Method for starting hot rolling of non-oriented silicon steel

Abstract

The embodiment of the application provides a hot rolling method of non-oriented silicon steel, and relates to the field of silicon steel hot rolling. The existing opening rolling material and the large temperature deviation of the subsequent silicon steel furnace gas and the vacancy problem are improved. The steel grade of the opening rolling material is X1300, X800 or X600, the control rolling thickness is 2.95mm or 2.75mm, the control rough rolling rolling pass is R1-3 passes, R2-5 passes, the intermediate blank thickness is 42mm, the control finishing rolling parameter is that the threading speed is 6-7m / s, the roll shifting value is F1-30, F2-20, the load distribution is F1-43, F2-38, F3-34, F4-23, F5-18, F6-14 and F7-10. Since the opening rolling material and the subsequent silicon steel are both silicon steels, the furnace gas temperature difference is small, and there is no need to have a vacancy, and the two-stage opening rolling strategy of X1300 is specially made to solidify the parameters, so that the opening rolling stability is enhanced.

Description

Technical Field

[0001] This invention relates to the field of hot rolling of silicon steel, and more specifically, to a method for hot rolling non-oriented silicon steel. Background Technology

[0002] The existing hot-rolled stock, namely the first and second pieces after the finishing mill roll change, is made of SPHC-1CAL and Q235B steel. Since these two steel grades can be rolled to a relatively thick thickness and are low-carbon steels, the finishing mill roll-out is relatively stable. Generally, 3-4 pieces of SPHC-1CAL / Q235B are rolled before silicon steel X800 / X600 / X470. The specific special processes are as follows: 1) For unrolled stock, non-silicon steel must have a clearance of ≥3 meters between it and silicon steel; 2) After unrolled stock enters the secondary furnace, the secondary furnace temperature should be controlled at 1200±20℃; after silicon steel enters the secondary furnace, the secondary furnace temperature should be controlled at 1180±20℃. After the unrolled stock completes the current section, the furnace gas temperature should be controlled according to the silicon steel process document requirements; 3) After unrolled stock enters the homogenizer, the homogenizer temperature should be controlled at 1180±20℃; after silicon steel enters the homogenizer, the homogenizer temperature should be controlled at 1160±20℃. After the unrolled stock completes the current section, the furnace gas temperature should be controlled according to the silicon steel process document requirements; 4) High-grade silicon steel, such as X350, X350D, X300, and X250, must be scheduled after the 15th batch in the planning stage; after high-grade silicon steel enters the furnace, the furnace gas temperature must be strictly controlled according to the high-grade silicon steel process requirements to avoid burn-out.

[0003] The biggest problem is: Question 1: The open-rolled steel grades SPHC-1CAL and Q235B have significantly different furnace gas temperatures compared to the subsequent silicon steel X800 / X600 / X470, and their heating process trends are opposite. For silicon steel, the temperature decreases from the initial heating temperature to the soaking temperature, while for open-rolled steel grades SPHC-1CAL and Q235B, the temperature increases. For example, the furnace exit temperature of open-rolled steel grades SPHC-1CAL and Q235B is 1220-1230℃, while that of silicon steel is 1110-1120℃, a difference of approximately 100℃. Furthermore, silicon steel requires very strict control of the furnace gas temperature; excessively high temperatures can lead to excessive iron loss and problems with magnetic properties.

[0004] Question 2: Because the thickness, width, and steel grade of the raw material for open rolling cannot be fixed, some parameters of the raw material cannot be standardized. Furthermore, due to the need to consider the furnace gas temperature of silicon steel, rolling marks, wear, damage, and even steel piling frequently occur during finishing rolling. For example, the composition contains C: 0.02-0.25%, Mn: 0.15-0.9%, S: ≤0.025%, P≤0.035%, SI≤0.35%, trace amounts of alloying elements, a thickness between 3.5-5.5mm, a width of 1100-1280mm, and a target furnace exit temperature of 1200-1270℃. These are all within a certain range, and these raw materials used for open rolling are also used normally in other standard materials. Therefore, some open rolling strategies for open rolling cannot be fixed, and the furnace gas temperature of silicon steel (1090-1140℃) must also be considered.

[0005] Question 3: Efficiency. Due to the significant temperature difference in the furnace gas, the clearance between the rolled stock and the silicon steel must be at least 3 meters. See the table below: Summary of the Invention

[0006] The objectives of this invention include, for example, providing a method for hot-rolling non-oriented silicon steel that can improve the problems of large temperature deviation between the existing hot-rolled material and the furnace gas of the subsequent silicon steel, as well as voids.

