Calculation method for tearing degree of silicon dioxide bottom layer of low-temperature copper-containing oriented silicon steel

Abstract

The invention discloses a method for calculating the tearing degree of a silicon dioxide bottom layer of low-temperature copper-containing oriented silicon steel. The calculation method comprises the following steps: carrying out hot rolling, primary cold rolling and decarburization annealing on an oriented silicon steel plate to obtain an annealed plate, and carrying out secondary cold rolling on the annealed plate under different rolling tensions to obtain oriented silicon steel subjected to secondary cold rolling; measuring the tearing ratio of the oriented silicon steel subjected to secondary cold rolling; establishing a relational expression between the rolling tension and the tearing ratio; and according to the rolling tension of secondary cold rolling, the tearing ratio of the corresponding rolling tension is calculated through the relational expression, and the tearing degree of the silicon dioxide bottom layer of the oriented silicon steel is obtained. The calculation method is simple in principle and convenient to operate, and realizes rapid and accurate prediction of the tearing degree of the silicon dioxide bottom layer of the low-temperature copper-containing oriented silicon steel.

Description

Technical Field

[0001] The invention relates to the technical field of oriented silicon steel manufacturing, and in particular to a method for calculating the tearing degree of a silicon dioxide bottom layer of low-temperature copper-containing oriented silicon steel. Background Art

[0002] The production process of traditional low-temperature copper-containing oriented silicon steel is hot rolling → primary cold rolling → decarburization annealing → secondary cold rolling → high-temperature annealing → coating of insulating layer. During the decarburization annealing process, silicon reacts with oxygen on the surface of the silicon steel to form a silicon dioxide film, which reacts with magnesium oxide coated on the surface of the strip during the subsequent high-temperature annealing process to form a magnesium silicate bottom layer, which plays a role in insulation and reducing iron loss. In the traditional low-temperature copper-containing oriented silicon steel process, secondary cold rolling is performed after decarburization annealing. Due to the large difference in the elastic modulus between silicon dioxide and the silicon steel matrix, the secondary cold rolling causes the silicon dioxide layer to tear or even fall off to varying degrees. The tearing and falling behavior will be inherited to the formation of the magnesium silicate bottom layer in the high-temperature annealing, resulting in imperfect formation of the magnesium silicate bottom layer, poor insulation on the surface of the finished product, and even crystal defects, which make it impossible to cover the matrix and affect the performance of the finished product.

[0003] At present, there are few studies on the problem of bottom layer tearing. On the one hand, there is no relevant research on the specific reasons for the tearing of the silica layer caused by rolling; on the other hand, the degree of bottom layer tearing can only be judged by sampling and observation after the second cold rolling, which has a lag and cannot be remedied, resulting in a waste of economic costs. For the problem of repairing the bottom layer tearing of silica, the conventional solution internationally is to add a low-temperature hydrogenation process to repair the silica layer, which increases time and economic costs. Summary of the invention

[0004] In view of the deficiencies of the prior art, the present invention provides a method for calculating the tearing degree of the bottom layer of silica in low-temperature copper-oriented silicon steel. The present invention constructs a method for calculating the tearing degree of the bottom layer of silica in low-temperature copper-oriented silicon steel, and can directly calculate the tearing degree under the corresponding rolling tension using a calculation formula, without the need for sampling verification, saving time and process costs, and improving production speed, thereby achieving a rapid and accurate prediction of the tearing degree of the bottom layer of silica in low-temperature copper-oriented silicon steel, and reflecting the quality of the bottom layer of silica by calculating the tearing degree, which has the advantages of simple principle, convenient operation and wide application.

[0005] The technical solution of the present invention is as follows:

[0006] A method for calculating the tearing degree of silicon dioxide bottom layer of low-temperature copper-containing oriented silicon steel comprises the following steps:

[0007] (1) hot rolling, primary cold rolling, and decarburization annealing are performed on the oriented silicon steel sheet to obtain an annealed sheet, and the annealed sheet is subjected to secondary cold rolling under different rolling tensions to obtain oriented silicon steel after secondary cold rolling;

[0008] (2) Determine the tear ratio of oriented silicon steel after secondary cold rolling;

[0009] (3) Establish the relationship between rolling tension and tearing ratio;

[0010] (4) According to the rolling tension of the secondary cold rolling, the tearing ratio corresponding to the rolling tension is calculated by the relationship obtained in step (3), that is, the tearing degree of the silicon dioxide bottom layer of the oriented silicon steel is obtained.

