Precipitation hardening martensite SUS630 stainless steel cold-rolled strip shape control method

Abstract

The invention discloses a plate shape control method for a precipitation-hardening martensite SUS630 stainless steel cold-rolled steel strip. The technical problem that the plate shape of the steel strip is difficult to control is solved. The plate shape control method comprises the following steps that S1, hot rolling, annealing and acid pickling are conducted on a steel strip, the thickness of the steel strip is controlled to be 5.0-6.0 mm, and the width of the steel strip is controlled to be 900-2100 mm; s2, 304 stainless steel leading belts matched with the base metal in width and thickness are welded to the head and the tail of the steel coil correspondingly; s3, cold rolling is conducted on the steel strip through a rolling mill; and S4, the steel strip is corrected through a withdrawal and straightening machine, and the finished steel strip is obtained. According to the method, effective control over the plate shape can be achieved, it is guaranteed that the plate shape of the SUS630 cold-rolled, annealed and pickled steel strip is straight, the unevenness of the plate is smaller than or equal to 3 mm after the plate is flattened, and the use requirement of the steel strip is met.

Description

Technical Field

[0001] The invention belongs to the technical field of precipitation hardening martensitic SUS630 stainless steel production, and in particular relates to a precipitation hardening martensitic SUS630 stainless steel cold-rolled steel strip shape control method. Background Art

[0002] Precipitation hardening martensitic SUS630 stainless steel, with the national standard grade of 0Crl7Ni4Cu4Nb, is a martensitic precipitation stainless steel developed by adding elements such as Cu and Nb on the basis of Crl7 stainless steel. Since SUS630 stainless steel is low in carbon, high in chromium, and contains copper, its corrosion resistance is better than that of conventional Crl3 martensitic stainless steel. After aging hardening, the hardness of SUS630 stainless steel can reach HRC50. It can ensure high strength, high hardness, and high corrosion resistance, and at the same time has no obvious thermal expansion and contraction phenomenon. It is widely used in electronic circuit boards, pressure vessels, turbine blades and other fields.

[0003] For SUS630 stainless steel flat plate, the plate shape requirements are extremely strict. The industry generally requires that the unevenness of the entire plate is ≤3mm, which requires the plate shape of the steel coil to be straight before flattening. During the production and processing of SUS630 steel coils in steel plants, the material structure exists in the form of solid solution or rolling state, with extremely high strength and hardness, but low elongation. For example, the yield strength is 800-1200MPa, the hardness HRC is 30-45, but the elongation of the material is only 2-9%. Therefore, production and plate shape control are extremely difficult.

[0004] Since SUS630 stainless steel has high strength and hardness, the hardness of the material is further increased and the toughness is reduced after cold rolling due to work hardening, which makes it difficult to control the plate shape, especially when rolling with large pressure and large deformation, the plate shape will be further deteriorated. In addition, the cold-rolled steel strip will deform after online annealing, which will affect the plate shape control and needs to be improved. Summary of the invention

[0005] In order to solve all or part of the above problems, the purpose of the present invention is to provide a precipitation hardened martensitic SUS630 stainless steel cold-rolled steel strip shape control method, which can achieve effective control of the plate shape, ensure that the plate shape of the SUS630 cold-rolled annealed pickled steel strip is straight, and the unevenness of the plate after flattening is ≤3mm, so as to meet the use requirements of the steel strip.

[0006] The present invention provides a method for controlling the shape of a precipitation hardened martensitic SUS630 stainless steel cold-rolled steel strip, comprising the following steps:

[0007] S1, hot rolling, annealing and pickling the steel strip, and controlling the thickness of the steel strip to be 5.0-6.0 mm and the width to be 900-2100 mm;

[0008] S2, 304 stainless steel guide strips matching the width and thickness of the parent material are welded at the head and tail of the steel coil;

[0009] S3, cold rolling the steel strip through a rolling mill;

[0010] S4, the steel strip is corrected by a tensioning and straightening machine to obtain a finished steel strip.

[0011] Optionally, in S2, the cold rolling step of the steel strip includes:

[0012] S31, rolling the steel strip for the first time and controlling the thickness of the steel strip to be 3.0-3.2 mm;

[0013] S32, annealing and pickling the steel strip, and cutting and trimming the edges of the steel strip;

[0014] S33, rolling the steel strip for the second time and controlling the thickness of the steel strip to be 1.8-2.2 mm;

[0015] S34, annealing and pickling the steel strip;

[0016] S35, rolling the steel strip for the third time and controlling the thickness of the steel strip to be 1.5-1.6 mm;

[0017] S36, annealing and pickling the steel strip.