[0007] The embodiments of the present invention can be implemented as follows: An embodiment of the present invention provides a method for hot-rolling non-oriented silicon steel, comprising: The steel grade used for open rolling is low-grade silicon steel X1300, X800 or X600, and the rolling thickness is controlled at 2.95mm or 2.75mm; The roughing rolling passes are controlled as follows: R1 mill - 3 passes, R2 mill - 5 passes, and the intermediate billet thickness is 42mm. The control parameters for finishing milling include: threading speed of 6-7 m / s, roll shifting value of F1 stand-30, F2 stand-20; and load distribution as follows: F1 stand-43, F2 stand-38, F3 stand-34, F4 stand-23, F5 stand-18, F6 stand-14, F7 stand-10.

[0008] In addition, the hot-rolling method for non-oriented silicon steel provided in the embodiments of the present invention may also have the following additional technical features: Optionally, the composition range of the low-grade silicon steel X1300, X800 or X600 includes: C: ≤0.0025%, Si: 0.15-0.6%, Mn: 0.15-0.4%, P: ≤0.1%, S: ≤0.0045%.

[0009] Optionally, the composition range of the low-grade silicon steel X1300, X800 or X600 includes: Si: 0.15-0.3%, Mn: 0.3-0.4%, P: 0.07-0.1%.

[0010] Optionally, the composition range of the low-grade silicon steel X1300 includes: C: ≤0.002%, Si: 0.25%, Mn: 0.35%, P: 0.085%, S: ≤0.004%.

[0011] Optionally, the threading speed of the finishing mill is controlled at 6.2 m / s.

[0012] Optionally, the furnace gas temperature parameters for each section of the low-grade silicon steel X1300 and X800 are controlled as follows: the first stage is controlled at 1150-1190℃, the second stage at 1135-1165℃, and the soaking temperature at 1100-1140℃.

[0013] Optionally, the furnace gas temperature parameters for each section of the low-grade silicon steel X1300 and X800 are controlled as follows: the first stage is controlled at 1170℃, the second stage at 1155℃, and the soaking stage at 1120℃.

[0014] Optionally, the furnace gas temperature parameters for each section of the low-grade silicon steel X600 are controlled as follows: the first stage is controlled at 1140-1180℃, the second stage at 1130-1170℃, and the soaking temperature at 1090-1130℃.

[0015] Optionally, the furnace gas temperature parameters for each section of the low-grade silicon steel X600 are controlled as follows: the first stage is controlled at 1160℃, the second stage at 1150℃, and the soaking stage at 1110℃.

[0016] Optionally, the first two pieces of the rolled stock can be flattened.

[0017] The beneficial effects of the hot-rolling non-oriented silicon steel rolling method of the present invention include, for example: The method for hot-rolling non-oriented silicon steel includes using low-grade silicon steel X1300, X800, or X600 as the raw material, controlling the rolling thickness to be 2.95mm or 2.75mm; controlling the number of roughing passes to be 3 passes on R1 mill and 5 passes on R2 mill, with an intermediate billet thickness of 42mm; controlling the finishing rolling parameters to include: a strip threading speed of 6-7 m / s, roll shifting values ​​of F1 stand-30, F2 stand-20; and load distribution as follows: F1 stand-43, F2 stand-38, F3 stand-34, F4 stand-23, F5 stand-18, F6 stand-14, and F7 stand-10.

[0018] By using X1300, X800, or X600 as the initial rolling stock, the problems of large furnace gas temperature deviations and voids are solved. Since X1300, X800, X600, and the subsequent silicon steel are all silicon steel, and the furnace gas temperatures are not significantly different, voids are not required, and no special process control requirements are needed. The steelmaking process can be directly executed according to the specifications. Furthermore, by controlling the roughing and finishing rolling processes and changing the thickness, a series of specially designed solidification parameters (2.95mm or 2.75mm) can be achieved. This enhances the stability of the initial rolling process, improving efficiency and quality. Attached Figure Description

[0019] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0020] Figure 1 A flowchart illustrating the steps of a method for hot-rolling non-oriented silicon steel according to an embodiment of the present invention. Detailed Implementation

[0021] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0022] Therefore, the following detailed description of the embodiments of the invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the invention without inventive effort are within the scope of protection of the invention.