[0011] Furthermore, in step (1), the raw material of the oriented silicon steel sheet contains the following components in mass fraction: C: 0.04-0.08%; Si: 2.8-3.2%; Mn: 0.15-0.20%; S: 0.01-0.03%; Als: 0.02-0.03%; N: 0.006-0.010%; Cu: 0.4-0.6%; and the rest is Fe and unavoidable impurities.

[0012] Furthermore, in step (1), the rolling tension of the secondary cold rolling is 2.5 to 100 kN.

[0013] Furthermore, in step (1), the secondary cold rolling is performed in a number of passes ranging from 1 to 5.

[0014] Furthermore, when the rolling passes are 2-5, the rolling tension of each rolling is the same.

[0015] Furthermore, in step (1), the reduction ratio of the secondary cold rolling is 19.69-60.61%.

[0016] Furthermore, in step (1), the rolling force of the secondary cold rolling is 200-500 kN.

[0017] Furthermore, in step (2), the tearing ratio is calculated by photographing the bottom layer of the oriented silicon steel after secondary cold rolling under a microscope and using Image J software.

[0018] Furthermore, in step (3), the relationship is as follows:

[0019] y=-5E -5 x 3 +0.0027x 2 -0.0207x+0.0502;

[0020] Where: x represents the rolling tension, unit is kN, y represents the bottom layer tearing ratio, unit is %.

[0021] The beneficial technical effects of the present invention are:

[0022] Based on the research on the secondary cold rolling process in the production process of low-temperature copper-containing oriented silicon steel, the present invention innovatively proposes a calculation method for accurately predicting the degree of tearing of the silica bottom layer of oriented silicon steel after secondary cold rolling by pre-setting the rolling tension. The calculation method is simple and highly reliable, which provides a solid theoretical basis for formulating the secondary cold rolling process parameters and significantly reduces the risk of improper selection of process parameters due to human misjudgment, thereby causing severe tearing of the silica layer.

[0023] Compared with the cumbersome process of the traditional process that relies on sampling and observation after secondary cold rolling, and then adopting low-temperature hydrogenation to repair the silica bottom layer, the present invention uses the relationship between rolling tension and tearing ratio to directly guide the adjustment of the secondary cold rolling process to ensure excellent bottom layer quality. This innovation not only avoids the cost and time waste caused by additional processes and improves production efficiency, but also demonstrates the significant advantages of simple principle, easy operation and wide applicability. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 The electron microscope images are of the annealed sheet after decarburization annealing and the oriented silicon steel sheet after secondary cold rolling according to Example 1 of the present invention. DETAILED DESCRIPTION

[0025] The present invention will be described in detail below in conjunction with the embodiments.

[0026] The raw materials of the oriented silicon steel sheet of the present invention contain the following components in mass fraction: C: 0.04-0.08%; Si: 2.8-3.2%; Mn: 0.15-0.20%; S: 0.01-0.03%; Als: 0.02-0.03%; N: 0.006-0.010%; Cu: 0.4-0.6%; the rest are Fe and inevitable impurities.

[0027] The oriented silicon steel sheets described in the following embodiments were purchased from Lian Steel. The oriented silicon steel sheets were sampled and tested. The raw materials contained the following components in mass fraction: C: 0.05%; Si: 3.16%; Mn: 0.17%; S: 0.01%; Als: 0.02%; N: 0.007%; Cu: 0.43% and the rest were Fe and unavoidable impurities.

[0028] The hot rolling described in the following embodiments is specifically: rough rolling followed by finish rolling, the rough rolling temperature is 1100-1250°C, and the finish rolling temperature is 850-1100°C; the thickness of the cold-rolled sheet obtained by the one cold rolling is 0.60-0.65mm; the decarburization annealing described in the following embodiments is to reduce the carbon content to within 50ppm, and the oxygen content is controlled at 500-900ppm.

