High-degree-of-freedom fine control method for microstructure of metal material

Abstract

The invention discloses a high-degree-of-freedom fine control method for a microstructure of a metal material, and relates to the technical field of material preparation, the method comprises the following specific steps: pretreatment preparation: selecting a metal material, cutting and grinding, and selecting a grinding ball and a matched pressure head which are matched with the metal in hardness; by means of multi-step refined parameter regulation and control, high-degree-of-freedom precise control over the microstructure of the surface of the metal material is achieved, and in the links of pretreatment, surface mechanical grinding nanocrystallization treatment, local heating / cooling treatment forming and the like, material selection, grinding parameter setting, cooling and heating unit layout and temperature control are achieved; the method has the advantages that the method can be flexibly adjusted according to specific requirements, so that various complicated and unique microstructures can be prepared, the requirements of the high-end manufacturing field on specific performance of materials and the pursuit of the artistic creation on unique appearance can be met, and the applicability of the metal material in different application scenes is greatly expanded.

Description

Technical Field

[0001] The present invention relates to the technical field of material preparation, and in particular to a method for finely controlling the microstructure of a metal material with a high degree of freedom. Background Art

[0002] In the field of material preparation, metal materials are widely used in many fields such as aerospace, automobile manufacturing, electronic information, and architectural decoration due to their excellent mechanical properties, electrical conductivity, thermal conductivity, and good machinability. The microstructure of metal materials, such as grain size, grain boundary characteristics, phase composition, and micromorphology, plays a decisive role in their macroscopic properties. Different microstructures will cause metal materials to show significant differences in strength, hardness, toughness, corrosion resistance, and electrical conductivity. Therefore, achieving effective control of the microstructure of metal materials is the key to meeting the diversified performance requirements of metal materials in different fields and promoting the development of metal material applications.

[0003] Traditional metal processing technology has many limitations in controlling the microstructure of metal materials, and it is difficult to meet the needs of modern industry and process fields for the diversification and refinement of the microstructure of metal materials. Taking the heat treatment and surface corrosion process in the production of bornite copper as an example, in the burning spot process, if the burning temperature is too low, the raw materials cannot fully react to form the ideal crystal form, resulting in the performance of the metal material failing to meet expectations. If the temperature is too high, it is very easy to cause damage to the workpiece, which not only wastes raw materials, but also increases production costs and process complexity. The burning spot process lacks systematic scientific theoretical guidance, making it difficult to achieve large-scale industrial production and technology inheritance. And innovation, moreover, the overall heating and annealing treatment of copper products under traditional technology makes the grain etching morphology single, mostly large-sized coarse grains, which seriously limits the exquisiteness and innovation of metal crafts. From the general problem of controlling the microstructure of metal materials, metal is a good conductor of heat, and its overall recrystallization behavior is difficult to accurately control. When the block local recrystallization treatment is used to prepare a specific external surface structure, the recrystallization nucleation is random, resulting in uncontrollable microstructure at the local position, and unable to accurately control the microscopic characteristics such as grain size, distribution and morphology, and it is difficult to meet the requirements of different fields for the special performance of the microstructure of metal materials. Summary of the Invention

[0004] The purpose of the present invention is to make up for the shortcomings of the existing technology and provide a method for high-degree-of-freedom fine control of the microstructure of metal materials. It can prepare various complex and unique microstructures through fine-tuning of parameters such as material selection and processing, grinding ball and indenter selection, load application, grinding ball penetration depth, indenter movement speed, cooling unit temperature, heating unit temperature, and contact time between the printing device and the nanocrystalline layer surface to meet the special requirements of material performance in different application scenarios. It not only has the advantages of precise control of microstructure, obvious process advantages, outstanding cost-effectiveness and high design flexibility, but also opens up new ways for performance optimization and innovative application of metal materials in high-end manufacturing, artistic creation and other fields, and has important scientific significance and practical application value.

