Wear-resistant stainless steel plate and method for manufacturing the same

Abstract

The application discloses a wear-resistant stainless steel plate and a preparation method thereof, and relates to the technical field of additive manufacturing, and comprises the following steps: step one, establishing a plate model with a bionic leaf vein recess structure; step two, using 316L stainless steel powder as printing material, starting printing according to preset scanning parameters to obtain a 316L stainless steel plate with a bionic leaf vein recess structure; step three, according to the following raw material ratio by mass percentage: 50%-70% of PEEK powder with a particle size of 20-50 mu m, 25%-45% of PTFE powder with a particle size of 200-500 nm, and 1%-5% of h-BN powder with a particle size of 1-5 mu m, the above-mentioned powders are mixed in a planetary ball mill for 3 hours to obtain a uniform composite powder; step four, the composite powder is fully filled into the 316L stainless steel plate with the bionic leaf vein recess structure, and a bionic 316L stainless steel-polymer composite plate is obtained after sintering.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of additive manufacturing, in particular to a wear-resistant stainless steel plate and a preparation method thereof. BACKGROUND

[0002] 316L stainless steel is widely used in key components of shipbuilding, chemical machinery, medical devices, aerospace and other fields, such as ship shafting, mechanical sealing ring, artificial joint, etc., due to its excellent corrosion resistance, comprehensive mechanical properties and biocompatibility. However, 316L stainless steel is relatively soft in texture, and its tribological properties, especially the friction reduction and wear resistance under dry friction or boundary lubrication conditions, are poor, which severely limits its service life and reliability under harsh working conditions.

[0003] In order to improve the surface tribological properties of metal materials, the existing technology usually adopts surface modification methods, mainly including the following two types. The first type is surface coating technology, such as preparing a hard coating (such as diamond-like carbon film DLC, titanium carbide TiC, etc.) or a soft lubricating coating (such as polytetrafluoroethylene PTFE) on the surface of the substrate by thermal spraying, electroplating or vapor deposition technology. Although this method can improve the surface properties to some extent, it also has obvious limitations, such as interface bonding strength problem. The coating and the metal substrate are mainly physically or simply chemically bonded, which belongs to typical "hard-hard" or "soft-hard" bonding. When subjected to high load, strong shear force or thermal cycle load, stress concentration is easy to occur, leading to coating cracking, peeling and invalidation of modification effect. In addition, traditional technology is difficult to prepare uniform coating on complex curved surface or internal structure, and has insufficient preparation capacity for surface strengthening layer with three-dimensional fine and complex structure. The second type is surface texturing technology. Laser surface texturing (LST) is a technology widely studied in recent years, which processes micron-scale regular patterns such as pits and grooves on the surface of the material by laser. These textures can store lubricants and capture wear debris, thereby improving the lubrication conditions. However, this technology also faces bottlenecks, such as the limitation of simple geometric effect. The texture only changes the surface in geometric form, and the improvement of its friction reduction and wear resistance depends on the continuous supply of external lubricant, which significantly decreases under lubrication-poor or solid lubrication conditions. In addition, the traditional texture is only a cavity and does not have lubrication ability itself, and its performance improvement has an upper limit.

[0004] In recent years, with the rapid development of additive manufacturing (AM) technology, laser powder bed fusion (LPBF) technology has brought revolutionary changes to the design and manufacture of metal parts. The layer-by-layer forming characteristics of LPBF technology make it possible to manufacture complex three-dimensional structures (such as porous structures and lattice structures). Currently, some studies have attempted to use LPBF to directly manufacture metal parts with three-dimensional complex structures. However, existing technologies mainly focus on using LPBF to manufacture lightweight or functionally integrated structures, and there is little research on in-situ forming fine biomimetic structures on a dense metal matrix to enhance the performance of specific surfaces (such as tribological performance) and in-situ compounding of solid lubricating materials with different properties.