[0029] The relationship between rolling tension and tearing ratio in the present invention is y=-5E -5 x3 +0.0027x 2 -0.0207x+0.0502 is based on the study of various parameters of the secondary cold rolling rolling process in the production of low-temperature copper-containing oriented silicon steel plates. The degree of silica layer tearing is used as the evaluation basis, and it is concluded that the rolling tension in the secondary cold rolling is the main cause of the bottom layer tearing. The relationship between the rolling tension and the degree of silica layer tearing is further fitted, so the proportion of bottom layer tearing can be calculated by given tension, which provides a theoretical basis for the formulation of rolling technology and greatly reduces the problem of silica layer tearing caused by poor selection of rolling process parameters due to subjective judgment.

[0030] The present invention provides a method for calculating the tearing degree of the silicon dioxide bottom layer of low-temperature copper-containing oriented silicon steel, and the calculation method comprises:

[0031] (1) After hot rolling, primary cold rolling and decarburization annealing, the oriented silicon steel sheet is obtained as an annealed sheet, and the oriented silicon steel sheet is subjected to secondary cold rolling in a rolling tension range of 2.5 to 100 kN (sample size > 1000). During the secondary cold rolling process, the rolling passes, reduction ratio and rolling force of each oriented silicon steel sheet are controlled to be the same, and the oriented silicon steel sheets after secondary cold rolling under different rolling tensions are obtained.

[0032] (2) Cutting the oriented silicon steel sheet obtained after secondary cold rolling in step (1), cutting 3-5 samples from each oriented silicon steel sheet, rinsing with alcohol, and drying for later use.

[0033] (3) A metallographic microscope was used to take photos of the tearing degree of the silica bottom layer of each sample obtained in step (2) at a magnification of 200 times, and the tearing ratio of each sample was calculated using Image J software. The rolling tension and the tearing ratio were fitted by a third-order polynomial in EXCEL, thereby establishing a relationship between the rolling tension and the tearing ratio, as shown in the following formula:

[0034] y=-5E -5 x 3 +0.0027x 2 -0.0207x+0.0502;

[0035] Where: x represents the rolling tension, unit is kN, y represents the bottom layer tearing ratio, unit is %.

[0036] (4) After hot rolling, primary cold rolling and decarburization annealing, the oriented silicon steel sheet is obtained as an annealed sheet, and the oriented silicon steel sheet is subjected to secondary cold rolling in the range of 1-5 rolling passes (sample size > 1000). During the secondary cold rolling process, the rolling tension, reduction rate and rolling force of each oriented silicon steel sheet are controlled to be the same, and the oriented silicon steel sheets after secondary cold rolling under different rolling passes are obtained.

[0037] (5) Cutting the oriented silicon steel sheet after secondary cold rolling obtained in step (4), cutting 3-5 samples from each oriented silicon steel sheet, rinsing with alcohol, and drying for later use.

[0038] (6) A metallographic microscope was used to take photos of the tearing degree of the silica bottom layer of each sample obtained in step (5) at a magnification of 200 times, and the tearing ratio of each sample was calculated using Image J software. The results showed that the tearing degree of the silica bottom layer of the oriented silicon steel sheet was not related to the rolling pass of the secondary cold rolling.

[0039] (7) The oriented silicon steel sheet is subjected to hot rolling, primary cold rolling, and decarburization annealing to obtain an annealed sheet, and the oriented silicon steel sheet is subjected to secondary cold rolling within a reduction ratio range of 19.69% to 60.61% (sample size > 1000). During the secondary cold rolling process, the rolling tension, rolling passes, and rolling force of each oriented silicon steel sheet are controlled to be the same, and the oriented silicon steel sheets after secondary cold rolling at different reduction ratios are obtained.

[0040] (8) Cut the oriented silicon steel sheet obtained after secondary cold rolling in step (7), cut 3-5 samples from each oriented silicon steel sheet, rinse with alcohol, and blow dry for later use.

[0041] (9) The tearing degree of the silica bottom layer of each sample obtained in step (8) was photographed by a metallographic microscope at a magnification of 200 times, and the tearing ratio of each sample was calculated using Image J software. The results showed that the tearing degree of the silica bottom layer of the oriented silicon steel sheet was not related to the reduction rate of the secondary cold rolling.

