Method and product for producing 65Mn cold-rolled steel strip using an 18-high single-stand rolling mill

Abstract

The present application provides a method and product for producing 65Mn cold-rolled steel strip using an 18-high single-stand rolling mill. The method comprises the following steps: S10 providing a 65Mn hot-rolled pickled steel strip; S20 cold-rolling the 65Mn hot-rolled pickled steel strip using an 18-high single-stand rolling mill to obtain the 65Mn cold-rolled steel strip. By using the 18-high single-stand rolling mill to perform five passes of rolling on the 65Mn hot-rolled pickled steel strip, and controlling the reduction rate, inlet unit tension, outlet unit tension, and rolling force of each pass, 65Mn cold-rolled steel strip of various specifications can be stably produced, and the thickness accuracy of the 65Mn cold-rolled steel strip can be significantly improved.

Description

Technical Field

[0001] The present application relates to the technical field of steel production, and in particular to a method and product for producing 65Mn cold-rolled steel strip using an 18-high single-stand rolling mill. Background Art

[0002] 65Mn is a common high-quality carbon structural steel with good comprehensive performance and a wide range of uses. It is the main material for manufacturing diamond saw blades, automotive fine-blanking structural parts, wear-resistant welded pipes, etc.

[0003] Currently, the market primarily supplies 65Mn cold-rolled narrow strip (width <800mm), typically produced using a six-high single-stand cold rolling mill. These mills, with their outdated technology and equipment, pose significant environmental risks, low production efficiency, and unstable product quality, no longer meet market demand. 65Mn cold-rolled wide strip (width ≥800mm) is also available using a five-stand continuous rolling mill, typically with a reduction ratio of 20%-50%. Too low a reduction ratio hinders the formation of a spheroidized structure in the annealing process, and can only produce 65Mn cold-rolled strip with a thickness of less than 2.5mm.

[0004] Therefore, it is necessary to provide a method for stably producing 65Mn cold-rolled steel strips of different thicknesses and widths. Summary of the Invention

[0005] The present application provides a method and product for producing 65Mn cold-rolled steel strip using an 18-roll single-stand rolling mill. The method uses an 18-roll single-stand rolling mill to produce 65Mn cold-rolled steel strip. By controlling the rolling conditions of each pass, stable production of 65Mn cold-rolled steel strip of different specifications can be achieved.

[0006] In a first aspect, the present application provides a method for producing 65Mn cold-rolled steel strip using an 18-high single-stand rolling mill, comprising the following steps:

[0007] S10 provides 65Mn hot-rolled pickled plate;

[0008] S20: cold rolling the 65Mn hot-rolled pickled steel plate using an 18-roll single-stand rolling mill to obtain a 65Mn cold-rolled steel strip.

[0009] The cold rolling process includes 5 passes, wherein the first pass has a reduction rate of 15% to 22% and an inlet unit tension of 50 to 120 N / mm. 2 , export unit tension 80~160N / mm 2 , rolling force 9~15MN; second pass reduction rate 12%~20%, entrance unit tension 50~120N / mm 2 , export unit tension 80~160N / mm 2, rolling force 9~15MN; 3rd pass reduction rate 12%~20%, entrance unit tension 50~120N / mm 2 , export unit tension 80~160N / mm 2 , rolling force 9~15MN; 4th pass reduction rate 12%~20%, entrance unit tension 50~120N / mm 2 , export unit tension 80~160N / mm 2 , rolling force 9~15MN; 5th pass reduction rate 7%~12%, entrance unit tension 50~120N / mm 2 , export unit tension 80~160N / mm 2 , rolling force 8~13MN.

[0010] In the technical solution of the present application, by using an eighteen-roll single-stand rolling mill to roll 65Mn hot-rolled pickled steel plate for five passes, and controlling the reduction rate, inlet unit tension, outlet unit tension and rolling force of each pass, 65Mn cold-rolled steel strips of different specifications can be stably produced, and the thickness accuracy of the 65Mn cold-rolled steel strips can be significantly improved.

[0011] In some embodiments of the present application, step S10 specifically includes:

[0012] 65Mn ingots are provided, and 65Mn hot-rolled pickled plates are obtained through hot rolling and pickling.