[0005] Therefore, by filling a polymer-based composite material (such as a composite material of polyether ether ketone PEEK, polytetrafluoroethylene PTFE and hexagonal boron nitride h-BN) with excellent self-lubricating properties as a lubricating phase into a biomimetic dendritic 316L stainless steel structure with strong mechanical interlocking ability manufactured in-situ by LPBF technology, a new type of lubrication-integrated material with high strength and high toughness of the metal matrix and the surface composite layer with continuous friction-reducing and wear-resistant properties can be constructed, which can effectively enhance the friction-reducing and wear-resistant properties of 316L stainless steel.

[0006] Therefore, there is an urgent need in the art for a new technical solution to fundamentally solve the problems of weak bonding force between the surface modification layer and the substrate, insufficient wear resistance under poor lubrication conditions, and single function of traditional surface texture. SUMMARY

[0007] The purpose of the present application is to solve the problems and deficiencies in the background art, and to provide a wear-resistant stainless steel plate and a preparation method thereof.

[0008] A preparation method of a wear-resistant stainless steel plate, comprising the following steps:

[0009] Step one: according to the structure and distribution characteristics of the veins, a plate model with a biomimetic vein recess structure is established;

[0010] Step two: using 316L stainless steel powder as the printing material, the plate model with the biomimetic vein recess structure is saved in stl. format, and after slicing processing using Magics software, it is imported into the LPBF printing equipment control software. The 316L stainless steel powder is placed in the printer powder bin, and high-purity argon is introduced into the printing chamber. After the oxygen content in the forming chamber is lower than 0.03%, the printing is started according to the preset scanning parameters to obtain a 316L stainless steel plate with a biomimetic vein recess structure;

[0011] Step three: the raw material ratio is as follows: 50%-70% of PEEK powder with a particle size of 20-50 microns, 25%-45% of PTFE powder with a particle size of 200-500 nanometers, and 1%-5% of h-BN powder with a particle size of 1-5 microns; the above powders are placed in a planetary ball mill and mixed at a speed of 250 rpm for 3 hours to obtain a uniform composite powder;

[0012] Step four: the composite powder is filled into the 316L stainless steel plate with the biomimetic leaf vein recess structure until the composite powder completely covers the biomimetic leaf vein recess structure, and is slightly vibrated to ensure the density of the filling, and then is placed in a hot-pressing sintering furnace, heated to 400 DEG C at a rate of 8 DEG C / min under nitrogen protection, and then the pressure of 20 MPa is applied at the temperature, and the pressure is maintained for 40 min, finally, the biomimetic 316L stainless steel-polymer composite plate is obtained after the furnace is cooled to below 100 DEG C and taken out.

[0013] Preferably, in step one, the biomimetic leaf vein recess structure is composed of main branch grooves and branch grooves, the branch grooves are symmetrically arranged on both sides of the main branch grooves, the biomimetic leaf vein recess structure is linearly arranged along the x axis, and the branch grooves on the side edges of the adjacent two main branch grooves are connected to each other to form a "three-dimensional interconnected pore dendritic branching metal structure".

[0014] Preferably, the angle b between the main branch groove and the branch groove is 30-60 DEG, the width a of the main branch groove is 0.4-0.8 mm, the width of the branch groove is half of the width of the main branch groove, the distance c between the main branch grooves is 0.6-1 mm, and the depth of the main branch groove and the branch groove is 0.2 mm.

[0015] Preferably, the scanning parameters include: the laser power is 190 W, the scanning speed is 1000 mm / s, the path spacing is 0.09 mm, the layer thickness is 0.03 mm, the interlayer rotation angle is 67 DEG, and the scanning strategy is strip scanning.

[0016] A wear-resistant stainless steel plate is prepared by the above method.