[0042] (10) The oriented silicon steel sheet is subjected to hot rolling, primary cold rolling, and decarburization annealing to obtain an annealed sheet, and the oriented silicon steel sheet is subjected to secondary cold rolling within a rolling force range of 200-500 kN (sample size > 1000). During the secondary cold rolling process, the rolling tension, rolling pass number, and reduction ratio of each oriented silicon steel sheet are controlled to be the same, and the oriented silicon steel sheets after secondary cold rolling under different rolling forces are obtained.

[0043] (11) Cut the oriented silicon steel sheet obtained after secondary cold rolling in step (10), cut 3-5 samples from each oriented silicon steel sheet, rinse with alcohol, and blow dry for later use.

[0044] (12) The tearing degree of the silica bottom layer of each sample obtained in step (11) was photographed by a metallographic microscope at a magnification of 200 times, and the tearing ratio of each sample was calculated using Image J software. The results showed that the tearing degree of the silica bottom layer of the oriented silicon steel sheet was not related to the rolling force of the secondary cold rolling.

[0045] Through the above steps (1) to (12), the tearing degree of the silicon dioxide layer is used as an evaluation basis. The present invention obtains a method for calculating the tearing degree of the silicon dioxide bottom layer of low-temperature copper-containing oriented silicon steel, so that the tearing degree under the corresponding rolling tension can be directly calculated using a formula without the need for sampling verification, thereby providing scientific guidance for the process control of secondary cold rolling of low-temperature copper-containing oriented silicon steel and improving production efficiency and yield rate.

[0046] Example 1

[0047] A method for calculating the tearing degree of silicon dioxide bottom layer of low-temperature copper-containing oriented silicon steel comprises the following steps:

[0048] (1) The oriented silicon steel sheet is subjected to hot rolling, primary cold rolling, and decarburization annealing to make the carbon content of the oriented silicon steel sheet less than 30 ppm, thereby obtaining an annealed sheet. A piece of oriented silicon steel decarburization annealed sheet with a size of 600×100×0.635 mm (length×width×thickness, with the long side along the rolling direction) is taken as the secondary cold rolling object, and three passes of rolling are performed using a twenty-roll cold rolling mill.

[0049] Among them, the roll gap of the first rolling pass is 0.6mm, and the rolling force is 128kN; the roll gap of the second rolling pass is 0.5mm, and the rolling force is 306kN; the roll gap of the third rolling pass is 0.4mm, and the rolling force is 375kN.

[0050] The rolling tension for each rolling pass is 12kN.

[0051] The decarburized annealed silicon steel sheet is subjected to secondary cold rolling to obtain a secondary cold rolled oriented silicon steel sheet.

[0052] (2) According to the rolling tension of secondary cold rolling, substitute into the following formula:

[0053] y=-5E -5 x 3 +0.0027x 2 -0.0207x+0.0502

[0054] Where: x represents the rolling tension, unit kN, y represents the bottom layer tearing ratio, unit %;

[0055] The theoretical value of the tearing degree of the oriented silicon steel sheet after secondary cold rolling in this embodiment is calculated to be 10.42%.

[0056] The annealed sheet after decarburization annealing and the oriented silicon steel sheet after secondary cold rolling in this embodiment were sampled and the surface morphology was examined by electron microscope. The results are as follows: Figure 1 As shown. Figure 1The results show that a uniform and dense silicon dioxide film is formed on the surface of the oriented silicon steel sheet after decarburization annealing. After secondary cold rolling, the silicon dioxide film on the surface of the oriented silicon steel sheet is cracked, forming a series of tearing cracks.

[0057] Embodiment 2-4

[0058] The calculation method of Example 2-4 is basically the same as that of Example 1, the only difference is that the rolling tension in step (1) of Example 2-4 is 11 kN, 10 kN, and 9 kN respectively, and the rest of the contents remain unchanged.

[0059] After calculation, the theoretical values ​​of the tearing degree of the oriented silicon steel sheets after secondary cold rolling in Examples 2-4 are 8.27%, 6.32% and 4.62% respectively.

[0060] Example 5

[0061] A method for calculating the tearing degree of silicon dioxide bottom layer of low-temperature copper-containing oriented silicon steel comprises the following steps:

[0062] (1) The oriented silicon steel sheet is subjected to hot rolling, primary cold rolling, and decarburization annealing to make the carbon content of the oriented silicon steel sheet less than 30 ppm, thereby obtaining an annealed sheet. A piece of oriented silicon steel decarburization annealed sheet with a size of 600×100×0.635 mm (length×width×thickness, with the long side along the rolling direction) is taken as the secondary cold rolling object, and three passes of rolling are performed using a twenty-roll cold rolling mill.

