Cold rolling process of 0.5-1.5 mm ZK60M magnesium alloy sheet

Abstract

The invention discloses a cold rolling process for a ZK60M magnesium alloy sheet with the thickness of 0.5-1.5 mm, and aims to overcome the defects of two production modes for rolling the ZK60M magnesium alloy sheet with the thickness of 0.5-1.5 mm in the current industry. According to the method, the free extension state of the process mode I and the bilateral tensile stress state of the process mode II in the two directions of the material head and the material tail in the rolling direction are changed into the bilateral compressive stress state, so that magnesium alloy grains are subjected to compressive deformation in the vertical direction of rolling pressure, and meanwhile, front-back horizontal compressive deformation in the rolling direction is assisted; therefore, deformed grains of the magnesium alloy sheet can be changed into a double-pressing and double-pressing state from a double-pressing and free elongation state and a double-pressing and double-stretching elongation state in four directions at present in the industry, the internal structure of the ZK60M magnesium alloy sheet reaches an equilibrium state in a deformation state, the grains are subjected to pressure stress in the four directions, the grain size is continuously and integrally compressed and reduced, and the deformation state of the magnesium alloy sheet is improved. And therefore, the purposes of balanced fine grain strengthening and toughness improvement are achieved.

Description

Technical Field

[0001] The invention relates to the technical field of magnesium alloy sheet production, in particular to a cold rolling process for a 0.5-1.5 mm ZK60M magnesium alloy thin plate. Background Art

[0002] Compared with traditional metal structural materials such as steel, copper plates and strips, and aluminum plates and strips, magnesium alloy plates have emerged in recent years, with market demand growing rapidly, becoming a hot spot for research and production in the field of metal processing. Among various types of magnesium alloy plates, ZK60M magnesium alloy thin plates are a structural material with excellent performance, featuring light weight, high strength, and high shielding properties, especially strong heat resistance and creep resistance at high temperatures. Therefore, they have developed rapidly in recent years and have become a key material in my country's aerospace and national defense military industries.

[0003] However, during use, the 0.5-1.5mm thick ZK60 magnesium alloy sheet is anisotropic during stamping and bending, mainly due to its special lattice type and rolling and other processing methods. At present, after the magnesium processing industry completes the rolling of the 0.5-1.5mm thick ZK60M sheet, it is generally processed by roller straightening, vacuum creep leveling, mechanical flattening during annealing, or artificial aging to reduce the internal stress and anisotropy of the product. However, after leveling, it will still have a certain degree of rebound and stress release, which is not conducive to secondary processing and later use.

[0004] Since magnesium alloy is a close-packed hexagonal lattice, it is difficult to deform. Generally, it needs to be heated to above 220℃ to activate the slip system in order to roll at a large reduction rate without cracking. The use of hot rolling (generally heated to above 380℃) or warm rolling (generally heated to above 220℃) for thick ZK60M plates helps to improve production efficiency and refine grains to improve the comprehensive mechanical properties of products. At present, the industry uses hot rolling for ZK60M magnesium alloy sheets with a thickness of 0.5-1.5mm. When rolled in a hot state, its slip system is activated and the internal stress is balanced. However, when the sheet cools to room temperature, its slip system returns to an inactive state. During the lattice reorganization process, the internal stress of the sheet begins to appear, the plate shape deteriorates, and the anisotropy is severe.

[0005] At present, there are two process modes for rolling ZK60M magnesium alloy sheets with a thickness of 0.5-1.5mm: Process mode 1: block process. During the rolling process, the head and tail of the ZK60M magnesium alloy sheet are in a free state. During rolling, the magnesium alloy grains are flattened in the vertical direction of the rolling pressure and the size decreases with the increase of the number of passes. However, the magnesium alloy grains along the head and tail of the rolling direction are not subjected to force, so the grains are continuously extended and the size increases with the increase of the number of passes. This block rolling method ultimately leads to a significant accumulation and increase of internal stress along the vertical rolling pressure direction of the ZK60M magnesium alloy sheet, while the internal stress on both sides of the head and tail of the sheet along the rolling direction is continuously released freely, which leads to the internal stress of the ZK60M magnesium alloy sheet in the +90° and -90° directions being significantly higher than that in the +180° and -180° directions, and the anisotropy is serious.

