Preparation method of ultrahigh-strength steel surface texture

Abstract

The invention relates to the technical field of surface microstructure preparation, in particular to a preparation method of an ultrahigh-strength steel surface texture, which comprises the following steps: determining that texture units meeting the wear resistance are cylindrical pits according to the wear resistance bionics principle; according to a hydrophobic mechanism, forming a basic texture by using a plurality of texture units with different sizes in a concentric circle distribution form; and a plurality of basic textures distributed in a set arrangement mode are machined on the surface of the ultrahigh-strength steel base body through the laser shock peening technology. The preparation method of the ultrahigh-strength steel surface texture aims at solving the problem that it is difficult to improve the corrosion resistance and the abrasion resistance of the surface of an ultrahigh-strength steel base material at the same time.

Description

Technical Field

[0001] This invention relates to the field of surface microstructure preparation technology, specifically to a method for preparing surface textures on ultra-high strength steel. Background Technology

[0002] Ultra-high strength steel is widely used in the moving components of advanced equipment due to its various performance advantages. However, when it is used in a corrosive marine environment, the high-speed friction and wear and marine corrosion damage that the moving components are subjected to seriously affect their technical indicators, reliability and serviceability. Therefore, in order to meet the equipment's combat and technical requirements, more stringent requirements have been put forward for the corrosion resistance and wear resistance of the material surface, which urgently need to be further improved.

[0003] Currently, surface technologies such as supersonic spraying, physical vapor deposition, chemical vapor deposition, laser cladding, electroplating, electroless plating, phosphating, and nitriding can all be used as means to protect and improve the performance of surfaces against sliding friction and wear. However, due to the low tempering temperature of materials and the high surface quality requirements of components, there are varying degrees of problems in dealing with temperature damage, coating peeling, and uniformity of preparation precision, which leads to application limitations and makes it difficult to meet the high reliability protection requirements of moving components of equipment under extreme corrosion and wear conditions.

[0004] Therefore, directly texturing the material surface to overcome the aforementioned process defects and improve the material's wear resistance while also enhancing its resistance to marine corrosion remains an urgent need.

[0005] Therefore, the inventors have provided a method for preparing ultra-high strength steel surface texture. Summary of the Invention

[0006] (1) Technical problems to be solved This invention provides a method for preparing surface texture of ultra-high strength steel, which solves the technical problem of simultaneously improving the corrosion resistance and wear resistance of ultra-high strength steel substrate materials.

[0007] (2) Technical solution This invention provides a method for preparing surface texture of ultra-high strength steel, comprising the following steps: Based on the biomimetic principle of wear resistance, the texture unit that meets the wear resistance performance is determined to be a cylindrical pit; Based on the hydrophobic mechanism, multiple texture units of different sizes are arranged in concentric circles to form the basic texture; Multiple basic textures are processed on the surface of the ultra-high strength steel substrate using a laser shock peening process, and distributed in a predetermined pattern.

[0008] Furthermore, the basic texture includes three texture units, the diameters of which are d / 3, 2d / 3 and d respectively.

[0009] Furthermore, the wall thickness of each texture unit is d / 12.

[0010] Furthermore, after determining that the texture unit that meets the wear resistance performance is a cylindrical pit based on the biomimetic principle of wear resistance, the following steps are also included: verifying the wear resistance performance of the texture unit based on the physical properties of the ultra-high strength steel substrate and the wear boundary conditions.

[0011] Furthermore, the diameter of the texture unit is 5–200 μm.

[0012] Furthermore, the depth of the texture unit is 5–50 μm.

[0013] Furthermore, the arrangement is a rectangular array, with the spacing between two adjacent basic textures on the left and right being d / 3 to 2d, and the spacing between two adjacent basic textures on the top and bottom being 0 to 2d.

[0014] Furthermore, the set arrangement is a diagonal grid arrangement, the spacing between two adjacent basic textures on the left and right is in the range of d / 3 to 2d, and the spacing between two adjacent basic textures on the top and bottom is in the range of -d / 2 to 2d.

[0015] Furthermore, the area of ​​all the aforementioned basic textures on the surface of the ultra-high strength steel substrate accounts for 20-75%.

[0016] Furthermore, the strengthening energy of the laser shock peening process is 20–40 J.

