤0.02%, 0.0012%≤S≤0.02%, 0.25%≤Cr≤0.33%, 0.05%≤Ni≤0.18%, Al≤0.06%, the rest is Fe and inevitable impurities.

[0032] The third object of the present application is to provide an application of the strip steel cold rolling method in the technical field of carbon steel cold rolling. BRIEF DESCRIPTION OF DRAWINGS

[0033] In order to more clearly illustrate the technical solutions in the embodiments or the prior art, the drawings needed to be used in the embodiments or prior art description will be briefly introduced. Obviously, the drawings in the following description are only some embodiments of the drawings, and other drawings can be obtained by those skilled in the art without creative labor on the basis of the structures shown in the drawings.

[0034] Figure 1 The cross-sectional structure of the turtle-back defect of the strip steel after the strip steel cold rolling method in the embodiments of the present application is shown.

[0035] The reference signs are explained as follows: 1 is the strip steel after cold rolling, 2 is the turtle-back height, 3 is the edge C30 position, and 4 is the center of the strip steel.

[0036] The implementation, functional features and advantages of the drawings will be further described with reference to the embodiments and the drawings. DETAILED DESCRIPTION

[0037] In order to make the objects, technical solutions and advantages of the present application more clear, the present application will be described and explained in the following embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and not to limit the present application. Based on the embodiments provided by the present application, all other embodiments obtained by those skilled in the art without creative labor are within the scope of protection of the present application.

[0038] Obviously, the following description is only some examples or embodiments of the present application, and those skilled in the art can apply the present application to other similar situations without creative labor. In addition, it can be understood that although the efforts made in this development process may be complex and lengthy, some design, manufacture or production changes based on the technical content disclosed in the present application are only routine technical means for those skilled in the art related to the content disclosed in the present application, and should not be understood as insufficient disclosure of the present application.

[0039] However, there are cases where unnecessary detailed description is omitted. For example, there are cases where detailed description of matters well known to those skilled in the art, repeated description of substantially the same structure are omitted. This is to avoid the following description unnecessarily becoming lengthy and to facilitate understanding by those skilled in the art. In addition, the following description is provided in order for those skilled in the art to fully understand the present application and is not intended to limit the subject matter recited in the claims.

[0040] All embodiments and optional embodiments of the present application can be combined with each other to form new technical solutions if there is no special description. All technical features and optional technical features of the present application can be combined with each other to form new technical solutions.

[0041] The term "pass ratio" is calculated to be 1 if it is not an integer when a specific pass is calculated. For example, the total pass is 6 times, the middle wave rolling pass ratio is 40%, and the calculation of the middle wave rolling pass is 2.4, which is 3 times.

[0042] Example 1

[0043] Example 1 proposes a strip steel, which is a 45Mn hot-rolled base plate, consisting of the following components by mass fraction: 0.41% C, 0.23% Si, 0.65% Mn, 0.003% S, 0.015% P, 0.01% Al, 0.33% Cr, 0.05% Ni, and the rest is Fe and unavoidable impurities. The specification of the strip steel is 2.3mm x 2250mm x full length.

[0044] Example 1 also proposes a cold rolling method of the strip steel of the present embodiment, which cold-rolls the strip steel proposed in the present embodiment after pickling, and the specific cold rolling steps include:

[0045] 1) The first, second and third passes are rolled by middle wave rolling, and the single pass reduction is 15%.

[0046] 2) The fourth, fifth and sixth passes are rolled by double edge wave rolling, wherein the double edge wave rolling strength is 15IU, the single pass reduction of the fourth and fifth passes is 15%, and the sixth pass rolling reduction is 5%.

[0047] 3) After double edge wave rolling, straightening treatment is carried out, that is, an acting force opposite to the deformation direction of the strip steel during rolling is applied to the strip steel, and the depth of the acting force pressed into the strip steel is 20mm.

[0048] Example 2

[0049] Example 2 proposes a strip steel, which is a 65Mn annealed steel coil, consisting of the following components by mass fraction:

[0050] 0.68% C, 0.17% Si, 0.43% Mn, 0.0012% S, 0.021% P, 0.05% Al, 0.25% Cr, 0.18% Ni, the balance being Fe and inevitable impurities. The strip steel has a specification of 1.8 mm x 2250 mm x full length.

[0051] Example 2 also proposes a cold rolling method of the strip steel of the present example, the steps of which are basically the same as those of Example 1, except that:

[0052] The middle wave rolling passes are the 1st, 2nd, 3rd, 4th and 5th passes; the double-side wave rolling pass is the 6th pass, and the rolling reduction of the 6th pass is 8%.