[0013] In some embodiments of the present application, the pickling includes a first pickling stage, a second pickling stage, a third pickling stage, a fourth pickling stage and a fifth pickling stage, wherein the acid concentration in the first pickling stage is 70-120 g / L, the acid concentration in the second pickling stage, the third pickling stage and the fourth pickling stage is 120-170 g / L, and the acid concentration in the fifth pickling stage is 160-200 g / L;

[0014] Optionally, the pickling temperature is 75-90° C., and the pickling speed is 70-100 m / min.

[0015] In some embodiments of the present application, in step S20, the 65Mn hot-rolled pickled plate is subjected to a primary annealing treatment and then cold-rolled using an 18-high single-stand rolling mill;

[0016] The primary annealing treatment includes: maintaining the temperature at 710-740° C. for 15-18 hours.

[0017] In some embodiments of the present application, in step S20, the total reduction ratio of the cold rolling is 45% to 62%.

[0018] In some embodiments of the present application, the eighteen-roll single-stand rolling mill includes an intermediate roll having a tapered roll with a first taper and a second taper, and a working roll arranged on a first side of the intermediate roll and in contact with the intermediate roll, the roll diameter of the working roll is 140 to 170 mm, and the working roll is used to roll the steel to be rolled.

[0019] In some embodiments of the present application, during the cold rolling, the contact length between the 65Mn hot-rolled pickled plate and the first taper corresponding zone I of the intermediate roll is 90 to 120 mm.

[0020] In some embodiments of the present application, the 65Mn cold-rolled steel strip has a thickness of 0.6 to 3.2 mm and a width of 900 to 1300 mm.

[0021] In some embodiments of the present application, the longitudinal thickness deviation of the 65Mn cold-rolled steel strip is within the range of -0.5%D to 0.5%D, and the transverse thickness deviation of the same plate is ≤1%D;

[0022] Wherein, D is the thickness of the 65Mn cold-rolled steel strip, in mm.

[0023] In a second aspect, the present application provides a product obtained by processing a 65Mn cold-rolled steel strip obtained by the method described in any embodiment of the first aspect.

[0024] In the technical solution of the present application, since the method of any embodiment of the first aspect can produce 65Mn cold-rolled steel strips of different specifications and high thickness precision, when the 65Mn cold-rolled steel strips are processed into products, the number of welding times can be reduced, the processing is easy, and the products have better performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the present application and, together with the description, serve to explain the principles of the present application.

[0026] Figure 1 This is a schematic diagram of the middle roll of the eighteen-roll single-stand rolling mill in the embodiment of the present application.

[0027] The above drawings illustrate specific embodiments of the present application, which will be described in more detail below. These drawings and the textual description are not intended to limit the scope of the present application in any way, but rather to illustrate the concepts of the present application to those skilled in the art by reference to specific embodiments. DETAILED DESCRIPTION

[0028] The various embodiments or implementation schemes in this specification are described in a progressive manner, and each embodiment focuses on the differences from other embodiments.

[0029] Throughout this specification, reference to terms such as "one embodiment," "some embodiments," "illustrative embodiments," "examples," "specific examples," or "some examples" means that a specific feature, structure, material, or characteristic described in conjunction with an embodiment or example is included in at least one embodiment or example of the present application. In this specification, illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.

[0030] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of the technical features being referred to. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of such features. Throughout the description of this application, "plurality" means at least two, for example, two, three, etc., unless otherwise specifically defined.

[0031] As described in the background technology, in the existing technology, 65Mn cold-rolled steel strip is usually produced using a six-high single-stand rolling mill or a five-stand six-high rolling mill. However, these methods have low efficiency and unstable product quality, which seriously affects the development and application of 65Mn cold-rolled steel strip.

[0032] After a large number of experiments and analyses, the inventors found that due to the high C and Mn content in 65Mn steel, in order to increase the reduction rate, the rolling force needs to be increased. However, the higher rolling force will seriously affect the stability of the rolling process, and is also not conducive to the control of the thickness accuracy of the 65Mn cold-rolled steel strip. Therefore, it is not conducive to the stable production of high-quality 65Mn cold-rolled steel strips of different specifications.

