A method for controlling the edge ridging of non-oriented silicon steel and the resulting non-oriented silicon steel

Abstract

The application provides a control method for edge ridging of non-oriented silicon steel and obtained non-oriented silicon steel, and comprises the following steps: sequentially performing rough rolling, finish rolling and coiling on a continuous casting billet to obtain non-oriented silicon steel; the continuous casting billet has an out-furnace temperature of 1050-1150 DEG C, the rough rolling has an outlet temperature of 950-1050 DEG C, the finish rolling has an inlet temperature of 950-1010 DEG C, the finish rolling has an outlet temperature of 860-880 DEG C, and the coiling has a temperature of 680-740 DEG C. The control method provided by the application controls the components of non-oriented silicon steel and the proportion between the components, the temperature of the continuous casting billet, the rough rolling temperature and the finish rolling temperature, so that the occurrence of the steel strip surface ridging phenomenon is avoided, the product quality is ensured, and the economic benefit is improved.

Description

Technical Field

[0001] This invention relates to the field of steel strip rolling technology, and in particular to a method for controlling edge rib formation in non-oriented silicon steel and the resulting non-oriented silicon steel. Background Technology

[0002] During the rolling process of non-oriented silicon steel, uneven temperature and stress can lead to uneven deformation of the strip, resulting in rib formation. Macroscopically, rib formation manifests as continuous strip-shaped ridges along the rolling direction, forming a straight ridge line. On the cross-sectional thickness curve of the strip, this appears as localized high points. Ribbing can cause product appearance and quality issues, leading to product downgrading and scrapping.

[0003] Currently, the relevant technologies for solving the problem of rib formation in non-oriented silicon steel mostly involve adjusting rolling parameters such as rolling force and rolling temperature to reduce the occurrence of rib formation. However, this method is not very effective and cannot completely avoid rib formation.

[0004] In summary, there is an urgent need for a method to control the edge reinforcement of non-oriented silicon steel and the resulting non-oriented silicon steel to solve the problems existing in the related technologies. Summary of the Invention

[0005] The main objective of this invention is to provide a method for controlling edge rib formation in non-oriented silicon steel and the resulting non-oriented silicon steel, so as to solve the technical problem that the related technologies are not effective and cannot completely avoid rib formation.

[0006] To achieve the above objectives, the present invention provides a method for controlling the edge reinforcement of non-oriented silicon steel, comprising the following steps:

[0007] The continuously cast billet is subjected to rough rolling, finish rolling and coiling in sequence to obtain non-oriented silicon steel; the continuous casting billet exit temperature is 1050-1150℃, the rough rolling exit temperature is 950-1050℃, the finish rolling inlet temperature is 950-1010℃, the finish rolling exit temperature is 860-880℃, and the coiling temperature is 680-740℃.

[0008] The composition of the continuously cast billet, by mass percentage, includes C<0.004%, S<0.006%, N<0.003%, Ti<0.003%, Cu<0.05%, Cr<0.05%, P<0.04%, Mn<0.03%, Al<0.35%, Si<0.85%, Ni<0.03%, As<0.03%, Mo<0.03%, Nb<0.03%, O<0.03%, and V<0.03%, with the balance being iron and unavoidable impurities.

[0009] Preferably, the finishing mill used in the finishing rolling step includes seven stands, F1-F7, the finishing rolling target wedge is -15 to 15 μm, and the finishing rolling target crown is 15-45 μm.

[0010] Preferably, in the finishing rolling step, the setting value of the shifting rolls for stands F1-F4 is 30-130mm, and the shifting rolls for other stands are set as free shifting rolls with equal spacing.

[0011] Preferably, the manual roll shifting value of the Fn stand in the finishing rolling step is set to N. n Its expression is as follows:

[0012] N n =b(W t -W0);

[0013] Where, N n This indicates the manual roll shifting value for frame Fn, where n ranges from 1, 2, and 3; W0 represents the standard width of the steel strip, W... t represents the width of the steel strip in batch t, ​​and b represents the learning parameter.

[0014] Preferably, the value of b is in the range of 0.1-0.35.