[0005] In order to solve the above technical problems, the present invention provides the following technical solutions: a method for finely controlling the microstructure of a metal material with high degrees of freedom, the method comprising the following specific steps:

[0006] Pre-treatment preparation: Select the metal material and cut and grind it, and choose the grinding balls and matching indenters that are suitable for the hardness of the metal;

[0007] Surface mechanical grinding nano-processing: using an indenter with grinding balls to apply pressure on the surface of a fixed metal sheet and perform mobile grinding to form a uniform nano-grain deformation layer on the surface of the sheet;

[0008] Printing device preparation and parameter setting: insert the semiconductor cooling unit and heating unit with a specific temperature control range into the insulation bracket according to the design and connect them to the control device, set the temperature of the cooling and heating units and the contact time between the printing device and the nanocrystalline layer;

[0009] Local heating and cooling treatment molding: After the cooling and heating units reach the set temperature, the printing device is attached to the surface of the nanocrystalline layer and maintained in contact for a set time to obtain a heterogeneous structure metal material with controllable grain size distribution.

[0010] Furthermore, in the pretreatment preparation step, metal materials are selected and cut and polished, the thickness of the metal plate is selected between 1-10 mm, and the surface polishing roughness is controlled at Ra0.1-Ra1.6 μm, effectively removing the surface oxide layer, impurities, etc., providing good basic conditions for subsequent surface mechanical grinding.

[0011] Furthermore, in the pretreatment preparation step, the grinding ball material is selected from high-hardness SiC or Al2O3. For metal materials with high hardness, SiC grinding balls are preferred, and Al2O3 grinding balls are selected for softer metal materials. The size of the indenter is adapted according to the size of the plate to be processed. When the plate is a small plate (side length less than 200mm), a indenter with a diameter of 20-50mm can be selected. When the plate is a large plate (side length greater than 200mm), a indenter with a diameter of 50-100mm is selected to ensure that the indenter can stably install the grinding balls and accurately apply the required load.

[0012] Furthermore, in the surface mechanical grinding nano-processing step, the applied load F is adjusted in the range of 0.2-40N according to the hardness of the metal material, the grinding ball is pressed into the depth D of 20-200μm, the indenter movement speed V is controlled at 1-30m / s, and the offset of each pass is 0.1-0.4mm.

[0013] Furthermore, in the surface mechanical grinding nano-processing step, the treated metal plate is firmly fixed on the base to prevent the plate from displacement during the grinding process, and the pressure head with the grinding ball is started. Starting from the upper left corner of the plate, the grinding ball is rolled and ground on the surface of the plate in a top-down and left-to-right order according to the pre-set load F, pressing depth D, movement speed V and offset parameters. This operation is continued until a uniform nano-grain deformation layer with a thickness d of not less than 5% of the plate thickness and in the range of 20-200μm is successfully formed on the surface of the plate, thereby achieving nano-processing of the plate surface.

[0014] Furthermore, in the printing device preparation and parameter setting steps, the temperature control range of the semiconductor cooling unit T1 is -100-0°C. If more fine grain areas are required, the cooling unit temperature T1 can be lowered.

[0015] Furthermore, in the printing device preparation and parameter setting steps, the temperature control range of the heating unit T2 is 100-700°C. If a larger coarse-grained area is desired, the temperature of the heating unit can be appropriately increased.

[0016] Furthermore, in the steps of preparing and setting parameters of the printing device, the number and arrangement of the cooling units and the heating units are reasonably arranged according to the target microstructure, and the cooling units and the heating units are inserted in an orderly manner into an insulating bracket made of porous vacuum silicon. The thermal conductivity of the insulating bracket is 0.014W / (m·K), which can effectively reduce the heat conduction between the units. The control lines of the cooling unit and the heating unit are respectively connected to the corresponding cooling control device and the heating control device to accurately control the temperature of each unit. The contact time t between the printing device and the surface of the nanocrystalline layer is set to 20-120s. If the area to be processed is large or the pattern is more complex, the contact time can be appropriately extended to ensure sufficient heat transfer and achieve the expected microstructural changes.

