Duplex Stainless Steel Wide Cold Rolled Sheet Shape Control Method

Abstract

This invention discloses a method for controlling the shape of wide cold-rolled duplex stainless steel sheets. The method includes employing a multi-pass rolling process with a total deformation rate of 38-45% in the finished product rolling pass, and using a pre-trimming rolling mode. It designs the crown of the two intermediate rolls and the work rolls, as well as the cone length and taper of the first intermediate roll. The total number of rolling passes in the finished product rolling pass is controlled to be 5-7 passes, with control over the rolling deformation rate, pre- and post-rolling tension, and rolling speed for each pass. The shape curves for passes 1 to 3 adopt a W-shaped target curve, and the actual stress deviation values ​​for the edges and center of each pass are controlled. The shape curves for passes 4 to the finished product pass adopt a concave-sided target curve, and the actual stress deviation values ​​for the edges and center of each pass are controlled. This invention significantly improves the shape control level of wide cold-rolled duplex stainless steel sheets and successfully solves the problem of difficult shape control in this process.

Description

Technical Field

[0001] This invention belongs to the field of reversible cold rolling technology of wide cold-rolled duplex stainless steel sheets, and particularly relates to a method for controlling the shape of wide cold-rolled duplex stainless steel sheets with a width of 1200-1400 mm. Background Technology

[0002] Duplex stainless steel is a type of stainless steel with approximately 50% ferritic and 50% austenitic components, combining the advantages of both ferritic and austenitic stainless steels, namely high strength, good toughness, excellent weldability, and corrosion resistance. Duplex stainless steel cold-rolled sheets are characterized by wide widths, good surface quality, excellent high-temperature performance, and high flatness. They are widely used in heat exchangers and cooling systems for seawater and high-temperature concentrated nitric acid in industries such as oil refining, fertilizer, papermaking, petroleum, and chemicals. It is an indispensable key material in various industrial sectors, and its quality level has a direct impact on the safety and stability of chemical production. With the development of the chemical industry, market demand has increased significantly, but customers have extremely high requirements for the sheet shape of this product, posing a challenge to the quality control level of manufacturing enterprises.

[0003] Wide cold-rolled duplex stainless steel sheets are typically rolled using a Sundwing 20-roll mill with multi-pass reversible rolling. The production challenges lie in the fact that duplex stainless steel, due to the complex composition of its two phases and its high strength and hardness, suffers from severe edge cracking after hot rolling, making subsequent cold rolling extremely difficult. The cold rolling process is prone to problems such as pull-out and pull-out, and the rolled sheet shape cannot be effectively controlled, easily resulting in complex wavy defects such as edge waviness and center waviness, failing to meet customer requirements and severely impacting market quality image. Therefore, developing a method for controlling the rolled sheet shape of wide cold-rolled duplex stainless steel sheets has become a pressing technical problem for those skilled in the art. Summary of the Invention

[0004] To address the technical problems existing in the prior art, the present invention provides a method for controlling the shape of duplex stainless steel wide cold-rolled sheets, comprising:

[0005] (1) Design of rolling process

[0006] Duplex stainless steel wide cold-rolled sheets are rolled using a 20-roll mill with a multi-pass rolling process. The total deformation rate of the finished product is controlled at 38-45%. The finished product rolling process adopts the mode of rolling after trimming.

[0007] (2) Design the roller system and roller shape

[0008] The crown of the intermediate roll of the second mill is designed to be 0.25–0.35 mm, and the crown of the work roll of the mill is designed to be 0.08–0.12 mm. The intermediate roll of the first mill adopts a composite cone shape with a total cone length of 570 mm. Among them, the 0–420 mm part is a straight cone with a cone length: cone height = 1: 0.001–0.002; the 420–570 mm part is a straight cone with a cone length: cone height = 1: 0.0002–0.0004.