[0015] Preferably, the reduction rates of stands F1-F7 in the finishing rolling step range from 40-52%, 38-49%, 34-48%, 30-34%, 18-30%, 12-26%, and 10-20%, respectively.

[0016] Preferably, the threading speeds of stands F1-F7 in the finishing rolling step are 1.20-1.35 m / s, 2.20-2.50 m / s, 3.6-4.20 m / s, 6.20-7.00 m / s, 9.00-9.60 m / s, 11.50-12.50 m / s, and 13.20-14.30 m / s, respectively.

[0017] Preferably, the cooling water flow rate between the stands of the finishing mill is 140-160 m³ / h. 3 / h, the flow rate of the lower working roller is 160-180m³ / h. 3 / h.

[0018] Preferably, the thickness of the intermediate billet obtained in the roughing rolling step is 32-48 mm.

[0019] Preferably, laminar flow cooling is further included between the finishing rolling step and the coiling step. In the laminar flow cooling step, the cooling rate is 7-15℃ / s, the initial cooling temperature is 860-880℃, and the target cooling temperature is 680-740℃.

[0020] The beneficial effects of this invention are as follows:

[0021] By controlling the composition of non-oriented silicon steel and the ratio between the components, the continuous casting billet temperature, the rough rolling temperature, and the finishing rolling temperature, the occurrence of surface rib formation in the steel strip can be avoided, thereby ensuring product quality.

[0022] The present invention also provides a non-oriented silicon steel, which is manufactured according to the above control method, and the non-oriented silicon steel has a width of 1100-1250mm and a thickness of 2.5-2.75mm. Detailed Implementation

[0023] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0024] It should be noted that all directional indicators (such as up, down, etc.) in the embodiments of the present invention are only used to explain the relative positional relationship and movement of the components in a specific posture. If the specific posture changes, the directional indicator will also change accordingly.

[0025] Furthermore, in this invention, descriptions involving "first," "second," etc., are for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined with "first" or "second" may explicitly or implicitly include at least one of that feature.

[0026] Furthermore, the technical solutions of the various embodiments of the present invention can be combined with each other, but only if they are based on the ability of those skilled in the art to implement them. When the combination of technical solutions is contradictory or cannot be implemented, it should be considered that such combination of technical solutions does not exist and is not within the scope of protection claimed by the present invention.

[0027] During the research and development process, the inventors discovered that methods used in related technologies to control steel rib formation by adjusting rolling parameters such as rolling force and rolling temperature cannot completely prevent steel surface rib formation. Further research revealed that, in addition to the influence of rolling force and rolling temperature, the chemical composition of the steel and the wear condition of the equipment (such as grooves on the work roll surface caused by scratches) also significantly affect the formation of ribs. To better solve the problem of steel rib formation and manufacture steel products that are more favored by the market, the inventors propose the following solution based on their findings and existing relevant factors:

[0028] This invention provides a method for controlling the edge reinforcement of non-oriented silicon steel, comprising the following steps:

[0029] The continuously cast billet is subjected to rough rolling, finish rolling and coiling in sequence to obtain non-oriented silicon steel; the continuous casting billet exit temperature is 1050-1150℃, the rough rolling exit temperature is 950-1050℃, the finish rolling inlet temperature is 950-1010℃, the finish rolling exit temperature is 860-880℃, and the coiling temperature is 680-740℃.

[0030] The composition of the continuously cast billet, by mass percentage, includes C<0.004%, S<0.006%, N<0.003%, Ti<0.003%, Cu<0.05%, Cr<0.05%, P<0.04%, Mn<0.03%, Al<0.35%, Si<0.85%, Ni<0.03%, As<0.03%, Mo<0.03%, Nb<0.03%, O<0.03%, and V<0.03%, with the balance being iron and unavoidable impurities.

[0031] in:

[0032] C (carbon): As one of the main elements in steel, its main function is to enhance the yield strength and tensile strength of steel. However, as the carbon content increases, the plasticity and toughness of steel decrease. During rolling, steel with higher carbon content requires greater rolling force, resulting in greater wear on equipment and a greater likelihood of dents appearing on the surface of the work rolls. This can easily lead to rib formation on the steel surface. Therefore, in this application, the carbon content is controlled to be less than 0.004 wt%, thereby reducing equipment wear and improving the surface properties of the steel.