[0023] It should be noted that similar labels and letters in the following figures indicate similar items. Therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures.

[0024] In the description of this invention, it should be noted that if terms such as "upper," "lower," "inner," or "outer" are used to indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship in which the product of this invention is usually placed, they are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this invention.

[0025] Furthermore, the terms "first" and "second" are used only to distinguish descriptions and should not be interpreted as indicating or implying relative importance.

[0026] It should be noted that, where there is no conflict, the features in the embodiments of the present invention can be combined with each other.

[0027] The following is combined with Figure 1 The method for hot-rolling non-oriented silicon steel provided in this embodiment is described in detail.

[0028] Please refer to Figure 1 The present invention provides a method for hot-rolling non-oriented silicon steel, comprising: The steel grade used for open rolling is low-grade silicon steel X1300, X800 or X600, and the rolling thickness is controlled at 2.95mm or 2.75mm; The roughing rolling passes are controlled as follows: R1 mill - 3 passes, R2 mill - 5 passes, and the intermediate billet thickness is 42mm. The control parameters for finishing milling include: threading speed of 6-7 m / s, roll shifting value of F1 stand-30, F2 stand-20; and load distribution as follows: F1 stand-43, F2 stand-38, F3 stand-34, F4 stand-23, F5 stand-18, F6 stand-14, F7 stand-10.

[0029] "X1300, X800, or X600" refers to X1300, X800, or X600 being used as the initial rolling stock. The rolling thickness is 2.95mm or 2.75mm. The rolling thickness of all three steel grades can be controlled to 2.95mm or 2.75mm.

[0030] R1 and R2 are two rolling mills. The slab is first rolled three times on R2, then five times on R2. The intermediate slab thickness is the same as the thickness after rough rolling and before finish rolling, taken into account rolling stability. The furnace gas temperature is not high, employing a multi-pass, small-deformation process to ensure a good roughing profile, providing a good foundation for finish rolling. The relatively low furnace gas temperature reduces deformation, minimizing deformation and increasing the number of passes; a 3+5 pass design yields a better slab profile. The threading speed is the speed at which the strip enters the finish mill; specifically, the threading speed for finish rolling is controlled at 6.2 m / s; this low threading speed ensures operators can adjust the slab profile promptly. The roll shifting value refers to the shifting position of the work rolls, which adjusts the crown and rolling stability to ensure the crown requirements are met. The roll shifting value is F1 frame-30, F2 frame-20. Such roll shifting values ​​ensure that the crown requirement is controlled within 40-50μm, thereby better improving rolling stability. The roll shifting value of F1 frame-30 means that the upper roll is shifted 30 mm towards the drive side and the lower roll is shifted 30 mm towards the operating side. The roll shifting value of F2 frame-20 means that the upper roll is shifted 20 mm towards the drive side and the lower roll is shifted 20 mm towards the operating side.

[0031] In the load distribution, racks F1, F2, F3, F4, F5, F6, and F7 are set sequentially. The "30" after F1 rack-30 indicates a reduction force of 30%. Similarly, F2 rack-20 indicates a reduction force of 20%, and so on. The meanings of F3 rack-34, F4 rack-23, F5 rack-18, F6 rack-14, and F7 rack-10 in the load distribution are not elaborated further. At higher temperatures, the first four racks undergo large reductions and deformations, while the latter three racks, under lower loads, exhibit uniform deformation and excellent plate shape at lower temperatures.

[0032] For the original steel grades SPHC-1CAL and Q235B used as the initial rolling stock, directly replace them with any one of the lower-grade silicon steels X1300, X800, or X600. Using X1300, X800, or X600 as the initial rolling stock solves the problems of large furnace gas temperature deviations and void spaces. Since X1300, X800, X600, and the subsequent silicon steel are all silicon steel, and the furnace gas temperature difference is not significant, void spaces are not required, and no special process control requirements are needed. Simply follow the steelmaking process requirements.

[0033] Since the normal rolling thickness of X1300 is 2.55mm, but as an open-roll material, a thickness of 2.95mm or 2.75mm is required, this can be achieved by controlling the roughing and finishing rolling processes. By changing the thickness, a series of specific solidification parameters of 2.95mm or 2.75mm can be designed. The process control parameters for X800 or X600 can be adjusted based on those for X1300.