[0063] Among them, the roll gap of the first rolling pass is 0.6mm, and the rolling force is 137kN; the roll gap of the second rolling pass is 0.5mm, and the rolling force is 286kN; the roll gap of the third rolling pass is 0.4mm, and the rolling force is 390kN.

[0064] The rolling tension for each rolling pass is 8kN.

[0065] The decarburized annealed silicon steel sheet is subjected to secondary cold rolling to obtain a secondary cold rolled oriented silicon steel sheet.

[0066] (2) According to the rolling tension of secondary cold rolling, substitute into the following formula:

[0067] y=-5E -5 x 3 +0.0027x 2 -0.0207x+0.0502

[0068] Where: x represents the rolling tension, unit kN, y represents the bottom layer tearing ratio, unit %;

[0069] The theoretical value of the tearing degree of the oriented silicon steel sheet after secondary cold rolling in this embodiment is calculated to be 3.18%.

[0070] Embodiment 6-8

[0071] The calculation method of Example 6-8 is basically the same as that of Example 5, the only difference is that the rolling tension in step (1) of Example 6-8 is 7kN, 6kN, and 5kN respectively, and the rest of the contents remain unchanged.

[0072] After calculation, the theoretical values ​​of the tearing degree of the oriented silicon steel sheets after secondary cold rolling in Examples 6-8 are 2.05%, 1.24% and 0.80% respectively.

[0073] Example 9

[0074] A method for calculating the tearing degree of silicon dioxide bottom layer of low-temperature copper-containing oriented silicon steel comprises the following steps:

[0075] (1) The oriented silicon steel sheet is subjected to hot rolling, primary cold rolling, and decarburization annealing to make the carbon content of the oriented silicon steel sheet less than 30 ppm, thereby obtaining an annealed sheet. A piece of oriented silicon steel decarburization annealed sheet with a size of 600×100×0.635 mm (length×width×thickness, with the long side along the rolling direction) is taken as the secondary cold rolling object, and a twenty-roller cold rolling mill is used to perform one pass rolling.

[0076] Among them, the roll gap is 0.2mm, the rolling force is 520kN, and the rolling tension is 12kN.

[0077] Performing secondary cold rolling on the decarburized annealed silicon steel sheet to obtain a secondary cold rolled oriented silicon steel sheet;

[0078] (2) According to the rolling tension of secondary cold rolling, substitute into the following formula:

[0079] y=-5E -5 x 3 +0.0027x 2 -0.0207x+0.0502

[0080] Where: x represents the rolling tension, unit kN, y represents the bottom layer tearing ratio, unit %;

[0081] The theoretical value of the tearing degree of the oriented silicon steel sheet after secondary cold rolling in this embodiment is calculated to be 10.42%.

[0082] Embodiment 10-11

[0083] The calculation method of Example 10-11 is basically the same as that of Example 9, the only difference is that the rolling passes in step (1) of Example 10-11 are 2 passes and 3 passes respectively, and the rest of the contents remain unchanged.

[0084] After calculation, the theoretical values ​​of the tearing degree of the oriented silicon steel sheets after secondary cold rolling in Examples 10-11 are 10.42% and 10.42% respectively.

[0085] Example 12

[0086] A method for calculating the tearing degree of silicon dioxide bottom layer of low-temperature copper-containing oriented silicon steel comprises the following steps:

[0087] (1) The oriented silicon steel sheet is subjected to hot rolling, primary cold rolling, and decarburization annealing to make the carbon content of the oriented silicon steel sheet less than 30 ppm, thereby obtaining an annealed sheet. A piece of oriented silicon steel decarburization annealed sheet with a size of 600×100×0.635 mm (length×width×thickness, with the long side along the rolling direction) is taken as the secondary cold rolling object, and a twenty-roller cold rolling mill is used to perform one pass rolling.

[0088] Among them, the roll gap is 0.5mm (that is, the reduction rate is 21.3%), the rolling force is 316kN, and the rolling tension is 12kN.

