CN115532827B

CN115532827B - Preparation method of ultrathin stainless steel strip

Info

Publication number: CN115532827B
Application number: CN202211348066.0A
Authority: CN
Inventors: 郁添裕
Original assignee: Jiangsu Guansen New Material Technology Co ltd
Current assignee: Jiangsu Guansen New Material Technology Co ltd
Priority date: 2022-10-31
Filing date: 2022-10-31
Publication date: 2023-09-15
Anticipated expiration: 2042-10-31
Also published as: CN115532827A

Abstract

The application relates to the technical field of stainless steel materials, and particularly discloses a preparation method of an ultrathin stainless steel belt. The method comprises the steps of rolling a stainless steel coil blank three times and carrying out solution annealing twice, and processing the stainless steel coil blank with the thickness of 1.0-1.2mm into a stainless steel belt with the thickness of 0.025-0.05 mm; the method comprises the steps of carrying out solution annealing between two adjacent rolling steps; the method comprises the steps of setting a plurality of rolling passes in three rolling passes, wherein the rolling force of the last 1-2 rolling passes of the third rolling is smaller than the rolling force of the rest rolling passes of the third rolling, and the rolling reduction rate of the last 1-2 rolling passes of the third rolling is 4-12%. The application optimizes the shape of the stainless steel band and improves the appearance quality of the ultrathin stainless steel band.

Description

Preparation method of ultrathin stainless steel strip

Technical Field

The application relates to the technical field of stainless steel products, in particular to a preparation method of an ultrathin stainless steel belt.

Background

Folding screen is one of the main trends in smart phone development, and according to the evaluation of CountePoint, the market volume of the 2021 folding screen mobile phone is tripled compared with 2020. By 2023, the market volume of the folding screen mobile phone is doubled again to reach the scale of about 3000 ten thousand parts. The whole smart phone market is seen, and almost all main stream factories are actively laying out folding screen mobile phone racetracks. The folding screen needs to be capable of repeatedly bearing bending in the use process, and in order to achieve the aim, an ultrathin stainless steel belt is needed.

Ultrathin stainless steel strip generally refers to stainless steel strip having a thickness of less than 0.05mm and is made from a stainless steel coil stock through processing steps including rolling and annealing. The stainless steel coil blank is thinned mainly through rolling, and residual stress generated in the rolling process can be eliminated through annealing, so that the stainless steel belt is enabled to be further thinned. At present, the process for producing the ultrathin stainless steel strip related to the related art mainly comprises the following steps: the method comprises the steps of roller preparation, raw material preparation, primary rolling, primary solution annealing, secondary rolling, surface cleaning, stretch bending straightening, secondary solution annealing, tertiary rolling, finished product cleaning, stretch bending straightening, slitting inspection and packaging into a warehouse, wherein the primary rolling, the secondary rolling and the tertiary rolling comprise a plurality of rolling processes.

In the above-described related art, the inventors considered that although the production of an ultra-thin stainless steel strip can be achieved by alternately performing rolling and annealing in the related art, as the number of rolling times increases, the resistance of the stainless steel strip to the rolling force increases, and it is necessary to increase the rolling force to achieve a sufficient reduction. The increase of the rolling force can affect the shape of the rolled steel strip, which is unfavorable for improving the appearance quality of the ultrathin stainless steel strip.

Disclosure of Invention

In the related art, along with the increase of the rolling times, the sufficient rolling reduction can be achieved by increasing the rolling force, and the increase of the rolling force can influence the plate shape of the rolled steel strip, which is not beneficial to improving the appearance quality of the ultrathin stainless steel strip. In order to improve the defect, the application provides a preparation method of an ultrathin stainless steel belt.

The application provides a preparation method of an ultrathin stainless steel belt, which adopts the following technical scheme:

the preparation method of the ultrathin stainless steel strip comprises the steps of rolling a stainless steel coil blank three times and carrying out solution annealing twice, and processing the stainless steel coil blank with the thickness of 1.0-1.2mm into the stainless steel strip with the thickness of 0.025-0.05 mm; the method comprises the steps of carrying out solution annealing between two adjacent rolling steps; the method comprises the steps of setting a plurality of rolling passes in three rolling passes, wherein the rolling force of the last 1-2 rolling passes of the third rolling is smaller than the rolling force of the rest rolling passes of the third rolling, and the rolling reduction rate of the last 1-2 rolling passes of the third rolling is 4-12%.