[0006] Process mode 2: using the belt process. During the rolling process, the head and tail of the ZK60M magnesium alloy sheet strip are in a tensile state under the tension of the front and rear coilers of the rolling mill. Similar to the rolling in process mode 1, the magnesium alloy grains are flattened in the vertical direction of the rolling pressure and the size continues to decrease with the increase of the number of passes. However, due to the action of the 10~150kN tension in the front and rear directions of the magnesium alloy grains along the rolling direction, the size increase of the grains along the running direction is enhanced compared with process mode 1. This belt rolling method ultimately leads to a significant accumulation and increase of internal stress along the vertical rolling pressure direction of the ZK60M magnesium alloy sheet, while the internal stress on both sides of the head and tail along the rolling direction is fully released under the continuous action of tensile stress. Compared with process mode 1, the internal stress of the ZK60M magnesium alloy sheet in the +90° and -90° directions is significantly higher than that in the +180° and -180° directions, and the anisotropy is more serious. This is also the reason why the magnesium alloy thin plate production field has not yet adopted a large-scale coiling process similar to the copper plate and aluminum plate industry. The non-uniformity of the mechanical properties of its products is more serious than that of the block method. Summary of the invention

[0007] The technical problem to be solved by the present invention is to overcome the existing defects and provide a cold rolling process for 0.5-1.5mm ZK60M magnesium alloy thin plates, which will not result in the anisotropy degree in the normal temperature state after rolling being significantly higher than the anisotropy during the hot rolling process in the heated state, and can achieve the purpose of balanced fine grain strengthening and improved toughness. The internal stresses in different directions of the magnesium alloy sheet product are effectively controlled during the rolling process, thereby reducing the anisotropy degree of the ZK60M magnesium alloy thin plates from the root, and can effectively solve the problems in the background technology.

[0008] To achieve the above object, the present invention provides the following technical solution: A cold rolling process for a 0.5-1.5 mm ZK60M magnesium alloy sheet, comprising the following steps: S1) Setting up the pair of rolls: a front pair of rolls device and a rear pair of rolls device are symmetrically set up in front of and behind the four-roller reversible cold rolling mill respectively; S2) Forward rolling: The ZK60M magnesium alloy sheet is subjected to forward block cold rolling from the front of the machine to the back of the machine. During the rolling process, the running speed of the front roll device is greater than the running speed of the upper and lower working rolls of the cold rolling mill and the upper and lower support rolls of the cold rolling mill, and the running speed of the rear roll device is less than the running speed of the upper and lower working rolls of the cold rolling mill and the upper and lower support rolls of the cold rolling mill; S3) Reverse rolling: The ZK60M magnesium alloy sheet is subjected to reverse block cold rolling from the rear of the machine to the front of the machine, and the running speed of the rear roll device is greater than the running speed of the upper and lower working rolls of the cold rolling mill and the upper and lower support rolls of the cold rolling mill, and the running speed of the front roll device is less than the running speed of the upper and lower working rolls of the cold rolling mill and the upper and lower support rolls of the cold rolling mill; S4) Leveling: After several times of forward rolling and several times of reverse rolling, the ZK60M magnesium alloy sheet is cold rolled and leveled when its thickness meets the thickness of the cold-rolled finished product.

[0009] As an optimal technical solution of the present invention, the front roll device and the rear roll device are symmetrically arranged in front of and behind the four-roll reversible cold rolling mill, respectively, at a distance of 0.5 to 2.0 m from the center line of the upper and lower working rolls and the upper and lower support rolls of the cold rolling mill.

