CN115532827A

CN115532827A - Preparation method of ultrathin stainless steel band

Info

Publication number: CN115532827A
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: 2022-12-30
Anticipated expiration: 2042-10-31
Also published as: CN115532827B

Abstract

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

Description

Preparation method of ultrathin stainless steel band

Technical Field

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

Background

The folding screen is one of the mainstream trends of smart phone development, and the market shipment volume of the folding screen mobile phone in 2021 is three times larger than that in 2020 according to the estimation of countrpoint. In 2023, the goods output of the folding screen mobile phone market is more than three times, and the size reaches about 3000 ten thousand. The whole smart phone market is put into the eye, and almost all mainstream manufacturers are actively laying out the folding screen mobile phone track. The folding screen needs to be able to withstand repeated bending during use, and to achieve this, ultra-thin stainless steel bands are required.

The ultra-thin stainless steel strip generally refers to a stainless steel strip with a thickness of less than 0.05mm, which is made from a stainless steel coil blank through processing steps including rolling and annealing. The stainless steel coil blank is thinned mainly by rolling, and the annealing can eliminate the residual stress generated in the rolling process, so that the stainless steel band has the possibility of further thinning. At present, the process for producing an ultra-thin stainless steel strip related in the related art mainly comprises the following steps: the method comprises the following 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, packaging and warehousing, wherein the primary rolling, the secondary rolling and the tertiary rolling all comprise a plurality of rolling processes.

In view of the above-mentioned related art, the inventors have 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, the resistance of the stainless steel strip against the rolling force is increased as the number of times of rolling is increased, 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, and is not beneficial to improving the appearance quality of the ultrathin stainless steel strip.

Disclosure of Invention

In the related art, as the rolling frequency is increased, the rolling force needs to be increased to achieve a sufficient rolling reduction, and the increase of the rolling force affects the shape of the rolled steel strip, which is not favorable for improving the appearance quality of the ultrathin stainless steel strip. In order to improve the defect, the application provides a preparation method of the ultrathin stainless steel strip.

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

a method for preparing an ultrathin stainless steel band comprises the steps of carrying out three times of rolling and two times of solution annealing on a stainless steel coil blank, and processing the stainless steel coil blank with the thickness of 1.0-1.2mm into the stainless steel band with the thickness of 0.025-0.05 mm; the method comprises the steps of carrying out solution annealing once between two adjacent rolling; the method comprises the steps that a plurality of rolling passes are arranged in three times of rolling, the rolling force of the third rolling in the last 1-2 rolling passes is smaller than that of the other rolling passes of the third rolling, and the reduction rate of the third rolling in the last 1-2 rolling passes is 4-12%.

By adopting the technical scheme, the rolling force is relatively large before the last 1-2 passes of the third rolling so as to achieve the enough reduction, then the rolling force is reduced downwards in the last 1-2 passes, and the reduction rate of the last 1-2 passes is limited to be 4-12%. Within the range of 4-12% of reduction ratio, the rolling force of the working roll on the stainless steel strip can be reduced to below 1000kN, so that the influence of rolling on the strip shape is reduced, and the appearance quality of the ultrathin stainless steel strip is improved.

Preferably, the method comprises rolling a stainless steel coil blank with a thickness of 1.0-1.2mm into a stainless steel strip with a thickness of 0.25-0.35mm in a first rolling, rolling a stainless steel strip with a thickness of 0.25-0.35mm into a stainless steel strip with a thickness of 0.06-0.1mm in a second rolling, and rolling a stainless steel strip with a thickness of 0.06-0.1mm into a stainless steel strip with 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 ranges of the stainless steel band in different rolling stages, and the risk of band breakage in the rolling process is reduced.

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

Through adopting above-mentioned technical scheme, this application has carried out the preferred to the working roll diameter that adopts when rolling, uses the working roll that diameter 45mm below can effectively reduce the influence to the plate shape, helps improving the appearance quality of ultra-thin stainless steel band.

Preferably, the method comprises using 8-9 rolling passes in each of the first rolling, the second rolling and the third rolling.

By adopting the technical scheme, in the three rolling processes, the rolling reduction of the stainless steel band at each time is in a decreasing trend, but the rolling difficulty of the stainless steel band is increased along with the increase of the rolling times. In the third rolling process, although the rolling reduction is only 0.01-0.075mm in total and is far less than that of the first two times of rolling, in order to successfully realize rolling, the rolling passes close to the first two times of rolling need to be continuously maintained, otherwise, in the case that the rolling passes are less than the first two times of rolling, the flatness of the ultrathin stainless steel strip is easily reduced, and the appearance quality of the ultrathin stainless steel strip is influenced.