[0017] The beneficial effects of the present application are as follows:

[0018] The application realizes high-strength combination of lubricating phase (composite powder) and metal base (316L stainless steel plate with bionic vein recess structure), solves the problem of easy peeling of traditional coating, and in-situ manufactures the dendritic metal structure with three-dimensional interconnected pores by using the LPBF technology, the structure provides a large specific surface area and complex three-dimensional space for the subsequent filled composite material, through the hot-pressing sintering process, the molten PEEK / PTFE / h-BN composite material fully infiltrates and wraps each dendritic metal structure and unmelted particles under pressure, and after cooling, a very firm "mechanical interlocking" effect is formed, which fundamentally surpasses the single chemical bonding or physical adsorption of the traditional coating, so that the composite material layer can withstand high load, strong shear force and thermal stress, effectively avoiding the peeling problem caused by interface failure under harsh working conditions, and greatly prolonging the service life of the part.

[0019] The surface is endowed with continuous, stable and excellent friction-reducing and wear-resistant performance, especially under dry friction conditions, the advantages of various solid lubricants are combined: PTFE provides extremely low friction coefficient; h-BN enhances the temperature resistance and load capacity; PEEK as a tough matrix ensures the overall wear resistance of the composite material and the adhesion to the metal structure, these lubricants are filled in the dendritic metal structure with three-dimensional interconnected pores after compounding, in the friction process, the composite material can form a continuous and stable transfer film on the surface of the counterpart, realize continuous lubrication, at the same time, the dendritic metal structure supports the composite material like a "skeleton", prevents it from being quickly worn, and can store wear debris, avoiding three-body wear, even under dry friction or boundary lubrication conditions with interrupted lubricating oil supply, the surface still exhibits extremely low friction coefficient and wear rate.

[0020] The process has high integration degree, realizes near-net forming manufacturing of surface functionalization of complex structure, the method fully utilizes the technical advantages of additive manufacturing, the LPBF process one-time forms the dense matrix and the bionic surface structure, avoids positioning error and interface pollution caused by secondary processing, the subsequent filling and sintering process is relatively simple and easy to control, the whole process does not need complex chemical treatment or expensive vapor deposition equipment, and the preparation period is short and the cost is low. BRIEF DESCRIPTION OF DRAWINGS

[0021] Figure 1 It is a schematic diagram for designing the bionic vein surface structure in the application;

[0022] Figure 2This is a schematic diagram of the composite powder preparation process in this invention;

[0023] Figure 3 This is a schematic diagram illustrating the preparation of the biomimetic 316L stainless steel-polymer composite plate in this invention;

[0024] Figure 4 This is a graph showing the friction coefficient curves of the biomimetic 316L stainless steel-polymer composite plates with different structural parameters in this invention.

[0025] Figure 5 This is a data graph showing the wear rate of biomimetic 316L stainless steel-polymer composite plates with different structural parameters in this invention.

[0026] Figure 6 This is a white light interference pattern of the wear marks on sample No. 3 in this invention;

[0027] Figure 7 This is a photograph of sample No. 3 in this invention;

[0028] In the figure: 1: Leaf vein; 2: 316L stainless steel plate with biomimetic leaf vein recessed structure; 21: Main support groove; 22: Branch groove; 3: Composite powder; 4: PEEK powder; 5: PTFE powder; 6: h-BN powder; 7: Planetary ball mill; 8: Hot pressing sintering furnace; 9: Biomimetic 316L stainless steel-polymer composite plate. Detailed Implementation

[0029] To better illustrate the preparation process involved in this invention and its advantages over the prior art, further explanation will be provided with reference to the accompanying drawings.

[0030] Example 1: A method for preparing wear-resistant stainless steel sheet, comprising the following steps:

[0031] Step 1: As Figure 1 As shown, leaf vein 1 has good liquid transport capacity. Based on the structure and distribution characteristics of leaf vein 1, a square plate is first created using SolidWorks 3D modeling software. Then, a biomimetic leaf vein shape pattern is drawn on the upper surface of the plate. The extrusion cut command is used to create a plate model with a biomimetic leaf vein concave structure.