By adopting the technical scheme, the application adopts relatively larger rolling force before the last 1-2 passes of the third rolling to reach enough rolling reduction, then the rolling force is adjusted downwards in the last 1-2 passes, and the rolling reduction of the last 1-2 passes is limited to be 4-12%. In the reduction rate range of 4-12%, the rolling force of the working roll on the stainless steel belt can be reduced to below 1000kN, so that the influence of rolling on the plate shape is reduced, and the appearance quality of the ultrathin stainless steel belt is improved.

Preferably, the method comprises rolling a stainless steel coil blank having a thickness of 1.0-1.2mm into a stainless steel strip having a thickness of 0.25-0.35mm in a first rolling, rolling a stainless steel strip having a thickness of 0.25-0.35mm into a stainless steel strip having a thickness of 0.06-0.1mm in a second rolling, and rolling a stainless steel strip having a thickness of 0.06-0.1mm into a stainless steel strip having a thickness of 0.025-0.05mm in a third rolling.

By adopting the technical scheme, the rolling reduction rate of each rolling is controlled by setting the thickness range of the stainless steel strip in different rolling stages, so that the risk of strip breakage in the rolling process is reduced.

Preferably, the method further comprises selecting working rolls with a diameter of 45mm or less when rolling.

By adopting the technical scheme, the diameter of the working roll adopted in rolling is optimized, and the influence on the shape of the plate can be effectively reduced by using the working roll with the diameter below 45mm, so that the appearance quality of the ultrathin stainless steel strip can be improved.

Preferably, the method comprises using 8 to 9 rolling passes in each of the primary rolling, the secondary rolling and the tertiary rolling.

By adopting the technical scheme, in the three-time rolling of the application, the rolling reduction of the stainless steel belt is gradually reduced, but the rolling difficulty of the stainless steel belt is increased along with the increase of the rolling times. In the third rolling process, the rolling reduction is only 0.01-0.075mm and is far smaller than that of the previous two rolling processes, but in order to successfully realize rolling, rolling passes close to the previous two rolling passes need to be kept continuously, otherwise, when the passes are smaller than the previous two rolling passes, the flatness of the ultrathin stainless steel strip is easily reduced, and the appearance quality of the ultrathin stainless steel strip is affected.

Preferably, the annealing temperature of the first solution annealing is 1150-1180 ℃.

By adopting the technical scheme, the temperature range of the first solution annealing is optimized, and when the temperature of the first solution annealing is lower than 1150-1180 ℃, the cold work hardening and residual stress in the stainless steel strip are not easy to be completely eliminated, so that the ductility of the stainless steel strip is affected. When the temperature of the first solution annealing exceeds 1180 ℃, the temperature easily has negative influence on the structure of the stainless steel strip, and the mechanical property of the stainless steel strip is easily influenced.

Preferably, the speed of the first solution annealing is 20-25m/min.

By adopting the technical scheme, the speed of the first solution annealing is optimized, the hardness of the stainless steel belt can be increased along with the increase of the annealing speed, but the flatness can be gradually deteriorated. Therefore, when the speed of the first solution annealing is between 20 and 25m/min, it is easier to achieve a balance between hardness and flatness.

Preferably, the temperature of the second solution annealing is 950-1050 ℃.

By adopting the technical scheme, the temperature of the second solution annealing is optimized, the ductility of the stainless steel strip is enhanced, and the mechanical property of the ultrathin stainless steel strip is improved.

Preferably, the speed of the second solution annealing is 30-35m/min.

By adopting the technical scheme, the speed of the second solution annealing is optimized, the ductility of the stainless steel strip is enhanced, and the flatness of the ultrathin stainless steel strip is improved.

Preferably, the method comprises using a rolling oil containing an antiwear agent, selected from magnesium hydroxy silicate, in a third rolling pass.

