A method for improving the strength and toughness of laser additive manufactured ferritic / martensitic steels

Abstract

The present application relates to a kind of methods for improving the strength and toughness of laser additive manufacturing ferrite / martensite steel, belong to laser additive manufacturing technical field.The present application provides a kind of methods for improving the strength and toughness of laser additive manufacturing ferrite / martensite steel, ferrite / martensite steel powder is dried, printing preparation is made;Three-dimensional modeling model of printing component is sliced according to preset thickness, slice file is analyzed and each layer information is extracted, all slice layers are converted into corresponding model file, laser process parameter is attached to each layer model file;The additional laser process parameter is alternately carried out according to A laser process parameter and B laser process parameter;Laser scanning strategy adopts strip filling mode;Layer by layer printing, and printing component is prepared.The present application constructs heteromorphous organization by regulating and controlling interlayer laser process parameter, cooperatively improves the strength and toughness comprehensive performance of ferrite / martensite steel, further guarantees the service safety of laser additive manufacturing forming fusion reactor component.

Description

Technical Field

[0001] This invention relates to the field of laser additive manufacturing technology, and in particular to a method for improving the strength and toughness of ferritic / martensitic steel manufactured by laser additive manufacturing. Background Technology

[0002] Ferritic / martensitic steel is considered one of the most promising structural materials for fusion reactors due to its excellent geometric stability, low coefficient of radiation swelling, low coefficient of thermal expansion, and high thermal conductivity. However, ferritic / martensitic steel components, such as the first wall, have complex internal flow channel structures, making them difficult to manufacture using traditional processes and significantly impacting the progress and operational safety of fusion reactor projects. Laser additive manufacturing technology, with its high degree of freedom in forming, can achieve integrated forming of complex components and holds promise for solving the research and production challenges of complex ferritic / martensitic steel components.

[0003] Currently, for laser additive manufacturing of ferritic / martensitic steel, improving the mechanical properties of the printed components is the primary task and an important prerequisite for ensuring the safe and reliable operation of fusion reactors.

[0004] Previous researchers optimized the mechanical properties of formed ferritic / martensitic steel samples by changing laser process parameters (such as laser energy density and scanning strategy), but no significant breakthroughs were achieved in their mechanical properties. Summary of the Invention

[0005] To address the aforementioned technical problems, this invention provides a method for improving the strength and toughness of ferritic / martensitic steel manufactured by laser additive manufacturing. This method constructs heterogeneous structures by controlling interlayer laser process parameters, thereby achieving the goal of synergistic improvement in the strength and toughness of ferritic / martensitic steel manufactured by laser additive manufacturing.

[0006] This invention is achieved through the following technical solution:

[0007] The first objective of this invention is to provide a method for improving the strength and toughness of laser additive manufacturing ferritic / martensitic steel, comprising the following steps:

[0008] S1. Dry the ferritic / martensitic steel powder in preparation for printing;

[0009] S2. Model processing and process parameters are as follows:

[0010] The 3D model of the printed component is sliced ​​according to a preset thickness. The sliced ​​files are parsed and the information of each layer is extracted. All sliced ​​layers are converted into corresponding model files. Laser process parameters are added to each model file. The addition of laser process parameters is carried out alternately with laser process parameters A and laser process parameters B.

[0011] S3. The laser scanning strategy adopts a strip filling method, which divides each layer of the printed component into multiple strips of preset width. After the laser scan completes a local strip area, it scans the next local strip area. After each layer is scanned, the laser scanning direction is rotated 67° after the powder is spread again.

[0012] S4. Print layer by layer to prepare the printed component.

[0013] In one embodiment of the present invention, in step S2, the number of consecutive layers of the A laser process parameters is ≥10 layers.

[0014] In one embodiment of the present invention, in step S2, the laser process parameters A are: laser energy density of 60 J / mm². 3 -75J / mm 3 The laser scanning speed is 800mm / s-2000mm / s, and the scanning interval is 0.1mm.

[0015] In one embodiment of the present invention, in step S2, the B laser process parameters are: laser energy density of 180 J / mm². 3 -200J / mm 3 The laser scanning speed is 400mm / s-1000mm / s, and the scanning interval is 0.1mm.

[0016] In one embodiment of the present invention, the B laser process parameters further include remelting parameters.

[0017] In one embodiment of the present invention, the remelting parameters are: laser energy density of 20 J / mm². 3 -40J / mm 3 The laser scanning speed is 1000mm / s-2000mm / s, and the scanning interval is 0.7mm-0.12mm.