[0033] To this end, the present application provides a method and product for producing 65Mn cold-rolled steel strip using an 18-high single-stand rolling mill. The method and product for producing 65Mn cold-rolled steel strip using an 18-high single-stand rolling mill provided in the present application are described in detail below.

[0034] In a first aspect, the present application provides a method for producing 65Mn cold-rolled steel strip using an 18-high single-stand rolling mill, comprising the following steps:

[0035] S10 provides 65Mn hot-rolled pickled plate;

[0036] S20 uses 18-roll single-stand rolling mill to cold-roll 65Mn hot-rolled pickled steel sheets to obtain 65Mn cold-rolled steel strips.

[0037] Among them, cold rolling includes 5 rolling passes, and the 5 rolling passes include: the first pass reduction rate is 15% to 22%, and the entrance unit tension is 50 to 120N / mm 2, export unit tension 80~160N / mm 2 , rolling force 9~15MN; second pass reduction rate 12%~20%, entrance unit tension 50~120N / mm 2 , export unit tension 80~160N / mm 2 , rolling force 9~15MN; 3rd pass reduction rate 12%~20%, entrance unit tension 50~120N / mm 2 , export unit tension 80~160N / mm 2 , rolling force 9~15MN; 4th pass reduction rate 12%~20%, entrance unit tension 50~120N / mm 2 , export unit tension 80~160N / mm 2 , rolling force 9~15MN; 5th pass reduction rate 7%~12%, entrance unit tension 50~120N / mm 2 , export unit tension 80~160N / mm 2 , rolling force 8~13MN.

[0038] In the technical solution of the present application, by using an eighteen-roll single-stand rolling mill to roll 65Mn hot-rolled pickled steel plate for five passes, and controlling the reduction rate, inlet unit tension, outlet unit tension and rolling force of each pass, 65Mn cold-rolled steel strips of different specifications can be stably produced, and the thickness accuracy of the 65Mn cold-rolled steel strips can be significantly improved.

[0039] In the technical solution of the present application, since the change in tension during the cold rolling process can significantly change the rolling pressure, the advantage of using an eighteen-roll single-stand rolling mill for cold rolling is that it can provide a large unit tension, which is beneficial to reduce the rolling force during the rolling process, making the rolling more stable, and thus less likely to break the strip during the rolling process, thereby improving the production efficiency of 65Mn cold-rolled steel strip.

[0040] In addition, according to the technical solution of the present application, cold rolling can include 5 rolling passes. Multi-pass rolling is conducive to the stable cold rolling process and thickness control. Among them, due to the high C and Mn content in the 65Mn hot-rolled pickled plate, and also contains a large amount of other alloying elements, the deformation resistance during the cold rolling process is very large, and as the thickness of the cold-rolled steel strip decreases, the deformation resistance of the steel strip gradually increases. Therefore, it is necessary to control the reduction rate of the first pass to the maximum. Under the condition of the same rolling force, a larger reduction rate can be achieved, thereby reducing the difficulty of subsequent rolling passes. It can be understood that during the cold rolling process, the reduction rate of each rolling pass is gradually reduced, which is conducive to the control of the unit tension and rolling force of the 18-high single-stand rolling mill, thereby ensuring stable rolling.

[0041] At the same time, as rolling progresses, the exit thickness of each pass gradually decreases. Due to the large plastic stiffness of the 65Mn steel strip, the effect of thickness control by adjusting the roll gap alone is relatively poor. However, since the tension is large during rolling on the 18-roll single-stand rolling mill, the thickness can be controlled by changing the tension. In this way, the thickness control is faster and more effective and can effectively improve the thickness accuracy of the steel strip, achieve smaller longitudinal thickness deviation and transverse thickness difference of the steel strip, and obtain 65Mn cold-rolled steel strip with good version.

[0042] In addition, it is worth mentioning that due to the greater risk of hardening of the weld zone of 65Mn, the material will become brittle after continuous laser welding, the weld is prone to cracking, and the strip is prone to breakage during rolling. Since the technical solution of this application uses an eighteen-roll single-stand rolling mill for cold rolling, there is no need to weld the 65Mn hot-rolled pickled plate, so there is no problem of difficulty in welding the 65Mn hot-rolled pickled plate.