[0010] As a preferred technical solution of the present invention, the diameters of the working rolls of the upper and lower working rolls of the cold rolling mill, the diameters of the rollers of the front roller device and the diameters of the rollers of the rear roller device are exactly the same.

[0011] As a preferred technical solution of the present invention, in steps S2) and S3), a speed difference of 0.1% to 5% is formed between the front roll device and the rear roll device and the upper and lower working rolls of the cold rolling mill, respectively.

[0012] As a preferred technical solution of the present invention, in step S2), the running speed V of the front roller device of the machine 机前对辊 =1.001~1.05V 冷轧机工作辊 , the running speed V of the roller device behind the machine 机后对辊 =0.999~0.95V 冷轧机工作辊 .

[0013] As a preferred technical solution of the present invention, in step S3), the running speed V of the front roller device of the machine 机前对辊 =0.999~0.95V 冷轧机工作辊 , the running speed V of the roller device behind the machine 机后对辊 =1.001~1.05V 冷轧机工作辊 .

[0014] As a preferred technical solution of the present invention, in the steps S2) and S3), the ZK60M magnesium alloy sheet is continuously subjected to a balanced state of compressive stress on four sides, i.e., double-sided compressive stress along the rolling pressure direction and double-sided compressive stress along the rolling direction, during the cold rolling process.

[0015] As a preferred technical solution of the present invention, in the steps S2) and S3), the ZK60M magnesium alloy sheet, the upper and lower working rolls of the cold rolling mill, the upper and lower support rolls of the cold rolling mill, the front roll device and the rear roll device are not subjected to any form of heating or insulation, and cold rolling is carried out by the block process in normal temperature and atmospheric environment.

[0016] As a preferred technical solution of the present invention, in the step S4), the ZK60M magnesium alloy sheet is vacuum creep leveled by stacking, without the need for multi-roller leveling using 23, 27 or 29 rollers according to conventional production processes, thereby meeting the requirements of the aerospace and defense military industries for plate quality and internal stress control.

[0017] Compared with the prior art, the present invention has the following beneficial effects: (1) The existing industry's 0.5-1.5mm thick ZK60M magnesium alloy sheet is changed from hot rolling or warm rolling in a heated state to pure cold rolling at room temperature. Although the maximum pass reduction rate is reduced from about 30% in hot rolling to 5%-12% in room temperature cold rolling, the slip system during the rolling process and the slip system at the end of rolling are the same structure, and the difference between the control value of the internal stress of the sheet during the rolling process and the internal stress value after the rolling can be ignored, and the anisotropy degree at room temperature after rolling will not be significantly higher than the anisotropy during the hot temperature rolling process in the heated state. At the same time, although the room temperature cold rolling of the present invention requires a certain number of rolling passes compared to hot temperature rolling, it does not require heating of the magnesium alloy sheet before rolling, thereby reducing the energy consumption required for heating.

[0018] (2) Based on the shortcomings of the two production modes for rolling ZK60M magnesium alloy sheets with a thickness of 0.5-1.5 mm in the current industry, the present invention changes the free extension state of process mode 1 and the bilateral tensile stress state of process mode 2 in the two directions of the material head and the material tail along the rolling direction into a bilateral compressive stress state. The goal is to compress and deform the magnesium alloy grains along the vertical direction of the rolling pressure while assisting in the horizontal compression deformation along the rolling direction. In this way, the deformed grains of the magnesium alloy sheet can be changed from the current "two pressures + free extension" and "two pressures + two tensile elongations" in the industry to the "two pressures + two pressures" state in four directions, so that the internal structure of the ZK60M magnesium alloy sheet reaches a balanced state under deformation. The grains are subjected to compressive stress in four directions, and the grain size is continuously compressed and reduced as a whole, thereby achieving the purpose of balanced fine grain strengthening and improved toughness. The internal stresses in different directions of the magnesium alloy sheet product are effectively controlled during the rolling process, thereby reducing the anisotropy of the ZK60M magnesium alloy sheet from the root. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 It is a schematic diagram of the process flow of the present invention. DETAILED DESCRIPTION