[0018] In one embodiment of the present invention, in step S1, the drying conditions are heating at 80°C-120°C for 8-12 hours.

[0019] In one embodiment of the present invention, in step S3, the thickness of the powder coating is 20μm-40μm.

[0020] A second objective of this invention is to provide ferritic / martensitic steel prepared by the method described above.

[0021] A second objective of this invention is to provide the application of the aforementioned ferritic / martensitic steel in the manufacture of fusion reactor structural materials.

[0022] In addition, the method of the present invention can also be applied to improve the strength and toughness of other two-phase structural materials in laser additive manufacturing.

[0023] The technical solution of the present invention has the following advantages compared with the prior art:

[0024] This invention provides a method for improving the strength and toughness of ferritic / martensitic steel manufactured by laser additive manufacturing. Based on the phase transformation principle of ferritic / martensitic steel, the method constructs heterogeneous structures by adjusting the interlayer laser process parameters, thereby synergistically improving the comprehensive strength and toughness of ferritic / martensitic steel and further ensuring the service safety of laser additive manufacturing fusion reactor components. Attached Figure Description

[0025] To make the content of this invention easier to understand, the invention will be further described in detail below with reference to specific embodiments and accompanying drawings, wherein...

[0026] Figure 1 This invention describes the microstructure and mechanical properties of ferritic / martensitic steel manufactured using laser additive manufacturing; where (a)-(c) are the microstructures after A, B and A / B alternating parameters, respectively; and (d) is the tensile stress-strain curve of the printed sample.

[0027] Figure 2 This invention describes the microstructure and mechanical properties of ferritic / martensitic steel manufactured using laser additive manufacturing; (a) shows the microstructure after alternating parameters A / B+C; and (b) shows the tensile stress-strain curve of the printed sample. Detailed Implementation

[0028] The present invention will be further described below with reference to the accompanying drawings and specific embodiments, so that those skilled in the art can better understand and implement the present invention. However, the embodiments described are not intended to limit the present invention.

[0029] Example 1

[0030] This invention provides a method for improving the strength and toughness of laser additive manufacturing ferritic / martensitic steel, specifically including the following steps:

[0031] S1. Place the ferritic / martensitic steel powder obtained by vacuum atomization into a vacuum drying oven, set the heating temperature to 120℃ and the heating time to 8h, and place the powder in the powder supply chamber after drying for printing preparation.

[0032] S2. Slice the 3D model of the printed component into 40μm thick slices, parse the slice files and extract all layer information, convert each layer information into a slice model file, and apply specific laser process parameters to each layer model file according to a certain rule. In this embodiment, parameter A is set as follows: VED = 62.5J / mm 3 The laser scanning speed is 800 mm / s and the B:VED = 194.4 J / mm. 3The laser scanning speed is 600 mm / s; the process parameters are applied alternately according to parameter A (15 layers) and parameter B (5 layers), with a scanning interval of 0.1 mm.

[0033] S3. The laser scanning strategy adopts a strip partitioning filling method, which divides each layer section into multiple strips. The strip width is set to 7mm. After the laser scan completes the local strip area, it scans the next local strip area until the printing of the layer is completed. After the powder is spread again, the laser scanning direction is rotated 67°.

[0034] S4. Print layer by layer according to the above additional parameters to finally form the required printed component.

[0035] Comparative Example 1

[0036] This comparative example provides a method for improving the strength and toughness of ferritic / martensitic steel manufactured by laser additive manufacturing. This method is similar to that in Example 1, except that in step S2, the laser process parameter attached to each layer of the model file is only parameter A: VED = 62.5 J / mm. 3 The laser scanning speed is 800 mm / s.

[0037] Comparative Example 2

[0038] This comparative example provides a method for improving the strength and toughness of ferritic / martensitic steel manufactured by laser additive manufacturing. This method is similar to that of Example 1, except that in step S2, the laser process parameter attached to each layer of the model file is only parameter B: VED = 194.4 J / mm. 3 The laser scanning speed is 600 mm / s.

[0039] A tensile test was performed on the printed part, and the results are as follows: Figure 1 As shown, the tensile strain rate is set to 5 × 10⁻⁶. -4 s -1 The ultimate tensile strength of the component with heterogeneous structure (Example 1) was found to be 1170 MPa, which was 6.8% higher than that of pure parameter B, and the elongation after fracture reached 15%.