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 completely eliminate, and the ductility of the stainless steel strip is influenced. When the temperature of the first solution annealing exceeds 1180 ℃, the temperature is easy to generate negative influence on the structure of the stainless steel strip, and the mechanical property of the stainless steel strip is easy to influence.

Preferably, the first solution annealing is performed at a rate of 20 to 25m/min.

By adopting the technical scheme, the first solution annealing rate is optimized, the hardness of the stainless steel strip can be increased along with the increase of the annealing speed, but the flatness can be gradually deteriorated. Therefore, when the rate of the first solution annealing is between 20 and 25m/min, the balance of hardness and flatness is more easily achieved.

Preferably, the temperature of the second solution treatment is 950 to 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 second solution treatment is performed at a rate of 30 to 35m/min.

Through adopting above-mentioned technical scheme, this application has preferably the speed of solution treatment for the second time, has strengthened the ductility of stainless steel band, helps improving the roughness of ultra-thin stainless steel band.

Preferably, the method comprises the step of using rolling oil containing an antiwear agent in the third rolling process, wherein the antiwear agent is magnesium silicate hydroxide.

By adopting the technical scheme, under the action of the rolling force, the magnesium silicate hydroxide in the rolling oil is attached to the surface of the stainless steel band in the rolling process to form a self-repairing film, so that the abrasion of the stainless steel band during rolling is reduced, the defects of the stainless steel band are repaired, the surface smoothness of the stainless steel band is improved, and the appearance quality of the ultrathin stainless steel band is improved.

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

Through adopting above-mentioned technical scheme, the rolling oil that the component contains vegetable oil and linoleic acid is selected for use to this application, and vegetable oil and linoleic acid are degradable composition, have reduced the pollution that waste rolling oil caused the environment. In addition, when the stainless steel band is washed to remove oil, the linoleic acid can also play a defoaming role and an emulsifying role, so that the separation of rolling oil and the stainless steel band is promoted, and the degreasing effect of the stainless steel band is improved.

In summary, the present application has the following beneficial effects:

1. according to the method, the rolling force is adjusted downwards in the last 1-2 passes of the third rolling while the rolling is carried out for three times, the reduction rate is controlled to be 4-12%, the influence of the rolling process on the shape of the stainless steel strip is reduced, and the product quality of the ultrathin stainless steel strip is improved.

2. In the application, rolling passes of 8-9 times are preferably adopted in the first rolling, the second rolling and the third rolling, wherein although the rolling reduction of the third rolling is far less than that of the first two times, the stainless steel band at the moment has strong resistance to the rolling force, so that the rolling passes close to the first two times need to be kept continuously, otherwise, in the case that the rolling passes are less than the first two times, the flatness of the ultrathin stainless steel band is easy to reduce, and the product quality of the ultrathin stainless steel band is influenced.

Detailed Description

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

Examples

Examples 1 to 5

The following description will be given by taking example 1 as an example.

Example 1

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

In this example, the ultra-thin stainless steel strip was prepared by the following steps:

the method comprises the following steps: roll preparation

Preparing a plurality of pairs of working rolls with the diameter of 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 bad appearance phenomena such as scratch, dirt and the like, and rewinding the stainless steel coil blank by using a recoiling machine, wherein the speed of the recoiling machine is set at 70m/min;

step three: one-pass rolling

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

step four: primary solution annealing

The semi-finished steel strip with the thickness of 0.25mm after primary rolling passes through a degreasing and cleaning section of a continuous annealing line, grease remained on the surface of the semi-finished steel strip during rolling is removed, and then the semi-finished steel strip is dried and enters a bright annealing furnace protected by total hydrogen; 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 level of 10 is obtained;

step five: secondary rolling

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

step six: cleaning surfaces

Enabling the stainless steel strip with the thickness of 0.06mm obtained in the step five to pass through a degreasing cleaning unit at the speed of 45m/min, and removing grease remained on the surface of a finished product steel strip during rolling;

step seven: stretch bending and straightening

Performing plate shape correction on the cleaned steel strip by adopting a twenty-three-roller withdrawal and straightening machine, wherein the steel strip is inclined by 2.6mm and has an elongation of 0.7 percent in the withdrawal and straightening process, and continuously withdrawing and straightening the steel strip after the head part is determined to be qualified on an outlet platform;

step eight: secondary solution annealing

Passing a steel strip which is subjected to stretch bending straightening and has the thickness of 0.06mm through a degreasing and cleaning section of a continuous annealing line, drying and entering a full-hydrogen protected 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 blue in the treatment process to obtain a soft blank with the grain size level of 10;

step nine: triple 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 times; in 8 passes, working rolls of Ra0.25-0.3 μm, ra0.15-0.2 μm, ra0.05-0.1 μm and Ra0.05-0.07 μm are selected for rolling in sequence; the rolling force is adjusted downwards in the last two rolling passes during the rolling, and the reduction rate is controlled to be 4%;

step ten: cleaning finished product

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

step eleven: stretch bending and straightening

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

Step twelve: slitting inspection

Performing width row cutter slitting on the finished product after the straightening by adopting a slitting machine group to obtain a stainless steel coil, and performing sampling test;

step thirteen: packaging and warehousing

And after the sampling test is finished, packaging and warehousing the stainless steel coil obtained in the step twelve, and finishing the whole preparation process.