[0017] Compared with the existing technology, this method for finely controlling the microstructure of metal materials with high degrees of freedom has the following beneficial effects:

[0018] 1. The present invention achieves high-degree-of-freedom and precise control of the surface microstructure of metal materials through multi-step refined parameter regulation. In the pretreatment, surface mechanical grinding nano-treatment and local heating / cooling treatment molding, from material selection, grinding parameter setting to cooling and heating unit layout and temperature control, all can be flexibly adjusted according to specific needs, so that various complex and unique microstructures can be prepared. Whether it is the requirements for specific material properties in the high-end manufacturing field or the pursuit of unique appearance in artistic creation, they can be met, greatly expanding the applicability of metal materials in different application scenarios.

[0019] 2. The present invention reduces damage to the material surface through surface mechanical grinding and local heating and cooling treatment processes, does not cause severe deformation of the material, and effectively maintains the original properties of the material. At the same time, the process flow is relatively simple, the equipment loss is low, the operation is convenient, and the operability is strong. In addition, the cooling / heating unit of the printing device can be freely designed and combined, and precise control of any microstructure can be achieved on a small-scale device, which reduces production costs and creates favorable conditions for the innovative application of metal materials in artistic creation, micro-nano manufacturing and other fields.

[0020] Other advantages, objects and features of the present invention will be described in part in the following description and, in part, will be apparent to those skilled in the art based on an examination of the following or may be learned from the practice of the invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] To more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. Those skilled in the art can also derive other drawings based on these drawings without inventive effort.

[0022] Figure 1 This is a flow chart of a method for high-degree-of-freedom fine control of the microstructure of metal materials;

[0023] Figure 2 A schematic diagram of the surface structure of a metal material after being processed using a high-degree-of-freedom fine control method for the microstructure of the metal material;

[0024] Figure 3 A schematic diagram of a printing device structure for a method for finely controlling the microstructure of metal materials with high degrees of freedom;

[0025] Figure 4 Schematic diagram of a method for obtaining the final surface structure of a metal material with high degree of freedom and fine control of its microstructure. DETAILED DESCRIPTION

[0026] In order to further illustrate the technical means and effects adopted by the present invention to achieve the predetermined purpose of the invention, the specific implementation methods, structures, features and effects of the present invention are described in detail below in conjunction with the accompanying drawings and preferred embodiments.

[0027] Example 1

[0028] High-grade copper-based alloy plates with a thickness of 3mm are selected. The surface roughness is controlled at Ra0.8μm through mechanical grinding to remove surface impurities and oxide layers. According to the hardness of the copper-based alloy, Al2O3 grinding balls are selected, which are suitable for the indenter with a diameter of 40mm. During the grinding and tool selection process, relevant process standards are strictly followed to ensure the surface treatment effect and tool adaptability.

[0029] According to the characteristics of copper-based alloy, the applied load F is set to 6N, the grinding ball penetration depth D is set to 60μm, the indenter movement speed V is set to 8m / s, and the offset per pass is set to 0.2mm. The plate is fixed on the base, and the indenter is started to grind according to the established parameters. Starting from the upper left corner of the plate, the operation is carried out from top to bottom and from left to right. The movement trajectory is as follows Figure 1 As shown in the figure, a high-precision displacement sensor is used to monitor the position of the indenter in real time during operation to ensure the accuracy of the motion trajectory until a uniform nano-grain deformation layer with a thickness of about 180 μm (meeting no less than 5% of the plate thickness) is formed on the plate surface. The surface morphology after grinding is as shown in the figure. Figure 2 shown.

[0030] According to the designed landscape pattern on the surface of the bornite handicraft, computer-aided design software is used to simulate the layout of the cooling and heating units to ensure the accurate presentation of the pattern and the reasonable layout of the semiconductor cooling unit and heating unit, such as Figure 3 As shown, insert the porous vacuum silicon insulation bracket, connect the control line to the corresponding control device, set the cooling unit temperature T1 to -60℃, the heating unit temperature T2 to 400℃, and the contact time t between the printing device and the nanocrystalline layer surface to 80s. During the temperature setting process, use a high-precision temperature sensor for calibration to ensure temperature accuracy.