[0089] The decarburized annealed silicon steel sheet is subjected to secondary cold rolling to obtain a secondary cold rolled oriented silicon steel sheet.

[0090] (2) According to the rolling tension of secondary cold rolling, substitute into the following formula:

[0091] y=-5E -5 x 3 +0.0027x 2 -0.0207x+0.0502

[0092] Where: x represents the rolling tension, unit kN, y represents the bottom layer tearing ratio, unit %;

[0093] The theoretical value of the tearing degree of the oriented silicon steel sheet after secondary cold rolling in this embodiment is calculated to be 10.42%.

[0094] Embodiment 13

[0095] The calculation method of Example 13 is basically the same as that of Example 12, except that the roll gap in step (1) of Example 13 is 0.4 mm (i.e., the reduction rate is 37.0%), the rolling force is 377 kN, and the rest of the contents remain unchanged.

[0096] The theoretical value of the tearing degree of the oriented silicon steel sheet after secondary cold rolling in this embodiment is calculated to be 10.42%.

[0097] Embodiment 14

[0098] The calculation method of Example 14 is basically the same as that of Example 12, except that the roll gap in step (1) of Example 14 is 0.3 mm (i.e., the reduction rate is 52.8%), the rolling force is 420 kN, and the rest of the contents remain unchanged.

[0099] The theoretical value of the tearing degree of the oriented silicon steel sheet after secondary cold rolling in this embodiment is calculated to be 10.42%.

[0100] Embodiment 15

[0101] A method for calculating the tearing degree of silicon dioxide bottom layer of low-temperature copper-containing oriented silicon steel comprises the following steps:

[0102] (1) The oriented silicon steel sheet is subjected to hot rolling, primary cold rolling, and decarburization annealing to make the carbon content of the oriented silicon steel sheet less than 30 ppm, thereby obtaining an annealed sheet. A piece of oriented silicon steel decarburization annealed sheet with a size of 600×100×0.635 mm (length×width×thickness, with the long side along the rolling direction) is taken as the secondary cold rolling object, and a twenty-roller cold rolling mill is used to perform one pass rolling.

[0103] Among them, the roll gap is 0.6mm, the rolling force is 250kN, and the rolling tension is 12kN.

[0104] The decarburized annealed silicon steel sheet is subjected to secondary cold rolling to obtain a secondary cold rolled oriented silicon steel sheet.

[0105] (2) According to the rolling tension of secondary cold rolling, substitute into the following formula:

[0106] y=-5E -5 x 3 +0.0027x 2 -0.0207x+0.0502

[0107] Where: x represents the rolling tension, unit kN, y represents the bottom layer tearing ratio, unit %;

[0108] The theoretical value of the tearing degree of the oriented silicon steel sheet after secondary cold rolling in this embodiment is calculated to be 10.42%.

[0109] Examples 16-17

[0110] The calculation method of Example 16 is basically the same as that of Example 15, the only difference is that the rolling force in step (1) of Example 16 is 350 kN, the roll gap is 0.5 mm, and the rest of the contents remain unchanged.

[0111] The calculation method of Example 17 is basically the same as that of Example 15, the only difference is that the rolling force in step (1) of Example 17 is 450 kN, the roll gap is 0.3 mm, and the rest of the contents remain unchanged.

[0112] After calculation, the theoretical values ​​of the tearing degree of the oriented silicon steel sheets after secondary cold rolling in Examples 16-17 are 10.42% and 10.42%, respectively.

[0113] Test Case

[0114] Take the oriented silicon steel sheet after secondary cold rolling obtained in step (1) of Example 1-17 of the present invention, and cut each oriented silicon steel sheet from the edge to different positions of the center along the width direction of the sheet, and cut 3-5 samples with a length and width of 10 mm in each group. After rinsing with alcohol, blow dry and set aside, and then take pictures of the tearing degree of the silicon dioxide bottom layer of each sample under a metallographic microscope at a magnification of 200 times, and use Image J software to calculate the actual value of the tearing ratio of each sample. The results are shown in Table 1.