[0017] (3) Beneficial effects In summary, the concentric distributed cylindrical recesses formed by laser shock peening in this invention can give the surface of ultra-high strength steel materials a higher texture density. These concentric distributed cylindrical recesses provide more stable support at the contact interface between kinematic and frictional pairs. Simultaneously, they offer greater advantages in reducing the contact area of ​​kinematic pair interfaces and controlling interface stress distribution, which is more conducive to the uniform dispersion and effective support of frictional load stress. The concentric distributed cylindrical recesses increase the recessed area of ​​the ultra-high strength steel surface and form multiple air cushions, increasing the contact angle with the surface and thus significantly improving its hydrophobicity. When corrosive droplets come into contact with such a material surface, they will be in a semi-suspended state, forming an air cushion effect, which greatly reduces the actual contact area between the corrosive medium and the material surface, resulting in superior corrosion resistance. Attached Figure Description

[0018] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the embodiments of the present invention will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0019] Figure 1 This is a schematic flowchart of a method for preparing surface texture of ultra-high strength steel according to an embodiment of the present invention; Figure 2 This is a schematic diagram of the dry friction mechanism of a microtexture provided in an embodiment of the present invention; Figure 3 This is a schematic diagram of a surface contact angle provided in an embodiment of the present invention; Figure 4 This is a schematic diagram of a basic texture arranged in a rectangular array according to an embodiment of the present invention; Figure 5 This is a schematic diagram of a basic texture arranged in a rectangular array according to an embodiment of the present invention; Figure 6 This is a schematic diagram of a basic texture with a diagonal grid arrangement provided in an embodiment of the present invention.

[0020] In the picture: 1-Basic texture; 101-First texture unit; 102-Second texture unit; 103-Third texture unit. Detailed Implementation

[0021] The embodiments of the present invention will be further described in detail below with reference to the accompanying drawings and examples. The following detailed description of the embodiments and the accompanying drawings are used to illustrate the principles of the present invention by way of example, but should not be used to limit the scope of the present invention, that is, the present invention is not limited to the described embodiments.

[0022] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. This application will now be described in detail with reference to the accompanying drawings and embodiments.

[0023] In the description of this invention, it should be understood that the terms "upper," "lower," "front," "rear," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship commonly used when the product of this invention is in use, or the orientation or positional relationship commonly understood by those skilled in the art. They are only used to facilitate the description of this invention and to simplify the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0024] This invention provides a method for preparing surface textures on ultra-high strength steel, see [link to relevant documentation]. Figure 1 The method may include the following steps: S100. Based on the biomimetic principle of wear resistance, the texture unit that meets the wear resistance performance is determined to be a cylindrical pit.

[0025] Specifically, using the wear-resistant exoskeleton of the jewel beetle as a biomimetic model, the wear-resistant basic unit of its circular pits was extracted and replicated through microscopic morphology testing. Calculation results show that the surface texture of the circular pits is beneficial for controlling the interfacial contact state and stress distribution. Experiments show that under dry friction, the surface texture of metal components can also accommodate wear debris generated during friction, improve the three-body abrasive wear between the contact surface and wear debris, and reduce adhesive friction wear, thereby improving the tribological properties of the contact surface.

[0026] According to Bowden's theory of adhesive friction, the frictional force of a moving system mainly consists of two parts: the adhesive effect and the grooving effect. Regarding the adhesive effect, due to the roughness of the solid surface, when two objects come into contact, the actual contact only occurs at the tops of individual discrete contact peaks (i.e., micro-protrusions) on the surface. These points where contact actually occurs are called true contact points, and the sum of the areas of these true contact points constitutes the true contact area (which accounts for only 0.01% to 0.1% of the apparent total area). Under load, the stress at the contact point will reach the compressive yield limit of the material, resulting in plastic deformation. During friction, the plastic flow at the contact point may generate instantaneous high temperatures, leading to adhesion between the moving metal surfaces. Subsequently, under the action of friction, the adhesive nodes are sheared, resulting in sliding. Thus, the adhesive effect of sliding friction is a process of alternating formation of adhesive nodes and shearing. The grooving effect occurs when the rough peaks of the hard surface in the friction pair embed into the soft surface under normal load, pushing the soft metal during sliding, causing it to flow plastically and plowing out a groove.