[0031] Turn on the cooling and heating control devices. After the cooling unit and heating unit reach the set temperature, the printing device is accurately attached to the surface of the nanocrystalline layer and kept in contact for 80 seconds. By precisely controlling the temperature and time, a specific grain size distribution is formed on the surface of the plate, making the surface of the bornite handicraft present a unique pattern like a landscape texture, such as Figure 4 As shown in the figure, after the treatment, the surface of the handicraft was subjected to microstructure inspection and hardness test. The microstructure showed that the distribution of coarse crystal and nano crystal areas was in line with the design expectations. The hardness test results showed that the surface hardness was increased by 20%, which significantly improved the artistic value and ornamental value of the handicraft.

[0032] Example 2

[0033] High-purity copper sheets are selected as raw materials with a thickness of 1.5mm. A combination of chemical cleaning and mechanical polishing is used to reduce the surface roughness of the copper sheets to Ra0.2μm, and impurities such as oil and oxides on the surface are thoroughly removed to ensure the effectiveness of subsequent processes. The copper sheets are first soaked and cleaned with professional chemical cleaning agents to remove oil and some oxides. High-precision mechanical polishing equipment is then used to polish according to specific polishing process parameters to ensure surface flatness and smoothness. Based on the soft properties of the copper sheets, Al2O3 grinding balls are selected and matched with a 25mm diameter indenter. This combination can ensure the grinding effect while avoiding excessive damage to the copper sheets. When selecting the grinding balls and indenters, their dimensional accuracy and hardness uniformity are strictly tested to ensure that they meet the process requirements.

[0034] Based on the material properties of the copper sheet, the applied load F was set to 3N. This load allows the grinding balls to effectively penetrate the copper sheet without causing excessive deformation. The grinding ball penetration depth D was set to 50μm to ensure a sufficiently deep plastic deformation zone and promote the formation of nanocrystals. The indenter movement speed V was set to 6m / s, with an offset of 0.15mm per pass. This parameter combination ensures uniform grinding across the copper sheet's surface. The copper sheet is securely fixed to a customized high-precision base with a special shock-absorbing and positioning design to reduce the impact of external vibrations on the grinding process. The indenter with the grinding balls is activated and, starting from the upper left corner of the copper sheet, the entire surface is systematically milled according to the set parameters. During the milling process, the grinding ball movement and copper surface deformation are monitored in real time using a high-speed camera. Any abnormality is immediately stopped and adjusted until a uniform nanocrystal deformation layer with a thickness of approximately 80μm (measuring at least 5% of the sheet thickness) is formed on the copper sheet's surface, achieving nanocrystalization on the copper sheet's surface.

[0035] Based on the special requirements of electronic equipment heat dissipation on the microstructure of copper sheets, the layout of semiconductor cooling units and heating units is carefully designed. Thermal simulation software is used to simulate and analyze different layout schemes, and the optimal layout is selected. They are inserted into the porous vacuum silicon insulation bracket in an orderly manner, and the control lines are connected to the corresponding cooling control device and heating control device. Considering the thermal conductivity and heat dissipation requirements of copper, the cooling unit temperature T1 is set to -40°C, the heating unit temperature T2 is set to 200°C, and the contact time t between the printing device and the nanocrystalline layer surface is 50s. Before setting the temperature and time parameters, multiple preliminary experiments are carried out, and the parameters are fine-tuned according to the experimental results to ensure the best processing effect.

[0036] Turn on the cooling and heating control devices, and closely monitor the temperature changes of the cooling unit and heating unit. When they stably reach the set temperatures of -40°C and 200°C respectively, quickly use a high-precision positioning device to accurately fit the printing device to the nanocrystalline layer surface of the copper sheet, maintaining a contact time of 50 seconds. In this process, the cooling unit and the heating unit work together to accurately control the recrystallization behavior of the micro-area on the surface of the copper sheet, so that a special heterogeneous structure is formed on the surface of the copper sheet, that is, some areas are tiny nanocrystals, and some areas are slightly larger grains. After the treatment is completed, a scanning electron microscope (SEM) is used to detect the microstructure of the copper sheet surface, and a thermal imager is used to test the heat dissipation performance of the copper sheet. The results show that the grain structure on the surface of the copper sheet meets the expected design. After being applied to the CPU cooling module of a certain model of mobile phone, it has been tested that under the same usage conditions, the temperature of the mobile phone CPU is reduced by 5-8°C compared with when using untreated copper sheet, effectively improving the operating stability and performance of the mobile phone.

