Method for preparing surface strengthening plate strip

Abstract

The invention belongs to the technical field of surface strengthening, and provides a method for preparing a surface-strengthened plate strip, which comprises the following steps: a metal material plate strip is rolled by using a roller group, the roller group comprises an upper roller and a lower roller, and the working surface of at least one of the upper roller and the lower roller is corrugated; in the advancing direction of the metal material plate strip, the wave crest dislocation value of the corresponding positions of the nth roller and the (n + 1) th roller in the multiple roller sets is 40-800 microns. In the surface strengthening process of the metal material plate strip, the roller with the corrugations on the surface is introduced for rolling, the surface layer of the metal material plate strip is subjected to grain refinement through local severe plastic deformation to form a gradient structure, and then local strengthening of the surface of the strip is achieved. The method is easy and convenient to operate, suitable for continuously producing the gradient nanostructure layer which is high in surface smoothness and free of damage on the metal strip, beneficial for greatly improving the performance of the strip, and high in production efficiency.

Description

Technical Field

[0001] The present invention relates to the field of surface strengthening technology, in particular to a method for preparing a surface strengthened plate strip. Background Art

[0002] Metal materials occupy a very important position in the development and research of many materials. Many metal materials will experience workpiece failure problems during use, and these failure problems mostly originate from the surface of the material, such as crack initiation during fatigue, friction and wear, corrosion and other behaviors. In order to solve the above problems and improve the application of metal materials, the surface of the metal material needs to adopt certain surface strengthening technologies to make the metal material have a longer service life. Since Academician Lu Ke and others discovered the surface gradient strengthening technology, a gradient strengthening structure has been formed on the surface of the metal material, which has achieved a simultaneous improvement in the strength, corrosion resistance and fatigue resistance of the metal material while making the material lose less or no plasticity.

[0003] Currently, there are many methods for introducing gradient strengthening on the surface of metal materials, such as shot peening technology, deep rolling technology, laser surface treatment, surface mechanical rolling technology, and surface mechanical rolling technology. However, these technologies all have certain technical limitations. For example, although shot peening technology is not limited by the size and shape of the sample, the surface roughness after treatment is high and the surface finish is low; deep rolling technology, surface mechanical rolling technology, and surface mechanical rolling technology are more suitable for rotating parts; for large plate or strip metal workpieces, they are limited by the influence of material processing line speed and local micro-area plastic deformation. Therefore, there is no method for the continuous production of gradient nanostructured plates and strips in the existing technology, and there is an urgent need to design an efficient means of mechanical strengthening of the strip surface. Summary of the Invention

[0004] The technical problem solved by the present invention is to provide a method for preparing surface-strengthened plates and strips. The method provided in this application can enable metal plates and strips to achieve both surface strengthening and surface smoothness without damage.

[0005] In view of this, the present application provides a method for preparing a surface-reinforced plate strip, comprising the following steps:

[0006] Rolling the metal material plate and strip using a roll group, wherein the roll group includes an upper roll and a lower roll, and the working surface of at least one of the upper roll and the lower roll is corrugated;

[0007] During the rolling process, a plurality of roller groups are arranged in the traveling direction of the metal material plate and strip, and the working surfaces of the upper rollers in the plurality of roller groups have the same shape and / or the working surfaces of the lower rollers have the same shape;

[0008] In the traveling direction of the metal material plate and strip, a peak misalignment value M between the nth roll and the n+1th roll in the plurality of roll groups is 40-800 μm.

[0009] In some specific embodiments, during the rolling process, the diameter corresponding to the contact area between the wave crest of the upper roller and / or the lower roller and the metal material plate and strip is recorded as d1, and the diameter corresponding to the contact area between the wave trough of the upper roller and / or the lower roller and the metal material plate and strip is recorded as d2, d1=1~8mm, d1=2d2.

[0010] In some specific embodiments, the height difference between adjacent crests and troughs of the upper roller and / or the lower roller is denoted as h, where h≥0.4 mm.

[0011] In some specific embodiments, the number of rolling passes is ≥1.

[0012] In some specific embodiments, in the roll group, the working surfaces of the upper roll and the lower roll are corrugated, the peak end of the upper roll corresponds to the peak end of the lower roll, and the trough end of the upper roll corresponds to the trough end of the lower roll.

[0013] In some specific embodiments, the misalignment value M is 40-400 μm.

[0014] In some specific embodiments, the crest roller diameter of the upper roller and / or the lower roller is recorded as D1, the trough roller diameter is recorded as D2, and 20mm≤D1=D2+2h≤200mm.

[0015] In some specific embodiments, the metal material is stainless steel, and in the upper roller and / or the lower roller, d1 is 2-8 mm, the misalignment value M is 100-600 μm; and the thickness of the stainless steel is 0.4 mm-4.5 mm.

[0016] In some specific embodiments, the metal material is titanium alloy, in the upper rolling roller and / or the lower rolling roller, d1 is 1~4 mm, and the misalignment value M is 100~400 μm; and / or, the metal material is aluminum alloy, in the upper rolling roller and / or the lower rolling roller, d1 is 2~6 mm, and the misalignment value M is 100~400 μm.

