A method for additive manufacturing of microscale biomimetic toughened structures with shell-like features

Abstract

This invention discloses a microscale biomimetic toughening additive manufacturing method for shell-like features. To address the current difficulty in achieving a balance between strength and toughness in laser additive manufacturing of metal components for the aerospace field, this invention draws inspiration from the "brick-and-mortar" biological structure of the nacreous layer of a shell. It employs a method of continuous laser layer-by-layer melting and forming / ultrafast laser interlayer micro-region precise toughening to design and construct a biomimetic toughening material with spatial overlap of "soft" and "hard" regions, thereby achieving a synergistic improvement in the strength and toughness of laser additive manufacturing of metal components.

Description

Technical Field

[0001] This invention belongs to the field of metal additive manufacturing, specifically relating to a method for additive manufacturing microscale biomimetic toughened structures with shell-like features. Background Technology

[0002] Metal laser additive manufacturing (LAM) is a rapidly developing advanced manufacturing technology in recent years. It can form three-dimensional metal components by selectively melting and depositing powder layer by layer using lasers. LLM offers advantages such as high designability, high material utilization, and integrated forming of complex components, showing broad application prospects in aerospace, transportation, and other fields. However, LLM metal components still face challenges such as limited strength and toughness, and difficulties in matching strength and toughness. As the number of reinforcing phases increases within the formed component, strength increases while ductility decreases significantly, and vice versa. Overcoming the contradictory relationship between "strength" and "toughness" in LLM metal components and achieving a synergistic improvement in strength and toughness remains a critical technological challenge to be solved.

[0003] Modern industry demands higher specific strength and fracture toughness from structural materials, but homogeneous materials are approaching their theoretical limits. Multi-scale microstructure design is one feasible technical approach to achieve a synergistic improvement in strength and toughness. While strength and toughness are mutually exclusive, biological structures in nature have achieved a synergistic improvement in strength and toughness. The key to this lies in the spatial arrangement of "soft" and "hard" phases at the microscale. Through millions of years of evolution and natural selection, biological systems have developed and optimized intricate structures to adapt to environmental changes, possessing unique properties that are difficult to achieve with artificially synthesized materials. For example, the nacreous structure of seashells consists of approximately 95% inorganic matter (hard phase) and approximately 5% organic matter (soft phase) by volume. Its spatial distribution exhibits a unique "brick-and-mortar" structure with alternating soft and hard zones, which can increase energy dissipation by several orders of magnitude and effectively enhance strength and toughness through the "crack deflection" effect.

[0004] Biomimetic microscale structural design based on biological inspiration is an effective method to achieve synergistic enhancement of material strength and toughness. Its main strengthening mechanism stems from the fact that the alternating spatial distribution of soft and hard phases can promote crack deflection, increase crack propagation pathways, and reduce the energy required. For metallic materials, the spatially alternating soft and hard distribution structure can also form a "heterogeneous deformation-induced strengthening" effect during deformation due to stress synergy. However, current biomimetic structural research mostly uses non-metallic materials. Since microscale biomimetic design involves precise control of the spatial distribution of "soft" and "hard" phases, this characteristic can be achieved in non-metals through processes such as ice templates, spraying, and self-assembly. The forming process of metallic materials often involves high temperature / high pressure and rapid melting / solidification processes. Therefore, achieving precise control of the spatial biomimetic distribution and properties of the soft and hard regions of metals at the microscale presents significant technical challenges to forming processes. Summary of the Invention

[0005] Purpose of the invention: To address the current challenge of achieving a balance between strength and toughness in laser additive manufacturing of metal components for the aerospace field, this invention proposes a microscale biomimetic toughening structure additive manufacturing method based on shell-like features, thereby achieving a synergistic improvement in the strength and toughness of laser additive manufactured metal components.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0007] A method for additive manufacturing of microscale biomimetic toughened structures with shell-like features, comprising the following steps:

[0008] (1) Based on the characteristics of the shell structure and the interface size characteristics, a microscale heterogeneous biomimetic model is established to determine the biomimetic microstructure with differences in "soft" and "hard" properties.

[0009] (2) Based on the working conditions and material properties, the hardness difference between the continuous laser action area and the ultrafast laser engraving area of ​​the same layer is measured, and the corresponding continuous laser and ultrafast laser process parameters under the condition of this difference are determined.

[0010] (3) Using the micro-region performance difference obtained in step (2) as input, and combining the "brick-mud" structural features of the shell, we carried out biomimetic toughening structure optimization and determined the geometric feature parameters of the micro-scale biomimetic structure.