[0032] Step two: using 316L stainless steel powder with a particle size of 15-53 pm as the printing material, saving the plate model with the biomimetic vein recess structure as stl. format, using Magics software for slicing processing and then importing into the LPBF printing equipment control software, opening the water cooling cycle, installing the substrate and scraper, placing the 316L stainless steel powder in the printer powder bin, and then introducing high-purity argon into the printing chamber, after the oxygen content in the forming chamber is lower than 0.03%, using the printing parameters of laser power 190 W, scanning speed 1000 mm / s, path interval 0.09 mm, layer thickness 0.03 mm, layer rotation angle 67°, and scanning strategy strip scanning to in-situ print and form the 316L stainless steel plate 2 with the biomimetic vein recess structure;

[0033] Step three: as shown in Figure 2 , the raw material ratio is as follows: 50%-70% of PEEK powder 4 with a particle size of 20-50 pm, 25%-45% of PTFE powder 5 with a particle size of 200-500 nm, and 1%-5% of h-BN powder 6 with a particle size of 1-5 pm; the above powders are placed in a planetary ball mill 7 and mixed at a speed of 250 rpm for 3 hours to obtain a uniform composite powder 3;

[0034] Step four: as shown in Figure 3 , the composite powder 3 is fully filled into the 316L stainless steel plate 2 with the biomimetic vein recess structure until the composite powder 3 completely covers the biomimetic vein recess structure, and is slightly vibrated to ensure the filling density, and then is placed into a hot-pressing sintering furnace 8, heated to 400°C at a rate of 8°C / min under nitrogen protection, and then a pressure of 20 MPa is applied and kept for 40 min, finally, after the furnace is cooled to below 100°C, it is taken out to obtain a biomimetic 316L stainless steel-polymer composite plate 9, i.e. a wear-resistant stainless steel plate.

[0035] Preferably, in step one, the biomimetic vein recess structure is composed of main branch grooves 21 and branch grooves 22, the branch grooves 22 are symmetrically arranged on both sides of the main branch grooves 21, and the branch grooves 22 between the side edges of two adjacent main branch grooves 21 are connected to each other to form a "three-dimensional interconnected pore dendritic branching metal structure".

[0036] Preferably, the angle b between the main branch grooves 21 and the branch grooves 22 is 30-60°, the width a of the main branch grooves 21 is 0.4-0.8 mm, the width of the branch grooves 22 is half of the width of the main branch grooves 21, the spacing c between the main branch grooves 21 is 0.6-1 mm and is linearly arranged along the x axis, and the depth of the main branch grooves 21 and the branch grooves 22 is 0.2 mm.

[0037] The biomimetic 316L stainless steel-polymer composite plate 9 obtained by the above method is subjected to experimental testing:

[0038] (1) Friction and wear test:

[0039] The biomimetic 316L stainless steel-polymer composite plate 9 prepared has different structural parameters, and the specific structural parameters and average friction coefficients are shown in Table 1. The No. A is a pure 316L stainless steel flat material. It can be seen that the average friction coefficient of the biomimetic 316L stainless steel-polymer composite plate 9 with all structural parameters is lower than that of the 316L stainless steel flat material, and the average friction coefficient of the No. 3 sample with structural parameters a = 0.8, b = 60°, and c = 1 is the lowest, which is 0.115, which is about 74.78% lower than that of the pure 316L stainless steel flat material.

[0040] The friction coefficient curve of the biomimetic 316L stainless steel-polymer composite plate 9 with different structural parameters is shown in Figure 4 The friction coefficients of the three biomimetic 316L stainless steel-polymer composite plates 9 are significantly lower than that of the pure 316L stainless steel flat material throughout the friction process, and the friction coefficient curve of the No. D sample with structural parameters a = 0.8, b = 60°, and c = 1 is the most stable and lower throughout the friction process.