[0018] Optionally, in S31, the rolling passes of the steel strip are controlled to be 7-11 passes, and the rolling pressure of each pass is 800-1400KN, the post tension of the first pass is controlled to be 250-350KN, and the tensions of the remaining passes are controlled to be 550-600KN, and the plate shape control mode during the rolling of the steel strip is mainly loose at the edges and tight in the middle.

[0019] Optionally, in S32, after the steel strip is cut and trimmed, it is laid between the steel coil layers with a specification of 32g / m 2 of transparent plastic film.

[0020] Optionally, in S33, the rolling passes of the steel strip are controlled to be 7-11 passes, and the rolling pressure of each pass is 600-1000KN, the post tension of the first pass is controlled to be 100-150KN, and the tensions of the remaining passes are controlled to be 550-600KN, and the plate shape control mode during the rolling of the steel strip is mainly loose at the edges and tight in the middle.

[0021] Optionally, in S34, after the steel strip is annealed and pickled, it is laid between the steel coil layers with a specification of 32g / m 2 of transparent plastic film.

[0022] Optionally, in S35, the rolling passes of the steel strip are controlled to be 5-9 passes, and the tension of each pass is 550-600KN respectively, the rolling speed of the pre-finished pass and the finished pass is controlled to be ≤150m / min, and the plate shape control of the finished pass is mainly straight, while ensuring that the thickness of the steel strip after rolling the finished pass is greater than the thickness of the finished steel strip by 0.03-0.08mm.

[0023] Optionally, in S35, the steel strip is judged to be qualified by checking the difference between the maximum and minimum flatness values ​​fed back by the rolling mill. If the flatness difference is ≤100N / mm 2 , then the steel strip is qualified, if the plate shape difference is > 100N / mm 2 , the steel strip is unqualified.

[0024] Optionally, in S4, the straightening machine adopts three groups of roller straightening machines, the two roller diameters of the first group of straightening rollers are 70 mm respectively, one of the roller diameters of the second group of straightening rollers is 70 mm, the other roller diameter is 200 mm, and the large roller diameter straightening roller is located below the small roller diameter straightening roller, and one of the roller diameters of the third group of straightening rollers is 70 mm, the other roller diameter is 200 mm, and the large roller diameter straightening roller is located above the small roller diameter straightening roller.

[0025] Optionally, in S4, the straightening machine adopts the bending tension straightening mode, controls the tension of the tensioning roller of the straightening machine to 400-800KN, controls the pressing angles of the three sets of straightening rollers to 40-80°, 40-60°, and 40-60° respectively, and ensures that the elongation of the steel strip after straightening is 0.3-0.7%.

[0026] It can be seen from the above technical solution that the precipitation hardened martensitic SUS630 stainless steel cold-rolled steel strip shape control method provided by the present invention has the following advantages:

[0027] By optimizing the rolling range, thickness deformation rate and tension parameters of the rolling mill, as well as optimizing the tension parameters of the tension leveler, effective control of the plate shape is achieved, ensuring that the shape of the SUS630 cold-rolled annealed pickled steel strip is straight, and the unevenness of the plate after flattening is ≤3mm, to meet the use requirements of the steel strip.

[0028] Other features and advantages of the present invention will be set forth in the description which follows. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] The accompanying drawings are used to provide a further understanding of the technical solution of the present invention and constitute a part of the specification. Together with the embodiments of the present invention, they are used to explain the technical solution of the present invention and do not constitute a limitation to the technical solution of the present invention.

[0030] Figure 1 is a flow chart of a plate shape control method in an embodiment of the present invention;

[0031] Figure 2 It is a schematic diagram of the structure of a twenty-roller Sendkimir rolling mill in an embodiment of the present invention. DETAILED DESCRIPTION

[0032] To make the purpose, technical solution and advantages of the present invention more clear, the embodiments of the present invention will be described in detail below with reference to the accompanying drawings. It should be noted that the embodiments of the present invention and the features in the embodiments can be combined with each other arbitrarily without conflict.

[0033] like Figure 1 , Figure 2 The embodiment of the present invention is shown in the figure, which discloses a method for controlling the shape of a precipitation hardened martensitic SUS630 stainless steel cold-rolled steel strip, comprising the following steps:

[0034] S1, hot rolling, annealing and pickling the steel strip, and controlling the thickness of the steel strip after annealing and pickling to be 5.0-6.0 mm and the width to be 900-2100 mm.

[0035] S2, 304 stainless steel guide strips matching the width and thickness of the parent material are welded at the head and tail of the steel coil.