[0011] (4) The optimized microscale shell-like "brick-mud" toughened structure obtained in step (4) is sliced ​​in layers to obtain slice information for laser additive manufacturing.

[0012] (5) Based on the results of layered slicing, a continuous laser melting powder and ultrafast laser interlayer micro-area carving process is adopted to realize the laser additive manufacturing of metal components with microscale biomimetic toughening structure.

[0013] Specifically, in step (2), the forming material is a material with precipitation strengthening properties, including any one of Al-Cu alloys, Al-Mg, Al-Zn alloys, and nickel-based superalloys. Preferably, it is an Al-Cu-Mg alloy of the 2xxx series, Al-Mg-Si alloy of the 6xxx series, Al-Zn alloy of the 7xxx series, or a trace element modified Al-Mg as specified in the standard GB / T 16474-1996 "Method for Designation of Wrought Aluminum and Aluminum Alloys". The trace element modified Al-Mg contains 2-6 wt.% Mg, 0.1-0.8 wt.% Sc, 0.1-0.6 wt.% Zr, 0-0.1 wt.% Fe, and the balance Al. This invention also has an improving effect on nickel-based superalloys with precipitation strengthening properties.

[0014] Specifically, in step (2), the range of differences in micro-area hardness performance under the different effects of continuous laser and ultrafast laser is determined. The test block is formed by using the process of continuous laser melting powder and ultrafast laser interlayer selective area secondary carving. The hardness difference between the continuous laser action area and the ultrafast laser carving area of ​​the same layer is determined by microhardness measurement.

[0015] Further, in step (2), the hardness difference in the micro-area is greater than 20%, and the corresponding continuous laser and ultrafast laser process parameters under this difference condition are determined.

[0016] Specifically, in step (3), the geometric feature parameters of the microscale biomimetic structure are optimized based on simulation software such as the finite element method.

[0017] Specifically, the shell "brick-mud" structural features include the size, spacing, and arrangement period of the hard "brick" region and the soft "mud" region. The characteristic structural parameters include the length d and height m of the hard "brick" region, the spacing l between identical layers, the spacing n between layers in different height directions, and the misalignment distance s between the brick layers. Considering the constraints of the laser spot radius and the geometric features of the shell brick-mud structure, the optimized key geometric parameter ranges are as follows: 60μm≤d≤200μm, 30μm≤m≤200μm, 10μm≤l≤50μm, 20μm≤n≤50μm, 5μm≤s≤50μm.

[0018] Specifically, in step (3), characteristic geometric parameter values ​​are set based on simulation software such as finite element method, and the stress distribution and bearing capacity of the configuration under external load are calculated under the constraints of working conditions and material properties to obtain optimized geometric characteristic values.

[0019] Specifically, in step (4), the slice information includes the continuous laser action area, path, and laser parameters, and the ultrafast laser interlayer action area, path, and laser parameters.

[0020] Furthermore, in step (5), a single layer of powder is first laid, and a continuous laser selectively melts the powder area based on the slice information. Then, an ultrafast laser selectively sculpts the corresponding area in the interlayer based on the cross-sectional information of the "soft" area in the microscale biomimetic toughening structure. The above process of powder laying-continuous laser melting of powder-ultrafast laser sculpting of the biomimetic "soft" area in the interlayer is repeated until the metal part with the microscale biomimetic toughening structure is formed.

[0021] Preferably, in step (5), the continuous laser parameters are: power of 100-400W, laser scanning speed of 500-2000mm / s, and layer thickness of 30-50μm.

[0022] Preferably, in step (5), the ultrafast laser is a nanosecond pulsed laser with a pulse wavelength of 1064nm, a power of 30-100W, a scanning speed of 100-250mm / s, and a laser frequency of 10-50Hz.

[0023] Beneficial effects:

[0024] (1) This invention combines the advantages of laser additive manufacturing technology with the concept of "learning from nature" to solve the problem of the difficulty in synergistic strength and toughness of laser additive manufacturing of metal components for the aerospace field. It proposes a microscale biomimetic toughening structure design and its additive manufacturing method based on the characteristics of shells. It draws on the "brick-mud" biological structure of the overlapping soft and hard areas of the nacreous layer of shells, and uses the method of continuous laser layer-by-layer melting and forming / ultrafast laser interlayer micro-region precise toughening to design and construct a biomimetic toughening material with the spatial overlap of "soft area" and "hard area", so as to achieve the synergistic improvement of strength and toughness of laser additive manufacturing of metal components.