[0009] (3) Determine the target plate shape after the finished rolling process

[0010] The target plate shape after the finished rolling process is determined to be "slight 1 / 4 wave + double-sided wave" plate shape;

[0011] (4) Control the finished product rolling process

[0012] The total number of rolling passes in the finished product rolling process is controlled to be 5 to 7. The rolling deformation rate of the first pass is controlled to be 10 to 13%, the rolling deformation rate of the second pass is controlled to be 11 to 15%, the rolling deformation rate of the third pass is controlled to be 10 to 15%, the rolling deformation rate of the fourth pass is controlled to be 9 to 13%, the rolling deformation rate of each pass between the fourth pass and the finished product pass is controlled to be 8 to 12%, the rolling deformation rate of the finished product pass is controlled to be 7 to 9%, the tension before each rolling pass is controlled to be 400 to 450 kN, the tension difference before and after the first pass is controlled to be 200 to 300 kN, the tension difference before and after the remaining passes is controlled to be 0 to 20 kN, the rolling speed of the first pass is controlled to be ≤150 m / min, the rolling speed of the second and third passes is controlled to be ≤200 m / min, and the rolling speed of the remaining passes is controlled to be ≤500 m / min.

[0013] (5) Controlling the finished product rolling process and shape

[0014] In the secondary calculation system of the automatic rolling control system of the 20-roll mill, the actual width of the plate without cracks after edge trimming is input. The W-shaped plate shape target curve is adopted for the first to third passes, and the actual stress deviation value of the edge plate shape is controlled within 10 to 80 N / mm. 2 Within the specified range, the actual stress deviation of the middle plate is controlled within 10–80 N / mm. 2 Within the specified range, the plate shape curve for the 4th to the finished product pass adopts a target plate shape curve with concave sides, and the actual stress deviation value of the edge plate shape is controlled within -20 to 0 N / mm. 2 Within the specified range, the actual stress deviation of the middle plate is controlled within 40–80 N / mm. 2 Within the range.

[0015] Furthermore, in the above-mentioned method for controlling the shape of wide cold-rolled duplex stainless steel sheets, the wide cold-rolled sheet is a stainless steel cold-rolled sheet with a width of 1200-1400 mm.

[0016] As one specific implementation method, the above-mentioned method for controlling the shape of duplex stainless steel wide cold-rolled sheets is applied to duplex stainless steel cold-rolled sheets with a rolling specification of 1.6mm thickness × 1250mm width, wherein:

[0017] In the design of the rolling process, the SUNDWING 20-roll mill adopts a double rolling process, and the finished product thickness is rolled from 2.9mm to 1.6mm. The total deformation rate of the finished product is 44.8%. The finished product rolling adopts the mode of rolling after trimming.

[0018] In the design of the roll system, the crown of the second intermediate roll of the rolling mill is designed to be 0.3 mm, the crown of the work roll of the rolling mill is designed to be 0.1 mm, and the first intermediate roll of the rolling mill adopts a composite cone shape with a total cone length of 570 mm. Among them, the part from 0 to 420 mm is a straight cone with a cone length: cone height = 1:0.0012; the part from 420 to 570 mm is a straight cone with a cone length: cone height = 1:0.00025.

[0019] In the finished product rolling process, the total number of rolling passes is 5. The deformation rate of the first pass is 12%, the deformation rate of the second pass is 13.28%, the deformation rate of the third pass is 11.39%, the deformation rate of the fourth pass is 9.48%, and the deformation rate of the fifth pass is 8%. The tensions before and after the first pass are 450KN and 230KN, respectively; the tensions before and after the second pass are 425KN and 420KN, respectively; the tensions before and after the third and fourth passes are 420KN and 420KN, respectively; and the tensions before and after the fifth pass are 420KN and 410KN, respectively. The rolling speeds of the first to fifth passes are 100m / min, 150m / min, 150m / min, 200m / min, and 200m / min, respectively.

[0020] In the process of controlling the finished product rolling shape, the actual width of the plate without cracks after edge trimming (1200mm) is input into the secondary calculation system of the SUNDWING 20-roll mill automatic rolling control system. The W-shaped plate shape target curve is adopted for the first to third passes. The actual stress deviation values ​​of the edge plate shape in the first, second, and third passes are controlled to be 80N / mm. 2 60N / mm 2 40N / mm 2 The actual stress deviation of the plate shape in the middle of the first, second, and third passes was controlled to be 60 N / mm. 2 40N / mm 2 40N / mm 2 The plate shape curves for the 4th and 5th passes adopt a concave plate shape target curve on both sides, and the actual stress deviation values ​​of the edge plate shape for the 4th and 5th passes are controlled to be -10N / mm. 2 -20N / mm 2The actual stress deviation of the middle plate shape in the 4th and 5th passes was controlled to be 60 N / mm. 2 40N / mm 2 .