[0017] In some specific embodiments, the rolling speed of the upper roller is 2000~20000 mm / min, and / or the rolling speed of the lower roller is 2000~20000 mm / min; and / or the single pressing depth of the rolling is 30~400 μm, and / or the working surfaces of the upper roller and the lower roller of the last group of rollers in the multiple roller groups are both flat.

[0018] The present application provides a method for preparing surface-strengthened plate and strip, wherein a metal plate and strip is rolled by a rolling roller group, wherein the rolling roller group includes an upper roller and a lower roller, and the working surface of at least one of the upper roller and the lower roller is corrugated; after the rolling, local stress concentration is formed on the surface of the metal plate and strip and a strain gradient is introduced, thereby finally achieving surface strengthening of the metal plate and strip; in the process of preparing the surface-strengthened plate and strip, an upper roller and / or a lower roller with a corrugated working surface is introduced, and the corrugated working surface acts on the strip surface, thereby introducing a corrugated rail The strain gradient of the trace causes the surface of the metal material plate and strip to undergo grain refinement through local severe plastic deformation and form a gradient structural organization, thereby achieving surface strengthening of the metal material plate and strip; further, the limitation of the offset value of the wave peaks of adjacent rolls in multiple roll groups causes each roll group to be repeatedly processed by other roll groups in the rolling corrugation track formed on the surface of the metal material plate and strip, and the local plastic deformation zone overlaps many times, thereby forming a continuous and dislocated smooth gradient structure on the surface of the metal material plate and strip, achieving both surface strengthening and surface smoothness without damage to the metal material plate and strip. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 Schematic diagrams of a single roll and the interaction between the roll and the plate and strip of the present invention, FIG A is a schematic diagram of the interaction between the upper roll and the plate and strip, FIG B is a side view of the roll, and FIG C is a schematic diagram of the interaction between the roll group and the plate and strip;

[0020] Figure 2 Schematic diagram of the assembly of multiple roller groups for rolling according to the present invention, FIG a is a planar assembly schematic diagram of the multiple roller groups, and FIG b is a three-dimensional assembly schematic diagram of the multiple roller groups;

[0021] Figure 3 Graph showing the cross-sectional hardness of 304 plate and strip after surface strengthening of three types of rollers in Example 1 of the present invention;

[0022] Figure 4 This is a cross-sectional hardness curve diagram of the 304 plate and strip material after double-sided surface strengthening in Example 2 of the present invention;

[0023] Figure 5 The microstructures of the plate and strip at different depths in Example 2 of the present invention are shown in FIG. Figure 5 a is the surface grain morphology, Figure 5 b is the tissue morphology at a distance of 600 μm from the surface. Figure 5 c is the tissue morphology at 2 mm from the surface;

[0024] Figure 6 The cross-sectional hardness distribution of the 310s stainless steel plate and strip after treatment in Example 3;

[0025] Figure 7 is the distribution of the microstructure of the TA2 cross section with depth in Example 4;

[0026] Figure 8 is the distribution of the hardness of the TA2 section with depth in Example 4;

[0027] Figure 9 These are the laser confocal image and 3-D contour image of the 2091 aluminum alloy in Example 5, FIG. a is a laser confocal image of the 2091 aluminum alloy, and FIG. b is a 3-D contour image of the 2091 aluminum alloy;

[0028] Figure 10 The distribution of cross-sectional hardness of 2091 aluminum alloy with depth in Example 5;

[0029] Figure 11 The cross-sectional hardness distribution diagram of the metal plate and strip after surface strengthening in Examples 6 to 9;

[0030] Figure 12 The cross-sectional hardness distribution diagram of the metal plate and strip after surface strengthening in Examples 10 to 13;

[0031] Figure 13 This is the cross-sectional hardness distribution diagram of the metal plate and strip after surface strengthening in Comparative Example 1;

[0032] Figure 14 The laser confocal image and 3-D contour image of the stainless steel after surface strengthening in Comparative Example 1 are shown. FIG. a is a laser confocal image of the stainless steel, and FIG. b is a 3-D contour image of the stainless steel.

[0033] Figure 15 The laser confocal image and 3-D contour image of the stainless steel after surface strengthening in comparative example 2, Figure a is a laser confocal image of the stainless steel, and Figure b is a 3-D contour image of the stainless steel;

[0034] Figure 16 The laser confocal image and 3-D contour image of the aluminum alloy after surface strengthening in Comparative Example 3, Figure a is a laser confocal image of the aluminum alloy, and Figure b is a 3-D contour image of the aluminum alloy;

[0035] Figure 17 This is a cross-sectional hardness distribution diagram of a metal material subjected to surface mechanical rolling treatment in comparative example 4;

[0036] Figure 18 This is the cross-sectional hardness distribution diagram of the metal material subjected to surface mechanical rolling treatment in comparative example 5. DETAILED DESCRIPTION

[0037] In order to further understand the present invention, preferred embodiments of the present invention are described below in conjunction with examples. However, it should be understood that these descriptions are only for further illustrating the features and advantages of the present invention, rather than limiting the claims of the present invention.