[0025] (2) This invention combines the highly designable process of laser additive manufacturing with a biomimetic toughening approach inspired by biological principles. Through a microscale toughening structure design mimicking the "brick-and-mortar" structure of a seashell, coupled with continuous laser / nanosecond pulse laser composite additive manufacturing, it achieves a spatially alternating distribution of "soft" and "hard" regions with biomimetic structural characteristics. The continuous laser-acted region exhibits a "hard" region due to the larger temperature gradient during melting and solidification, resulting in finer internal grains and more dispersed nanoprecipitates. Conversely, the interlayer nanosecond pulse laser-acted region exhibits "soft" characteristics due to the smaller temperature gradient, leading to larger grains and coarser precipitates. Based on continuous laser / nanosecond pulse laser composite additive manufacturing, a molded specimen with a controllable three-dimensional biomimetic distribution of soft and hard micro-regions can be constructed, achieving a toughening effect mimicking the "brick-and-mortar" characteristics of a seashell and synergistically improving the strength and toughness of the molded specimen compared to traditional processes. Attached Figure Description

[0026] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments, and the advantages of the present invention in the above and / or other aspects will become clearer.

[0027] Figure 1 This is a flowchart of the additive manufacturing method for a microscale biomimetic toughened structure with shell-like features according to the present invention.

[0028] Figure 2 Typical parameters and models for the design optimization of the microscale biomimetic toughening structure with shell-like features of this invention are presented.

[0029] Figure 3 This is a schematic diagram illustrating the additive manufacturing principle of the microscale biomimetic toughened structure with shell-like features of the present invention.

[0030] Figure 4 The surface morphology of the microscale biomimetic toughened metal component formed in Example 1. Detailed Implementation

[0031] The present invention can be better understood from the following embodiments.

[0032] This invention combines the advantages of laser additive manufacturing technology with the concept of "learning from nature" to address the current challenge of achieving a balance between strength and toughness in laser additive manufacturing of metal components for the aerospace field. It proposes a microscale biomimetic toughening structure additive manufacturing method based on shell-like characteristics. The method optimizes the design of a microscale biomimetic toughening structure for metal based on the "brick-and-mortar" biological structure of shells. Then, based on the layered slicing results, it performs integrated laser additive manufacturing, simultaneously introducing a continuous laser melting powder / ultrafast laser interlayer micro-region sculpting process to achieve laser additive manufacturing of metal components with microscale biomimetic toughening structures. Figure 1 The specific steps are as follows:

[0033] Step one involves analyzing the structural characteristics and interface dimensional properties of seashells to establish a microscale heterogeneous biomimetic structural model. Inspired by the microscale "brick-and-mortar" structural features of seashells, and combining the structural characteristics of the application object, a seashell-like microstructure with spatially overlapping "soft" and "hard" zones is designed.

[0034] Step two: Based on the working conditions and the characteristics of the materials used, optimize the feature structure. First, determine the range of differences in micro-area hardness performance under the different effects of continuous laser and ultrafast laser. A test block is formed using a process of continuous laser melting powder / ultrafast laser selective interlayer carving. The hardness difference between the continuous laser-treated area and the ultrafast laser-carved area in the same layer is measured by microhardness testing. The test performance of the above "soft" and "hard" areas is used as model input, and high-performance calculations of the load-bearing capacity of the microscale biomimetic toughened structure under different structural features are performed using finite element simulation. Figure 2 This allows for the acquisition of optimized "soft" and "hard" zone sizes and distribution characteristics, resulting in a microscale biomimetic toughening structure with optimized shell-like features.

[0035] Step 3: Slice the optimized biomimetic structure into layers and obtain 3D printing information. Using dedicated 3D printing software, slice the optimized microscale biomimetic toughened structure obtained in Step 2 to obtain raw data suitable for metal 3D printers. This data should include the continuous laser scanning area, contour and laser power, laser scanning speed, scanning interval, and laser vector arrangement; it should also include the region, contour, laser power, laser frequency, and laser scanning method of the nanosecond pulsed laser interlayer toughening micro-region.