[0043] The method can be widely used in the production of 65Mn cold-rolled steel strip by domestic or imported 18-high single-stand rolling mills, and can be beneficial to the localization and application of 18-high single-stand rolling mills.

[0044] In the technical solution of this application, since the specific chemical composition of 65Mn steel is known from the prior art, no further definition of 65Mn hot-rolled pickled plate is provided. It is understood that those skilled in the art can manufacture or purchase the steel according to their specific circumstances. For example, in some embodiments of this application, the 65Mn hot-rolled pickled plate used is sourced from the 65Mn production line of Lianyuan Iron and Steel.

[0045] In some embodiments of the present application, step S10 specifically includes:

[0046] 65Mn ingots are provided, and 65Mn hot-rolled pickled plates are obtained through hot rolling and pickling.

[0047] In some of the above embodiments, 65Mn hot-rolled pickled plate is obtained by hot rolling and pickling 65Mn ingot. In order to obtain 65Mn cold-rolled steel strips of different specifications, it is necessary to determine the thickness of the 65Mn hot-rolled pickled plate based on the total reduction rate of cold rolling and the target thickness of the 65Mn cold-rolled steel strip. Therefore, the 65Mn ingot can be rolled to a suitable thickness by hot rolling, thereby reducing the difficulty and stability of cold rolling.

[0048] In addition, since a layer of iron oxide scale is generated on the surface of the hot-rolled plate obtained by hot rolling, if it is not removed, the defect of iron oxide scale pressing in will appear during the subsequent cold rolling process, resulting in poor surface quality of the cold-rolled steel strip. At the same time, it will also damage the roller surface of the working roll of the rolling mill, resulting in the inability to carry out cold rolling smoothly. Therefore, pickling is required after hot rolling to remove the iron oxide scale on the surface to ensure the quality of the cold-rolled steel strip and smooth production.

[0049] In some embodiments of the present application, the pickling includes a first pickling stage, a second pickling stage, a third pickling stage, a fourth pickling stage, and a fifth pickling stage. The acid concentration in the first pickling stage is 70-120 g / L, the acid concentration in the second pickling stage, the third pickling stage, and the fourth pickling stage is 120-170 g / L, and the acid concentration in the fifth pickling stage is 160-200 g / L.

[0050] Optionally, the pickling temperature is 75-90° C., and the pickling speed is 70-100 m / min.

[0051] In some of the above embodiments, since the mass fraction of Si element in 65Mn steel is generally 0.17% to 0.37%, the Si content is relatively high, and Si and Fe easily generate Fe2SiO4 between the iron oxide scale and the steel base, thereby strengthening the adhesion of the iron oxide scale and making it difficult to remove using general pickling conditions. Therefore, in some embodiments of the present application, a separate pickling process is formulated, and the pickling may include 5 stages of pickling, so that the iron oxide scale on the surface of the hot-rolled plate is removed more completely, and the acid concentration in each stage of pickling gradually increases, which can evenly remove the iron oxide scale on the surface, while reducing iron loss and preventing problems such as over-pickling, over-corrosion and hydrogen embrittlement. Through this pickling condition, the iron oxide scale can be removed while ensuring the quality of the hot-rolled pickled plate.

[0052] Furthermore, the pickling temperature can be controlled at 75-90°C and the pickling speed can be controlled at 70-100 m / min. Since the pickling efficiency is related to the pickling temperature, if the pickling temperature is too low, the pickling efficiency will be too low, affecting production efficiency. If the pickling temperature is too high, it may cause over-pickling of the hot-rolled plate, resulting in surface defects and color difference. Therefore, the pickling temperature needs to be controlled within an appropriate range. At the same time, if the pickling speed is too fast, the iron oxide scale cannot be completely removed. If it is too slow, it may increase iron loss and cause over-corrosion, while affecting production efficiency. Therefore, the pickling speed also needs to be controlled within an appropriate range.