[0020] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0021] See also Figure 1 The present invention provides a technical solution: a cold rolling process for a 0.5-1.5mm ZK60M magnesium alloy sheet, in which a front roller device and a rear roller device are symmetrically arranged in front of and behind a four-roller reversible cold rolling mill for magnesium alloy sheets. Different from the conventional rolling mill, in which roller devices for clamping, pulling and generating tension on the rolled sheet are arranged in front of and behind the rolling mill body, the front roller device and the rear roller device in the present application both generate compressive stress on the 0.5-1.5mm thick ZK60M magnesium alloy sheet. The compressive stress of the magnesium alloy sheet in the front of the rolling mill is generated by the speed difference between the front roller device and the upper and lower working rolls of the cold rolling mill; the compressive stress of the magnesium alloy sheet in the rear of the rolling mill is generated by the speed difference between the rear roller device and the upper and lower working rolls of the cold rolling mill. While ensuring that the diameters of the upper and lower working rolls, the front roll device, and the rear roll device of the cold rolling mill are exactly the same as r, the compressive stress control method is as follows: when the ZK60M magnesium alloy sheet is rolled in the forward direction from the front of the machine to the rear of the machine, the running speed V of the front roll device is机前对辊 =1.001~1.05V 冷轧机工作辊 , the running speed V of the roller device behind the machine 机后对辊 =0.999~0.95V 冷轧机工作辊 When the ZK60M magnesium alloy sheet is rolled in the reverse direction from the rear of the machine to the front of the machine, the running speed V of the front roller device is 机前对辊 =0.999~0.95V 冷轧机工作辊 , the running speed V of the roller device behind the machine 机后对辊 =1.001~1.05V 冷轧机工作辊 .

[0022] During the cold rolling process, the 0.1% to 5% speed difference between the front roll device and the rear roll device and the upper and lower working rolls of the four-roll cold rolling mill formed a "rubbing rolling mode" for the ZK60M magnesium alloy sheet, weakening the deformation interface of the magnesium alloy sheet and reducing the internal stress and anisotropy of the product.

[0023] The traditional ZK60M magnesium alloy sheet that needs to be heated for warm rolling is designed to be cold rolled at room temperature, saving energy consumption during the heating process. In particular, the anisotropy and internal stress caused by the difference between the rolling environment and the use environment of the magnesium alloy sheet being in the heating and room temperature states respectively are improved to the rolling environment and the use environment being both at room temperature, avoiding the manifestation of internal stress and anisotropy caused by different environments.

[0024] The free-state block rolling and belt rolling of ZK60M magnesium alloy thin plates with traditional technology to form tensile stress are designed as dual compressive stress state rolling before and after the machine, which effectively changes the deformation mode of the internal structure and grains of the magnesium alloy plate. The multi-directional compressive stress rolling method effectively reduces the uneven distortion of the structure, reduces the uneven internal stress and the degree of anisotropy of the plate.

[0025] At the same time, the present application does not change the main roll system and main structural type of the existing rolling mill, and the overall cold rolling structure is simple, the process is flexible, and it is easy to implement.

[0026] Take the hot-rolled ZK60M magnesium alloy slab with a thickness of 3 mm and a target cold-rolled finished product thickness of 1.16 mm as an example: (1) The front and rear roll devices are symmetrically arranged at a distance of 0.5 to 2 m from the center line of the upper and lower working rolls and the upper and lower support rolls of the cold rolling mill in front and rear of the four-roll reversible cold rolling mill. The roll diameters of the front and rear roll devices are the same as the roll diameters of the upper and lower working rolls of the cold rolling mill.