By adopting the technical scheme, under the action of rolling force, magnesium hydroxy silicate in rolling oil is adhered to the surface of the stainless steel strip in the rolling process to form a self-repairing film, so that abrasion of the stainless steel strip in rolling is reduced, the defect of the stainless steel strip is repaired, the smoothness of the surface of the stainless steel strip is improved, and the appearance quality of the ultrathin stainless steel strip is improved.

Preferably, the rolling oil comprises vegetable oil and an antioxidant, and the antioxidant is linoleic acid.

By adopting the technical scheme, the rolling oil with the components containing the vegetable oil and the linoleic acid is selected as the degradable components, so that the pollution of the waste rolling oil to the environment is reduced. In addition, when the stainless steel belt is washed and deoiled, the linoleic acid can also play a role in defoaming and emulsifying, so that the separation of the rolling oil and the stainless steel belt is promoted, and the degreasing effect of the stainless steel belt is improved.

In summary, the application has the following beneficial effects:

1. the application reduces the rolling force of the last 1-2 passes of the third rolling and controls the rolling reduction to 4-12% while rolling for three times, reduces the influence of the rolling process on the shape of the stainless steel strip, and improves the product quality of the ultrathin stainless steel strip.

2. In the application, the rolling passes of 8-9 times are preferably adopted in the primary rolling, the secondary rolling and the tertiary rolling, wherein the rolling reduction of the tertiary rolling is far smaller than that of the former two times, but the stainless steel strip has stronger resistance to rolling force at the moment, so that the rolling passes close to the former two times need to be kept, otherwise, the flatness of the ultrathin stainless steel strip is easily reduced under the condition that the passes are smaller than the former two times, and the product quality of the ultrathin stainless steel strip is influenced.

Detailed Description

The present application will be described in further detail with reference to examples, preparations and comparative examples, and the raw materials according to the present application are all commercially available.

Examples

Examples 1 to 5

The following description will take example 1 as an example.

Example 1

In this embodiment, the rolling oil selected is castor oil.

In this example, an ultrathin stainless steel strip was prepared according to the following steps:

step one: roll preparation

Preparing a plurality of pairs of working rolls with diameters below 45mm for primary rolling, secondary rolling and tertiary rolling;

step two: raw material preparation

Selecting a 316 stainless steel coil blank with the thickness of 1.0mm and the width of 620mm, wherein the surface of the steel coil has no appearance defects such as scratch, dirt and the like, rewinding the stainless steel coil blank by using a rewinding machine, and the speed of the rewinding machine is set at 70m/min;

step three: one-pass rolling

Rolling the stainless steel coil blank product with the width of 620mm and the length of 1.0mm obtained in the second step through a 20-roll mill, and rolling into a semi-finished steel belt with the thickness of 0.25mm through 8 passes;

step four: primary solution annealing

Degreasing and cleaning the rolled 0.25mm semi-product steel belt by a continuous annealing line, removing grease remained on the surface of the semi-product steel belt during rolling, and then drying the semi-product steel belt to enter a full-hydrogen protected bright annealing furnace; the annealing speed is 20m/min, the annealing temperature is 1150 ℃, and the surface of the steel strip is determined not to be oxidized and blued in the treatment process, so that a soft blank with the grain size of 10 is obtained;

step five: secondary rolling

Rolling the semi-product steel belt with the thickness of 0.25mm obtained in the step four by a 20-roll mill, and rolling the semi-product steel belt into a steel belt with the thickness of 0.06mm by 8 passes;

step six: cleaning a surface

The stainless steel strip with the thickness of 0.06mm obtained in the fifth step passes through a degreasing cleaning unit at the speed of 45m/min, and grease remained on the surface of the finished steel strip during rolling is removed;

step seven: stretch bending straightening

Carrying out plate type correction on the cleaned steel belt by adopting a twenty-three roller withdrawal and straightening machine, wherein the inclination is 2.6mm and the elongation is 0.7% in the withdrawal and straightening process, and the head part confirms that the plate type is qualified on an outlet platform and then carries out continuous withdrawal and straightening;