[0036] Step four, the composite additive manufacturing process of continuous laser and nanosecond pulsed laser. Specifically, it includes the following features: Based on the slicing information, a powder-laying arm uniformly lays a single layer of metal powder on the forming substrate. Under the control of a computer and a high-speed galvanometer, a high-energy continuous laser beam selectively scans the original powder according to the slicing information. At this point, the continuous laser scanning area corresponds to the "hard" matrix in the shell structure. Further, after the continuous laser completes the single-layer scanning, the nanosecond pulsed laser selectively melts the solidified area acted upon by the continuous laser, forming a two-dimensional overlapping distribution of pulsed laser interlayer toughening micro-regions. Figure 3 At this point, the interlayer action area of ​​the pulsed laser corresponds to the "soft" region in the shell structure. The above powder-spreading and printing process is repeated until the processing is complete, resulting in a microscale biomimetic toughened metal component.

[0037] Example 1

[0038] The specific implementation steps of the microscale biomimetic toughened structure additive manufacturing method based on seashell features in this embodiment are as follows:

[0039] (1) Based on the spatial overlapping structure of the soft and hard zones of seashells, a structure is constructed as follows: Figure 2 The microscale biomimetic toughening structure shown has a dark area corresponding to the "soft" area of ​​nanosecond pulsed laser interlayer toughening, while the light area corresponds to the "hard" area of ​​continuous laser melting of powder.

[0040] (2) Determine the range of differences in micro-area hardness performance under the different effects of continuous laser and nanosecond pulsed laser. High-performance aluminum alloy material was selected as the original powder. The main elemental contents of the powder included: Mg: 5wt.%, Si: 0.5wt.%, Zr: 0.2wt.%, Sc: 0.4wt.%, with the balance being Al. The spherical metal powder particle size was 15-53μm. Metal specimens were formed using a combination of continuous laser and nanosecond pulsed laser. The continuous laser parameters were 400W, scanning speed 1000mm / s, scanning interval 60μm, and laser spot diameter 70μm; the pulsed laser parameters were a pulse wavelength of 1064nm, power of 75W, scanning speed of 175mm / s, and laser frequency of 25Hz.

[0041] Before laser additive manufacturing in step (2), the high-performance aluminum alloy powder is placed in a vacuum drying oven and dried at 120°C for 6 hours.

[0042] In step (2) of the laser additive manufacturing process, a powder-laying arm first evenly lays a single layer of powder on the substrate, with a powder layer thickness of 30 μm. Then, a continuous laser melts the original metal powder in a square area of ​​the test block, and further, a nanosecond pulsed laser locally melts the solidified area between the layers. The above process is repeated until the metal test block is formed.

[0043] After forming, the cross-section of the formed specimen was subjected to a standard metallographic treatment process, including diamond sandpaper grinding and silica polishing paste polishing, to obtain a smooth and clean formed cross-section. The hardness of the continuous laser-treated area and the nanosecond pulsed laser-treated interlayer area of ​​the cross-section was measured using a microhardness tester. The average hardness of the continuous laser-treated area was measured to be 170±3HV, while the hardness of the nanosecond pulsed laser-treated area was 140±5HV.

[0044] Using the performance values ​​obtained above as input, a high-performance calculation and structural optimization process for the load-bearing capacity of microscale biomimetic toughened structures under different structural features is carried out through finite element simulation. Figure 2 By analyzing the stress concentration and bearing capacity of microscale toughened structures under external force constraints with different structural features, an optimized biomimetic microscale toughened configuration was obtained. In this case, the optimized structural features are d = 180 μm, m = 150 μm, l = 50 μm, n = 50 μm, and s = 50 μm.

[0045] (3) The optimized biomimetic structure obtained in step (2) is sliced ​​into layers, and 3D printing information is obtained. At this time, the laser parameters are set in the same way as in the process experiment in step (2), that is, the continuous laser parameters are 400W, scanning speed is 1000mm / s, scanning spacing is 60μm, and laser spot diameter is 70μm; the pulsed laser parameters are pulse wavelength is 1064nm, power is 75W, scanning speed is 175mm / s, and laser frequency is 25Hz. The layer thickness is 30m.

[0046] (4) Continuous laser / nanosecond pulsed laser composite additive manufacturing process. Using the process parameters specified in step (3), based on the microscale biomimetic toughening configuration and its layered slicing information obtained from step (2), the original powder is high-performance aluminum alloy spherical metal powder consistent with that in step (2), and the composite laser additive manufacturing process is carried out.