[0027] (2) The ZK60M magnesium alloy sheet, the upper and lower working rolls of the cold rolling mill, the upper and lower support rolls of the cold rolling mill, the front roll device and the rear roll device are not heated, and cold rolling is carried out by the block process in a room temperature and atmospheric environment.

[0028] (3) The ZK60M magnesium alloy sheet is subjected to the first pass of block cold rolling from the front to the back of the machine, with a pass reduction of 0.21 mm and a pass reduction rate of 7%. The rolling speed of the cold rolling mill, i.e., the upper and lower working rolls of the cold rolling mill and the upper and lower support rolls of the cold rolling mill, is 12 m / min. At this time, the running speed V of the front roller device is controlled. 机前对辊 =12.1m / min, the running speed of the roller device behind the machine is V 机后对辊 =11.92m / min. The thickness of the ZK60M magnesium alloy sheet after the first pass of block cold rolling is 2.79mm.

[0029] (4) The ZK60M magnesium alloy sheet is subjected to the second pass of block cold rolling from the back of the machine to the front of the machine, with a pass reduction of 0.28 mm and a pass reduction rate of 10%. The rolling speed of the cold rolling mill, i.e., the upper and lower working rolls of the cold rolling mill and the upper and lower support rolls of the cold rolling mill, is 15 m / min. At this time, the running speed V of the front roller device is controlled. 机前对辊 =14.85m / min, the running speed of the roller device behind the machine is V 机后对辊 =15.15m / min. The thickness of the ZK60M magnesium alloy sheet after the second block cold rolling is 2.51mm.

[0030] (5) The ZK60M magnesium alloy sheet is subjected to the third pass of block cold rolling from the front to the back of the machine, with a pass reduction of 0.27 mm and a pass reduction rate of 10.8%. The rolling speed of the cold rolling mill, i.e., the upper and lower working rolls of the cold rolling mill and the upper and lower support rolls of the cold rolling mill, is 18 m / min. At this time, the running speed V of the front roller device is controlled. 机前对辊 =18.2m / min, the running speed of the roller device behind the machine is V 机后对辊 =17.80m / min. The thickness of the ZK60M magnesium alloy sheet after the third block cold rolling is 2.24mm.

[0031] (6) The ZK60M magnesium alloy sheet is subjected to the fourth pass of block cold rolling from the back of the machine to the front of the machine, with a pass reduction of 0.24 mm and a pass reduction rate of 10%. The rolling speed of the cold rolling mill, i.e., the upper and lower working rolls of the cold rolling mill and the upper and lower support rolls of the cold rolling mill, is 24 m / min. At this time, the running speed V of the front roller device is controlled. 机前对辊 =23.85m / min, the running speed of the roller device behind the machine is V 机后对辊 =24.15m / min. The thickness of the ZK60M magnesium alloy sheet after the fourth block cold rolling is 2.0mm.

[0032] (7) The ZK60M magnesium alloy sheet is subjected to the fifth pass of block cold rolling from the front to the back of the machine, with a pass reduction of 0.24 mm and a pass reduction rate of 12%. The rolling speed of the cold rolling mill, i.e., the upper and lower working rolls of the cold rolling mill and the upper and lower support rolls of the cold rolling mill, is 26 m / min. At this time, the running speed V of the front roller device is controlled. 机前对辊 =26.18m / min, the running speed of the roller device behind the machine is V 机后对辊 =25.82m / min. The thickness of the ZK60M magnesium alloy sheet after the fifth block cold rolling is 1.76mm.

[0033] (8) The ZK60M magnesium alloy sheet was subjected to the 6th pass of block cold rolling from the back of the machine to the front of the machine, with a pass reduction of 0.2 mm and a pass reduction rate of 11.4%. The rolling speed of the cold rolling mill, i.e., the upper and lower working rolls of the cold rolling mill and the upper and lower support rolls of the cold rolling mill, was 28 m / min. At this time, the running speed V of the front roller device was controlled. 机前对辊 =27.90m / min, the running speed of the roller device behind the machine is V 机后对辊 =28.1m / min. The thickness of the ZK60M magnesium alloy sheet after the 6th pass of block cold rolling is 1.56mm.