[0038] In view of the requirements of metal materials for surface strengthening and surface finish in the prior art, the present application provides a method for preparing surface-strengthened plate and strip, which adopts an upper roller and / or a lower roller with a corrugated working surface and limits the peak offset value of the corresponding positions of adjacent rollers, so that the metal material plate and strip forms strain gradient strengthening on the surface while undergoing multiple repeated deformations in the local plastic deformation zone, thereby ensuring surface finish and surface strengthening, and avoiding problems such as cracks and surface peeling of the strip. Specifically, an embodiment of the present invention discloses a method for preparing surface-strengthened plate and strip, comprising the following steps:

[0039] Rolling the metal material plate and strip using a roll group, wherein the roll group includes an upper roll and a lower roll, and the working surface of at least one of the upper roll and the lower roll is corrugated;

[0040] During the rolling process, a plurality of roller groups are arranged in the traveling direction of the metal material plate and strip, and the working surfaces of the upper rollers in the plurality of roller groups have the same shape and / or the working surfaces of the lower rollers have the same shape;

[0041] In the traveling direction of the metal material plate and strip, the peak misalignment value M of the corresponding positions of the nth roller and the (n+1)th roller in the roller group is 40-800 μm.

[0042] In the preparation method of surface-strengthened plate and strip provided in the present application, the working surface shape of the roller is designed to be corrugated. By controlling the shape of the surface corrugations, strain gradients and local stress concentrations are introduced on the surface of the roller and the plate and strip, thereby achieving local severe plastic deformation on the surface of the plate and strip. The schematic diagram of the roller shape and the interaction between the roller and the plate and strip is shown in FIG. Figure 1 As shown, Figure A is a schematic diagram of the interaction between the upper roll and the plate and strip, Figure B is a side view of the roll, and Figure C is a schematic diagram of the interaction between the roll group and the plate and strip; Figure 1 is the upper roll, 2 is the metal plate and strip, and 3 is the lower roll. In order to achieve continuous deformation and repeated rolling deformation of local deformation areas to improve production efficiency and control the surface quality of the plate and strip, multiple roll groups are arranged for rolling, as shown in the schematic diagram. Figure 2As shown, the metal material plate and strip is used as the raw material, and its preparation method is prepared according to the method well known to those skilled in the art. This application does not impose any special restrictions on this. The material of the metal material plate and strip is not particularly limited, and it can be an aluminum alloy, a titanium alloy, a nickel-based alloy, or stainless steel. In this application, although there is no special restriction on the material of the metal material plate and strip, the relevant parameters of the roll group determined for different metal material plates and strips are different. This application does not impose any special restrictions on the thickness of the metal material plate and strip. For example, the thickness of the metal material plate and strip is 0.2mm~10mm, more specifically, the thickness of the metal material plate and strip is 0.4mm~7mm, and more specifically, the thickness of the metal material plate and strip is 1mm~5mm.

[0043] The present application uses multiple roller groups to roll metal sheet and strip, wherein each roller group includes an upper roller and a lower roller, and the working surface of at least one of the upper roller and the lower roller is corrugated. The metal sheet and strip are fed along a direction perpendicular to the direction of travel of the roller group. The upper roller and the lower roller can roll freely. After the metal sheet and strip are processed by the roller group, the surface is strengthened. In the present application, the structural diagram of the upper roller and / or the lower roller of the roller group is as follows Figure 1 Specifically, the working surface of the upper roller of the roller group is corrugated, and the working surface of the lower roller is flat, or the working surface of the upper roller of the roller group is corrugated, and the working surface of the lower roller is corrugated (such as Figure 1 C in the figure); similarly, the working surface of the lower roll of the roll group is corrugated, and the working surface of the upper roll is flat; that is, the working surfaces of the upper roll and the lower roll of the roll group are selected according to the processing requirements of the metal material plate and strip, and this application does not impose any special restrictions on this.

[0044] Specifically, taking the example of the working surfaces of the upper and lower rolls of the rolling group being corrugated, when the rolling group is working, the front end of the corrugated peaks of the upper and lower rolls act on the surface of the metal material plate and strip, introducing a strain gradient, and the surface of the metal material plate and strip undergoes grain refinement through local severe plastic deformation to form a gradient structural organization, thereby achieving local strengthening of the upper and lower surfaces of the strip. However, such completion of rolling will form a single deformation zone on the surface of the metal material plate and strip, and an obvious rolling track can be observed on the surface of the metal strip with the naked eye, thereby affecting the smoothness, uniformity and surface strengthening effect of the metal material plate and strip; therefore, after research, the combination of the strain gradient of the metal material plate and strip after rolling and the repeated local plastic deformation zone is introduced to achieve the metal material plate and strip A smooth gradient structure; from a technical point of view, during the rolling process, in the traveling direction of the metal material plate and strip, in multiple roller groups, the peak misalignment value M of the corresponding position of the nth roller and the n+1th roller is 40~800μm, that is, the peak misalignment value M at the same position of adjacent rollers is 40~800μm. For example, the misalignment value of the first peak of the first upper roller and the first peak of the second upper roller in the multiple roller groups is M, the misalignment value of the second peak of the first upper roller and the second peak of the second upper roller is M,..., the misalignment value of the nth peak of the first upper roller and the nth peak of the second upper roller is M, and similarly, the peaks of the second upper roller and the third upper roller also have the above-mentioned misalignment value M. The above-mentioned misalignment value M is determined by the diameter d1 corresponding to the contact area between the wave trough of the upper roller and / or the lower roller and the metal material plate and strip and the reduction a of the rolling. p The relationship is as follows:

[0045] ;

[0046] The left side of the above relationship represents the lateral width (i.e., local deformation zone) of the track formed by a single upper roller or a single lower roller on the surface of the metal material plate and strip. This lateral width needs to be filled by n wave peak offset values ​​M to achieve surface strengthening, uniformity and smooth preparation of metal material plates and strips; in this way, during the rolling process of multiple roller groups, the rolling track of the metal material plate and strip by one roller group is repeatedly rolled by the subsequent roller group; from an ideal point of view, the larger n is, the smaller M is, the better the surface strengthening effect is, but it will also increase the difficulty of roller processing and damage the surface of the metal material plate and strip. Therefore, in order to balance many factors such as the surface morphology of the metal material plate and strip, the strengthening effect and roller processing, the n is preferably 2~10, and the offset value M is 40~800μm; specifically, the misalignment value M is 80~400μm; for example, the misalignment value described in this application is 50μm, 60μm, 70μm, 80μm, 90μm, 100μm, 200μm, 300μm, 500μm, 600μm or 700μm; more specifically, the metal material is stainless steel, the peak misalignment value is 100~600μm, the metal material is titanium alloy, the peak misalignment value is 100~400μm, the metal material is aluminum alloy, the peak misalignment value is 100~400μm; that is, according to the strengthening requirements of the metal material plate and strip, the rolling mill with a peak misalignment arrangement is selected for processing to obtain full surface coverage strengthening and ensure the surface smoothness of the metal material plate and strip.

[0047] During the rolling process, the diameter corresponding to the contact area between the wave crest of the upper roller and / or the lower roller and the metal material plate and strip is recorded as d1, and the diameter corresponding to the contact area between the wave trough of the upper roller and / or the lower roller and the metal material plate and strip is recorded as d2, d1=1~8mm, d1=2d2; the above-mentioned contact area is actually the contact point between the wave crest of the upper roller and / or the lower roller and the metal material plate and strip, and the diameter corresponding to the circle where the contact point is located is d1. Specifically, the metal material is stainless steel, and the d1 is 2~8mm, more specifically, the d1 is 2mm, 3mm, 4mm, 5mm, 6mm, 7mm or 8mm; the metal material is titanium alloy, and the d1 is 1~4mm, more specifically, the d1 is 1mm, 1.5mm, 2mm, 3mm, 4mm; the metal material is aluminum alloy, and the d1 is 2~6mm, more specifically, the d1 is 2mm, 3mm, 4mm, 5mm, 6mm. The d1 and d2 affect the surface roughness and cracking of the metal plate and strip to a certain extent. The height difference between adjacent crests and troughs of the upper roller and / or the lower roller is h, and the distance between adjacent crests and troughs is L. The specific marking parts are as follows: Figure 1Figure A, where h ≥ 0.4 mm and L ≥ 3 mm. In this application, the number of roll groups = L / M. In theory, the smaller L is, the more conducive it is to obtaining plate and strip materials with good surface quality. However, the smaller L is, the more difficult it is to process the rolls. To achieve a balance between the two, L is at least ≥ 3 mm. The roller diameter of the crest of the upper roll and / or the lower roll is D1, and the roller diameter of the trough of the upper roll and / or the lower roll is D2. That is, overall, the maximum radial diameter of the upper roll and / or the lower roll (where the crest is located) is D1, and the minimum diameter (where the trough is located) is D2. 20 mm ≤ D1 = D2 + 2h ≤ 200 mm. Specifically, 30 mm ≤ D1 ≤ 80 mm, and h is 0.6 mm to 3 mm. More specifically, 40 mm ≤ D1 ≤ 50 mm, and h is 0.8 mm to 1.2 mm.

[0048] More specifically, the upper roller and / or the lower roller may include the following specifications and dimensions:

[0049] 1) The metal material plate and strip is stainless steel, D1 is 50 mm, d1 is 8 mm, D2 is 44 mm, d2 is 4 mm, h is 3 mm, d2 is 4 mm, L is 5.2 mm, and M is 100 μm;

[0050] 2) The metal material plate and strip is stainless steel, D1 is 30 mm, d1 is 4 mm, D2 is 29.2 mm, d2 is 2 mm, h is 0.4 mm, d2 is 2 mm, L is 3 mm, and M is 100 μm;

[0051] 3) The metal material plate and strip is stainless steel, D1 is 30 mm, d1 is 4 mm, D2 is 29.2 mm, d2 is 2 mm, h is 0.4 mm, d2 is 2 mm, L is 3 mm, and M is 200 μm;

[0052] 4) The metal material plate and strip is stainless steel, D1 is 30 mm, d1 is 4 mm, D2 is 29.2 mm, d2 is 2 mm, h is 0.4 mm, d2 is 2 mm, L is 3 mm, and M is 400 μm;

[0053] 5) The metal material plate and strip is stainless steel, D1 is 30 mm, d1 is 4 mm, D2 is 29.2 mm, d2 is 2 mm, h is 0.4 mm, d2 is 2 mm, L is 3 mm, and M is 600 μm;

[0054] 6) The metal material plate and strip is titanium alloy, D1 is 20 mm, d1 is 4 mm, D2 is 19.2 mm, d2 is 2 mm, h is 0.4 mm, L is 2 mm, and M is 200 μm;

[0055] 7) The metal material plate and strip is aluminum alloy, D1 is 30 mm, d1 is 2 mm, D2 is 28.4 mm, d2 is 1 mm, h is 0.8 mm, L is 6 mm, and M is 100 μm.