step eight: secondary solution annealing

The method comprises the steps of (1) passing a stretch-bent and straightened steel strip with the thickness of 0.06mm through a continuous annealing line degreasing cleaning section, then drying and entering a full-hydrogen protection bright annealing furnace, wherein the annealing speed is 30m/min, the annealing temperature is 950 ℃, and the surface of the steel strip is determined not to be oxidized and blued in the treatment process, so that a soft blank with the grain size grade of 10 is obtained;

step nine: three times of rolling

Rolling the semi-finished steel strip with the thickness of 0.06mm obtained in the step nine by a 20-roll mill, and rolling the semi-finished steel strip into a steel strip with the thickness of 0.025mm by 8 passes; in 8 passes, working rolls with the diameters of Ra0.25-0.3 mu m, ra0.15-0.2 mu m, ra0.05-0.1 mu m and Ra0.05-0.07 mu m are sequentially selected for rolling; the rolling force is adjusted downwards in the last two rolling processes during rolling, and the rolling reduction is controlled to be 4%;

step ten: cleaning of finished products

Passing the finished steel strip with the thickness of 0.025mm after three times of rolling through a degreasing cleaning unit at the speed of 8 m/min;

step eleven: stretch bending straightening

Cleaning the roller path and the roller box, carrying out plate type correction on the finished steel belt after finished product cleaning by adopting a twenty-three roller withdrawal and straightening machine, controlling the inclination to be 1.7mm in the withdrawal and straightening process, controlling the elongation to be 0.3, and continuously withdrawing and straightening the head of the steel belt after confirming that the plate type is qualified on an outlet platform to obtain the ultrathin stainless steel belt.

Step twelve: slitting test

The finished product after withdrawal and straightening is subjected to width cutter arrangement slitting by adopting a longitudinal shearing unit to obtain a stainless steel coil, and a sampling test is carried out;

step thirteen: packaging and warehousing

And after the sampling test is finished, packaging the stainless steel coil obtained in the step twelve into a warehouse to complete the whole preparation process.

As shown in Table 1, examples 1-5 were different mainly in the thickness of the steel strip at each stage in the production process.

TABLE 1 thickness of Steel strip before and after Rolling

Examples 6 to 9

As shown in table 2, example 1 is different from examples 6 to 9 in that the reduction ratios of the last two passes during the third rolling are different.

TABLE 2 reduction of last two passes during third pass

Example 10

This example differs from example 9 in that the reduction of the last pass is controlled to be 12% during the third pass.

Examples 11 to 14

As shown in Table 3, example 1 differs from examples 11-14 in that the diameter of the work rolls used in rolling was different.

Table 3 diameter of work rolls used in rolling

Sample of	Example 1	Example 11	Example 12	Example 13	Example 14
						Diameter/mm	35	38	40	43	45

Example 15

This example differs from example 14 in that 9 passes were used in each of the first, second and third passes, wherein the third pass was a roll of 0.25-0.3 μm, 0.15-0.2 μm, 0.2-0.05-0.1 μm, 0.05-0.07 μm.

Examples 16 to 19

As shown in Table 4, examples 16-19 differ from example 1 in the temperature of the first solution anneal.

TABLE 4 temperature of first solution annealing

Sample of	Example 1	Example 16	Example 17	Example 18	Example 19
						Temperature/. Degree.C	1150	1160	1170	1180	1200

Examples 20 to 23

As shown in Table 5, example 17 differs from examples 20-23 in the speed of the first solution annealing.

TABLE 5 speed of first solution annealing

Sample of	Example 17	Example 20	Example 21	Example 22	Example 23
						Speed/(m/min)	18	20	23	25	27

Examples 24 to 27

As shown in Table 6, examples 24-27 differ from example 1 in the temperature of the second solution anneal.

TABLE 6 temperatures of second solution annealing

Sample of	Example 1	Example 24	Example 25	Example 26	Example 27
						Temperature/. Degree.C	950	970	1000	1020	1050

Examples 28 to 31

As shown in Table 7, example 25 differs from examples 28-31 in the speed of the second solution annealing.