[0027] Based on this, in the dry friction contact model, the contact area consists of two parts ( Figure 2 As shown): one part is the normal supporting cylindrical surface, which is the area where the adhesive effect occurs, and shearing occurs during sliding; the other part is the end face compression shear surface, which is the area where the furrowing effect occurs, and the hard peaks push against the soft material during sliding. Therefore, friction... F Its composition is: F = F a + F p = Aτ b + Sσ s (1) In the formula, F a Shear force,A The adhesive area is the normal support area. σ s It is the compressive yield limit; F p For furrowing force, S The furrow area is the area of ​​the end face pushing. τ b The shear strength is in the sliding direction.

[0028] In simple adhesion theory, only the compressive yield strength is considered when analyzing the actual contact area. σ s However, when calculating friction, only the shear strength limit is considered. τ b This is reasonable for static friction. However, for sliding friction, due to the presence of tangential force, the actual contact area... A r The deformation condition at the contact point depends on the compressive stress generated by the normal load. W and shear stress generated by tangential force F t The combined effect of.

[0029] A r 2 =( W / σ s ) 2 + α ( F t / σ s ) 2 (2) In the formula, α It is an undetermined constant, as proven by experiments. α <25, Bowden et al. took α =9. W / σ s Indicates normal load W The contact area under static friction conditions, and α ( F t / σ s ) 2 Reflecting tangential force, i.e., frictional force F t The increased contact area results in a significantly larger contact area derived from the modified adhesion theory, leading to a friction coefficient value that is much larger than that of the simple adhesion theory and is closer to reality.

[0030] For the dry friction sliding model with micropatterned texture, the contact area under static friction is mainly determined by the normal load. W and compressive yield strength σ s The ratio determines the surface texture, therefore the processing of the surface texture has basically no effect on the size of the normal support area under static friction, but it does affect the tangential friction force. F t The increased contact area, caused by the texture disrupting the continuity of the contact area, helps to suppress tangential friction. F t The increased contact area reduces the actual adhesive area, thus suppressing severe adhesive wear. Regarding the furrowing effect, since the textured areas are cavitary, the end-face pushing area decreases when furrowing occurs in the textured areas, which helps improve the furrowing effect. However, to balance the normal load, the plastic deformation in the non-textured areas will increase, leading to an increase in indentation depth. Therefore, the end-face pushing area in the non-textured areas will increase, exacerbating the furrowing effect. Thus, surface texture is beneficial for suppressing adhesive friction, but its impact on the furrowing effect depends on the actual operating conditions.

[0031] Important parameters of surface texture (which can significantly affect the actual friction and wear behavior of the surface). (1) Texture diameter If the texture diameter is too small, it has limited effect on reducing the actual contact area and improving the stress distribution at the interface. At the same time, it is difficult to effectively capture and store abrasive particles at the interface of the moving pair in the actual process. However, when the texture diameter is too large, the indentation depth and stress concentration will also be aggravated, which will also cause the friction and wear of the moving pair to be aggravated.

[0032] (2) Texture surface density Texture density also affects the actual contact area of ​​the surface during wear, the distribution of interfacial stress, and the effective area of ​​the interface for capturing and storing abrasive particles, thus affecting the friction and wear behavior of the system.

[0033] (3) Texture depth Increasing the texture depth helps to store more wear particles, which is beneficial for improving the friction and wear state of the kinematic pair interface over a long period of time. However, the specific effect depends on the actual working conditions.

[0034] (4) Texture shape Different texture shapes not only affect the stress distribution at the interface of the kinematic pair, but also the degree of matching between the texture shape and the abrasive morphology, which in turn affects the abrasive's capture and storage performance, and consequently the friction and wear behavior of the kinematic pair system.

[0035] S200. Based on the hydrophobic mechanism, multiple texture units of different sizes are distributed in concentric circles to form the basic texture.

[0036] Specifically, based on the hydrophobic morphology of biological surfaces in nature, a concentric circular basic unit texture is extracted. This texture is then used to model the surface to achieve hydrophobicity and thus improve surface corrosion resistance. According to the Wenzel contact model, the presence of a rough surface means that the actual solid-liquid contact area is larger than the area observed geometrically, thus geometrically enhancing hydrophobicity (or hydrophilicity).