[0053] In some embodiments of the present application, in step S20, the 65Mn hot-rolled pickled plate is subjected to a primary annealing treatment and then cold-rolled using an 18-high single-stand rolling mill;

[0054] The primary annealing treatment includes: keeping the temperature at 710-740°C for 15-18 hours.

[0055] In some of the above embodiments, 65Mn steel has a high carbon content, generally ranging from 0.62% to 0.7% by mass, and is classified as medium-high carbon steel, characterized by significant cold rolling work hardening and high brittleness. If 65Mn hot-rolled pickled steel is directly cold-rolled, it is prone to strip breakage. Therefore, a primary annealing of the 65Mn hot-rolled pickled steel prior to cold rolling can avoid strip breakage during cold rolling. Furthermore, the primary annealing softens the steel, allowing for a higher reduction ratio and facilitating the subsequent secondary annealing to achieve a sufficiently spheroidized structure. The specific conditions for the primary annealing are a holding temperature of 710-740°C for 15-18 hours.

[0056] In some embodiments of the present application, in step S20, the total reduction ratio of cold rolling is 45% to 62%.

[0057] In some of the aforementioned embodiments, the use of an 18-high single-stand rolling mill allows for stable rolling at high reduction rates through high rolling tension and a smaller work roll diameter, thereby enabling the stable production of 65Mn cold-rolled steel strip of varying specifications. Furthermore, a greater total reduction leads to greater cold deformation, which in turn creates numerous defects such as vacancies and high-density dislocations in the microstructure. These defects create high-rate diffusion pathways for carbon. During the subsequent secondary annealing stage, these pathways promote carbon diffusion and the spheroidization of lamellar carbides, thereby increasing the spheroidization rate of the 65Mn cold-rolled steel strip and, consequently, improving its quality.

[0058] In some embodiments of the present application, an eighteen-roll single-stand rolling mill includes an intermediate roll having a tapered roll with a first taper and a second taper, and a working roll arranged on a first side of the intermediate roll and in contact with the intermediate roll, the roll diameter of the working roll is 140 to 170 mm, and the working roll is used to roll the steel to be rolled.

[0059] In some of the above embodiments, the eighteen-high single-stand rolling mill includes an intermediate roll having a first taper and a second taper, and the schematic diagram of the intermediate roll is as shown in FIG. Figure 1 As shown in the figure, it can be seen that the intermediate roll adopts a two-stage taper roll with different slopes. Compared with the traditional one-stage taper, this roll shape can reduce the contact stress concentration between the rolls at the taper corner, enhance the adjustment effect of the shifting rolls, and eliminate the rapid elastic flattening and elastic deformation of the roll edge, which is beneficial to improving the transverse plate difference and edge plate quality. In addition, the working rolls of the 18-roll single-stand rolling mill have a smaller roll diameter of 140-170mm. The smaller roll diameter is more conducive to achieving a large reduction rate and can reduce the harmful contact area with the steel strip. The corresponding edge drop of the steel strip is small. Compared with the large roll diameter rolls of the six-roll working rolls in the existing technology, the steel strip edge drop control effect is good, which is beneficial to improving the plate difference of the steel strip.

[0060] In some embodiments of the present application, during cold rolling, the contact length between the 65Mn hot-rolled pickled plate and the first taper corresponding to zone I of the intermediate roll is 90 to 120 mm.

[0061] In some of the aforementioned embodiments, the contact length between the 65Mn hot-rolled pickled strip and the first taper corresponding to zone I of the intermediate roll (hereinafter referred to as the taper contact value) is controlled within a range of 90 to 120 mm. This is because a larger taper contact value results in less reduction at the strip edge, which is more conducive to improving transverse uniformity. However, a larger taper contact value results in greater reduction and extension in the middle portion, which increases the likelihood of mid-wave formation. Through extensive experiments, the inventors have discovered that controlling the taper contact value within a range of 90 to 120 mm can achieve a balanced transverse uniformity while minimizing mid-wave formation, resulting in higher-quality 65Mn cold-rolled strip.

[0062] In some embodiments of the present application, the thickness of the 65Mn cold-rolled steel strip is 0.6-3.2 mm, and the width is 900-1300 mm.