[0115] Table 1

[0116]

[0117] From the results in Table 1, it can be seen that the theoretical value of the tearing ratio of the oriented silicon steel sheet after secondary cold rolling calculated by the formula of the present invention is within 10% of the actual value, indicating that the fitted formula y=-5E -5 x 3 +0.0027x 2 -0.0207x+0.0502 can accurately predict the degree of bottom layer tearing of oriented silicon steel sheets after secondary cold rolling. At the same time, it can be seen from the results of Examples 1-8 that the degree of bottom layer tearing of oriented silicon steel sheets after secondary cold rolling is related to the rolling tension; it can be seen from the results of Examples 9-11 that the degree of bottom layer tearing of oriented silicon steel sheets after secondary cold rolling is independent of the rolling pass; it can be seen from the results of Examples 12-14 that the degree of bottom layer tearing of oriented silicon steel sheets after secondary cold rolling is independent of the rolling reduction rate; it can be seen from the results of Examples 15-17 that the degree of bottom layer tearing of oriented silicon steel sheets after secondary cold rolling is independent of the rolling force. In summary, the method for calculating the degree of bottom layer tearing of silica in low-temperature copper-containing oriented silicon steel provided by the present invention can calculate the proportion of bottom layer tearing by given tension, thereby accurately predicting the degree of bottom layer tearing of oriented silicon steel sheets after secondary cold rolling, avoiding the process of repairing the bottom layer of silica after tearing, improving production efficiency, and providing a theoretical basis for the formulation of the rolling process of secondary cold rolling in industrial production, which greatly reduces the poor selection of rolling process parameters that may be caused by subjective judgment, resulting in the problem of silica layer tearing. Compared with the conventional method of repairing the silicon dioxide bottom layer by adding a low-temperature hydrogenation process, the present invention can adjust the tension on the original process through an empirical equation to obtain excellent bottom layer quality, saving time and process costs, and has the advantages of simple principle, convenient operation and wide application.

[0118] The above is only a preferred embodiment of the present invention, and the present invention is not limited to the above embodiments. It is understood that other improvements and changes directly derived or associated by those skilled in the art without departing from the spirit and concept of the present invention should be considered to be included in the protection scope of the present invention.

Claims

1. A method for calculating the tearing degree of the silicon dioxide bottom layer of low-temperature copper-containing oriented silicon steel, characterized in that: The steps include: (1) hot rolling, primary cold rolling, and decarburization annealing are performed on the oriented silicon steel sheet to obtain an annealed sheet, and the annealed sheet is subjected to secondary cold rolling under different rolling tensions to obtain oriented silicon steel after secondary cold rolling; (2) Determine the tear ratio of oriented silicon steel after secondary cold rolling; (3) Establish the relationship between rolling tension and tearing ratio; (4) According to the rolling tension of the secondary cold rolling, the tearing ratio corresponding to the rolling tension is calculated by the relationship obtained in step (3), that is, the tearing degree of the silicon dioxide bottom layer of the oriented silicon steel is obtained.

2. The calculation method according to claim 1, characterized in that: In step (1), the raw material of the oriented silicon steel sheet contains the following components by mass fraction: C: 0.04-0.08%; Si: 2.8-3.2%; Mn: 0.15-0.20%; S：0.01-0.03％； Als: 0.02-0.03%; N: 0.006-0.010%; Cu: 0.4-0.6%; the rest is Fe and inevitable impurities.

3. The calculation method according to claim 1, characterized in that: In step (1), the rolling tension of the secondary cold rolling is 2.5 to 100 kN.

4. The calculation method according to claim 1, characterized in that: In step (1), the secondary cold rolling is performed in a number of passes ranging from 1 to 5.

5. The calculation method according to claim 4, characterized in that: When the rolling passes are 2-5 times, the rolling tension is the same for each rolling.

6. The calculation method according to claim 1, characterized in that: In step (1), the reduction ratio of the secondary cold rolling is 19.69-60.61%.

7. The calculation method according to claim 1, characterized in that: In step (1), the rolling force of the secondary cold rolling is 200-500 kN.

8. The calculation method according to claim 1, characterized in that: In step (2), the tearing ratio is calculated by photographing the bottom layer of the oriented silicon steel after secondary cold rolling under a microscope and using Image J software.

9. The calculation method according to claim 1, characterized in that: In step (3), the relationship is as follows: y=-5E -5 x 3 +0.0027x 2 -0.0207x+0.0502; Where: x represents the rolling tension, unit is kN, y represents the bottom layer tearing ratio, unit is %.

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