[0041]

[0042] (2) Wear rate test:

[0043] As shown in Figure 5 , the wear rate of the sample is calculated by the following formula (1), wherein the wear volume is calculated by a white light interference device, and the wear scar morphology of the No. C sample with structural parameters a = 0.8, b = 60°, and c = 1 is shown in Figure 6 It can be found that the wear rate of the No. C sample is still the lowest, which is 4.08 x 10 -5 mm 3 / Nm, which is about 65.42% lower than that of the pure 316L stainless steel flat material. The wear rate calculation formula (1) is as follows:

[0044] ε = μ / (F x L) formula (1)

[0045] Wherein ε is the wear rate (mm 3 / Nm), μ is the wear volume (mm 3 ), F is the load size (N), and L is the friction sliding distance (m).

Claims

1. A method for preparing wear-resistant stainless steel sheet, characterized in that: Includes the following steps: Step 1: Based on the structure and distribution characteristics of leaf veins (1), establish a board model with a biomimetic leaf vein concave structure; Step 2: Using 316L stainless steel powder as printing material, the plate model with biomimetic leaf vein recessed structure is saved as stl. format. After slicing with Magics software, it is imported into the LPBF printing equipment control software. After placing 316L stainless steel powder in the printer powder hopper, high-purity argon gas is introduced into the printing chamber. After the oxygen content in the forming chamber is lower than 0.03%, printing begins according to the preset scanning parameters to obtain 316L stainless steel plate with biomimetic leaf vein recessed structure (2). Step 3: The raw materials are proportioned as follows by mass percentage: 50%-70% of PEEK powder with a particle size of 20-50μm (4), 25%-45% of PTFE powder with a particle size of 200-500nm (5), and 1%-5% of h-BN powder with a particle size of 1-5μm (6). The above powders are placed in a planetary ball mill (7) and mixed at a speed of 250rpm for 3 hours to obtain a uniform composite powder (3). Step 4: The composite powder (3) is fully filled into the 316L stainless steel plate (2) with the biomimetic leaf vein recess structure until the composite powder (3) completely covers the biomimetic leaf vein recess structure. The plate is then slightly vibrated to ensure dense filling. The plate is then placed in a hot press sintering furnace (8) and heated to 400°C at a rate of 8°C / min under nitrogen protection. At this temperature, a pressure of 20MPa is applied and the plate is held at the temperature and pressure for 40min. Finally, the plate is cooled to below 100°C in the furnace and then removed to obtain the biomimetic 316L stainless steel-polymer composite plate (9).

2. The method for preparing a wear-resistant stainless steel plate according to claim 1, characterized in that: In step one, the biomimetic leaf vein recessed structure consists of a main branch groove (21) and a branch groove (22). The branch grooves (22) are symmetrically arrayed on both sides of the main branch groove (21). The biomimetic leaf vein recessed structure is linearly arrayed along the x-axis. The branch grooves (22) on the sides of two adjacent main branch grooves (21) are interconnected to form a "three-dimensional interconnected pore tree branching metal structure".

3. The method for preparing a wear-resistant stainless steel plate according to claim 1, characterized in that: The angle b between the main support groove (21) and the branch groove (22) is 30-60°, the width a of the main support groove (21) is 0.4-0.8mm, the width of the branch groove (22) is half the width of the main support groove (21), the spacing c between the main support grooves (21) is 0.6-1mm, and the depth of both the main support groove (21) and the branch groove (22) is 0.2mm.

4. The method for preparing a wear-resistant stainless steel plate according to claim 1, characterized in that: The scanning parameters include: laser power of 190W, scanning speed of 1000mm / s, path spacing of 0.09mm, layer thickness of 0.03mm, interlayer rotation angle of 67°, and scanning strategy of strip scanning.

5. A wear-resistant stainless steel sheet, characterized in that: It is prepared by any one of the preparation methods of wear-resistant stainless steel sheet according to claims 1 to 3 above.

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