As shown in Table 1, examples 1 to 5 are different mainly in the thickness of the steel strip in each stage of the manufacturing process.

TABLE 1 thickness before and after rolling of the strip

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 rolling passes during the third rolling are different.

TABLE 2 reduction of the last two passes during the third pass

Example 10

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

Examples 11 to 14

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

TABLE 3 working roll diameter used in Rolling

Sample(s)	Example 1	Example 11	Example 12	Example 13	Example 14
						Diameter/mm	35	38	40	43	45

Example 15

The difference between the embodiment and the embodiment 14 is that 9 rolling passes are adopted in the primary rolling, the secondary rolling and the tertiary rolling, wherein the working rolls of Ra0.25-0.3 μm, ra0.15-0.2 μm, ra0.05-0.1 μm and Ra0.05-0.07 μm are adopted in the third rolling.

Examples 16 to 19

As shown in Table 4, examples 16 to 19 were different from example 1 in the temperature of the first solution treatment.

TABLE 4 temperature of first solution annealing

Sample(s)	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 to 23 in the rate of the first solution treatment.

TABLE 5 first solution annealing speed

Sample(s)	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 to 27 were different from example 1 in the temperature of the second solution treatment.

TABLE 6 temperature of the second solution annealing

Sample(s)	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 is different from examples 28 to 31 in that the rate of the second solution treatment is different.

TABLE 7 second solution annealing rates

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

Example 32

The difference between this example and example 1 is that rolling oil containing an anti-wear agent selected from magnesium hydroxy silicate is used in the third rolling process, and the rolling oil is formed by mixing 60kg of castor oil and 2kg of magnesium hydroxy silicate.

Example 33

This example differs from example 36 in that the rolling oil was a blend of 60kg castor oil, 2kg antioxidant and 2kg magnesium hydroxy silicate, the antioxidant being 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 pass.

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 pass.

Performance detection test method

The results of the Vickers hardness test conducted on the ultra-thin stainless steel strips of the examples and comparative examples with reference to GB/T4340 "Metal Vickers hardness test" are shown in Table 8.

The ultra-thin stainless steel strips of the examples and comparative examples were subjected to flatness tests, 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 band which is cooled to 20 ℃ after being rolled for the third time, washing the stainless steel band by using cleaning water at the speed of 5L/min, stopping washing after 3min, drying the ultrathin stainless steel band until the weight of the ultrathin stainless steel band is not changed, and recording the dry weight of the ultrathin stainless steel band as M ₁ 。

Measure M ₁ Then, 20.00g of stainless steel band of the same batch is taken, heated at 800 ℃ for 15min and then naturally cooled, the weight of the ultrathin stainless steel band after cooling is weighed at 20 ℃, and the result is recorded as M ₂ 。

To obtain M ₁ And M ₂ Thereafter, the oil removing rate was calculated as follows, and the results are shown in Table 9.

TABLE 8

TABLE 9

Sample(s)	Oil removal rate/%)
		Example 1	62.3
Example 36	63.6
		Example 37	82.4

It can be seen by combining example 1 and comparative examples 1-2 and table 8 that the hardness measured in example 1 is slightly lower than that measured in comparative example 1 and comparative example 2, but the flatness is obviously better than that measured in comparative example 1 and comparative example 2, which shows that the application realizes obviously improved flatness on the premise of less hardness reduction by controlling the reduction rate of the third rolling in the last 1-2 rolling passes, optimizes the plate shape after rolling and improves the appearance quality of the ultrathin stainless steel strip.

As can be seen by combining examples 1-5 with Table 8, the products of examples 1-5 have progressively higher thicknesses and progressively lower measured hardness, but with the hardness decreasing, a better flatness is obtained.

It can be seen from the combination of example 1 and examples 6-9 and table 8 that, as the reduction ratio generated in the last 2 rolling passes of the third rolling is increased, the hardness of the product generally tends to increase, and the flatness generally tends to deteriorate, and it can be seen that an excessively high reduction ratio affects the shape of the rolled strip, which is not favorable for improving the appearance quality of the ultra-thin stainless steel strip.