[0034] This solves the problems of large furnace gas temperature deviation and void space, thereby improving hot rolling efficiency and quality.

[0035] In this embodiment, the composition range of low-grade silicon steel X1300, X800 or X600 includes: C: ≤0.0025%, Si: 0.15-0.6%, Mn: 0.15-0.4%, P: ≤0.1%, S: ≤0.0045%.

[0036] The composition of X1300 includes C: ≤0.0025%, Si: 0.15-0.6%, Mn: 0.15-0.4%, P: ≤0.1%, and S: ≤0.0045%. The composition of X800 includes C: ≤0.0025%, Si: 0.15-0.6%, Mn: 0.15-0.4%, P: ≤0.1%, and S: ≤0.0045%. The composition of X600 includes C: ≤0.0025%, Si: 0.15-0.6%, Mn: 0.15-0.4%, P: ≤0.1%, and S: ≤0.0045%. The composition of silicon steel X1300, X800, or X600 falls within the above ranges.

[0037] Furthermore, the composition range of low-grade silicon steel X1300, X800 or X600 includes: Si: 0.15-0.3%, Mn: 0.3-0.4%, P: 0.07-0.1%.

[0038] The composition range of X1300 includes: Si: 0.15-0.3%, Mn: 0.3-0.4%, P: 0.07-0.1%. The composition range of X800 includes: Si: 0.15-0.3%, Mn: 0.3-0.4%, P: 0.07-0.1%. The composition range of X600 includes: Si: 0.15-0.3%, Mn: 0.3-0.4%, P: 0.07-0.1%.

[0039] Specifically, the composition range of low-grade silicon steel X1300 includes: C: ≤0.002%, Si: 0.25%, Mn: 0.35%, P: 0.085%, S: ≤0.004%.

[0040] The raw material for rolling is silicon steel X1300, X800 or X600. The chemical composition of X1300 is shown in Table 1.

[0041]

[0042] In Table 1, Cu / Cr refers to Cu or Cr, and O / V refers to O or V.

[0043] The composition of Q235B is shown in Table 2.

[0044] Table 2

[0045] A comparison of the compositions of X1300 and Q235B reveals minimal differences in Si, S, and P content. However, Q235B has a significantly higher C content than X1300. Furthermore, Q235B contains more Mn than X1300. C and Mn are the primary strengthening elements in steel; higher content results in greater strength. Therefore, any steel grade with lower C and Mn content than Q235B can be used for open-rolling, without considering the addition of alloying elements. This allows Q235B to be used for open-rolling, and X1300 is even better suited for it, allowing for thinner open-rolling. The lower strength of X1300 compared to Q235B provides a foundation for improved stability in finish rolling.

[0046] In this embodiment, the furnace gas temperature parameters for each section of low-grade silicon steel X1300 and X800 are controlled as follows: the first stage is controlled at 1150-1190℃, the second stage at 1135-1165℃, and the homogenization at 1100-1140℃.

[0047] Since both are silicon steel and the furnace gas temperatures are similar, no vacancy is required, and no special process control is needed. The steelmaking process can be directly executed according to the specifications. See Table 3 for details.

[0048] Table 3

[0049] Specifically, the furnace gas temperature parameters for each section of low-grade silicon steel X1300 and X800 are controlled as follows: the first stage is controlled at 1170℃, the second stage at 1155℃, and the soaking temperature at 1120℃.

[0050] In this embodiment, the furnace gas temperature parameters for each section of low-grade silicon steel X600 are controlled as follows: the first stage is controlled at 1140-1180℃, the second stage at 1130-1170℃, and the homogenization at 1090-1130℃.

[0051] Specifically, the furnace gas temperature parameters for each section of low-grade silicon steel X600 are controlled as follows: the first stage is controlled at 1160℃, the second stage at 1150℃, and the soaking stage at 1110℃.

[0052] In this embodiment, the first two pieces of the unrolled material are flattened. The first two X1300 pieces must be flattened due to their poor shape before they can proceed to the next process.

[0053] According to the method for hot-rolling non-oriented silicon steel provided in this embodiment, the working principle of the method is as follows: by directly using X1300 silicon steel as the initial rolling stock, the problem of mismatched furnace gas temperature when using SPHC-1CAL and Q235B is solved. Because X1300, X800, and X600 are similar steel grades, the furnace gas temperature difference is very small, so there is no need to leave a gap. In addition, through composition comparison, X1300 has less C and Mn content than Q235B, and its finishing rolling force is smaller. The composition of X1300 is more suitable as an initial rolling stock than Q235B. Furthermore, by implementing a two-stage initial rolling strategy specifically for X1300 to solidify the parameters, the initial rolling stability is enhanced.