[0021] The method for controlling the shape of duplex stainless steel wide cold-rolled sheets of the present invention has the following advantages and beneficial effects:

[0022] (1) By designing the rolling process and the edge-cutting rolling mode, it can be ensured that the rolling stability and plate shape control of the finished product will not be affected by edge cracks.

[0023] (2) By designing the roll system roll shape, a roll system with sufficient convexity and taper can be provided. Through the combination of convexity adjustment and axial lateral movement of the intermediate roll, the expected value of the plate shape control during the rolling process can be met and realized, ensuring that the plate shape after rolling at each transverse position is controllable.

[0024] (3) By determining the target plate shape after the finished rolling process, the plate shape after annealing can be made to be straight, reducing the difficulty of subsequent processes in improving the plate shape;

[0025] (4) By controlling the rolling process of the finished product rolling process, it is possible to effectively control the excessive deformation martensite generated in the first to third passes due to excessive rolling deformation rate and excessive rolling speed, which will affect the plate shape control of subsequent passes.

[0026] (5) By controlling the rolling process and plate shape process of the finished product rolling process, it is possible to ensure that the rolling pressure distribution of each pass is reasonable, effectively reduce the rolling breakage and pull-out problems, achieve the matching of the rolling process and plate shape target curve, eliminate composite plate shape defects, obtain the optimal post-rolled physical plate shape, significantly improve the plate shape control level of duplex stainless steel wide cold plate rolling, and successfully solve the problem of difficult plate shape control of duplex stainless steel wide cold plate rolling. According to actual calculation, the plate shape qualification rate has increased from less than 85% of the existing technology to more than 95%. Attached Figure Description

[0027] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort. In the drawings:

[0028] Figure 1 This is a schematic diagram of the W-shaped target curve used in the method for controlling the shape of wide cold-rolled duplex stainless steel sheets of the present invention.

[0029] Figure 2 This is a schematic diagram of the target curve of the concave-shaped plate used in the shape control method for wide cold-rolled duplex stainless steel sheets of the present invention. Detailed Implementation

[0030] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below in conjunction with specific embodiments and corresponding drawings. Obviously, the described embodiments are only a part of the embodiments of this invention, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0031] The method for controlling the shape of duplex stainless steel wide cold-rolled sheets of the present invention includes:

[0032] (1) Design of rolling process

[0033] Duplex stainless steel wide cold-rolled sheets are rolled using a 20-roll mill with a multi-pass rolling process. The total deformation rate of the finished product is controlled at 38-45%, and the finished product rolling process adopts the mode of rolling after trimming.

[0034] (2) Design the roller system and roller shape

[0035] The crown of the intermediate roll of the second mill is designed to be 0.25-0.35 mm (25-35 passes), and the crown of the work roll of the mill is designed to be 0.08-0.12 mm (8-12 passes). The intermediate roll of the first mill adopts a composite cone shape with a total cone length of 570 mm. The part from 0 to 420 mm is a straight cone with a cone length: cone height = 1: 0.001-0.002; the part from 420 to 570 mm is a straight cone with a cone length: cone height = 1: 0.0002-0.0004.

[0036] (3) Determine the target plate shape after the finished rolling process

[0037] The target plate shape after the finished rolling process is determined to be "slight 1 / 4 wave + double-sided wave".