[0037] The contact angle is defined as the angle between the tangent line drawn at the gas-liquid interface at the solid-liquid-gas three-phase junction and the solid-liquid interface line. Figure 3 As shown. The contact angle is used to measure the degree of wetting of a solid by a liquid. The contact angle of a water droplet on a wetting surface is defined as between 0° and 90°, and the contact angle of a water droplet on a non-wetting surface is between 90° and 180°. The contact angles of 0° and 180° correspond to completely wetting and completely non-wetting surfaces, respectively.

[0038] That is: ① When θ < 90°, θ decreases with the increase of surface roughness, and the surface becomes more hydrophilic; ② When θ > 90°, θ increases with the increase of surface roughness, and the surface becomes more hydrophobic.

[0039] For hydrophobic surfaces, the interaction between the solid surface and the droplet is weak, resulting in a non-wetting contact between the droplet and the solid surface. The grooves on the rough surface trap air, forming an air cushion. Therefore, the apparent liquid-solid contact surface is actually composed of both solid and gas, with the air-water contact angle θ = 180°. Thus, the Cassie-Baxter model can be used to analyze the wetting contact angle variation of chemically modified textured surfaces under different parameters. Test results show that the optimized concentric circular texture, due to its multi-level pattern, significantly increases the contact area between the droplet and the metal surface, making it more effective in altering the hydrophilic properties of the metal surface and successfully achieving superhydrophobicity.

[0040] Superhydrophobic surfaces, as surface structures with unique properties and broad application prospects, have wide applications in various fields, including corrosion protection and self-cleaning. In the field of corrosion protection, superhydrophobic surfaces, relying on their low surface free energy and unique micro-nano rough structures, not only change the wetting properties of traditional metal surfaces but also introduce new corrosion protection mechanisms. Compared with traditional corrosion methods (such as adding corrosion inhibitors), superhydrophobic coatings have better corrosion protection effects on metal surfaces and are widely used in various fields, such as aerospace. In recent years, the corrosion protection mechanisms of superhydrophobic coatings have mainly included: the Lotus effect, inhibition of electrochemical corrosion, improvement of interfacial adhesion, and the cushion effect.

[0041] The Lotus effect, also known as the lotus leaf effect, refers to the phenomenon where water droplets, when falling on a surface resembling a lotus leaf, form a near-perfect sphere and easily roll off, carrying away adhering dirt and particles. This effect, through the microstructure of the substrate surface and low adhesion, effectively removes surface contaminants and corrosive media, thus maintaining a long-term corrosion protection effect.

[0042] Electrochemical corrosion is one of the most common forms of corrosion in metals. It usually occurs in metals and electrolyte solutions (water). Due to the high contact angle of the superhydrophobic coating, the actual contact area between the water droplet and the metal surface is smaller, thereby reducing the formation of corrosion microcells, blocking the occurrence of electrochemical corrosion process, and improving the corrosion resistance of the metal surface.

[0043] Improving interfacial bonding is crucial because metals often corrode due to friction, impact, and vibration. Since superhydrophobic materials not only have good hydrophobicity, but also, under certain conditions, if the superhydrophobic surface can resist mechanical wear, it can reduce corrosion problems caused by physical damage.

[0044] The air cushion effect refers to the phenomenon where, when a water droplet or liquid droplet comes into contact with a superhydrophobic surface, the surface's special structure and chemical properties prevent the water droplet from completely adhering to the surface, resulting in a semi-suspended state. In this case, the droplet forms a thin gas film with the surface, thus creating an air cushion-like phenomenon. Its role in metal corrosion protection is to reduce the need for corrosive elements to directly contact the metal and cause corrosion by forming an air cushion.

[0045] Furthermore, see Figure 4 The basic texture 1 comprises three texture units of different sizes, with diameters of d / 3, 2d / 3, and d, respectively, namely the first texture unit 101, the second texture unit 102, and the third texture unit 103. The wall thickness of each texture unit is d / 12. The selection of crucial dimensional process parameters during the fabrication of the textured pattern must be within the correct range, which is key to its successful fabrication. Through calculation and analysis of the influence of texture parameters on its friction, wear, and super-repellent anti-corrosion properties, the diameters of each concentric circle were determined to be d / 3, 2d / 3, and d. The equidistant distribution of the concentric circles is most conducive to uniform stress distribution and avoids stress concentration. Excessively large texture dimensions exacerbate furrowing and stress concentration, while excessively small dimensions result in insufficient ability to block adhesion effects. First, based on the size range of the matrix particles (0.1–10 µm for in-situ abrasive particles and 5–20 µm for external abrasive particles), the minimum diameter of the basic texture is initially determined to be 5 µm. In addition, based on the wear profile size range of the matrix material during actual wear tests, the maximum diameter of the basic texture is determined to be 200 µm, and the depth range is 5–50 µm.