[0036] S3, cold rolling the steel strip through a rolling mill.

[0037] S4, the steel strip is corrected by a tensioning and straightening machine to obtain a finished steel strip.

[0038] In S2, the stainless steel guide and the steel strip are welded and fixed by metal inert gas welding (MIG welding). By setting the stainless steel guide, the loss of the head and tail of the steel strip during cold rolling is reduced, thereby improving the yield rate of the steel strip.

[0039] In S3, a twenty-roller Sendkimier mill is used to cold-roll the steel strip, and the steel strip is cold-rolled through three rolling processes in total. The specific cold rolling steps are as follows:

[0040] S31, rolling the steel strip for the first time and controlling the thickness of the steel strip to be 3.0-3.2 mm.

[0041] S32, annealing and pickling the steel strip, and cutting and trimming the edges of the steel strip.

[0042] S33, rolling the steel strip for the second time and controlling the thickness of the steel strip to be 1.8-2.2 mm.

[0043] S34, annealing and pickling the steel strip.

[0044] S35, rolling the steel strip for the third time and controlling the thickness of the steel strip to be 1.5-1.6 mm.

[0045] S36, annealing and pickling the steel strip.

[0046] In S31, the rolling passes of the steel strip are controlled to be 7-11 passes, and the rolling pressure of each pass is 800-1400KN respectively. The post tension of the first pass is controlled to be 250-350KN, and the tension of the remaining passes is 550-600KN respectively. At the same time, the plate shape control mode during the steel strip rolling process is mainly loose at the edges and tight in the middle.

[0047] In S32, after the first rolling of the steel strip, the edge cracks or uneven parts of the steel strip are cut off. The main purpose of trimming is to prevent the steel strip from being broken due to defects on the edge of the steel strip during the subsequent plate shape control process. At the same time, in order to prevent paper rubbing marks on the surface of the steel strip during the subsequent rolling process, after the steel strip is trimmed, a plastic film is laid between the steel coil layers. In this embodiment, a plastic film with a specification of 32g / m 2 of transparent plastic film.

[0048] In S33, the rolling passes of the steel strip are controlled to be 7-11 passes, and the rolling pressure of each pass is 600-1000KN respectively. The post tension of the first pass is controlled to be 100-150KN, and the tension of the remaining passes is 550-600KN respectively. At the same time, the plate shape control mode during the steel strip rolling process is mainly loose at the edges and tight in the middle.

[0049] In S34, after the steel strip is annealed and pickled, the specification of the mat between the steel coil layers is 32g / m, the same as S32. 2 A transparent plastic film is used to prevent paper rubbing marks on the surface of the steel strip during the subsequent rolling process, thereby improving product quality.

[0050] In S35, the steel strip is rolled 5-9 times, and the tension of each time is 550-600KN, the rolling speed of the pre-finished pass and the finished pass is controlled to be ≤150m / min, and the shape of the finished pass is mainly controlled to be straight. After the third rolling of the steel strip, the subsequent annealing, pickling, and straightening and leveling are considered to reduce the thickness of the steel strip. Therefore, the thickness of the steel strip after the finished pass is guaranteed to be greater than the thickness of the finished steel strip by 0.03-0.08mm.

[0051] like Figure 2 As shown, in this embodiment, the working roll diameter of the twenty-roll Sendzimir mill is 85-93 mm, the taper length of an intermediate roll is 250-380 mm, and the steel strip is rolled using the principle of "small reduction, multiple passes". At the same time, during the rolling of the steel strip by the twenty-roll Sendzimir mill, the axial force of an intermediate roll and the AS-U-ROLL crown of the support roll can be used to achieve plate shape control.

[0052] In S35, the difference between the maximum and minimum flatness values ​​fed back by the rolling mill is used to determine whether the steel strip is qualified. If the flatness difference is ≤100N / mm2 , then the steel strip is qualified, if the plate shape difference is > 100N / mm 2 , the steel belt is unqualified, which makes it convenient for the staff to quickly judge whether the steel belt meets the requirements.

[0053] In S4, the straightening machine adopts three sets of roller straightening machines. The two roller diameters of the first set of straightening rollers are 70 mm respectively, one of the roller diameters of the second set of straightening rollers is 70 mm and the other roller diameter is 200 mm, and the large roller diameter straightening roller is located below the small roller diameter straightening roller, and one of the roller diameters of the third set of straightening rollers is 70 mm and the other roller diameter is 200 mm, and the large roller diameter straightening roller is located above the small roller diameter straightening roller.