[0038] (4) Control the finished product rolling process

[0039] The total number of rolling passes in the finished product rolling process is controlled to be 5 to 7. The rolling deformation rate of the first pass is controlled to be 10 to 13%, the rolling deformation rate of the second pass is controlled to be 11 to 15%, the rolling deformation rate of the third pass is controlled to be 10 to 15%, the rolling deformation rate of the fourth pass is controlled to be 9 to 13%, the rolling deformation rate of each pass between the fourth pass and the finished product pass is controlled to be 8 to 12%, the rolling deformation rate of the finished product pass is controlled to be 7 to 9%, the tension before each rolling pass is controlled to be 400 to 450 kN, the tension difference before and after the first pass is controlled to be 200 to 300 kN, the tension difference before and after the remaining passes is controlled to be 0 to 20 kN, the rolling speed of the first pass is controlled to be ≤150 m / min, the rolling speed of the second and third passes is controlled to be ≤200 m / min, and the rolling speed of the remaining passes is controlled to be ≤500 m / min.

[0040] (5) Controlling the finished product rolling process and shape

[0041] In the secondary calculation system of the automatic rolling control system of the 20-roll mill, the actual width of the plate without cracks after edge trimming is input, and the plate shape curves for the first to third passes are as follows: Figure 1 The target curve for the W-shaped plate shown indicates that the actual stress deviation at the edge of the plate is controlled within 10–80 N / mm. 2 Within the specified range, the actual stress deviation of the middle plate is controlled within 10–80 N / mm. 2 Within the range, the slab profile curve for the 4th to the finished product pass adopts the following... Figure 2 The target curve for the concave plate shape shown has an actual stress deviation value at the edge of the plate controlled within -20 to 0 N / mm. 2 Within the specified range, the actual stress deviation of the middle plate is controlled within 40–80 N / mm. 2 Within the range.

[0042] In one specific embodiment, in the method for controlling the shape of duplex stainless steel wide cold-rolled sheet rolling of the present invention, the wide cold-rolled sheet refers to a stainless steel cold-rolled sheet with a width specification of 1200-1400mm.

[0043] Furthermore, in the method for controlling the rolling shape of wide cold-rolled duplex stainless steel sheets of the present invention, the W-shaped target curve and the concave-shaped target curve are rolling shape curves that are built into the automatic rolling control system of the 20-roll mill.

[0044] The following detailed description of the method for controlling the shape of duplex stainless steel wide cold-rolled sheets according to the present invention, with reference to specific embodiments, is provided in detail.

[0045] The method for controlling the shape of wide cold-rolled duplex stainless steel sheets according to this invention is applied to S32205 duplex stainless steel cold-rolled sheets with a rolling specification of 1.6mm thickness × 1250mm width, and includes the following steps:

[0046] (1) Design of rolling process

[0047] The SUNDWING 20-roll mill uses a double-pass rolling process, rolling the finished product from 2.9mm thick to 1.6mm thick, with a total deformation rate of 44.8%. The finished product rolling process adopts a trimming and then rolling mode.

[0048] (2) Design the roller system and roller shape

[0049] The crown of the intermediate roll of the second mill is designed to be 0.3 mm, and the crown of the work roll of the mill is designed to be 0.1 mm. The intermediate roll of the first mill adopts a composite cone shape with a total cone length of 570 mm. The part from 0 to 420 mm is a straight cone with a cone length: cone height = 1:0.0012; the part from 420 to 570 mm is a straight cone with a cone length: cone height = 1:0.00025.

[0050] (3) Determine the target plate shape after the finished rolling process

[0051] The target plate shape after the finished rolling process is determined to be "slight 1 / 4 wave + double-sided wave".

[0052] (4) Control the finished product rolling process

[0053] The finished product rolling process consists of 5 passes. The deformation rate of the first pass is 12%, the second pass is 13.28%, the third pass is 11.39%, the fourth pass is 9.48%, and the fifth pass is 8%. The tensions before and after the first pass are 450KN and 230KN, respectively; the tensions before and after the second pass are 425KN and 420KN, respectively; the tensions before and after the third and fourth passes are 420KN and 420KN, respectively; and the tensions before and after the fifth pass are 420KN and 410KN, respectively. The rolling speeds for the first to fifth passes are 100m / min, 150m / min, 150m / min, 200m / min, and 200m / min, respectively.