[0037] Example 3

[0038] A specific aluminum alloy sheet with a thickness of 2 mm was selected for the manufacture of automobile engine pistons. The aluminum alloy sheet was pretreated by a process combining mechanical grinding and chemical degreasing. First, coarse sandpaper was used for preliminary grinding to remove larger defects and oxide layers on the surface of the sheet. Finer sandpaper was then replaced for fine grinding until the surface roughness reached Ra1.2μm. Subsequently, the sheet was immersed in a specially configured chemical degreasing agent solution to remove surface oil through chemical reaction to ensure that the surface cleanliness of the sheet met the subsequent processing standards. In view of the medium hardness of the aluminum alloy, SiC grinding balls were selected to match the indenter with a diameter of 50 mm. When selecting the grinding balls and indenter, key performance indicators such as hardness and density were strictly tested to ensure their stable quality and compliance with process requirements.

[0039] According to the characteristics of aluminum alloy, the applied load F is set to 8N to ensure that the grinding ball can be fully pressed into the surface of the plate, causing the material to undergo plastic deformation and thus form a nanocrystalline structure. The grinding ball is pressed into the surface to a depth D of 120μm, the indenter movement speed V is 12m / s, and the offset per pass is 0.25mm. The aluminum alloy plate is firmly fixed on a special high-strength base with a shock-absorbing and anti-slip design to effectively reduce the vibration and displacement generated during the grinding process. The indenter is started and the entire plate surface is evenly ground starting from the upper left corner of the plate according to the set parameters. During the grinding process, sensors are used to monitor parameters such as the pressure, speed, and displacement of the indenter in real time to ensure parameter stability. At the same time, the microstructure of the ground area is detected at regular intervals to observe the formation of nanocrystals until a uniform nanocrystalline grain deformation layer with a thickness of about 120μm (not less than 5% of the plate thickness) is formed on the plate surface, completing the surface nano-treatment.

[0040] Based on the requirements of automobile engine pistons for the high-temperature strength and wear resistance of aluminum alloy materials, computer simulation technology is used to optimize the layout of the semiconductor cooling unit and heating unit in the insulation bracket to achieve the most ideal microstructure control effect. The cooling unit and heating unit are inserted into the porous vacuum silicon insulation bracket in an orderly manner, and the control lines are connected to the corresponding control devices. The cooling unit temperature T1 is set to -70°C, the heating unit temperature T2 is set to 550°C, and the contact time t between the printing device and the nanocrystalline layer surface is set to 90s. Before setting these parameters, a large number of simulation experiments and small-batch trial production are carried out, and the microstructure and performance changes of the aluminum alloy materials under different parameter combinations are comprehensively analyzed to determine the optimal parameter values.

[0041] The cooling and heating control devices were activated, and their temperature changes were closely monitored by a high-precision temperature control system. Once they reached the set temperatures of -70°C and 550°C, respectively, a highly automated robotic arm with a positioning accuracy of ±0.01mm accurately attached the printing device to the nanocrystalline layer of the aluminum alloy sheet, maintaining a contact time of 90 seconds. During this process, the cooling and heating units worked synergistically to precisely control the recrystallization behavior of the aluminum alloy sheet's surface micro-regions, forming a specific heterogeneous structure on the surface. After the treatment, the aluminum alloy sheet was subjected to comprehensive performance testing, including hardness testing, tensile testing, wear resistance testing, and fatigue testing under high-temperature conditions. The results showed that compared to the untreated aluminum alloy material, the surface hardness of the treated material increased by 35%, the wear rate under simulated engine high-temperature conditions decreased by 30%, and the tensile strength increased by 20%. The treated aluminum alloy material was then manufactured into an automobile engine piston for bench testing. After a long period of operation simulating actual operating conditions, disassembly and inspection revealed that the piston wear was significantly reduced, effectively extending the piston's service life and improving the overall performance and reliability of the engine.