[0054] In S4, the straightening machine adopts the bending tension straightening mode, controls the tension of the tensioning roller of the straightening machine to 400-800KN, controls the pressing angles of the three sets of straightening rollers to 40-80°, 40-60°, and 40-60° respectively, and at the same time, ensures that the elongation of the steel strip after straightening is 0.3-0.7%.

[0055] In order to more clearly illustrate this embodiment, the specific examples are as follows:

[0056] A roll of SUS630 hot-rolled annealed and pickled steel coil is used as the raw material. Its chemical composition by mass percentage is: C: 0.0337%, Cr: 15.2013%, Ni: 4.2652%, Cu: 3.4975%, Nb: 0.2295%, Si: 0.3666%, Mn: 0.6745%, P: 0.0161%, S: 0.0011%, N: 0.0308%, and the rest is Fe and other inevitable impurities. The specifications of the steel coil are: thickness 5.0mm, width 1514mm, weight 25080Kg.

[0057] The steel coil with welded lead strip is sent to the twenty-roller Sendkimir mill for cold rolling. The first rolling process controls the rolling thickness to 3.2mm. There are 9 rolling passes in total. The rolling pressure for each pass is 800-1200KN. The post-tension of the first pass should be 2500KN. The tension of the other passes is 550-600KN. During the first rolling process, the plate shape control is mainly based on the conventional loose edge and tight middle. After the first rolling process, annealing and pickling are carried out, and then trimming is carried out to cut off the edge cracks or uneven parts. After trimming, the width of the steel strip is 1450mm. Subsequently, the pad specification between the steel coil layers is 32g / m 2 of transparent plastic film.

[0058] Afterwards, the trimmed steel strip is rolled in the second rolling process. The rolling thickness is controlled to be 2.0mm in the second rolling process. There are 7 rolling passes in total. The rolling pressure of each pass is 600-800KN. The post-tension of the first pass is 120KN, and the tension of the other passes is 550-600KN. The plate shape control during the second rolling process is mainly loose at the edge and tight in the middle. Annealing is carried out after the second rolling process. The pad specification between the layers of the steel coil after annealing is 32g / m 2 of transparent plastic film.

[0059] Subsequently, the steel strip is rolled in the third rolling process. The working roll diameter of the twenty-roll Sendzimir rolling mill is 89mm, the cone length of an intermediate roll is 330mm, the post-tensioning force of the first pass is 120KN, and the tensions of the remaining passes are 550-600KN. A total of 7 passes are rolled, and the rolling speeds of the pre-finished pass and the finished pass are 130m / min.

[0060] Subsequently, the annealed and pickled steel strip was straightened, the tension of the tension roller of the straightening machine was controlled to be 600KN, and the pressing angles of the three sets of rollers were 55°, 50°, and 50° respectively. The elongation of the steel strip after straightening was 0.47%. After testing, the width of the finished steel strip was greater than 1200mm, the plate shape was straight, and the unevenness of the steel strip was ≤3mm. The product quality was qualified and met the subsequent use requirements.

[0061] From the above, it can be seen that the plate shape control method has the following advantages:

[0062] (1) Effectively solve the problems of SUS630 stainless steel material, such as high strength and hardness, low elongation, and difficulty in plate shape control, so that production can proceed smoothly;

[0063] (2) It can produce SUS630 cold-rolled annealed pickled steel strip with straight plate shape and form mass production on the production line, and the products can meet customer needs;

[0064] (3) It can produce qualified SUS630 cold-rolled wide steel strip (width > 1200mm), filling the gap of this variety in the domestic market and completing import substitution.

[0065] It should be noted that, unless otherwise specified, the technical terms or scientific terms used in the present invention should have the common meanings understood by those skilled in the art to which the present invention belongs.

[0066] In addition, the terms "first", "second", etc. are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. In the description of the present invention, the meaning of "plurality" is more than two, unless otherwise clearly and specifically defined.

[0067] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit them; although the present invention 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 replace some or all of the technical features therein by equivalents; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present invention, and they should all be included in the scope of the claims and specification of the present invention. In particular, as long as there is no structural conflict, the various technical features mentioned in each embodiment can be combined in any way. The present invention is not limited to the specific embodiments disclosed herein, but includes all technical solutions that fall within the scope of the claims.