[0047] Specifically, in the composite laser additive manufacturing process, the powder-laying arm first uniformly lays a single layer of metal powder with a thickness of 30 μm on the forming substrate; then, a continuous laser selectively melts and solidifies the original metal powder based on the slice information; subsequently, a nanosecond pulsed laser selectively toughens the solidified solid area based on the size characteristics and boundaries of the "softened" region in the microscale biomimetic toughened structure. This process is repeated until the microscale biomimetic toughened metal component is successfully formed. The surface morphology of the formed specimen is as follows: Figure 4 As shown. After molding, the specimen was separated from the substrate by wire cutting, and the room temperature tensile properties of the molded specimen were tested according to standards.

[0048] Comparative Example 1

[0049] As a comparative reference, Comparative Example 1 differs from Example 1 in that it does not introduce biomimetic toughening technology and does not adopt the continuous laser / nanosecond pulse laser composite additive manufacturing process, that is, it uses the traditional additive manufacturing method to form the specimen.

[0050] Specifically, steps (1) and (2) in Example 1 are omitted, and high-performance aluminum alloy specimens are directly formed using continuous laser forming. The aluminum alloy composition remains consistent with that in Example 1, namely Mg: 5 wt.%, Si: 0.5 wt.%, Zr: 0.2 wt.%, Sc: 0.4 wt.%, with the balance being Al. The spherical metal powder has a particle size of 15-53 μm. Before laser additive manufacturing, the high-performance aluminum alloy powder is placed in a vacuum drying oven and dried at 120°C for 6 hours.

[0051] The continuous laser parameters are the same as in Example 1, namely, 400W, scanning speed 1000mm / s, scanning spacing 60μm, laser spot diameter 70μm, and layer thickness 30μm.

[0052] After molding, the specimen was separated from the substrate by wire cutting, and the room temperature tensile properties of the molded specimen were tested according to the standard.

[0053] Comparative Example 2

[0054] As a comparative reference, Comparative Example 2 differs from Example 1 in that it introduces a biomimetic toughening technique, but uses the same continuous laser / nanosecond pulsed laser composite additive manufacturing process. That is, when toughening the interlayer nanosecond pulsed laser, a biomimetic strategy is not adopted, but rather the whole layer is toughened.

[0055] Specifically, steps (1) and (2) in Example 1 are omitted, and high-performance aluminum alloy specimens are formed directly using the continuous laser / nanosecond pulse laser composite additive manufacturing process.

[0056] The aluminum alloy composition remained consistent with that in Example 1, namely Mg: 5 wt.%, Si: 0.5 wt.%, Zr: 0.2 wt.%, Sc: 0.4 wt.%, with the balance being Al. The spherical metal powder had a particle size of 15-53 μm. Before laser additive manufacturing, the high-performance aluminum alloy powder was placed in a vacuum drying oven and dried at 120°C for 6 hours. The laser parameters were consistent with those in Example 1.

[0057] During the forming process, the powder-laying arm first uniformly lays a single layer of metal powder with a thickness of 30 μm on the forming substrate. Then, a continuous laser selectively melts and solidifies the original metal powder based on the slice information, followed by nanosecond pulsed laser to completely toughen the solidified solid area between layers. This process is repeated until the microscale biomimetic toughened metal component is successfully formed.

[0058] After molding, the specimen was separated from the substrate by wire cutting, and the room temperature tensile properties of the molded specimen were tested according to the standard.

[0059] The room temperature tensile mechanical properties of Example 1, Comparative Example 1 and Comparative Example 2, which employ the method of the present invention, are compared and the results are shown in Table 1.

[0060] Table 1

[0061] Yield strength (MPa) Tensile strength (MPa) Elongation at break (%) Example 1 442.5 483.4 13.1 Comparative Example 1 415.7 443.8 12.5 Comparative Example 2 380.6 408.7 14.5

[0062] A comparison reveals that the microscale biomimetic toughening structure design and additive manufacturing method with shell-like features proposed in this invention, compared to the traditional laser additive manufacturing process, can construct a microscale structure with biomimetic toughening effect inside the formed specimen, achieving a synergistic improvement in strength and toughness. This is mainly attributed to the excellent crack deflection effect of the spatially overlapping "soft" and "hard" structures with biomimetic distribution characteristics, which significantly improves the strength and toughness of the additively manufactured component during service load-bearing.

[0063] This invention provides a concept and method for additive manufacturing of microscale biomimetic toughened structures with shell-like features. Many methods and approaches exist for implementing this technical solution; the above description is merely a preferred embodiment of the invention. It should be noted that those skilled in the art can make various improvements and modifications without departing from the principles of this invention, and these improvements and modifications should also be considered within the scope of protection of this invention. All components not explicitly stated in this embodiment can be implemented using existing technologies.

