Cold rolling method for high-precision ultra-thin strip special steel

Abstract

The invention provides a cold rolling method of high-precision ultra-thin strip special steel, which comprises the following steps: (1) the thickness of a steel coil before cold rolling is 2.5-3.0 mm, and a cold rolling production method of a pickling-continuous rolling combined unit and a twenty-roller combination is adopted; (2) a secondary cold rolling method is adopted, the raw materials are rolled to the middle thickness through five-rack four-roller continuous rolling in the first cold rolling process, and the target thickness is rolled from the middle thickness through secondary rolling of a 20-roller reversible rolling mill in the second cold rolling process; (3) in the first cold rolling process, a five-rack four-roller mill rolls the raw material from the thickness of 2.5 mm-3. 0mm to the middle thickness of 0.5 mm-0. 8mm, and the total reduction rate is 65%-80%; (4) carrying out secondary cold rolling by adopting a twenty-roller reversible mill for three-pass cold rolling; the reduction rate of the first pass and the reduction rate of the second pass are controlled to be 30%-36%, and the reduction rate of the third pass is controlled to be 20%-28%; and (5) the rolled product is 0.19 mm to 0.25 mm. And the thickness control precision is + / -1 [mu] m.

Description

Technical Field

[0001] The present invention relates to the field of steel rolling, and in particular to a method for cold rolling high-precision ultra-thin strip special steel, and in particular to a method for cold rolling thin-gauge high-precision battery steel. Background Art

[0002] For special steel with thickness below 0.25mm (such as battery steel), in the traditional five-stand continuous rolling mill, due to the limited control ability, the thickness and plate difference control ability is limited, and it is impossible to obtain extremely thin products that meet the high-precision thickness. Or the traditional pickling plate and twenty-high rolling mill production process is used, which has relatively high costs and long production time. Both cannot meet the requirements of low production cost and high strip precision at the same time.

[0003] In summary, the prior art has the following problems: high-precision ultra-thin strip steel with a thickness below 0.25 mm has a slow production pace, high cost and low production efficiency. Summary of the invention

[0004] The present invention provides a cold rolling method for high-precision ultra-thin strip special steel to solve the problems of slow production rhythm, high cost and low production efficiency of high-precision ultra-thin strip steel with a thickness below 0.25 mm.

[0005] To this end, the present invention provides a cold rolling method for high-precision ultra-thin strip special steel, wherein the high-precision ultra-thin strip special steel is, for example, battery steel with a thickness of less than 0.25 mm, and the cold rolling method for high-precision ultra-thin strip special steel comprises the following steps:

[0006] (1) The thickness of the steel coil before cold rolling is 2.5 mm to 3.0 mm, and a cold rolling production method using a pickling-continuous rolling combined unit and a twenty-roller combination is adopted;

[0007] (2) A double cold rolling method is used, in which the first cold rolling is performed using a 5-stand four-roll continuous rolling mill to roll the raw material to an intermediate thickness, and the second cold rolling is performed using a 20-roll reversible rolling mill to roll the target thickness from the intermediate thickness;

[0008] (3) In the first cold rolling, the 5-stand four-roll mill adopts the conventional low-carbon steel production process to reduce the raw material from thickness to

[0009] 2.5mm~3.0mm is rolled to the intermediate thickness of 0.5mm~0.8mm, and the total reduction rate is 65%~80%;

[0010] (4) The second cold rolling is performed by three cold rolling passes using a twenty-roller reversible rolling mill;

[0011] 4.1) Control the first and second pass reduction rates at 30% to 36%, and the third pass reduction rate at 20% to 28%;

[0012] 4.2) Select different roughness of the twenty-high mill working roll according to the annealing process;

[0013] (5) The thickness of the rolled product is between 0.19 mm and 0.25 mm. The thickness control accuracy is ±1 μm.

[0014] After the present invention is used, a finished steel strip with good strip surface quality, high dimensional accuracy and low same-plate difference can be obtained. Moreover, compared with the traditional pickling plate and twenty-roll mill production, it can save production time and cost. Compared with the traditional method, this method can save costs by nearly 80 yuan / ton and improve production efficiency. The successful application of new battery steel technology indicates that Liugang has the ability to produce special steel strips with extremely thin specifications, and at the same time, it has further increased the proportion of high value-added products, creating considerable economic benefits for the company. On the other hand, it has also opened up the market for special steel grades and improved the competitiveness of varieties. DETAILED DESCRIPTION

[0015] In order to have a clearer understanding of the technical features, purposes and effects of the present invention, the present invention is now described.