[0053] Example 3

[0054] Example 3 proposes a strip steel, the component content and specification of which are the same as those of Example 1.

[0055] Example 3 also proposes a cold rolling method of the strip steel of the present example, the steps of which are basically the same as those of Example 1, except that the rolling reduction of the 6th pass is 2%.

[0056] Example 4

[0057] Example 4 proposes a strip steel, the component content and specification of which are the same as those of Example 1.

[0058] Example 4 also proposes a cold rolling method of the strip steel of the present example, the steps of which are basically the same as those of Example 1, except that the rolling reduction of the 6th pass is 8%.

[0059] Example 5

[0060] Example 5 proposes a strip steel, the component content and specification of which are the same as those of Example 1.

[0061] Example 5 also proposes a cold rolling method of the strip steel of the present example, the steps of which are basically the same as those of Example 1, except that the rolling reduction of the 6th pass is 12%.

[0062] Example 6

[0063] Example 6 proposes a strip steel, the component content and specification of which are the same as those of Example 1.

[0064] Example 6 also proposes a cold rolling method of the strip steel of the present example, the steps of which are basically the same as those of Example 1, except that the rolling reduction of the 6th pass is 15%.

[0065] Example 7

[0066] Example 7 proposes a strip steel, the component content and specification of which are the same as those of Example 1.

[0067] Example 7 also proposes a cold rolling method of the strip steel of the present example, the steps of which are substantially the same as those of Example 1, except that the depth of the force pressing into the strip steel is 10 mm.

[0068] Example 8

[0069] Example 8 proposes a strip steel, the component content and specifications of which are the same as those of Example 1.

[0070] Example 8 also proposes a cold rolling method of the strip steel of the present example, the steps of which are substantially the same as those of Example 1, except that the depth of the force pressing into the strip steel is 40 mm.

[0071] Example 9

[0072] Example 9 proposes a strip steel, the component content and specifications of which are the same as those of Example 1.

[0073] Example 9 also proposes a cold rolling method of the strip steel of the present example, the steps of which are substantially the same as those of Example 1, except that the depth of the force pressing into the strip steel is 58 mm.

[0074] Example 10

[0075] Example 10 proposes a strip steel, the component content and specifications of which are the same as those of Example 1.

[0076] Example 10 also proposes a cold rolling method of the strip steel of the present example, the steps of which are substantially the same as those of Example 1, except that the depth of the force pressing into the strip steel is 72 mm.

[0077] Example 11

[0078] Example 11 proposes a strip steel, the component content and specifications of which are the same as those of Example 1.

[0079] Example 11 also proposes a cold rolling method of the strip steel of the present example, the steps of which are substantially the same as those of Example 1, except that the depth of the force pressing into the strip steel is 80 mm.

[0080] Example 12

[0081] Example 12 proposes a strip steel, the component content and specifications of which are the same as those of Example 1.

[0082] Example 12 also proposes a cold rolling method of the strip steel of the present example, the steps of which are substantially the same as those of Example 1, except that the strip steel is not subjected to straightening treatment.

[0083] Comparative Example 1

[0084] Comparative Example 1 proposes a strip steel, the component content and specifications of which are the same as those of Example 1.

[0085] Comparative Example 1 also proposes a cold rolling method for the strip steel of this comparative example. The steps are basically the same as those of Example 1, except that the middle wave rolling passes are the 1st to 6th passes (i.e., not combined with double-side wave rolling), and the reduction in the 6th pass (the last pass) is 5%.

[0086] Comparative Example 2

[0087] Comparative Example 2 proposes a steel strip having the same component content and specifications as those of Example 1.

[0088] Comparative Example 2 also proposes a cold rolling method for the strip steel of this comparative example, and the steps are basically the same as those of Example 1, except that the reduction in the 6th pass (the last pass) is 50%.

[0089] Comparative Example 3

[0090] Comparative Example 3 proposes a steel strip having the same component content and specifications as those of Example 1.

[0091] Comparative Example 3 also proposes a cold rolling method for the steel strip of this comparative example, the steps of which are basically the same as those of Example 1, except that the depth of the force pressed into the steel strip is 10 mm.

[0092] Comparative Example 4

[0093] Comparative Example 4 proposes a steel strip whose component content and specifications are the same as those of Example 1.

[0094] Comparative Example 4 also proposes a cold rolling method for the steel strip of this comparative example, the steps of which are basically the same as those of Example 1, except that the depth of the force pressed into the steel strip is 100 mm.