[0046] (1) Based on numerical calculation, a concentric circular texture was constructed and optimized. The influence of the surface texture design of the friction pair on the wear behavior of the ring-block motion system was analyzed, and it was verified that the surface concentric circular texture is beneficial to improving the wear performance of the system.

[0047] (2) The basic texture of concentric circles has better friction reduction performance. Analysis shows that the geometric features of concentric circles have higher texture surface density, which has a better effect on reducing the contact area of ​​the kinematic pair interface and controlling the interface stress distribution, thus resulting in better friction reduction effect.

[0048] (3) Theoretical analysis shows that constructing textured surface morphology is also beneficial to alleviate the increase in contact area caused by tangential friction. In addition, it is also beneficial to capture and store wear debris in the actual process, further improving the wear performance of the system.

[0049] The spacing between two adjacent basic texture edges is set as 'a'. Different arrangement patterns of the resulting concentric circular textured surfaces, after optimization, can achieve excellent wear and corrosion resistance. This application illustrates this with the following two examples: like Figure 5 As shown, the arrangement is set as a rectangular array (hereinafter referred to as sequential arrangement). The spacing between two adjacent basic textures 1 on the left and right is d / 3 to 2d, and the spacing between two adjacent basic textures 1 on the top and bottom is 0 to 2d. The selection of the spacing between two adjacent basic textures 1 is based on friction and wear performance: mainly considering the uniformity of frictional force distribution and surface support strength. If the spacing is too small, the support strength of the friction pair is insufficient; if the spacing is too large, the surface distribution of frictional force is insufficient, and stress concentration problems will appear. In addition, a reasonable spacing distribution of the textures is conducive to the timely and effective collection and storage of wear debris generated during friction and wear, thereby reducing the secondary wear damage to the surface by wear particles. All of these will affect the friction and wear resistance of the material surface. Regarding corrosion resistance: if the texture spacing is too large, corrosive droplets cannot form an effective air cushion effect when in contact with the surface, etc., weakening the hydrophobicity and affecting the corrosion resistance.

[0050] like Figure 6As shown, the arrangement is set as a diagonal grid pattern (hereinafter referred to as dislocation arrangement). The spacing between two adjacent basic textures 1 on the left and right is in the range of d / 3 to 2d, and the spacing between two adjacent basic textures 1 on the top and bottom is in the range of -d / 2 to 2d. The selection of the spacing between two adjacent basic textures 1 is for friction and wear performance: it is mainly considered from the aspects of uniform dispersion of friction force and surface support strength. If the spacing is too small, the support strength of the friction pair is insufficient; if the spacing is too large, the surface dispersion of friction force is insufficient, and stress concentration problems will appear. In addition, a reasonable spacing distribution of the texture is conducive to the timely and effective collection and storage of wear debris generated during friction and wear, thereby reducing the secondary wear damage to the surface by wear particles. All of these will affect the friction and wear resistance of the material surface. Regarding corrosion resistance: if the texture spacing is too large, corrosive droplets cannot form an effective air cushion effect when in contact with the surface, etc., the hydrophobicity is weakened, affecting the corrosion resistance.

[0051] S300 uses laser shock peening technology to process multiple basic textures distributed in a predetermined pattern on the surface of an ultra-high strength steel substrate.

[0052] Specifically, this application employs laser shock peening to create a textured structure on the surface of ultra-high-strength steel (taking AF1410 as an example) to enhance the material's corrosion and wear resistance. Laser shock peening can impart deep residual compressive stress and gradient nanostructures to the surface, significantly improving the material's fatigue resistance and enhancing its surface corrosion and wear resistance. Simultaneously, the specific textured structure formed by shock peening can alter the effective contact area for friction and wear, disperse frictional force, and change the distribution pattern of surface stress. Furthermore, the texture can store wear debris, reducing further wear and damage to the surface caused by wear particles during friction and wear, thereby improving friction reduction and wear resistance.