[0063] In some of the above embodiments, by using the method provided in the present application, stable production of 65Mn cold-rolled steel strips of various specifications can be achieved. The maximum thickness of the produced 65Mn cold-rolled steel strips can reach 3.2 mm, and the maximum width can reach 1300 mm. This can meet the delivery requirements of 65Mn cold-rolled steel strips of different specifications and expand the application scenarios of 65Mn cold-rolled steel strips.

[0064] In some embodiments of the present application, the longitudinal thickness deviation of the 65Mn cold-rolled steel strip is within the range of -0.5%D to 0.5%D, and the transverse thickness deviation of the same plate is ≤1%D;

[0065] Wherein, D is the thickness of 65Mn cold-rolled steel strip, in mm.

[0066] In some of the above embodiments, the longitudinal thickness deviation and transverse same-plate difference of the 65Mn cold-rolled steel strip produced by using the method provided by the present application are very small. The longitudinal thickness deviation can be controlled within ±0.5% of the thickness, and the transverse same-plate difference can be controlled within 1% of the thickness. This shows that the method provided by the present application has good control over the thickness accuracy of the 65Mn cold-rolled steel strip, and high-quality 65Mn cold-rolled steel strip can be obtained, which is beneficial to subsequent processing and utilization.

[0067] In some embodiments of the present application, in step S20, secondary annealing, leveling, and finishing treatment are further performed after cold rolling to obtain a 65Mn cold-rolled steel strip.

[0068] It is understood that the production of 65Mn cold-rolled steel strip also requires a secondary annealing treatment of the cold-rolled steel strip to enhance its plasticity, toughness, and workability. Simultaneously, flattening and finishing the secondary annealed steel strip further enhances its quality. These secondary annealing, flattening, and finishing steps are well known to those skilled in the art in the production of 65Mn cold-rolled steel strip. The specific conditions and procedures are not limited here, and those skilled in the art may select their own methods as needed.

[0069] In a second aspect, the present application provides a product obtained by processing a 65Mn cold-rolled steel strip obtained by the method according to any embodiment of the first aspect.

[0070] In the technical solution of the present application, since the method of any embodiment of the first aspect can produce 65Mn cold-rolled steel strips of different specifications and high thickness precision, when the 65Mn cold-rolled steel strips are processed into products, the number of welding times can be reduced, the processing is easy, and the products have better performance.

[0071] Hereinafter, an eighteen-high single-stand rolling mill for producing 65Mn cold-rolled steel strip according to the present application will be described in more detail through examples, but the present application is not limited to these examples.

[0072] The specific embodiment of this application uses an eighteen-high single-stand rolling mill with a model number of 1450.

[0073] Example 1

[0074] Preparation of 65Mn cold-rolled steel strip with a thickness of 0.8mm and a width of 1000mm:

[0075] 65Mn ingots are provided, hot rolled and pickled to obtain 2mm thick 65Mn hot rolled pickled plates.

[0076] Among them, the pickling speed is 90m / min, the pickling temperature is 88℃, the acid concentration of the first pickling tank is 110g / L, the acid concentration of the second to fourth pickling tanks is 160g / L, and the acid concentration of the fifth pickling tank is 180g / L.

[0077] After the 65Mn hot-rolled pickled plate is annealed once, it is cold-rolled for 5 passes using an 18-roll single-stand rolling mill. The taper contact value is set to 115mm. The first pass: the entry thickness is 2.0mm, the exit thickness is 1.58mm, the reduction rate is 21%, and the entry unit tension is 78N / mm. 2 , export unit tension 126N / mm 2 , rolling force 11MN; 2nd pass: outlet thickness 1.29mm, reduction rate 18.4%, inlet unit tension 79N / mm 2 , export unit tension 127N / mm2 , rolling force 10.7MN; 3rd pass: outlet thickness 1.06mm, reduction rate 17.8%, inlet unit tension 85N / mm 2 , export unit tension 126N / mm 2 , rolling force 10.5MN; 4th pass: exit thickness 0.89mm, reduction rate 16.0%, entrance unit tension 85N / mm 2 , export unit tension 138N / mm 2 , rolling force 10MN; 5th pass: exit thickness 0.8mm, reduction rate 10.1%, entrance unit tension 98N / mm 2 , export unit tension 151N / mm 2 , rolling force 9.8MN. Total reduction rate 60%, rolling stability.