[0056] During the rolling process, the rolling speed of the upper roller and / or the lower roller is 2000-20000 mm / min, specifically 4000-10000 mm / min. In a specific embodiment, the rolling speeds of the upper roller and the lower roller are the same. The single pressing depth is 30-400 μm, specifically 40-200 μm, and more specifically 100-150 μm.

[0057] Furthermore, the working surfaces of the upper roller and the lower roller of the last roller group among the multiple roller groups are both flat.

[0058] In the process of preparing surface-strengthened plates and strips, the present invention introduces a corrugated working surface on the surface of the upper roller and / or the lower roller, and utilizes local plastic deformation during the rolling process to achieve grain refinement, thereby introducing a strain gradient. Furthermore, combined with the regulation of the peak misalignment value and the indentation depth, surface strengthening is achieved while ensuring the surface finish and non-destructive preparation of the metal material plates and strips.

[0059] In order to further understand the present invention, the method for preparing a surface-strengthened plate strip provided by the present invention is described in detail below with reference to examples. The protection scope of the present invention is not limited by the following examples.

[0060] Example 1

[0061] Three 3mm thick 304 stainless steel strips were placed in a set of rollers of different specifications for rolling. The upper roller of the roller set was corrugated and the lower roller was a plain roller. The rolling speed of the upper and lower rollers was 4000mm / min, and the misalignment value M was 100μm.

[0062] The specific parameters of the upper roller used in sample 1 are: D1 is 50 mm, d1 is 8 mm, D2 is 44 mm, d2 is 4 mm, h is 3 mm, and L is 5.2 mm; the indentation depth is 100 μm;

[0063] In this embodiment, the specific parameters of the upper roller selected for sample 2 are: D1 is 30 mm, d1 is 4 mm, D2 is 29.2 mm, d2 is 2 mm, h is 0.4 mm, and L is 3 mm; the pressing depth is 100 μm;

[0064] In this embodiment, the specific parameters of the upper roller selected for sample 3 are: D1 is 30 mm, d1 is 4 mm, D2 is 29.2 mm, d2 is 2 mm, h is 0.4 mm, and L is 3 mm; the indentation depth is 200 μm;

[0065] The surface of the stainless steel strip is significantly strengthened after rolling, the surface of the material is mirror-like, and the cross-sectional hardness distribution is as follows: Figure 3 This embodiment proves that the method provided by the present invention is feasible. By setting the upper roller to be corrugated and the lower roller to be a normal flat roller, the production of single-sided gradient plate and strip can be achieved. It also shows that reducing the roller diameter D1 and lowering the active end d1 are beneficial to surface strengthening.

[0066] Example 2

[0067] A 4.5 mm thick 304 stainless steel strip was placed in a four-roller group for rolling. The working surfaces of the upper and lower rollers were corrugated. The rolling speed of the upper and lower rollers was 4000 mm / min, the pressing depth was 100 μm, and the offset value was 100 μm.

[0068] The specific parameters of the upper roller and the lower roller in this embodiment are: D1 is 30 mm, d1 is 4 mm, D2 is 29.2 mm, d2 is 2 mm, h is 0.4 mm, and L is 3 mm.

[0069] The stainless steel sheet and strip are significantly strengthened after rolling, and the surface of the material is mirror-like. Figure 4 The cross-sectional hardness distribution of 304 stainless steel sheet and strip after treatment shows that a gradient layer is constructed on both sides of the sample, with a thickness of ~2mm. The surface hardness is increased from the original ~200HV to over 500HV. Figure 5 The microstructure of stainless steel strip at different depths is shown in Figure 2. Figure 5 a is the surface microstructure, and it is found that the grains are significantly refined to ~50nm. 5b is the microstructure at 600μm from the surface, both of which are deformed laths. 5c is the microstructure at 2mm from the surface, which is a typical coarse-grained structure.

[0070] Example 3

[0071] A 0.4 mm thick 310s stainless steel strip was placed in an eight-roller group for rolling. The working surfaces of the upper and lower rollers were corrugated. The rolling speed of the upper and lower rollers was 10,000 mm / min, the pressing depth was 100 μm, and the offset value was 100 μm.

[0072] The specific parameters of the upper roller and the lower roller in this embodiment are: D1 is 30 mm, d1 is 4 mm, D2 is 29.2 mm, d2 is 2 mm, h is 0.4 mm, and L is 3 mm.