Claims

1. A method for additive manufacturing of microscale biomimetic toughened structures with shell-like features, characterized in that, Includes the following steps: (1) Based on the characteristics of the shell structure and the interface size characteristics, a microscale heterogeneous biomimetic model was established to determine the shell-like microstructure of soft and hard regions with spatial overlapping characteristics. (2) Based on the working conditions and the characteristics of the forming material, test blocks were formed by continuous laser melting powder and ultrafast laser interlayer micro-area carving process. The hardness difference between the continuous laser action area and the ultrafast laser interlayer micro-area carving area of ​​the same layer was measured, and the corresponding continuous laser and ultrafast laser process parameters under the condition of this difference were determined. (3) Using the micro-area hardness difference obtained in step (2) as input, and combining the structural characteristics of the shell, we carried out biomimetic toughening structure optimization and determined the geometric characteristic parameters of the micro-scale biomimetic toughening structure. (4) Perform layered slicing on the optimized microscale biomimetic toughened structure obtained in step (3) to obtain slicing information for laser additive manufacturing; (5) Based on the results of layered slicing, a continuous laser melting powder and ultrafast laser interlayer micro-area carving process is adopted to realize the laser additive manufacturing of metal components with microscale biomimetic toughening structure; In step (5), the ultrafast laser is a nanosecond pulsed laser with a pulse wavelength of 1064 nm, a power of 30-100 W, a scanning speed of 100-250 mm / s, and a laser frequency of 10-50 Hz. In step (2), the forming material is a material with precipitation strengthening properties, including any one of Al-Cu alloy, Al-Mg, Al-Zn alloy and nickel-based high-temperature alloy; The microscale biomimetic toughening structure, mimicking shell features, includes two types of regions: a "brick" hard region and a "mud" soft region, with variations in size, spacing, and arrangement period; among them, the length of the "brick" hard region... d ,high m Same layer spacing l Spacing in different height directions of different layers n and the staggered distance between brick layers s 60μm≤ d ≤200μm, 30μm≤ m ≤200μm, 10μm≤ l ≤50μm, 20μm≤ n ≤50μm, 5μm≤s≤50μm; In step (5), the powder spreading arm evenly spreads a single layer of metal powder on the forming substrate. Under the control of a computer and a high-speed galvanometer, the continuous laser beam selectively scans the metal powder according to the slice information. At this time, the continuous laser scanning area corresponds to the hard area in the microscale biomimetic toughening structure. After the continuous laser completes the single-layer scan, the nanosecond pulsed laser selectively melts the solidified area affected by the continuous laser according to the slice information, forming a two-dimensional overlapping distribution of pulsed laser interlayer toughening micro-regions. At this time, the pulsed laser interlayer action area corresponds to the soft area in the microscale biomimetic toughening structure. The above process of powder laying-continuous laser melting of powder-ultrafast laser interlayer micro-region sculpting of biomimetic soft area is repeated until the metal part with microscale biomimetic toughening structure is formed.

2. The additive manufacturing method for microscale biomimetic toughened structures with shell-like features according to claim 1, characterized in that, In step (2), the range of differences in micro-area hardness performance under the action of continuous laser and ultrafast laser is determined. The test block is formed by the process of continuous laser melting powder and ultrafast laser interlayer micro-area carving. The hardness difference between the continuous laser action area and the ultrafast laser interlayer micro-area carving area of ​​the same layer is measured by a microhardness tester.

3. The additive manufacturing method for microscale biomimetic toughened structures with shell-like features according to claim 1, characterized in that, In step (2), the hardness difference is greater than 20%, and the corresponding continuous laser and ultrafast laser process parameters under this difference condition are determined.

4. The additive manufacturing method for microscale biomimetic toughened structures with shell-like features according to claim 1, characterized in that, In step (3), the geometric feature parameters of the shell-like microstructure are optimized based on finite element simulation software.

5. The additive manufacturing method for microscale biomimetic toughened structures with shell-like features according to claim 1, characterized in that, In step (4), the slice information includes the continuous laser action area, path and laser parameters, and the ultrafast laser interlayer action area, path and laser parameters.

6. The additive manufacturing method for microscale biomimetic toughened structures with shell-like features according to claim 1, characterized in that, In step (5), the continuous laser parameters are: power of 100-400W, laser scanning speed of 500-2000 mm / s, and layer thickness of 30-50 μm.

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