[0054] (5) Controlling the finished product rolling process and shape

[0055] The actual width of the sheet metal after trimming without cracks was measured to be 1200mm. This actual width of 1200mm was then input into the secondary calculation system of the SUNDWING 20-roll mill automatic rolling control system. The sheet shape curves for the first to third passes were as follows: Figure 1 The W-shaped target curve shown has its actual stress deviation at the edge of the plate controlled at 80 N / mm for the 1st, 2nd, and 3rd passes. 2 60N / mm 2 40N / mm 2 The actual stress deviation of the plate shape in the middle of the first, second, and third passes was controlled to be 60 N / mm. 2 40N / mm2 40N / mm 2 The 4th and 5th pass plate shape curves adopt the following... Figure 2 The target curves for the concave plate shape shown on both sides are configured such that the actual stress deviations at the edges of the plate in the 4th and 5th passes are controlled to be -10 N / mm. 2 -20N / mm 2 The actual stress deviation of the middle plate shape in the 4th and 5th passes was controlled to be 60 N / mm. 2 40N / mm 2 .

[0056] The cold-rolled sheet obtained by applying the shape control method of the duplex stainless steel wide cold-rolled sheet in this embodiment of the invention has a slight 1 / 4 wave + double-sided wave shape, and the sheet shape is straight after cold wire annealing.

[0057] In summary, compared with the prior art, the method for controlling the shape of duplex stainless steel wide cold-rolled sheets of the present invention has the following advantages and beneficial effects:

[0058] (1) By designing the rolling process and the edge-cutting rolling mode, it can be ensured that the rolling stability and plate shape control of the finished product will not be affected by edge cracks.

[0059] (2) By designing the roll system roll shape, a roll system with sufficient convexity and taper can be provided. Through the combination of convexity adjustment and axial lateral movement of the intermediate roll, the expected value of the plate shape control during the rolling process can be met and realized, ensuring that the plate shape after rolling at each transverse position is controllable.

[0060] (3) By determining the target plate shape after the finished rolling process, the plate shape after annealing can be made to be straight, reducing the difficulty of subsequent processes in improving the plate shape;

[0061] (4) By controlling the rolling process of the finished product rolling process, it is possible to effectively control the excessive deformation martensite generated in the first to third passes due to excessive rolling deformation rate and excessive rolling speed, which will affect the plate shape control of subsequent passes.

[0062] (5) By controlling the rolling process and plate shape process of the finished product rolling process, it is possible to ensure that the rolling pressure distribution of each pass is reasonable, effectively reduce the rolling breakage and pull-out problems, achieve the matching of the rolling process and plate shape target curve, eliminate composite plate shape defects, obtain the optimal post-rolled physical plate shape, significantly improve the plate shape control level of duplex stainless steel wide cold plate rolling, and successfully solve the problem of difficult plate shape control of duplex stainless steel wide cold plate rolling. According to actual calculation, the plate shape qualification rate has increased from less than 85% of the existing technology to more than 95%.

[0063] It should be noted that, in this document, the term "comprising" or any other variation thereof is intended to cover non-exclusive inclusion, such that an article or device that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such an article or device.