[0034] (9) The ZK60M magnesium alloy sheet was subjected to the 7th pass of block cold rolling from the front to the back of the machine, with a pass reduction of 0.18 mm and a pass reduction rate of 11.5%. The rolling speed of the cold rolling mill, i.e., the upper and lower working rolls of the cold rolling mill and the upper and lower support rolls of the cold rolling mill, was 30 m / min. At this time, the running speed V of the front roller device of the machine was controlled. 机前对辊 =30.08m / min, the running speed of the roller device behind the machine is V 机后对辊 =29.92m / min. The thickness of the ZK60M magnesium alloy sheet after the 7th block cold rolling is 1.38mm.

[0035] (10) The ZK60M magnesium alloy sheet was subjected to the 8th pass of block cold rolling from the back of the machine to the front of the machine, with a pass reduction of 0.12 mm and a pass reduction rate of 8.7%. The rolling speed of the cold rolling mill, i.e., the upper and lower working rolls of the cold rolling mill and the upper and lower support rolls of the cold rolling mill, was 24 m / min. At this time, the running speed of the front roller device V 机前对辊 =23.95m / min, the running speed of the roller device behind the machine is V 机后对辊 =24.05m / min. The thickness of the ZK60M magnesium alloy sheet after the 8th pass of block cold rolling is 1.26mm.

[0036] (11) The ZK60M magnesium alloy sheet was subjected to the 9th pass of block cold rolling from the front to the back of the machine, with a pass reduction of 0.1 mm and a pass reduction rate of 7.9%. The rolling speed of the cold rolling mill, i.e., the upper and lower working rolls of the cold rolling mill and the upper and lower support rolls of the cold rolling mill, was 18 m / min. At this time, the running speed V of the front roller device of the machine was controlled. 机前对辊 =18.12m / min, the running speed of the roller device behind the machine is V 机后对辊 =17.82m / min. The thickness of the ZK60M magnesium alloy sheet after the 9th pass of block cold rolling is 1.16mm.

[0037] (12) The ZK60M magnesium alloy sheet is vacuum creep leveled by stacking, eliminating the need for multi-roller leveling using 23, 27 or 29 rollers according to conventional production processes. This can meet the requirements of the aerospace and defense military industries for plate quality and internal stress control.

[0038] After testing, the yield strength, tensile strength and isotropy of the 1.16mm thick ZK60M magnesium alloy sheet produced by the cold rolling + compressive stress process of this technical solution are better than those produced by the traditional warm rolling block method and belt method, but the absolute value of the elongation is slightly lower than that of the warm rolling block method product. See Table 1 below for the tensile strength, yield strength, elongation and corresponding longitudinal and transverse test values ​​of the "cold rolling + compressive stress block method" of this technical solution compared with the traditional process "warm rolling + free block method" and "belt method tensile stress process".

[0039] Table 1 Performance of ZK60M magnesium alloy sheet produced by this technical solution process compared with traditional process

[0040] The undisclosed parts in the present invention are all prior art, and their specific structures, materials and working principles are not described in detail. Although the embodiments of the present invention have been shown and described, it is understood by those skilled in the art that various changes, modifications, substitutions and variations can be made to these embodiments without departing from the principles and spirit of the present invention, and the scope of the present invention is defined by the attached claims and their equivalents.