TABLE 7 speed of second solution annealing

Sample of	Example 25	Example 28	Example 29	Example 30	Example 31
						Speed/(m/min)	28	30	32	35	37

Example 32

This example differs from example 1 in that in the third rolling pass a rolling oil containing an antiwear agent, magnesium hydroxysilicate, was used, the rolling oil being composed of 60kg castor oil and 2kg magnesium hydroxysilicate.

Example 33

This example differs from example 36 in that the rolling oil is made up of 60kg castor oil, 2kg antioxidant and 2kg magnesium hydroxy silicate, and the antioxidant is linoleic acid.

Comparative example

Comparative example 1

This comparative example differs from example 1 in that the reduction was controlled to 13% in the last two passes of the third rolling.

Comparative example 2

This comparative example differs from example 1 in that the reduction was controlled to 15% in the last two passes of the third rolling.

Performance detection test method

The ultra-thin stainless steel strips of each example and comparative example were tested for vickers hardness with reference to GB/T4340 "metal vickers hardness test", and the results are shown in table 8.

The ultra-thin stainless steel strips of each example and comparative example were subjected to flatness test, and the results are shown in Table 8.

The degreasing rates of example 1, example 36 and example 37 were measured as follows: taking 20.00g of stainless steel belt cooled to 20 ℃ after third rolling, flushing with cleaning water at a rate of 5L/min, stopping flushing after 3min, drying the ultrathin stainless steel belt until the weight is no longer changed, and recording the dry weight of the ultrathin stainless steel belt as M ₁ 。

Measurement of M ₁ Then, taking 20.00g stainless steel strips in the same batch, heating at 800 ℃ for 15min, waiting for natural cooling, weighing the cooled ultrathin stainless steel strips at 20 ℃, and marking the result as M ₂ 。

Obtaining M ₁ And M ₂ After that, the oil removal rate was calculated according to the following formula, and the results are shown in Table 9.

TABLE 8

TABLE 9

Sample of	Oil removal rate/%
		Example 1	62.3
Example 36	63.6
		Example 37	82.4

As can be seen from the combination of examples 1 and comparative examples 1 to 2 and table 8, the hardness measured in example 1 is slightly lower than that in comparative examples 1 and 2, but the flatness is significantly better than that in comparative examples 1 and 2, which demonstrates that the present application achieves a significant improvement in flatness with less reduction in hardness by controlling the reduction rate of the last 1 to 2 rolling passes in the third rolling, optimizing the rolled strip shape, and improving the appearance quality of the ultra-thin stainless steel strip.

As can be seen in connection with examples 1-5 and in connection with table 8, the product thickness of examples 1-5 was gradually increased and the measured hardness was gradually decreased, but better flatness was obtained with decreasing hardness.

As can be seen from the combination of examples 1 and examples 6 to 9 and table 8, as the reduction ratio generated in the last 2 rolling passes of the third rolling increases, the hardness of the product generally exhibits an upward trend, the flatness generally exhibits a deterioration trend, and it is seen that an excessively high reduction ratio may affect the rolled plate shape, which is disadvantageous in improving the appearance quality of the ultra-thin stainless steel strip.

As can be seen from the combination of example 9, example 10 and table 8, when the rolling reduction is controlled only in the last pass of the third rolling, the hardness of the product is increased, and the flatness is lowered, which means that the rolling reduction is controlled in the last two passes of the third rolling to further contribute to improving the appearance quality of the ultra-thin stainless steel strip.

As can be seen from the combination of examples 1, 11-14 and Table 8, the increase in the roll diameter resulted in a decrease in the flatness of the ultra-thin stainless steel strip, which was detrimental to improving the appearance quality of the ultra-thin stainless steel strip.

It can be seen from the combination of example 15, example 14 and table 8 that the addition of rolling passes increases the production cost, but can increase the hardness of the ultra-thin stainless steel strip and improve the flatness of the ultra-thin stainless steel strip.

In combination with examples 1, 16-19 and Table 8, it can be seen that when the temperature of the first solution annealing exceeds 1170 ℃, the hardness of the ultra-thin stainless steel strip is affected, which is detrimental to improving the mechanical properties of the ultra-thin stainless steel strip, while when the temperature of the first solution annealing is below 1200 ℃, excessive fluctuations in the flatness of the ultra-thin stainless steel strip do not occur.