[0064] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method of shape control for wide cold-rolled sheet of duplex stainless steel, characterized by, It includes: (1) Designing rolling process The wide cold plate of duplex stainless steel is rolled by twenty-roller rolling mill using multi-pass rolling process, the total deformation rate of finished product rolling is controlled in 38-45%, and the finished product rolling adopts the mode of rolling after trimming; (2) Designing roll shape The camber of the second intermediate roller of the rolling mill is designed as 0.25-0.35mm, the camber of the working roller of the rolling mill is designed as 0.08-0.12mm, the first intermediate roller of the rolling mill adopts composite taper, the total taper length is 570mm, wherein the part of 0-420mm is straight taper, the taper length:taper height = 1:0.001-0.002; the part of 420-570mm is straight taper, the taper length:taper height = 1:0.0002-0.0004; (3) Determining the target plate shape after finished product rolling The target plate shape after finished product rolling is determined as "slight 1 / 4 wave + double edge wave" plate shape; (4) Controlling finished product rolling process The total pass of finished product rolling is controlled as 5-7 passes, the deformation rate of the first pass is controlled as 10-13%, the deformation rate of the second pass is controlled as 11-15%, the deformation rate of the third pass is controlled as 10-15%, the deformation rate of the fourth pass is controlled as 9-13%, the deformation rate of each pass between the fourth pass and the finished product pass is controlled as 8-12%, the deformation rate of the finished product pass is controlled as 7-9%, the tension before each pass is controlled as 400-450KN, the difference of tension before and after the first pass is controlled as 200-300KN, the difference of tension before and after the rest passes is controlled as 0-20KN, the rolling speed of the first pass is controlled as ≤150m / min, the rolling speed of the second and third passes is controlled as ≤200m / min, and the rolling speed of the rest passes is controlled as ≤500m / min; (5) Controlling plate shape process of finished product rolling In the second computing system of the twenty-roller rolling mill automatic rolling control system, the actual width of the plate after cutting edge without crack is input, the first to third pass plate shape curve adopts W type plate shape target curve, the actual stress deviation value of the edge plate shape is controlled in the range of 10-80 N / mm 2 , the actual stress deviation value of the middle plate shape is controlled in the range of 10-80 N / mm 2 , the fourth to finished product pass plate shape curve adopts two-side concave type plate shape target curve, the actual stress deviation value of the edge plate shape is controlled in the range of-20-0 N / mm 2 , the actual stress deviation value of the middle plate shape is controlled in the range of 40-80 N / mm 2 .

2. The DP steel wide cold plate rolling shape control method according to claim 1, characterized by, The wide cold plate is stainless steel cold-rolled plate with width specification of 1200-1400mm.

3. The duplex stainless steel wide cold plate rolling plate shape control method according to claim 1 applied to rolling specification of 1.6mm thick × 1250mm wide duplex stainless steel cold plate, characterized in that: In the designing rolling process, the SUNDWING twenty-roller rolling mill is used for double-pass rolling, the finished product rolling is rolled from 2.9mm thick to 1.6mm thick, the total deformation rate of finished product rolling is 44.8%, and the finished product rolling adopts the mode of rolling after trimming; In the designing roll shape, the camber of the second intermediate roller of the rolling mill is designed as 0.3mm, the camber of the working roller of the rolling mill is designed as 0.1mm, and the first intermediate roller of the rolling mill adopts composite taper, the total taper length is 570mm, wherein the part of 0-420mm is straight taper, the taper length:taper height = 1:0.0012; the part of 420-570mm is straight taper, the taper length:taper height = 1:0.00025; In the control finished product rolling process, the total pass of finished product rolling is 5 passes, the deformation rate of the first pass is 12%, the deformation rate of the second pass is 13.28%, the deformation rate of the third pass is 11.39%, the deformation rate of the fourth pass is 9.48%, the deformation rate of the fifth pass is 8%, the front and rear tension of the first pass is 450KN and 230KN respectively, the front and rear tension of the second pass is 425KN and 420KN respectively, the front and rear tension of the third and fourth pass is 420KN and 420KN respectively, the front and rear tension of the fifth pass is 420KN and 410KN respectively, the rolling speed of the first to fifth pass is 100m / min, 150m / min, 150m / min, 200m / min and 200m / min respectively; In the control of finished product rolling process, the actual width of the plate after cutting edge is input in the second calculation system of SUNDWING twenty-roller rolling mill automatic steel rolling control system, the plate shape curve of the first to third passes adopts W-shaped plate shape target curve, the actual stress deviation value of the edge part plate shape of the first, second and third passes is controlled to be 80 N / mm 2 , 60 N / mm 2 , 40 N / mm 2 , respectively, the actual stress deviation value of the middle part plate shape of the first, second and third passes is controlled to be 60 N / mm 2 , 40 N / mm 2 , 40 N / mm 2 , respectively, the plate shape curve of the fourth and fifth passes adopts two-side concave plate shape target curve, the actual stress deviation value of the edge part plate shape of the fourth and fifth passes is controlled to be-10 N / mm 2 , -20 N / mm 2 , respectively, the actual stress deviation value of the middle part plate shape of the fourth and fifth passes is controlled to be 60 N / mm 2 , 40 N / mm 2 .

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