[0033] Silicon (Si): Belongs to the same group as carbon, and plays a similar role in steel. However, while a certain amount of silicon can increase the yield strength and tensile strength of steel, its impact on the plasticity and toughness is smaller than that of carbon. Therefore, in this application, the silicon content is controlled to be less than 0.85%.

[0034] Manganese (Mn): Manganese can form a solid solution with iron, increasing the hardness and strength of ferrite and austenite in steel. Furthermore, manganese is a good deoxidizer and desulfurizer. On one hand, it can form MnS with sulfur, preventing sulfur-induced hot brittleness and thus improving the hot working properties of steel. On the other hand, it can combine with oxygen to form a dense manganese dioxide layer. However, with increasing manganese content, the thermal conductivity of steel decreases sharply, and the coefficient of linear expansion increases, leading to significant internal stress during rapid heating or cooling, which can easily cause cracking. Therefore, in this application, the manganese content is controlled to be less than 0.03%. This allows for the chemical adsorption of sulfur to reduce hot brittleness while avoiding excessive manganese content that could lead to cracking. This also reduces equipment wear and the formation of ribs due to wear during the rolling process.

[0035] Phosphorus (P): Phosphorus has a strong solid solution strengthening and cold work hardening effect in steel. While phosphorus dissolves in ferrite and can improve the strength and hardness of steel, its greatest drawback is severe segregation, which increases temper brittleness and significantly reduces the plasticity and toughness of the steel. This makes the steel prone to brittle fracture during cold working, a phenomenon known as "cold brittleness." Phosphorus dissolved in the steel matrix increases the wear and tear on equipment and is a harmful element in steel; its content should be controlled below 0.04 wt%.

[0036] Nitrogen (N): Nitrogen is partially soluble in iron, providing solid solution strengthening and improving hardenability, though these effects are not significant. Due to the precipitation of nitrides at grain boundaries, it can improve the high-temperature strength of grain boundaries and increase the creep strength of steel, exhibiting precipitation hardening properties. Although nitrogen can increase the strength of steel, it is not conducive to reducing wear; therefore, nitrogen content is controlled below 0.003 wt%.

[0037] Cr (chromium): While chromium increases the hardenability and secondary hardening properties of steel, it also improves the hardness and wear resistance of steel without making it brittle. Therefore, as chromium content increases, the wear of equipment also increases; its content should be controlled below 0.05% wt.

[0038] Mo (Mo): It can form solid solutions or compounds with iron atoms in steel. Molybdenum makes the microstructure denser and refines and improves the uniform distribution of graphite. Molybdenum can refine pearlite, increase its content, and strengthen the ferrite in pearlite, thus effectively improving the strength, hardness, and wear resistance of the material. However, molybdenum is expensive and does not help with equipment wear, so Mo should be less than 0.03 wt%.

[0039] Ti, Nb, and V strengthen the steel through grain refinement, increasing its strength and resistance to deformation during rolling, thus increasing wear on the equipment. Therefore, the compositions were controlled at Ti < 0.003 wt%, Nb < 0.03 wt%, and V < 0.03 wt%, respectively. However, these compositions do not have a major impact on equipment wear.

[0040] This application controls the composition of non-oriented silicon steel and the ratio between the components, the continuous casting billet temperature, the rough rolling temperature, and the finish rolling temperature to avoid the occurrence of surface ribs in the steel strip, thereby ensuring product quality.

[0041] This application also sets a relatively high finishing rolling temperature (950-1010℃), which makes the steel strip after rough rolling have better plasticity, so that it can achieve better deformation under the action of the finishing mill during the finishing rolling process, and reduce the wear on the finishing mill.