Claims

1. A cold rolling process for 0.5-1.5 mm ZK60M magnesium alloy sheet, characterized in that: The following steps are involved: S1) Setting up the pair of rolls: a front pair of rolls device and a rear pair of rolls device are symmetrically set up in front of and behind the four-roller reversible cold rolling mill respectively; S2) Forward rolling: The ZK60M magnesium alloy sheet is subjected to forward block cold rolling from the front of the machine to the back of the machine. During the rolling process, the running speed of the front roll device is greater than the running speed of the upper and lower working rolls of the cold rolling mill and the upper and lower support rolls of the cold rolling mill, and the running speed of the rear roll device is less than the running speed of the upper and lower working rolls of the cold rolling mill and the upper and lower support rolls of the cold rolling mill; S3) Reverse rolling: The ZK60M magnesium alloy sheet is subjected to reverse block cold rolling from the rear of the machine to the front of the machine, and the running speed of the rear roll device is greater than the running speed of the upper and lower working rolls of the cold rolling mill and the upper and lower support rolls of the cold rolling mill, and the running speed of the front roll device is less than the running speed of the upper and lower working rolls of the cold rolling mill and the upper and lower support rolls of the cold rolling mill; S4) Leveling: After several times of forward rolling and several times of reverse rolling, the ZK60M magnesium alloy sheet is cold rolled and leveled when its thickness meets the thickness of the cold-rolled finished product.

2. The cold rolling process of a 0.5-1.5 mm ZK60M magnesium alloy sheet according to claim 1, characterized in that: The front roller device and the rear roller device are symmetrically arranged in front of and behind the four-roller reversible cold rolling mill, respectively, at a distance of 0.5 to 2.0 m from the center line of the upper and lower working rolls and the upper and lower supporting rolls of the cold rolling mill.

3. The cold rolling process of a 0.5-1.5 mm ZK60M magnesium alloy sheet according to claim 1, characterized in that: The diameter of the working rolls of the upper and lower working rolls of the cold rolling mill, the diameter of the pair of rolls of the front pair of rolls device and the diameter of the pair of rolls of the rear pair of rolls device are completely the same.

4. The cold rolling process of a 0.5-1.5 mm ZK60M magnesium alloy sheet according to claim 1, characterized in that: In the steps S2) and S3), the speed difference between the front roll device and the rear roll device and the upper and lower working rolls of the cold rolling mill is 0.1% to 5%.

5. The cold rolling process of a 0.5-1.5 mm ZK60M magnesium alloy sheet according to claim 4, characterized in that: In the step S2), the running speed V of the front roller device is 机前对辊 =1.001~1.05V 冷轧机工作辊 , the running speed V of the roller device behind the machine 机后对辊 =0.999~0.95V 冷轧机工作辊 .

6. The cold rolling process of a 0.5-1.5 mm ZK60M magnesium alloy sheet according to claim 4, characterized in that: In the step S3), the running speed V of the front roller device is 机前对辊 =0.999~0.95V 冷轧机工作辊 , the running speed V of the roller device behind the machine 机后对辊 =1.001~1.05V 冷轧机工作辊 .

7. The cold rolling process of a 0.5-1.5 mm ZK60M magnesium alloy sheet according to claim 1, characterized in that: In the steps S2) and S3), the ZK60M magnesium alloy sheet is continuously subjected to a four-sided compressive stress equilibrium state of the double-sided compressive stress along the rolling pressure direction and the rolling running direction during the cold rolling process.

8. The cold rolling process of a 0.5-1.5 mm ZK60M magnesium alloy sheet according to claim 1, characterized in that: In the steps S2) and S3), the ZK60M magnesium alloy sheet, the upper and lower working rolls of the cold rolling mill, the upper and lower support rolls of the cold rolling mill, the front roll device and the rear roll device are not heated or kept warm in any form, and the cold rolling is carried out by the block process in a room temperature and atmospheric environment.

9. The cold rolling process of a 0.5-1.5 mm ZK60M magnesium alloy sheet according to claim 1, characterized in that: In the step S4), the ZK60M magnesium alloy thin plates are subjected to vacuum creep leveling by stacking.

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