Claims

1. A method for controlling the shape of a precipitation hardened martensitic SUS630 stainless steel cold-rolled strip, characterized in that: The steps include: S1, hot rolling, annealing and pickling the steel strip, and controlling the thickness of the steel strip to be 5.0-6.0 mm and the width to be 900-2100 mm; S2, 304 stainless steel guide strips matching the width and thickness of the parent material are welded at the head and tail of the steel coil; S3, cold rolling the steel strip through a rolling mill; S4, the steel strip is corrected by a tensioning and straightening machine to obtain a finished steel strip.

2. The method for controlling the shape of a precipitation hardened martensitic SUS630 stainless steel cold-rolled steel strip according to claim 1, characterized in that: In S3, the cold rolling step of the steel strip includes: S31, rolling the steel strip for the first time and controlling the thickness of the steel strip to be 3.0-3.2 mm; S32, annealing and pickling the steel strip, and cutting and trimming the edges of the steel strip; S33, rolling the steel strip for the second time and controlling the thickness of the steel strip to be 1.8-2.2 mm; S34, annealing and pickling the steel strip; S35, rolling the steel strip for the third time and controlling the thickness of the steel strip to be 1.5-1.6 mm; S36, annealing and pickling the steel strip.

3. The method for controlling the shape of a precipitation hardened martensitic SUS630 stainless steel cold-rolled steel strip according to claim 2, characterized in that: In S31, the rolling passes of the steel strip are controlled to be 7-11 passes, and the rolling pressure of each pass is 800-1400KN respectively. The post tension of the first pass is controlled to be 250-350KN, and the tension of the remaining passes is 550-600KN respectively. In the process of rolling the steel strip, the plate shape control mode is mainly loose at the edge and tight in the middle.

4. The method for controlling the shape of a precipitation hardened martensitic SUS630 stainless steel cold-rolled steel strip according to claim 2, characterized in that: In S32, the steel strip is cut and trimmed and laid between steel coils with a specification of 32g / m 2 of transparent plastic film.

5. The method for controlling the shape of a precipitation hardened martensitic SUS630 stainless steel cold-rolled steel strip according to claim 2, characterized in that: In S33, the rolling passes of the steel strip are controlled to be 7-11 passes, and the rolling pressure of each pass is 600-1000KN respectively, the post tension of the first pass is controlled to be 100-150KN, and the tension of the remaining passes is 550-600KN respectively, and the plate shape control mode during the steel strip rolling process is mainly loose at the edges and tight in the middle.

6. The method for controlling the shape of a precipitation hardened martensitic SUS630 stainless steel cold-rolled steel strip according to claim 2, characterized in that: In S34, after annealing and pickling, the steel strip is laid between the steel coil layers with a specification of 32g / m 2 of transparent plastic film.

7. The method for controlling the shape of a precipitation hardened martensitic SUS630 stainless steel cold-rolled steel strip according to claim 2, characterized in that: In S35, the rolling passes of the steel strip are controlled to be 5-9 passes, and the tension of each pass is 550-600KN respectively, the rolling speed of the pre-finished pass and the finished pass is controlled to be ≤150m / min, and the plate shape control of the finished pass is mainly straight, while ensuring that the thickness of the steel strip after rolling the finished pass is greater than the thickness of the finished steel strip by 0.03-0.08mm.

8. The method for controlling the shape of a precipitation hardened martensitic SUS630 stainless steel cold-rolled steel strip according to claim 7, characterized in that: In S35, the difference between the maximum and minimum flatness values ​​fed back by the rolling mill is used to determine whether the steel strip is qualified. If the flatness difference is ≤100N / mm 2 , then the steel strip is qualified, if the plate shape difference is > 100N / mm 2 , the steel strip is unqualified.

9. The method for controlling the shape of a precipitation hardened martensitic SUS630 stainless steel cold-rolled steel strip according to claim 1, characterized in that: In S4, the straightening machine adopts three sets of roller straightening machines. The two roller diameters of the first set of straightening rollers are 70 mm respectively, one of the roller diameters of the second set of straightening rollers is 70 mm and the other roller diameter is 200 mm, and the large roller diameter straightening roller is located below the small roller diameter straightening roller, and one of the roller diameters of the third set of straightening rollers is 70 mm and the other roller diameter is 200 mm, and the large roller diameter straightening roller is located above the small roller diameter straightening roller.

10. The method for controlling the shape of a precipitation hardened martensitic SUS630 stainless steel cold-rolled steel strip according to claim 9, characterized in that: In S4, the straightening machine adopts the bending tension straightening mode, controls the tension of the tensioning roller of the straightening machine to 400-800KN, controls the pressing angles of the three sets of straightening rollers to 40-80°, 40-60°, and 40-60° respectively, and ensures that the elongation of the steel strip after straightening is 0.3-0.7%.

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