[0042] In some embodiments, the finishing mill used in the finishing rolling step includes seven stands, F1-F7, and the finishing rolling target wedge is -15 to 15 μm; the finishing rolling target crown is 15-45 μm. It is worth noting that the finishing rolling target crown is different for different batches of non-oriented silicon steel. For example, in a specific embodiment, there are three batches of non-oriented silicon steel. The finishing rolling target crown of the first batch is 15-25 μm, the finishing rolling target crown of the second batch is 15-35 μm, and the finishing rolling target crown of the third batch is 15-45 μm. If the number of batches is greater than 3, then the finishing rolling target crown of the batches after the third batch is all 15-45 μm.

[0043] In some embodiments, the roll setting value for stands F1-F4 in the finishing rolling step is 30-130mm, and the roll setting for other stands is set as a free roll with equal spacing.

[0044] The roll shifting setting for F1-F4 is 30-130mm. One reason is to increase the roll shifting value to expand the range window of the roll shifting in the later stage based on the required crown. The other reason is that the manual roll shifting value is adjusted based on this roll shifting setting.

[0045] In some embodiments, the manual roll shifting value of the Fn stand in the finishing rolling step is set to N. n Its expression is as follows:

[0046] N n =b(W t -W0);

[0047] Where, N n This indicates the manual roll shifting value for frame Fn, where n ranges from 1, 2, and 3; W0 represents the standard width of the steel strip (1200mm), W... t represents the width of the steel strip in batch t, ​​and b represents the learning parameter.

[0048] This application adjusts the manual roller value according to the width of the steel strip, thereby meeting the production requirements of steel strips of different specifications and helping to solve the problem of steel plate rib formation.

[0049] In some embodiments, the value of b ranges from 0.1 to 0.35.

[0050] In some embodiments, the reduction rates of stands F1-F7 in the finishing rolling step range from 40-52%, 38-49%, 34-48%, 30-34%, 18-30%, 12-26%, and 10-20%, respectively.

[0051] In this application, the finishing mill used in the finishing rolling step is a 7-stand 4-high mill. By adjusting the reduction rate range of the F1-F7 stands, the reduction load is distributed to the front stands as much as possible. Therefore, although the wear of the front stands is increased, the wear of the rear stands is reduced. Even if the strip develops ribs due to surface defects of the work rolls of the front stands after rolling, the relatively smooth work rolls in the rear stands can smooth it out under the rolling force of the rear stands, so that the final product does not show any rib formation.

[0052] In some embodiments, the threading speeds of stands F1-F7 in the finishing rolling step are 1.20-1.35 m / s, 2.20-2.50 m / s, 3.6-4.20 m / s, 6.20-7.00 m / s, 9.00-9.60 m / s, 11.50-12.50 m / s, and 13.20-14.30 m / s, respectively.

[0053] When the speed difference is large, the friction is small. The lower the speed, the greater the friction, the more severe the wear on the equipment, and the less conducive it is to reducing rib formation. Therefore, the above speed range is selected to reduce friction, thereby reducing rib formation.

[0054] In some embodiments, the cooling water flow rate between the stands of the finishing mill, and the flow rate of the work rolls thereon, is 140-160 m³ / h. 3 / h, the flow rate of the lower working roller is 160-180m³ / h. 3 / h.

[0055] In some embodiments, the thickness of the intermediate billet obtained by the roughing rolling step is 32-48 mm.

[0056] In some embodiments, laminar flow cooling is further included between the finishing rolling step and the coiling step. The laminar flow cooling is a sparse cooling in the later stage (i.e., not all laminar cooling manifolds are working. For example, there are 16 groups of laminar cooling manifolds. The first 6 groups are all opened, and the last 10 groups of manifolds are cooled in a mode of opening one and closing two respectively). The cooling rate is 7-15℃ / s, the cooling start temperature is 860-880℃, and the cooling target temperature is 680-740℃.

[0057] This application achieves relatively uniform steel strip temperature within the same work roll rolling area by spraying water onto the surface of the steel strip undergoing finishing rolling. This avoids uneven steel strip temperature, which can lead to varying plasticity and localized high points during rolling, resulting in rib formation.

[0058] The present invention also provides a non-oriented silicon steel, which is manufactured according to the above control method, and the non-oriented silicon steel has a width of 1100-1250mm and a thickness of 2.5-2.75mm.