[0042] The above description is merely a preferred embodiment of the present invention and does not constitute any form of limitation to the present invention. Although the present invention has been disclosed as above in terms of a preferred embodiment, it is not intended to limit the present invention. Any person skilled in the art can, without departing from the scope of the technical solution of the present invention, make some changes or modifications to equivalent embodiments using the technical contents disclosed above. However, any brief modifications, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solution of the present invention are still within the scope of the technical solution of the present invention.

Claims

1. A method for finely controlling the microstructure of a metal material with high degree of freedom, characterized in that: The method comprises the following specific steps: Pre-treatment preparation: Select the metal material and cut and grind it, and choose the grinding balls and matching indenters that are suitable for the hardness of the metal; Surface mechanical grinding nano-processing: using an indenter with grinding balls to apply pressure on the surface of a fixed metal sheet and perform mobile grinding to form a uniform nano-grain deformation layer on the surface of the sheet; Printing device preparation and parameter setting: insert the semiconductor cooling unit and heating unit with a specific temperature control range into the insulation bracket according to the design and connect them to the control device, set the temperature of the cooling and heating units and the contact time between the printing device and the nanocrystalline layer; Local heating and cooling treatment molding: After the cooling and heating units reach the set temperature, the printing device is attached to the surface of the nanocrystalline layer and maintained for the set contact time to obtain a heterogeneous structure metal material with controllable grain size distribution.

2. A high degree of freedom fine control method for the microstructure of a metal material according to claim 1, characterized in that: In the pretreatment preparation step, metal materials are selected and cut and polished. The thickness of the metal sheet is selected between 1-10 mm, and the surface polishing roughness is controlled within Ra0.1-Ra1.6 μm.

3. A high degree of freedom fine control method for the microstructure of a metal material according to claim 1, characterized in that: In the pretreatment preparation step, the grinding ball material is selected from SiC or Al2O3 with high hardness. For metal materials with high hardness, SiC grinding balls are preferred, while Al2O3 grinding balls are preferred for softer metal materials.

4. A high degree of freedom fine control method for the microstructure of a metal material according to claim 1, characterized in that: In the surface mechanical grinding nano-processing step, the applied load F is adjusted in the range of 0.2-40N according to the hardness of the metal material, the grinding ball is pressed into the depth D of 20-200μm, the indenter movement speed V is controlled at 1-30m / s, and the offset of each pass is 0.1-0.4mm.

5. The method for high-degree-of-freedom fine control of the microstructure of a metal material according to claim 1, characterized in that: In the surface mechanical grinding and nano-processing step, the treated metal plate is firmly fixed on the base, the pressure head with grinding balls is started, and the surface of the plate is ground according to the set parameters. The grinding direction is from top to bottom and from left to right until a uniform nano-grain deformation layer with a thickness d of not less than 5% of the plate thickness and in the range of 20-200μm is formed on the surface of the plate.

6. A high degree of freedom fine control method for metal material microstructure according to claim 1, characterized in that: In the printing device preparation and parameter setting steps, the temperature control range of the semiconductor cooling unit is -100-0°C.

7. The method for high-degree-of-freedom fine control of the microstructure of a metal material according to claim 1, characterized in that: In the printing device preparation and parameter setting steps, the temperature control range of the heating unit is 100-700°C.

8. The method for high-degree-of-freedom fine control of the microstructure of a metal material according to claim 1, characterized in that: During the printing device preparation and parameter setting steps, the number and arrangement of cooling and heating units are rationally arranged according to the target microstructure, and an insulating bracket made of porous vacuum silicon with a thermal conductivity of 0.014 W / (m·K) is inserted. The contact time t between the printing device and the surface of the nanocrystalline layer is 20-120 seconds.

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