[0040] Example 2

[0041] This invention provides a method for improving the strength and toughness of laser additive manufacturing ferritic / martensitic steel, specifically including the following steps:

[0042] S1. Place the ferritic / martensitic steel powder obtained by vacuum atomization into a vacuum drying oven, set the heating temperature to 120℃ and the heating time to 8h, and place the powder in the powder supply chamber after drying for printing preparation.

[0043] S2. Slice the 3D model of the printed component into 40μm thick slices, parse the slice files and extract all layer information, convert each layer information into a slice model file, and apply specific laser process parameters to each layer model file according to a certain rule. In this embodiment, parameter A is set as follows: VED = 62.5J / mm 3 The laser scanning speed is 800 mm / s; B: VED = 194.4 J / mm 3 +C: Remelting parameter VED = 30 J / mm 3 The laser scanning speed for B is 600 mm / s, and the laser scanning speed for C is 1200 mm / s. Process parameters are applied alternately with 15 layers of parameter A and 5 layers of parameters B+C, with a scanning interval of 0.1 mm.

[0044] S3. The laser scanning strategy adopts a strip partitioning filling method, which divides each layer section into multiple strips. The strip width is set to 7mm. After the laser scan completes the local strip area, it scans the next local strip area until the printing of the layer is completed. After the powder is spread again, the laser scanning direction is rotated 67°.

[0045] S4. Print layer by layer according to the above additional parameters to finally form the required printed component.

[0046] Comparative Example 3

[0047] This comparative example provides a method for improving the strength and toughness of ferritic / martensitic steel manufactured by laser additive manufacturing. This method is similar to that in Example 2, except that in step S2, the laser process parameter attached to each layer of the model file is only parameter B: VED = 194.4 J / mm. 3 +C: Remelting parameter VED = 30 J / mm 3 Among them, the laser scanning speed of B is 600 mm / s, and the laser scanning speed of C is 1200 mm / s.

[0048] Tensile tests were conducted on the parts printed in Example 2, Comparative Example 1, and Comparative Example 3, and the results are as follows: Figure 2 As shown, the tensile strain rate is set to 5 × 10⁻⁶. -4 s -1 The ultimate tensile strength of the component with heterogeneous structure was measured to be 1203 MPa, which is 9.8% higher than that of the pure parameter B+C, and the elongation after fracture was 17.5%.

[0049] Obviously, the above embodiments are merely illustrative examples for clear explanation and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here. However, obvious variations or modifications derived therefrom are still within the scope of protection of this invention.

Claims

1. A method for improving the strength and toughness of laser additive manufacturing ferritic / martensitic steel, characterized in that, Includes the following steps: S1. Dry the ferritic / martensitic steel powder in preparation for printing; S2. Model processing and process parameters are as follows: The 3D model of the printed component is sliced ​​according to a preset thickness. The sliced ​​files are parsed and the information of each layer is extracted. All sliced ​​layers are converted into corresponding model files. Laser process parameters are added to each model file. The addition of laser process parameters is carried out alternately with laser process parameters A and laser process parameters B. S3. The laser scanning strategy adopts a strip filling method, which divides each layer of the printed component into multiple strips of preset width. After the laser scan completes a local strip area, it scans the next local strip area. After each layer is scanned, the laser scanning direction is rotated 67° after the powder is spread again. S4. Print layer by layer to prepare the printed components; In step S2, the number of consecutive layers of the A laser process parameters is ≥10 layers; In step S2, the laser process parameters for A are: laser energy density of 60 J / mm². 3 -75J / mm 3 The laser scanning speed is 800mm / s-2000mm / s; In step S2, the B laser process parameters are: laser energy density of 180 J / mm². 3 -200J / mm 3 The laser scanning speed is 400mm / s-1000mm / s; The B-laser process parameters also include remelting parameters; the remelting parameters are: laser energy density of 20 J / mm². 3 -40J / mm 3 The laser scanning speed is 1000mm / s-2000mm / s, and the scanning interval is 0.12mm-0.7mm.

2. The method according to claim 1, characterized in that, In step S1, the drying conditions are heating at 80℃-120℃ for 8-12 hours.

3. The method according to claim 1, characterized in that, In step S3, the thickness of the powder coating is 20μm-40μm.

4. Ferritic / martensitic steel prepared by the method according to any one of claims 1-3.

5. The application of the ferritic / martensitic steel of claim 4 in the manufacture of fusion reactor structural materials.

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