[0059] Example

[0060] The following embodiments describe the disclosure of this application in more detail. These embodiments are merely illustrative, as various modifications and variations will be apparent to those skilled in the art within the scope of the disclosure of this application. Unless otherwise stated, all parts, percentages, and ratios reported in the following embodiments are based on weight, and all reagents used in the embodiments are commercially available or synthesized by conventional methods and can be used directly without further processing, and the instruments used in the embodiments are commercially available.

[0061] Example 1

[0062] A method for controlling edge reinforcement of non-oriented silicon steel includes the following steps:

[0063] The continuously cast billet (240 mm thick) is subjected to rough rolling, finish rolling, laminar flow cooling, and coiling in sequence to obtain non-oriented silicon steel. The continuous casting billet exit temperature is 1150℃, the rough rolling exit temperature is 1050℃, the finish rolling inlet temperature is 1010℃, and the finish rolling exit temperature is 880℃. The laminar flow cooling is a sparse cooling in the later stage, with a cooling rate of 7-15℃ / s, a cooling start temperature of 880℃, a cooling target temperature of 680℃, and a coiling temperature of 680℃.

[0064] The composition of the continuously cast billet, by mass percentage, includes C<0.004%, S<0.006%, N<0.003%, Ti<0.003%, Cu<0.05%, Cr<0.05%, P<0.04%, Mn<0.03%, Al<0.35%, Si<0.85%, Ni<0.03%, As<0.03%, Mo<0.03%, Nb<0.03%, O<0.03%, and V<0.03%, with the balance being iron and unavoidable impurities; the composition of the non-oriented silicon steel is the same as that of the continuously cast billet, and the non-oriented silicon steel has a width of 1100 mm and a thickness of 2.5 mm.

[0065] In this embodiment, the finishing mill used in the finishing rolling step is a 7-stand 4-roll mill, including seven stands from F1 to F7. The finishing rolling target wedge is -15 to 15 μm, and the finishing rolling target crown is 15 to 25 μm.

[0066] In this embodiment, the roll setting value for stands F1-F4 in the finishing rolling step is 30-130mm, and the roll setting for other stands is set as a free roll with equal spacing.

[0067] In this embodiment, the manual roll shifting value of the Fn stand in the finishing rolling step is set to N. n Its expression is as follows:

[0068] N n =b(W t -W0);

[0069] Where, N n This indicates the manual roll shifting value for frame Fn, where n ranges from 1, 2, and 3; W0 represents the standard width of the steel strip (in this embodiment, the standard width of the steel strip is 1200mm), W t represents the width of the steel strip in batch t, ​​and b represents the learning parameter.

[0070] In this embodiment, the value of b is 0.1-0.35, which is calculated as 10-35mm by the above formula.

[0071] In this embodiment, the reduction rates of stands F1-F7 in the finishing rolling step range from 50%, 45%, 40%, 30%, 18%, 15%, and 10%, respectively.

[0072] In this embodiment, the threading speeds of stands F1-F7 in the finishing rolling step are 1.2m / s, 2.2m / s, 3.6m / s, 6.6m / s, 9.6m / s, 12.5m / s and 14.3m / s respectively.

[0073] In this embodiment, the cooling water flow rate of the interstand cooling water of the finishing mill, with the flow rate of the work rolls being 140-160 m³ / h. 3 / h, the flow rate of the lower working roller is 160-180m³ / h. 3 / h.

[0074] In this embodiment, the thickness of the intermediate billet obtained by the rough rolling step is 48 mm.

[0075] Examples 2-3 and Comparative Examples 1-2

[0076] The differences between Examples 2-3 and Comparative Examples 1-2 and Example 1 are in the chemical composition and process parameters. Other aspects not mentioned are the same as in Example 1. The differences in chemical composition are shown in Table 1, and the differences in process parameters are shown in Table 2.

[0077] Table 1. Differences in Chemical Components

[0078]

[0079] Table 2 Differences in process parameters

[0080]

[0081] The actual value of the skewed roller is the difference between the set value and the manual skewed roller value.