It can be seen from the combination of examples 9 and 10 and table 8 that the hardness of the product is increased and the flatness is decreased when the reduction ratio is controlled only in the last pass of the third rolling, which means that the control of the reduction ratio in the last two passes of the third rolling is more helpful to improve the appearance quality of the ultra-thin stainless steel strip.

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

As can be seen from the combination of examples 15 and 14 and table 8, although the increase of the rolling pass increases the production cost, the hardness of the ultra-thin stainless steel strip can be increased and the flatness of the ultra-thin stainless steel strip can be improved.

It can be seen from the combination of example 1, examples 16 to 19 and table 8 that when the temperature of the first solution annealing is higher than 1170 ℃, the hardness of the ultra-thin stainless steel strip is affected, which is not favorable for improving the mechanical properties of the ultra-thin stainless steel strip, and when the temperature of the first solution annealing is lower than 1200 ℃, the flatness of the ultra-thin stainless steel strip does not fluctuate excessively.

It can be seen from the combination of example 17, examples 20 to 23 and Table 8 that the hardness of the ultra-thin stainless steel strip gradually increases with the increase in the rolling speed during the first solution treatment, but the flatness is also gradually deteriorated.

It can be seen from the combination of examples 1, 24 to 27 and Table 8 that in the range of 950 to 1050 ℃, the hardness of the ultra-thin stainless steel strip increases first and then decreases as the temperature of the second solution annealing increases, while the flatness continues to deteriorate as the temperature increases, and the annealing temperature around 1000 ℃ is preferred to obtain the ultra-thin stainless steel strip having relatively high hardness.

As can be seen by combining examples 25, 28 to 31 and Table 8, the annealing temperature of about 32m/s is preferred to obtain an ultra-thin stainless steel strip having a relatively good flatness.

Combining example 1, examples 32-33 and table 8, it can be seen that examples 32-33 measured slightly higher hardness than example 1 and also had better flatness than example 1. The magnesium silicate hydroxide in the rolling oil is attached 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 defects of the stainless steel strip are repaired, the surface smoothness of the stainless steel strip is improved, and the appearance quality of the ultrathin stainless steel strip is improved.

It can be seen from the combination of example 1, examples 32 to 33 and table 9 that the degreasing rate measured in example 33 is high, and example 1 and example 32 show that linoleic acid can also exert a defoaming action and an emulsifying action when washing and degreasing the stainless steel strip, thereby promoting the separation of rolling oil from the stainless steel strip and improving the degreasing effect of the stainless steel strip.

The present embodiment is only for explaining the present application, and it is not limited to the present application, and those skilled in the art can make modifications of the present embodiment without inventive contribution as needed after reading the present specification, but all of them are protected by patent law within the scope of the claims of the present application.

Claims

1. The method for preparing the ultrathin stainless steel strip is characterized by comprising the steps of carrying out three times of rolling and two times of solution annealing on a stainless steel coil blank, 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 once between two adjacent rolling; the method comprises the steps of setting a plurality of rolling passes in three times of rolling, wherein the rolling force of the third rolling in the last 1-2 rolling passes is smaller than that of the other rolling passes of the third rolling, and the reduction rate of the third rolling in the last 1-2 rolling passes is 4-12%.

2. The method of claim 1, wherein the method comprises rolling the stainless steel coil blank with a thickness of 1.0-1.2mm into the stainless steel strip with a thickness of 0.25-0.35mm in the first rolling, rolling the stainless steel strip with a thickness of 0.25-0.35mm into the stainless steel strip with a thickness of 0.06-0.1mm in the second rolling, and rolling the stainless steel strip with a thickness of 0.06-0.1mm into the stainless steel strip with a thickness of 0.025-0.05mm in the third rolling.

3. The method of claim 2, further comprising using working rolls having a diameter of 45mm or less for rolling.

4. The method of claim 3, wherein the method comprises using 8-9 passes in each of the first rolling, the second rolling and the third rolling.

5. The method of claim 2, wherein the annealing temperature of the first solution annealing is 1150-1180 ℃.

6. The method for preparing an ultra-thin stainless steel strip according to claim 5, wherein the first solution annealing speed is 20-25m/min.

7. The method of claim 2, wherein the second solution annealing is performed at a temperature of 950 to 1050 ℃.

8. The method for preparing an ultra-thin stainless steel strip according to claim 7, wherein the second solution annealing is performed at a rate of 30-35m/min.

9. The method for preparing the ultrathin stainless steel strip as claimed in claim 1, characterized by comprising the step of using rolling oil containing an antiwear agent in the third rolling process, wherein the antiwear agent is magnesium silicate hydroxide.

10. The method for preparing an ultra-thin stainless steel strip as claimed in claim 9, wherein the components of said rolling oil comprise vegetable oil and antioxidant, said antioxidant being linoleic acid.