It can be seen from the combination of examples 17, examples 20 to 23 and table 8 that the hardness of the ultra-thin stainless steel strip gradually increased with an increase in rolling speed during the first solution annealing, but the flatness was also gradually deteriorated.

In combination with examples 1, 24-27 and Table 8, it can be seen that in the range of 950-1050℃, as the temperature of the second solution annealing increases, the hardness of the ultra-thin stainless steel strip increases and then decreases, while the flatness continues to deteriorate as the temperature increases, and annealing temperatures around 1000℃ are preferred to give ultra-thin stainless steel strips with relatively high hardness.

As can be seen from a combination of examples 25, examples 28-31 and Table 8, an annealing temperature of around 32m/s is preferred to obtain an ultra-thin stainless steel strip with relatively good flatness.

It can be seen from the combination of example 1, examples 32 to 33 and Table 8 that the hardness measured in examples 32 to 33 was slightly higher than in example 1, and the flatness was also better than in example 1. The magnesium hydroxy silicate in the rolling oil is adhered to the surface of the stainless steel strip in the rolling process to form a self-repairing film under the action of the rolling force, so that the abrasion of the stainless steel strip in the rolling process is reduced, the defect of the stainless steel strip is repaired, the smoothness of the surface of the stainless steel strip is improved, and the appearance quality of the ultrathin stainless steel strip is improved.

As can be seen from the combination of examples 1 and examples 32 to 33 and the combination of Table 9, the oil removal rate measured in example 33 is high in examples 1 and 32, which shows that the linoleic acid can also play a role in defoaming and emulsifying when the stainless steel strip is washed and degreased, so that the separation of the rolling oil and the stainless steel strip is promoted, and the degreasing effect of the stainless steel strip is improved.

The present embodiment is only for explanation of the present application and is not to be construed as limiting the present application, and modifications to the present embodiment, which may not creatively contribute to the present application as required by those skilled in the art after reading the present specification, are all protected by patent laws within the scope of claims of the present application.

Claims

1. The preparation method of the ultrathin stainless steel strip is characterized by comprising the steps of rolling a stainless steel coil blank three times and carrying out solution annealing twice, and processing the stainless steel coil blank with the thickness of 1.0-1.2mm into the stainless steel strip with the thickness of 0.025-0.05 mm; the method comprises the steps of carrying out solution annealing between two adjacent rolling steps; the method comprises the steps that a plurality of rolling passes are arranged in three rolling, the rolling force of the last 1-2 rolling passes in the third rolling is smaller than the rolling force of the rest rolling passes in the third rolling, and the rolling rate of the third rolling in the last 1-2 rolling passes is 4-12%; the method comprises the steps of rolling a stainless steel coil blank with the thickness of 1.0-1.2mm into a stainless steel strip with the thickness of 0.25-0.35mm in the first rolling, rolling the stainless steel strip with the thickness of 0.25-0.35mm into a stainless steel strip with the thickness of 0.06-0.1mm in the second rolling, and rolling the stainless steel strip with the thickness of 0.06-0.1mm into a stainless steel strip with the thickness of 0.025-0.05mm in the third rolling; the method comprises the steps of adopting 8-9 rolling passes in the primary rolling, the secondary rolling and the tertiary rolling.

2. The method of claim 1, further comprising selecting a work roll having a diameter of 45mm or less for rolling.

3. The method of claim 1, wherein the first solution annealing is performed at a temperature of 1150-1180 ℃.

4. A method of producing an ultra-thin stainless steel strip according to claim 3, wherein said first solution annealing is performed at a speed of 20-25m/min.

5. The method of producing an ultra-thin stainless steel strip according to claim 1, wherein the second solution annealing is performed at a temperature of 950-1050 ℃.

6. The method of producing an ultra-thin stainless steel strip according to claim 5, wherein said second solution annealing is performed at a speed of 30-35m/min.

7. The method of claim 1, wherein the method comprises using a rolling oil containing an antiwear agent selected from magnesium hydroxysilicate during the third rolling process.

8. The method of claim 7, wherein the rolling oil comprises vegetable oil and an antioxidant, and the antioxidant is linoleic acid.