[0078] The longitudinal thickness deviation of the 65Mn cold-rolled steel strip obtained by cold rolling is -0.004 to 0.004 mm, and the transverse thickness deviation of the same plate is ≤0.007 mm.

[0079] Example 2

[0080] Preparation of 65Mn cold-rolled steel strip with a thickness of 2.1mm and a width of 1290mm:

[0081] 65Mn ingots were provided, and hot-rolled and pickled to obtain 4.8mm thick 65Mn hot-rolled pickled plates with no oxide residue on the surface.

[0082] Among them, the pickling speed is 80m / min, the pickling temperature is 85℃, the acid concentration of the first pickling tank is 100g / L, the acid concentration of the second to fourth pickling tanks is 145g / L, and the acid concentration of the fifth pickling tank is 175g / L.

[0083] After the 65Mn hot-rolled pickled plate is annealed once, it is cold-rolled for 5 passes using an 18-roll single-stand rolling mill. The taper contact value is set to 105mm. The first pass: the entry thickness is 4.8mm, the exit thickness is 3.88mm, the reduction rate is 19.2%, and the entry unit tension is 64N / mm. 2 , export unit tension 125N / mm 2 , rolling force 10.8MN; 2nd pass: outlet thickness 3.22mm, reduction rate 17.0%, inlet unit tension 78N / mm 2 , export unit tension 117N / mm 2 , rolling force 10.3MN; 3rd pass: exit thickness 2.72mm, reduction rate 15.5%, entrance unit tension 83N / mm 2 , export unit tension 123N / mm 2, rolling force 10.1MN; 4th pass: exit thickness 2.3mm, reduction rate 15.4%, entrance unit tension 87N / mm 2 , export unit tension 117N / mm 2 , rolling force 10.3MN; 5th pass: exit thickness 2.1mm, reduction rate 8.7%, entrance unit tension 80N / mm 2 , export unit tension 121N / mm 2 , rolling force 9.5MN. Total reduction rate 56.3%, rolling stability.

[0084] The longitudinal thickness deviation of the 65Mn cold-rolled steel strip obtained by cold rolling is -0.009 to 0.009 mm, and the transverse thickness deviation of the same plate is ≤0.014 mm.

[0085] Example 3

[0086] Preparation of 65Mn cold-rolled steel strip with a thickness of 3.2mm and a width of 1245mm:

[0087] 65Mn ingots were provided, and hot-rolled and pickled to obtain 6.2mm thick 65Mn hot-rolled pickled plates with no oxide residue on the surface.

[0088] Among them, the pickling speed is 70m / min, the pickling temperature is 82℃, the acid concentration of the first pickling tank is 90g / L, the acid concentration of the second to fourth pickling tanks is 130g / L, and the acid concentration of the fifth pickling tank is 170g / L.

[0089] After the 65Mn hot-rolled pickled plate is annealed once, it is cold-rolled for 5 passes using an 18-roll single-stand rolling mill. The taper contact value is set to 90mm. The first pass: the entry thickness is 6.2mm, the exit thickness is 5.26mm, the reduction rate is 15.2%, and the entry unit tension is 52N / mm. 2 , export unit tension 92N / mm 2 , rolling force 11.8MN; 2nd pass: outlet thickness 4.52mm, reduction rate 14.1%, inlet unit tension 61N / mm 2 , export unit tension 107N / mm 2 , rolling force 11.5MN; 3rd pass: outlet thickness 3.91mm, reduction rate 13.5%, inlet unit tension 71N / mm 2 , export unit tension 113N / mm 2 , rolling force 11.2MN; 4th pass: exit thickness 3.48mm, reduction rate 11.0%, entrance unit tension 78N / mm 2 , export unit tension 120N / mm 2, rolling force 10.8MN; 5th pass: outlet thickness 3.2mm, reduction rate 8.0%, inlet unit tension 81N / mm 2 , export unit tension 126N / mm 2 , rolling force 10.2MN. Total reduction rate 48.4%, rolling stability.