[0082] The rib height of the non-oriented silicon steel prepared in Examples 1-3 and Comparative Examples 1-2 was measured, and the results are shown in Table 3:

[0083] Table 3 Results of reinforcement height detection

[0084]

[0085]

[0086] As can be seen from the data in Table 3, the maximum rib height of the steel strip produced by this application is 0.08 mm, which meets the standard (rib height is less than 0.1 mm). However, when the selection of chemical composition or process parameters is not within the preferred range of this application, such as in Comparative Examples 1 and 2, the rib height of the steel strip produced does not meet the requirements.

[0087] Therefore, it can be seen that the method for controlling the edge reinforcement of non-oriented silicon steel provided in this application can effectively reduce the reinforcement height.

[0088] The above technical solutions of the present invention are merely preferred embodiments of the present invention and do not limit the patent scope of the present invention. All equivalent structural transformations made using the contents of the present invention under the technical concept of the present invention, or direct / indirect applications in other related technical fields, are included in the patent protection scope of the present invention.

Claims

1. A method of controlling the edge ridging of a non-oriented silicon steel characterized by, The method comprises the following steps: The continuous casting billet is sequentially subjected to rough rolling, finish rolling and coiling to obtain the non-oriented silicon steel; the continuous casting billet has a tapping temperature of 1050-1150℃, a rough rolling outlet temperature of 950-1050℃, a finish rolling inlet temperature of 950-1010℃, a finish rolling outlet temperature of 860-880℃ and a coiling temperature of 680-740℃; The continuous casting billet comprises, in percentage by mass, C<0.004%, S<0.006%, N<0.003%, Ti<0.003%, Cu<0.05%, Cr<0.05%, P<0.04%, Mn<0.03%, Al<0.35%, Si<0.85%, Ni<0.03%, As<0.03%, Mo<0.03%, Nb<0.03%, O<0.03% and V<0.03%, and the balance is iron and inevitable impurities; The finish rolling mill used in the finish rolling step comprises seven stands F1-F7, the finish rolling target wedge is -15-15μm, and the finish rolling target crown is 15-45μm. The strip passing speeds of the stands F1-F7 in the finish rolling step are 1.20-1.35m / s, 2.20-2.50m / s, 3.6-4.20m / s, 6.20-7.00m / s, 9.00-9.60m / s, 11.50-12.50m / s and 13.20-14.30m / s, respectively.

2. The control method according to claim 1, characterized by, Different batches of the non-oriented silicon steel correspond to different finish rolling target crowns; at least three batches are included, the finish rolling target crown of the first batch is 15-25μm, the finish rolling target crown of the second batch is 15-35μm, and the finish rolling target crown of the third batch and subsequent batches is 15-45μm.

3. The control method according to claim 1, characterized by, The roll shifting set values of the stands F1-F4 in the finish rolling step are all 30-130mm, and the roll shifting of the other stands is set to equal pitch free roll shifting.

4. The control method according to claim 3, characterized by The manual roll shifting value of the Fn rack in the finishing step is set as N n The expression is as follows: N n = b(W t -W0); wherein N n represents the manual roll shifting value of the Fn rack, n is in the range of 1, 2 and 3; W0 represents the standard width of the steel strip, W t represents the width of the t-th batch of steel strip, b represents a learning parameter.

5. The control method according to claim 4, characterized by The value range of b is 0.1-0.

35.

6. The control method according to claim 1, characterized by The reduction ranges of the stands F1-F7 in the finish rolling step are 40-52%, 38-49%, 34-48%, 30-34%, 18-30%, 12-26% and 10-20%, respectively.

7. The control method according to claim 1, characterized by, The inter-stand cooling water of the finishing mill has a flow rate of 140-160 m 3 / h for the upper work roll and 160-180 m 3 / h for the lower work roll.

8. The control method according to claim 1, characterized by, The thickness of the intermediate billet obtained in the rough rolling step is 32-48mm.

9. A non-oriented silicon steel characterized by, The non-oriented silicon steel prepared by the control method of any one of claims 1-8 has a width of 1100-1250mm and a thickness of 2.5-2.75mm.

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