[0053] Laser Shock Peening (LSP) is an advanced metal surface modification technology that uses high-energy laser pulses to generate high-intensity shock waves on the material surface, thereby improving the material's mechanical properties. Its core principle can be summarized in the following stages: (1) Laser energy absorption and plasma formation (high energy density (GW / cm) 2 When a short-pulse laser (10–30 ns) is irradiated onto an absorption layer on a metal surface (such as aluminum foil or black paint), the absorption layer vaporizes instantaneously under the laser's action, generating a high temperature (>10°C). 7 K), high-pressure (>GPa) plasma); (2) Plasma expansion and shock wave generation (the plasma expands rapidly under the confinement of the confinement layer, generating a high-intensity shock wave with a pressure peak of up to 10 GPa). (3) Shock wave propagation and material plastic deformation (the shock wave propagates into the material. When the pressure exceeds the dynamic yield strength of the material, plastic deformation occurs on the surface of the material. This deformation forms residual compressive stress on the surface and induces grain refinement, forming a gradient nanostructure). (4) Residual compressive stress and performance improvement (residual compressive stress can effectively inhibit the initiation and propagation of cracks, and significantly improve the fatigue life and corrosion resistance of materials).

[0054] Technical characteristics: Laser shock peening features high pressure (1 GPa ~ 1 TPa), high energy (>1 GW), ultrafast (nanosecond level), and ultra-high strain rate (>10). 6 s -1 Its properties make it suitable for a variety of metallic materials, including stainless steel, aluminum alloys, and titanium alloys. Its core lies in the interaction between the shock wave and the material, rather than the thermal effect, which gives it a unique advantage in the field of material surface modification.

[0055] For ultra-high strength steel matrix material (AF1410), considering the requirements of friction reduction, wear resistance and super-hydrophobic corrosion resistance of the textured surface, a petal texture morphology is achieved by laser shock peening process. The optimal limit range of laser shock peening process parameters is: strengthening energy 20J≤P≤40J.

[0056] As an optional implementation, after determining that the texture unit that meets the wear resistance performance is a cylindrical pit through the biomimetic principle of wear resistance in step S100, the following steps are also included: verifying the wear resistance performance of the texture unit based on the physical properties of the ultra-high strength steel substrate and the boundary conditions of wear.

[0057] Specifically, the wear resistance and corrosion resistance of the textured surface are tested, and the dimensional parameters of the textured pattern are improved and optimized based on the experimental results. According to the national standard GB / T 12444-2006 "Test Methods for Wear of Metallic Materials - Sliding Wear Test of Test Rings and Blocks", dry friction wear tests and lubricated friction wear tests were conducted respectively. The grinding ring was in direct contact with the sample, and the transmission device drove the grinding ring to rotate. The test load was 100 N, the rotation speed was 200 r / min, the test time was 2 h, and the lubrication condition was extreme pressure high temperature grease. To reduce test errors, each sample was tested five times. Before and after each wear test, the sample was immersed in an ethanol solution, ultrasonically cleaned, and then dried with a hair dryer. The sample was weighed using a precision balance, with the weight accurate to 0.00001 g. The weight difference of the sample before and after wear was taken as the weight loss of the sample, and the weight loss rate (mg / min) of the sample was calculated.

[0058] The sliding friction and wear properties of samples with different surface texture patterns were studied and compared. The texture pattern arrangement in this application is beneficial to significantly improve the surface's resistance to sliding friction and wear, especially the dry friction and wear performance under conditions without lubrication.

[0059] As an optional implementation, the area ratio of all basic textures on the surface of the ultra-high strength steel substrate ranges from 20% to 75%. It should be noted that the area ratio of the basic textures on the entire surface of the ultra-high strength steel substrate directly affects the texture's effectiveness in reducing surface friction and wear, as well as achieving hydrophobicity and corrosion resistance; there is an optimal value. On the one hand, if the area ratio of the texture is too small, it is insufficient to effectively disperse frictional forces and effectively collect abrasive particles during friction and wear, resulting in decreased friction and wear resistance. If the area ratio is too small, it is also difficult to form an effective air cushion effect when corrosive droplets contact the surface, reducing hydrophobicity and weakening corrosion resistance. On the other hand, if the area ratio of the texture is too large, the material surface will lack sufficient support strength for the friction pair load, exacerbating surface friction and wear.