[0095] In order to verify the progress of the cold rolling method of the strip steel provided in the embodiment of the present application, the cross-sectional view of the strip steel after cold rolling is as follows: Figure 1 As shown, the turtleback height (the turtleback height refers to the horizontal distance between the position 3 30 mm (C30) from the edge and the center 4 of the strip) of the steel strip 1 after cold rolling according to the cold rolling method provided in the embodiment and the comparative example, and the thickness difference between the position 3 30 mm (C30) from the edge and the center 4 of the strip without trimming after cold rolling were measured and calculated, and the measurement and calculation results are shown in Table 1 below.

[0096] Table 1

[0097]

[0098]

[0099] From Table 1 above, we can at least draw the following conclusions:

[0100] ①In the strip steel cold rolling method of the embodiment of the present application, after the strip steel is subjected to the middle wave rolling, the double-side wave rolling and the correction treatment, the turtle-back defect is obviously improved, and the thickness difference between the edge C30 position and the center is small.

[0101] ②In the strip steel cold rolling method of the embodiment of the present application, the metal flow in the width direction of the strip steel is more uniform during the cold rolling, and the warping caused by the deformation and work hardening of the strip steel in the length direction due to the reciprocating rolling is effectively weakened. Thus, the turtle-back warping defect of the high-strength carbon steel at the outlet of the cold rolling is effectively reduced, and the yield is improved.

[0102] ③In the strip steel cold rolling method of the embodiment of the present application, the small final pass reduction can reduce the warping (L warping) in the length direction of the strip steel.

[0103] ④In the strip steel cold rolling method of the embodiment of the present application, the middle wave rolling is 3 times (i.e. 50%), the double-side wave rolling is 3 times, and when the depth of the force pressing into the strip steel is 20 mm, the turtle-back is obviously improved, and the thickness difference between the edge C30 position and the center is minimum.

[0104] ⑤As can be seen from the data of the embodiment 12, even if the strip steel is not subjected to the straightening treatment, the turtle-back height after the cold rolling is only 12 mm, and the thickness difference is only 26 μm. It is shown that in the strip steel cold rolling method of the embodiment of the present application, the middle wave and the double-side wave rolling mode can effectively reduce the turtle-back height and the thickness difference of the strip steel.

[0105] ⑥As can be seen from the data of the embodiment 1 and the comparative examples 3-4, when the depth of the force pressing into the strip steel is between 10 mm and 80 mm, the turtle-back height and the thickness difference of the strip steel after the cold rolling are in a reasonable range, too shallow depth will result in too high turtle-back height, and too deep depth will increase the thickness difference between the edge C30 position and the center.

[0106] It should be noted that the present application is not limited to the above-mentioned embodiments. The above-mentioned embodiments are only examples, and the embodiments having the same technical idea and playing the same role within the technical solution range of the present application are all included in the technical solution range of the present application. In addition, within the range not departing from the main idea of the present application, various modifications of the embodiments that can be thought of by those skilled in the art, and other ways constructed by combining part of the constituent elements in the embodiments are also included in the range of the present application.

Claims

1. A method for cold rolling a steel strip, characterized in that: The steps include: The steel strip raw material is subjected to the steps of medium corrugation rolling and double-side corrugation rolling to obtain a cold-rolled steel strip; Among them, the total number of rolling passes is 3 to 10; the middle wave rolling passes account for 10% to 90%; In the double-side wave rolling step, the reduction in a single pass is 1% to 30%; The rolling temperature of the double-side corrugated rolling is 50°C to 200°C; The strength of the double-sided corrugated rolling is 1IU~20IU; The strip cold rolling method further comprises the steps of: The strip steel after the middle wave rolling and the double side wave rolling is straightened by applying a force on the strip steel in the opposite direction to the deformation direction of the strip steel during rolling.

2. The strip cold rolling method according to claim 1, characterized in that: The medium wave rolling passes account for 10% to 50%.

3. The strip cold rolling method according to claim 1 or 2, characterized in that: In the wave rolling step, the reduction in a single pass is 10% to 30%; The rolling temperature of the wave rolling is 50°C to 200°C.

4. The strip cold rolling method according to claim 1, characterized in that: In the strip cold rolling method, the final reduction is 2% to 15%.

5. The strip cold rolling method according to claim 1, characterized in that: The depth of the force pressing into the strip steel is 10mm~80mm.

6. A steel strip produced according to the steel strip cold rolling method according to any one of claims 1 to 5, comprising iron, characterized in that: Also included are the following components by mass fraction: 0.1%≤C≤1.5%、0.1%≤Si≤0.50%、0.1%≤Mn≤1.4%、P≤0.02%、S≤0.02%、W （Cr+Ni+Mo） ≤2.0%、Al≤0.06%。

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