[0090] The longitudinal thickness deviation of the 65Mn cold-rolled steel strip obtained by cold rolling is -0.013 to 0.013 mm, and the transverse thickness deviation of the same plate is ≤0.019 mm.

[0091] As shown in Examples 1-3, the 18-high single-stand rolling mill provided by this application can produce 65Mn cold-rolled steel strip in various specifications through stable rolling. The resulting 65Mn cold-rolled steel strip has minimal longitudinal thickness deviation and transverse thickness variation, resulting in high quality and ease of subsequent processing and utilization. This method can be widely applied to the production of 65Mn cold-rolled steel strip using domestic or imported 18-high single-stand rolling mills, facilitating the localization and application of 18-high single-stand rolling mills.

[0092] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit them. Although the present application has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some or all of the technical features therein. These modifications or replacements do not deviate the essence of the corresponding technical solutions from the scope of the technical solutions of the embodiments of the present application.

Claims

1. A method for producing 65Mn cold-rolled steel strip using an 18-high single-stand rolling mill, characterized in that: The following steps are involved: S10 provides 65Mn hot-rolled pickled plate; S20: subjecting the 65Mn hot-rolled pickled steel sheet to a primary annealing treatment and then cold rolling it using an 18-high single-stand rolling mill to obtain a 65Mn cold-rolled steel strip, wherein the primary annealing treatment comprises: maintaining the temperature at 710-740° C. for 15-18 hours; the 18-high single-stand rolling mill comprises an intermediate roll having a first taper and a second taper, and a work roll disposed on a first side of the intermediate roll and in contact with the intermediate roll; In the cold rolling, the contact length between the 65Mn hot-rolled pickled plate and the first taper corresponding zone I of the intermediate roll is 90-120 mm; the cold rolling includes 5 passes, and the 5 passes include: the first pass has a reduction rate of 15%-22%, and an inlet unit tension of 50-120 N / mm 2 , export unit tension 80~160N / mm 2 , rolling force 9~15MN; second pass reduction rate 12%~20%, entrance unit tension 50~120N / mm 2 , export unit tension 80~160N / mm 2 , rolling force 9~15MN; 3rd pass reduction rate 12%~20%, entrance unit tension 50~120N / mm 2 , export unit tension 80~160N / mm 2 , rolling force 9~15MN; 4th pass reduction rate 12%~20%, entrance unit tension 50~120N / mm 2 , export unit tension 80~160N / mm 2 , rolling force 9~15MN; 5th pass reduction rate 7%~12%, entrance unit tension 50~120N / mm 2 , export unit tension 80~160N / mm 2 , rolling force 8~13MN.

2. The method according to claim 1, characterized in that S10 specifically includes: 65Mn ingots are provided, and 65Mn hot-rolled pickled plates are obtained through hot rolling and pickling.

3. The method according to claim 2, characterized in that The pickling includes a first pickling stage, a second pickling stage, a third pickling stage, a fourth pickling stage and a fifth pickling stage. The acid concentration in the first pickling stage is 70-120 g / L, the acid concentration in the second pickling stage, the third pickling stage and the fourth pickling stage is 120-170 g / L, and the acid concentration in the fifth pickling stage is 160-200 g / L.

4. The method according to claim 2, characterized in that The pickling temperature is 75-90° C., and the pickling speed is 70-100 m / min.

5. The method according to claim 1, characterized in that In S20, the total reduction ratio of the cold rolling is 45% to 62%.

6. The method according to claim 1, characterized in that The working rolls have a roll diameter of 140-170 mm, and are used for rolling the steel to be rolled.

7. The method according to claim 1, characterized in that The 65Mn cold-rolled steel strip has a thickness of 0.6-3.2 mm and a width of 900-1300 mm.

8. The method according to claim 1, characterized in that The longitudinal thickness deviation of the 65Mn cold-rolled steel strip is within the range of -0.5%D to 0.5%D, and the transverse thickness deviation of the same plate is ≤1%D; Wherein, D is the thickness of the 65Mn cold-rolled steel strip, in mm.

9. A 65Mn cold-rolled steel strip product, characterized in that: The method is obtained by processing the 65Mn cold-rolled steel strip obtained by the method according to any one of claims 1 to 8.

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