[0060] This invention, through biomimetic extraction and numerical calculation design optimization, utilizes a concentric ring texture formed by laser shock peening to effectively reduce the mass wear rate of high-strength steel surfaces under dry sliding friction wear (the surface mass wear rate of the textured structure can reach 16.6% of the base material's mass wear rate), significantly improving the material's surface resistance to sliding friction wear. Under lubricating conditions, the textured structure also exhibits excellent resistance to lubricating friction wear (friction coefficients are all less than 0.15, and the surface mass wear rate of the textured structure can be reduced to 75% of the base material's mass wear rate). Furthermore, the textured material surface in this invention also demonstrates excellent corrosion resistance; after 1000 hours of neutral salt spray corrosion, the increase in corrosion products on the textured surface is less than 75% of the increase in corrosion products on the base material surface, indicating a significant improvement in corrosion resistance.

[0061] First, the concentric circle texture, which is designed and optimized by calculation, has friction-reducing, wear-resistant, and hydrophobic properties. Second, laser shock strengthening generates deep compressive residual stress and gradient nanostructure on the surface of ultra-high strength steel through plasma shock waves induced by high-energy lasers. This process is particularly beneficial for improving the material's fatigue resistance, corrosion resistance, and wear resistance.

[0062] Furthermore, under dry friction and wear conditions, the cylindrical pit-like texture can collect abrasive particles. Simultaneously, because the texture reduces the effective contact area during surface friction and wear, it regulates the interfacial stress distribution, thereby reducing the probability of abrasive wear on the contact surface and improving the surface's wear resistance. Under lubricating medium conditions, the surface structure of the textured sample can not only collect wear particles but also store lubricant. The solid lubricant filled within the texture is extracted to the texture edge during friction, thus sustaining the lubricating film. The high texture density structure also facilitates the replenishment of lubricating medium, thus ensuring excellent surface friction and wear resistance. Using laser shock peening to form the texture does not damage the overall integrity of the material surface, which further enhances the material's corrosion resistance.

[0063] Example 1 This embodiment uses a high-energy laser shock enhancement device with an energy of 20J.

[0064] Table 1. Main dimensional parameters of concentric circle texture 2. Test results of anti-sliding friction and wear performance Dry friction wear tests and lubricated friction wear tests were conducted at room temperature and in a dry environment according to GB / T 12444-2006 "Test Methods for Wear of Metallic Materials - Sliding Wear Test of Test Rings and Blocks". The grinding ring was in direct contact with the sample, and the grinding ring was rotated by a transmission device. The test load was 100 N, the rotation speed was 200 r / min, and the test time was 2 h. The lubrication condition was extreme pressure high temperature grease. To reduce test error, each sample was tested five times. Before and after each wear test, the sample was immersed in an ethanol solution, ultrasonically cleaned, and then dried with a hair dryer. The sample was weighed using a precision balance to an accuracy of 0.00001 g. The weight difference before and after wear was taken as the weight loss of the sample, and the weight loss rate (mg / min) was calculated.

[0065] (1) Comparison of dry sliding friction and wear performance under no lubricating medium conditions Table 2. Mass wear rate (mg / min) and friction coefficient of dry sliding friction wear Table 2 shows that the samples with concentric circular surface textures all exhibited excellent resistance to sliding friction and wear. Within the diameter range of Φ5–Φ200µm, the average mass wear rate of the samples with concentric circular surface textures was lower than that of the base material. In particular, the mass wear rate of the sequentially arranged concentric circular textures, at a diameter of Φ60µm, was only 41.6% of that of the base material (0.4084mg / min). When using dislocation arrangement, with a concentric circle diameter of Φ60µm, the mass wear rate (0.0679mg / min) was only 16.6% of that of the base material (0.4084mg / min). This indicates that under conditions without lubrication, the concentric circular textures prepared by laser shock peening, regardless of whether they are sequentially or dislocationally arranged, can effectively improve the material's resistance to sliding friction and wear.

[0066] (2) Comparison of sliding friction and wear performance under lubricating medium conditions Table 3. Lubrication, friction, and wear mass: wear rate (mg / min) and its coefficient of friction. Generally, a material with a surface friction coefficient less than 0.15 indicates excellent anti-friction and wear performance. As shown in Table 3, under sliding friction and wear conditions with a lubricating medium, both textured and untextured surfaces exhibit friction coefficients far less than 0.15, and their mass wear rates are also low. This demonstrates that in the presence of a lubricating medium, regardless of surface texture, both surfaces possess superior friction coefficients and anti-sliding friction and wear performance. Among them, the optimal set of dislocation concentric circle texture #2 in this experiment showed a 25% reduction in mass wear rate compared to the substrate under lubricated conditions.