[0016] Example 1

[0017] A pickling-five-rolling combined mill and a Sendzimir twenty-high mill are used to roll high-precision ultra-thin special steel with a C content of less than 0.03%. The specific chemical composition of the steel plate in this embodiment is shown in Table 1:

[0018] Table 1 Chemical composition (weight percentage)

[0019]

[0020] The specific control steps are as follows:

[0021] 1) The smelting and hot rolling follow the conventional low-carbon steel production method, and the thickness of the steel coil before cold rolling is 2.7 mm;

[0022] 2) The strip is rolled to an intermediate thickness of 0.7 mm by a single cold rolling method using a pickling pickling-five-tandem rolling combined unit;

[0023] 3) Continue to use the twenty-high mill secondary cold rolling method to perform continuous reversible three-pass cold rolling to the target thickness;

[0024] 3.1) Use working rollers (φ65mm) with a roughness of ≥1.2μm to prevent bonding defects caused by post-process annealing.

[0025] 3.2) Control the reduction rate between 18% and 40%, of which the first pass reduction rate is 32.9%, the second pass reduction rate is 31.9%, and the last pass reduction rate is 25.0%. For specific reduction rates, refer to Table 1.

[0026] 3.3) During rolling, the unit tension at the inlet side is controlled at 5-16 kg / mm ​​for each pass. 2 , the outlet side tension is 10~26kg / mm 2 The unit tension at the entrance side of the first pass is 7-9kg / mm 2 , the unit tension at the outlet side is 15~18kg / mm 2 , for specific allocation, refer to Table 1;

[0027] 3.4) The maximum stable rolling speed can reach 800m / min, and the thickness of the rolled product is 0.24mm;

[0028] 4) The subsequent processes are carried out according to the conventional process. It should be noted that if the plate surface requires a smooth surface with low roughness, the working roller of the leveling machine needs to use a smooth roller with a roughness of less than 0.5μm to reduce the plate surface roughness to less than 0.6μm;

[0029] The final product of this embodiment is excellent, has good stamping performance, and a hardness value HR30T of 52.8. Compared with the traditional method, this method can save costs by nearly 80 yuan / ton. The specific analysis is shown in Table 3.

[0030] Example 2

[0031] The pickling-five-rolling combined mill and the Sendzimir twenty-high mill are used to roll low-carbon, high-precision, ultra-thin strip special steel. The specific chemical composition of the steel plate in this embodiment is shown in Table 2:

[0032] Table 2 Chemical composition (weight percentage)

[0033]

[0034] The specific control steps are as follows:

[0035] 1) The smelting and hot rolling follow the conventional low-carbon steel production method, and the thickness of the steel coil before cold rolling is 2.5 mm;

[0036] 2) The strip is rolled to an intermediate thickness of 0.6 mm by a single cold rolling method using a pickling pickling-five-tandem rolling combined unit;

[0037] 3) Continue to use the twenty-high mill secondary cold rolling method to perform continuous reversible three-pass cold rolling to the target thickness;

[0038] 3.1) Use working rollers (φ65mm) with a roughness of ≥1.2μm to prevent bonding defects caused by post-process annealing.

[0039] 3.2) Control the reduction rate between 18% and 40%, of which the first pass reduction rate is 35.0%, the second pass reduction rate is 33.3%, and the last pass reduction rate is 26.9%. For specific reduction rates, refer to Table 4.

[0040] 3.3) During rolling, the unit tension at the inlet side is controlled at 5-16 kg / mm ​​for each pass. 2 , the outlet side tension is 10~26kg / mm 2 The unit tension at the entrance side of the first pass is 7-9kg / mm 2 , the unit tension at the outlet side is 15~18kg / mm 2 , refer to Table 2 for specific allocation;

[0041] 3.4) The maximum stable rolling speed can reach 800m / min, and the thickness of the rolled product is 0.19mm.

[0042] 4) The subsequent processes are carried out according to the conventional process. It should be noted that if the plate surface requires a smooth surface with low roughness, the working roller of the leveling machine needs to use a smooth roller with a roughness of less than 0.5μm to reduce the plate surface roughness to less than 0.6μm;

[0043] The final product of this embodiment is excellent, has good stamping performance, and a hardness value HR30T of 53.2. Similarly, this method can save costs by nearly 80 yuan / ton compared with the traditional method.

[0044] Table 3 Example 1 (finished product thickness 0.24mm) Pressing distribution system

[0045]

[0046] Table 4 Example 2 (finished product thickness 0.19 mm) Pressing distribution system

[0047]

[0048]

[0049] Table 5 Cost of a ton of steel (unit: yuan / ton)

[0050]

[0051] In summary, although the new process of the present invention adds five-stand four-roller continuous rolling, the number of twenty-roller passes is greatly reduced. The high-precision ultra-thin strip steel produced by cold rolling according to the process in Example 1 and Example 2 has a flat plate shape, stable strip steel, a thickness accuracy of ±1μm, and good performance, as shown in Table 6. The cost per ton of steel can be saved by 120 yuan, as shown in Table 5.