[0054] The hot-rolling method for non-oriented silicon steel provided in this embodiment has at least the following advantages: By using X1300, X800, or X600 as the initial rolling stock, the problems of large furnace gas temperature deviations and voids are solved. Since X1300, X800, X600, and the subsequent silicon steel are all silicon steel, and the furnace gas temperatures are not significantly different, voids are not required, and no special process control requirements are needed. The steelmaking process can be directly executed according to the specifications. Furthermore, by controlling the roughing and finishing rolling processes and changing the thickness, a series of specially designed solidification parameters (2.95mm or 2.75mm) can be achieved. This enhances the stability of the initial rolling process, improving efficiency and quality.

[0055] The existing method requires waiting for space, and the furnace gas temperature difference is significant. The space between the rolling stock and the silicon steel must be at least 3 meters, which necessitates the use of a walking beam, resulting in approximately 10 minutes of no rolling. This waiting period is mandatory for each plan. The new method eliminates this waiting, saving 10 minutes per plan. Currently, our plant's machine output is 800 tons / hour, or 13.33 tons / minute. Assuming each plan produces 1350 tons of silicon steel, the total silicon steel output is 1.6 million tons, requiring 1185 plans. This will increase annual capacity by 158,000 tons. Based on the current market profit of approximately 300 yuan / ton for silicon steel, this will generate a profit of 47.4 million yuan.

[0056]

[0057] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A method for hot-rolling non-oriented silicon steel, characterized in that, include: The steel grade used for open rolling is low-grade silicon steel X1300, X800, or X600, and the rolling thickness is controlled at 2.95mm or 2.75mm. The composition range of the low-grade silicon steel X1300, X800, or X600 includes: C: ≤0.0025%, Si: 0.15-0.6%, Mn: 0.15-0.4%, P: ≤0.1%, S: ≤0.0045%. The roughing rolling passes are controlled as follows: R1 mill - 3 passes, R2 mill - 5 passes, and the intermediate billet thickness is 42mm. The control parameters for the finishing mill include: threading speed of 6-7 m / s, roll shifting value of F1 stand-30, F2 stand-20; and load distribution as follows: F1 stand-43, F2 stand-38, F3 stand-34, F4 stand-23, F5 stand-18, F6 stand-14, F7 stand-10. The furnace gas temperature parameters for each section of the low-grade silicon steel X1300 and X800 are controlled as follows: the first stage is controlled at 1150-1190℃, the second stage at 1135-1165℃, and the soaking temperature is controlled at 1100-1140℃; the furnace gas temperature parameters for each section of the low-grade silicon steel X600 are controlled as follows: the first stage is controlled at 1140-1180℃, the second stage at 1130-1170℃, and the soaking temperature is controlled at 1090-1130℃.

2. The method for hot-rolling non-oriented silicon steel according to claim 1, characterized in that: The composition range of the low-grade silicon steel X1300, X800 or X600 includes: Si: 0.15-0.3%, Mn: 0.3-0.4%, P: 0.07-0.1%.

3. The method for hot-rolling non-oriented silicon steel according to claim 2, characterized in that: The composition range of the low-grade silicon steel X1300 includes: C: ≤0.002%, Si: 0.25%, Mn: 0.35%, P: 0.085%, S: ≤0.004%.

4. The method for hot-rolling non-oriented silicon steel according to claim 1, characterized in that: The threading speed of the finishing mill is controlled at 6.2 m / s.

5. The method for hot-rolling non-oriented silicon steel according to claim 1, characterized in that: The furnace gas temperature parameters for each section of the low-grade silicon steel X1300 and X800 are controlled as follows: the first stage is controlled at 1170℃, the second stage at 1155℃, and the soaking temperature at 1120℃.

6. The method for hot-rolling non-oriented silicon steel according to claim 1, characterized in that: The furnace gas temperature parameters for each section of the low-grade silicon steel X600 are controlled as follows: the first stage is controlled at 1160℃, the second stage at 1150℃, and the soaking stage at 1110℃.

7. The method for hot-rolling non-oriented silicon steel according to claim 1, characterized in that: The first two pieces of the split-rolled material are flattened.

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