[0073] The stainless steel sheet and strip are significantly strengthened after rolling, and the surface of the material is mirror-like. Figure 6 The cross-sectional hardness distribution of 310s stainless steel strip after treatment shows that the gradient layer is constructed on both sides of the sample, increasing the surface hardness to over 400 HV. This example demonstrates that the technical effect of constructing a double-sided gradient layer can also be achieved on thin stainless steel strips.

[0074] Example 4

[0075] A 2mm thick TA2 titanium alloy strip was rolled in a roll group with corrugated working surfaces on both the upper and lower rolls. The rolling speed of the upper and lower rolls was 6000mm / min, the pressing depth was 0.20mm, and the misalignment value was 200μm.

[0076] The specific parameters of the upper roller and the lower roller in this embodiment are: D1 is 20 mm, d1 is 4 mm, D2 is 19.2 mm, d2 is 2 mm, h is 0.4 mm, and L is 2 mm.

[0077] The surface finish of TA2 plate and strip after rolling is good, and a significant gradient nano twin structure is formed, such as Figure 7 As shown in Figure 2, as the distance from the plate and strip surface approaches, the twin density gradually increases and the grains gradually refine. Among them, the near surface is significantly strengthened, and the cross-sectional hardness is as shown in Figure 2. Figure 8 As shown in FIG, the surface hardness of the titanium alloy plate and strip after surface strengthening is uniform and is increased to about 250HV.

[0078] Example 5

[0079] A 0.5 mm thick 2091 aluminum alloy strip was rolled between two roller sets. The working surfaces of the upper and lower rollers of the roller set were corrugated. The rolling speed of the upper and lower rollers was 3000 mm / min, the pressing depth was 150 μm, and the offset value was 100 μm.

[0080] The specific parameters of the upper roller and the lower roller in this embodiment are: D1 is 30 mm, d1 is 2 mm, D2 is 28.4 mm, d2 is 1 mm, h is 0.8 mm, and L is 6 mm.

[0081] The surface of the aluminum alloy strip after rolling is significantly strengthened, and the surface of the material is mirror-like. The laser confocal image and 3-D profile are as follows: Figure 9 , the cross-section hardness distribution is as follows Figure 10 shown.

[0082] Example 6

[0083] A 3mm thick 304 stainless steel strip was placed in two sets of rollers for rolling. The upper roller working surface of the roller set was corrugated, and the lower roller working surface was flat. The rolling speed of the upper and lower rollers was 4000mm / min, the pressing depth was 200μm, and the offset value was 600μm.

[0084] The specific parameters of the upper roller in this embodiment are: D1 is 30 mm, d1 is 4 mm, D2 is 29.2 mm, d2 is 2 mm, h is 0.4 mm, and L is 3 mm.

[0085] The surface of the stainless steel plate and strip is significantly strengthened after rolling, and the cross-sectional hardness distribution is as follows: Figure 11 As shown in sample 1.

[0086] Example 7

[0087] A 3mm thick 304 stainless steel strip was placed in two sets of rollers for rolling. The upper roller working surface of the roller set was corrugated, and the lower roller working surface was flat. The rolling speed of the upper and lower rollers was 4000mm / min, the pressing depth was 200μm, and the offset value was 400μm.

[0088] The specific parameters of the upper roller in this embodiment are: D1 is 30 mm, d1 is 4 mm, D2 is 29.2 mm, d2 is 2 mm, h is 0.4 mm, and L is 3 mm.

[0089] The surface of the stainless steel plate and strip is significantly strengthened after rolling, and the cross-sectional hardness distribution is as follows: Figure 11 As shown in sample 2.

[0090] Example 8

[0091] A 3mm thick 304 stainless steel strip was placed in two sets of rollers for rolling. The upper roller working surface of the roller set was corrugated, and the lower roller working surface was flat. The rolling speed of the upper and lower rollers was 4000mm / min, the pressing depth was 200μm, and the offset value was 200μm.

[0092] The specific parameters of the upper roller in this embodiment are: D1 is 30 mm, d1 is 4 mm, D2 is 29.2 mm, d2 is 2 mm, h is 0.4 mm, and L is 3 mm.

[0093] The surface of the stainless steel plate and strip is significantly strengthened after rolling, and the cross-sectional hardness distribution is as follows: Figure 11 As shown in sample 3.

[0094] Example 9

[0095] A 3mm thick 304 stainless steel strip was placed in two sets of rollers for rolling. The upper roller working surface of the roller set was corrugated, and the lower roller working surface was flat. The rolling speed of the upper and lower rollers was 4000mm / min, the pressing depth was 200μm, and the offset value was 100μm.

[0096] The specific parameters of the upper roller in this embodiment are: D1 is 30 mm, d1 is 4 mm, D2 is 29.2 mm, d2 is 2 mm, h is 0.4 mm, and L is 3 mm.

[0097] The surface of the stainless steel plate and strip is significantly strengthened after rolling, and the cross-sectional hardness distribution is as follows: Figure 11 As shown in sample 4.

[0098] The difference between the four processes of Examples 6 to 9 is that the misalignment values ​​of adjacent peaks are different, the surface roughness of the four samples decreases significantly with the decrease of the misalignment value, and the thickness of the gradient layer is similar; among them, the surface hardness of sample 1 is ~420Hv, the surface hardness of samples 2 and 3 is ~430Hv, and the surface hardness of sample 4 is ~530Hv. This shows that within a certain range, when the roller parameters are fixed, reducing the misalignment value can increase the surface hardness and reduce the surface roughness.