[0052] Table 6 Mechanical properties requirements of finished products

[0053]

[0054] The above description is only an illustrative embodiment of the present invention and is not intended to limit the scope of the present invention. The components of the present invention can be combined with each other without conflict, and any equivalent changes and modifications made by any technician in the field without departing from the concept and principle of the present invention should fall within the scope of protection of the present invention.

Claims

1. A cold rolling method for high-precision ultra-thin strip special steel, characterized in that: The cold rolling method of the high-precision ultra-thin strip special steel comprises the following steps: 1) The thickness of the steel coil before cold rolling is 2.5mm-3.0mm, and a cold rolling production method using a pickling-continuous rolling combined unit and a twenty-roller combination is adopted; 2) Using the double cold rolling method, the first cold rolling uses a 5-stand four-roll continuous rolling mill to roll from the raw material to the intermediate thickness, and the second cold rolling uses a 20-roller reversible rolling mill to roll from the intermediate thickness to the target thickness; 3) In the first cold rolling, the 5-stand 4-high rolling mill adopts the conventional low-carbon steel production process to roll the raw material from a thickness of 2.5mm to 3.0mm to an intermediate thickness of 0.5mm to 0.8mm, with a total reduction rate of 65% to 80%; 4) The second cold rolling is performed by three passes of cold rolling using a twenty-roller reversible rolling mill; 4.1) Control the first and second pass reduction rates at 30% to 36%, and the third pass reduction rate at 20% to 28%; 4.2) Select different roughness of the twenty-high mill working roll according to the annealing process; 5) The thickness of the rolled product is 0.19mm~0.25mm.

2. The cold rolling method for high-precision ultra-thin strip special steel according to claim 1, characterized in that: The cold rolling method is specifically: The pickling-five-rolling combined mill and the Sendzimir twenty-high mill are used to roll high-precision, ultra-thin special steel with a C content of less than 0.03%. The thickness of the steel coil before cold rolling is 2.7 mm; The strip is rolled to an intermediate thickness of 0.7 mm using a single cold rolling method using a pickling pickling-five-tandem rolling mill; Using a twenty-high mill secondary cold rolling method, continuous reversible three-pass cold rolling is performed to the target thickness; Use working rolls with a diameter of 65 mm and a roughness of ≥1.2 μm to prevent bonding defects caused by annealing in the subsequent process; The reduction rate is controlled at 18% to 40%, of which the first pass reduction rate is 32.9%, the second pass reduction rate is 31.9%, and the last pass reduction rate is 25.0%; During rolling, the unit tension at the inlet side is controlled at 5-16 kg / mm ​​for each pass. 2 , the outlet side tension is 10~26kg / mm 2 The unit tension at the entrance side of the first pass is 7-9kg / mm 2 , the unit tension at the outlet side is 15~18kg / mm 2 ; The maximum stable rolling speed is 800m / min, and the thickness of the rolled product is 0.24mm.

3. The cold rolling method according to claim 2, characterized in that: The product plate surface requirement is smooth and low roughness, and the working roller of the leveling machine needs to use a smooth roller with a roughness of less than 0.5μm.

4. The cold rolling method of high-precision ultra-thin strip special steel according to claim 1, characterized in that: The cold rolling method is specifically: The pickling-five-rolling combined mill and the Sendzimir twenty-high mill are used to produce high-precision, ultra-thin special steel with a carbon content of less than 0.08%. The thickness of the steel coil before cold rolling is 2.5 mm; The strip is rolled to an intermediate thickness of 0.6 mm using a single cold rolling method using a pickling pickling-five-tandem rolling mill; Using a twenty-high mill secondary cold rolling method, continuous reversible three-pass cold rolling is performed to the target thickness; Use working rolls with a diameter of 65 mm and a roughness of ≥1.2 μm to prevent bonding defects caused by annealing in the subsequent process; The reduction rate is controlled at 18% to 40%, of which the first pass reduction rate is 35.0%, the second pass reduction rate is 33.3%, and the last pass reduction rate is 26.9%; During rolling, the unit tension at the inlet side is controlled at 5-16 kg / mm ​​for each pass. 2 , the outlet side tension is 10~26kg / mm 2 The unit tension at the entrance side of the first pass is 7-9kg / mm 2 , the unit tension at the outlet side is 15~18kg / mm 2 ; The maximum stable rolling speed is 800m / min, and the thickness of the rolled product is 0.24mm.

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