[0067] 3. Comparison of resistance to neutral salt spray corrosion results Test conditions: The corrosion resistance of the samples was characterized by a neutral salt spray test (GB / T10125-1997 standard). The solution was a 5 wt.% NaCl aqueous solution with a pH of 6.8–7.2, a temperature of 35℃±2℃, and continuous salt spray. The salt spray deposition rate was 80 cm / s. 2 The rate is 1 ml / h to 2 ml / h over a given area, with a corrosion time of 1000 h.

[0068] The results of the neutral salt spray corrosion performance are shown in Table 4. The average increase of corrosion products before and after salt spray corrosion of the sample with concentric circle texture ranged from 0.42 to 0.50 g, while the average increase of corrosion products after corrosion of the substrate material was 0.62 g. Therefore, in this invention, the concentric circle texture processed by laser shock peening effectively improves the salt spray corrosion resistance of the material. When a better texture arrangement is adopted, the increase of surface corrosion products can be reduced by 25% compared with the substrate surface.

[0069] Table 4. Increase in corrosion products (g) before and after salt spray corrosion of textured specimens and matrix specimens. It should be noted that the various embodiments in this specification are described in a progressive manner, and the same or similar parts between the various embodiments can be referred to mutually. Each embodiment focuses on describing the differences from other embodiments. The present invention is not limited to the specific steps and structures described above and shown in the figures. Furthermore, for the sake of brevity, detailed descriptions of known methods and techniques are omitted here.

[0070] The above are merely embodiments of this application and are not intended to limit the scope of this application. Various modifications and variations can be made to this application by those skilled in the art without departing from the scope of the invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principle of this application should be included within the scope of the claims of this application.

Claims

1. A method for preparing surface texture of ultra-high strength steel, characterized in that, The method includes the following steps: Based on the biomimetic principle of wear resistance, the texture unit that meets the wear resistance performance is determined to be a cylindrical pit; Based on the hydrophobic mechanism, multiple texture units of different sizes are arranged in concentric circles to form the basic texture; Multiple basic textures are processed on the surface of the ultra-high strength steel substrate using a laser shock peening process, and distributed in a predetermined pattern.

2. The method for preparing the surface texture of ultra-high strength steel according to claim 1, characterized in that, The basic texture includes three texture units, with diameters of d / 3, 2d / 3 and d respectively.

3. The method for preparing the surface texture of ultra-high strength steel according to claim 2, characterized in that, The wall thickness of each texture unit is d / 12.

4. The method for preparing the surface texture of ultra-high strength steel according to claim 1, characterized in that, After determining that the texture unit that meets the wear resistance performance is a cylindrical pit based on the biomimetic principle of wear resistance, the following steps are also included: The wear resistance of the textured unit was verified by considering the physical properties of the ultra-high strength steel matrix and the wear boundary conditions.

5. The method for preparing the surface texture of ultra-high strength steel according to claim 1, characterized in that, The diameter of the texture unit is 5–200 μm.

6. The method for preparing the surface texture of ultra-high strength steel according to claim 5, characterized in that, The depth of the texture unit is 5–50 μm.

7. The method for preparing the surface texture of ultra-high strength steel according to claim 3, characterized in that, The arrangement is a rectangular array, with the spacing between two adjacent basic textures on the left and right being d / 3 to 2d, and the spacing between two adjacent basic textures on the top and bottom being 0 to 2d.

8. The method for preparing the surface texture of ultra-high strength steel according to claim 3, characterized in that, The specified arrangement is a diagonal grid pattern, with the spacing between two adjacent basic textures on the left and right sides ranging from d / 3 to 2d, and the spacing between two adjacent basic textures on the top and bottom sides ranging from -d / 2 to 2d.

9. The method for preparing the surface texture of ultra-high strength steel according to claim 1, characterized in that, All of the aforementioned basic textures account for 20-75% of the surface area of ​​the ultra-high strength steel substrate.

10. The method for preparing the surface texture of ultra-high strength steel according to claim 1, characterized in that, The strengthening energy of laser shock peening process is 20-40 J.

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