[0099] Example 10

[0100] A 3mm thick 304 stainless steel strip was placed in two sets of rollers for rolling. The upper roller working surface of the roller set was corrugated, and the lower roller working surface was flat. The rolling speed of the upper and lower rollers was 4000mm / min, the pressing depth was 200μm, and the offset value was 50μm.

[0101] The specific parameters of the upper roller in this embodiment are: D1 is 30 mm, d1 is 4 mm, D2 is 29.2 mm, d2 is 2 mm, h is 0.4 mm, and L is 3 mm.

[0102] The surface of the stainless steel plate and strip is significantly strengthened after rolling, and the cross-sectional hardness distribution is as follows: Figure 12 As shown in sample 1.

[0103] Example 11

[0104] A 3mm thick 304 stainless steel strip was placed in two sets of rollers for rolling. The upper roller working surface of the roller set was corrugated, and the lower roller working surface was flat. The rolling speed of the upper and lower rollers was 4000mm / min, the pressing depth was 200μm, and the offset value was 30μm.

[0105] The specific parameters of the upper roller in this embodiment are: D1 is 30 mm, d1 is 4 mm, D2 is 29.2 mm, d2 is 2 mm, h is 0.4 mm, and L is 3 mm.

[0106] The surface of the stainless steel plate and strip is significantly strengthened after rolling, and the cross-sectional hardness distribution is as follows: Figure 12 As shown in sample 2.

[0107] Example 12

[0108] A 3mm thick 304 stainless steel strip was placed in two sets of rollers for rolling. The upper roller working surface of the roller set was corrugated, and the lower roller working surface was flat. The rolling speed of the upper and lower rollers was 4000mm / min, the pressing depth was 200μm, and the offset value was 15μm.

[0109] The specific parameters of the upper roller in this embodiment are: D1 is 30 mm, d1 is 4 mm, D2 is 29.2 mm, d2 is 2 mm, h is 0.4 mm, and L is 3 mm.

[0110] The surface of the stainless steel plate and strip is significantly strengthened after rolling, and the cross-sectional hardness distribution is as follows: Figure 12 As shown in sample 3.

[0111] Example 13

[0112] A 3mm thick 304 stainless steel strip was placed in two sets of rollers for rolling. The upper roller working surface of the roller set was corrugated, and the lower roller working surface was flat. The rolling speed of the upper and lower rollers was 4000mm / min, the pressing depth was 200μm, and the offset value was 10μm.

[0113] The specific parameters of the upper roller in this embodiment are: D1 is 30 mm, d1 is 4 mm, D2 is 29.2 mm, d2 is 2 mm, h is 0.4 mm, and L is 3 mm.

[0114] The surface of the stainless steel plate and strip is significantly strengthened after rolling, and the cross-sectional hardness distribution is as follows: Figure 12 As shown in sample 4.

[0115] The difference between the four processes of Examples 10 to 13 is that the misalignment values ​​of adjacent wave peaks are different. The misalignment value used in Sample 1 is 50 μm, the misalignment value of Sample 2 is 30 μm, the misalignment value of Sample 3 is 15 μm, and the misalignment value of Sample 4 is 10 μm. The surface roughness of the four samples can reach Ra < 0.2 μm, and the cross-sectional hardness distribution is almost the same, which means that a misalignment value that is too small is meaningless for improving hardness and surface roughness, but will reduce efficiency.

[0116] Comparative Example 1

[0117] A 3mm thick 304 stainless steel strip was placed in two sets of rollers for rolling. The upper roller working surface of the roller set was corrugated, and the lower roller working surface was flat. The rolling speed of the upper and lower rollers was 4000mm / min, the pressing depth was 200μm, and the offset value was 800μm.

[0118] The specific parameters of the upper roller in this embodiment are: D1 is 50 mm, d1 is 8 mm, D2 is 48.4 mm, d2 is 4 mm, h is 0.8 mm, and L is 6 mm.

[0119] The surface of the stainless steel strip is slightly strengthened after rolling, and the hardness is increased to about 225HV~270HV. The surface hardness distribution is uneven, and the cross-sectional hardness distribution is Figure 13 In addition, larger misalignment values ​​lead to more obvious surface undulations, such as Figure 14 shown.

[0120] Comparative Example 2

[0121] A 3mm thick 304 stainless steel strip was placed in two sets of rollers for rolling. The upper roller working surface of the roller set was corrugated, and the lower roller working surface was flat. The rolling speed of the upper and lower rollers was 4000mm / min, the pressing depth was 200μm, and the offset value was 800μm.

[0122] The specific parameters of the upper roller in this embodiment are: D1 is 30 mm, d1 is 1 mm, D2 is 29.2 mm, d2 is 0.5 mm, h is 0.4 mm, and L is 3 mm.

[0123] After rolling, cracks appear on the surface of the stainless steel plate and strip, and the surface quality is reduced. Figure 15 As shown in the figure, it is proved that a smaller d1 value may increase the contact stress on the surface, which is beneficial to the surface grain refinement, but a too small d1 value will lead to the initiation of surface cracks.

[0124] Comparative Example 3

[0125] A 0.5 mm thick 2091 aluminum alloy strip was rolled between two roller sets. The working surfaces of the upper and lower rollers of both roller sets were corrugated. The rolling speed of the upper and lower rollers was 3000 mm / min, the pressing depth was 150 μm, and the offset value was 100 μm.

[0126] The specific parameters of the upper roller and the lower roller in this embodiment are: D1 is 30 mm, d1 is 1 mm, D2 is 28.4 mm, d2 is 0.5 mm, h is 0.8 mm, and L is 6 mm.

[0127] After rolling, the surface of the aluminum alloy strip peels off. Figure 16 shown.

[0128] Comparative Example 4

[0129] The gradient nanostructured 304 sheet and strip was prepared by the surface mechanical rolling technology (P-SMRT) of the flat plate type. The rolling speed was 2000 mm / min, the final pass depth was 50 μm, and the single-side treatment was one pass. The line spacing during the rolling process was 50 μm. The time required to process the 40 mm × 200 mm sheet and strip was 80 minutes. The cross-sectional hardness distribution is shown in the figure. Figure 17 As shown, the technical effect is similar to that achieved by the present invention, but the time required to prepare the plate and strip of the same size using the method of the present application is only 3 minutes.

[0130] Comparative Example 5

[0131] The gradient nanostructured 304 sheet and strip was prepared by the surface mechanical rolling technology (P-SMRT) of the flat plate type. The rolling speed was 2000 mm / min, the final pass pressure was 50 μm, and the single-side treatment was performed in 3 passes. The line spacing during the rolling process was 100 μm. The time required to process the 40 mm × 200 mm sheet and strip was 120 minutes. The cross-sectional hardness distribution is shown in the figure. Figure 18 As shown, the technical effect is similar to that achieved by the present invention, but the time required to prepare the plate and strip of the same size by adopting the method of the present invention is only 5 minutes.

[0132] The above embodiments are only intended to help understand the method and core concept of the present invention. It should be noted that, without departing from the principles of the present invention, a number of improvements and modifications may be made to the present invention by those skilled in the art, and such improvements and modifications also fall within the scope of protection of the claims of the present invention.

[0133] The above description of the disclosed embodiments is intended to enable one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be readily apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention is not limited to the embodiments shown herein but is intended to conform to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for preparing a surface-strengthened plate strip, comprising the following steps: Rolling the metal material plate and strip using a roll group, wherein the roll group includes an upper roll and a lower roll, and the working surface of at least one of the upper roll and the lower roll is corrugated; During the rolling process, a plurality of roller groups are arranged in the traveling direction of the metal material plate and strip, and the working surfaces of the upper rollers in the plurality of roller groups have the same shape and / or the working surfaces of the lower rollers have the same shape; In the traveling direction of the metal material plate and strip, a peak misalignment value M between the nth roll and the n+1th roll in the plurality of roll groups is 40-800 μm.

2. The method according to claim 1, characterized in that During the rolling process, the diameter corresponding to the contact area between the wave crest of the upper roller and / or the lower roller and the metal material plate and strip is recorded as d1, and the diameter corresponding to the contact area between the wave trough of the upper roller and / or the lower roller and the metal material plate and strip is recorded as d2, d1=1~8mm, d1=2d2.

3. The method according to claim 1, characterized in that The height difference between adjacent wave crests and wave troughs of the upper roller and / or the lower roller is denoted as h, where h≥0.4 mm.

4. The method according to claim 1 or 2, characterized in that The number of rolling passes is ≥1.

5. The method according to claim 1 or 2, characterized in that In the roller group, the working surfaces of the upper roller and the lower roller are both corrugated, the peak end of the upper roller corresponds to the peak end of the lower roller, and the trough end of the upper roller corresponds to the trough end of the lower roller.

6. The method according to claim 1 or 2, characterized in that The misalignment value M is 40-400 μm.

7. The method according to claim 3, characterized in that The peak roller diameter of the upper roller and / or the lower roller is recorded as D1, and the trough roller diameter is recorded as D2, and 20mm≤D1=D2+2h≤200mm.

8. The method according to claim 1, characterized in that The metal material is stainless steel. In the upper roller and / or the lower roller, d1 is 2-8 mm, and the misalignment value M is 100-600 μm. The thickness of the stainless steel is 0.4 mm-4.5 mm.

9. The method according to claim 1, characterized in that The metal material is titanium alloy, in the upper roller and / or lower roller, d1 is 1~4mm, and the misalignment value M is 100~400μm; and / or, the metal material is aluminum alloy, in the upper roller and / or lower roller, d1 is 2~6mm, and the misalignment value M is 100~400μm.

10. The method according to claim 1 or 2, characterized in that The rolling speed of the upper roller is 2000-20000 mm / min, and / or the rolling speed of the lower roller is 2000-20000 mm / min; And / or, the single pressing depth of the rolling is 30-400 μm, and / or, the working surfaces of the upper roll and the lower roll of the last roll group among the multiple roll groups are both flat.

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