Selective laser melting additive manufacturing process optimization method based on Abaqus thermal field analysis model

Abstract

The invention discloses a selective laser melting additive manufacturing process optimization method based on an Abaqus thermal field analysis model, and the method comprises the steps: determining the shape and size of a molten pool corresponding to different process parameters through selective laser melting single-layer forming, taking the shape and size of the molten pool as reference data of the model, building a'process parameter-molten pool size 'molten pool thermal field model, and using a numerical simulation method to simulate the shape and size of the molten pool; a molten pool temperature field is calculated, a proper temperature field window is found in combination with a density and forming reliability analysis result, and defect formation is predicted and avoided according to temperature field analysis, so that forming process optimization design is scientifically and efficiently carried out, and alloy selective laser melting process optimization is realized. Therefore, the problems of high optimization cost, low efficiency and the like of the current process are solved.

Description

Technical Field

[0001] The present invention relates to the technical field of selective laser process, and in particular to a selective laser melting additive manufacturing process optimization method based on an Abaqus thermal field analysis model. Background Art

[0002] Copper and copper alloys have excellent electrical conductivity, thermal conductivity, wear resistance and corrosion resistance. They are widely used in electronic information, rail transportation, aerospace and other fields, and play an extremely important role in the national economy and scientific and technological progress. With the development of industry, my country's demand for high-performance copper alloy parts continues to rise. In particular, the rapid development of the electronics industry has put forward new requirements and challenges for the performance of copper alloys: in high-intensity and high-stability working scenarios, copper alloys need to have higher strength and plasticity; in the electrical industry and some special heat conduction scenarios, they need to maintain good thermal and electrical conductivity; in the electrical and rail transportation fields, materials need to maintain stable current carrying under conditions of arc erosion, high temperature, high speed and extreme weather, which puts high demands on the hardness, conductivity, current-carrying friction, wear and corrosion resistance of copper alloys.

[0003] Although copper alloys are easy to extrude and cast, they are difficult to weld. It is difficult to prepare copper alloy parts with complex shapes by casting and forging processes. Additive Manufacturing (AM), also known as 3D printing, is a new manufacturing technology that uses digital model data and accumulates materials layer by layer according to certain process principles to achieve rapid manufacturing of parts and components. It has the advantages of flexible design, high production efficiency, and material saving. It can eliminate many manufacturing problems of traditional manufacturing technology, such as complex shapes, small batch products, and high-value products. It is widely used in many fields such as aviation, aerospace, medical, automotive, and machinery.

[0004] Selective laser melting (SLM) is an additive manufacturing technology that uses high-energy lasers as heat sources to stack metal powders layer by layer and melt and solidify them layer by layer to produce dense parts. Compared with other metal part forming methods, SLM technology is characterized by fast forming speed and high material utilization. It does not require molds or other special tools used in traditional processing methods, and can produce parts with complex structures such as cavities and pores.

[0005] At present, the research on the selective laser melting process of metal alloy powders is mostly based on the orthogonal experimental method. For metal powders with low laser absorption rate such as copper alloys, the density of alloy parts manufactured by selective laser melting is mostly below 99%, and the density of very few studies can reach 99.5%. The technical maturity of preparing high-density parts is low, and there is a lack of theoretical analysis of process parameters and defect formation.

[0006] Some process optimization measures proposed in existing studies, such as the use of high-power lasers and short-wavelength lasers, are costly, have low operability, and are not easy to popularize and promote on a large scale. How to establish a quantitative relationship between parameters and dimensions, build a "process parameter-molten pool size" molten pool thermal field model, use numerical simulation methods to predict and optimize the welding temperature field, molten pool formation and solidification, and substrate heat-affected zone during welding, conduct scientific and efficient forming process optimization design, predict and avoid the formation of defects, and obtain high-density forming, are important issues that need to be solved in the current development of copper alloy selective laser melting forming. Summary of the invention

[0007] The purpose of the present invention is to provide a selective laser melting additive manufacturing process optimization method based on the Abaqus thermal field analysis model in order to address the technical defects existing in the prior art.

[0008] The technical solution adopted to achieve the purpose of the present invention is:

[0009] A selective laser melting additive manufacturing process optimization method based on an Abaqus thermal field analysis model comprises the following steps:

[0010] Step 1) preparing pre-alloyed powder of the alloy, and conducting block experiments and single-layer experiments of laser melting in the first parameter range, the block sample is used for density testing and microstructure observation, and the cross section of the single-layer sample is ground, polished, corroded and observed under a light microscope to obtain the molten pool size under different process parameters;

[0011] Step 2) Based on the experimental process parameters and the obtained molten pool size, an Abaqus model is established, the heat source movement route is designed according to the actual experimental parameters, the heat input value is set, and the thermal field analysis of the model is performed;

[0012] Step 3) combining the microstructure and density of the blocks formed by different parameters, analyzing the corresponding model thermal field conditions;

[0013] Step 4) Perform thermal field analysis and microstructure prediction of the alloy selective laser melting forming process within the second parameter range, calculate the thermal field temperature gradient and temperature peak, and obtain the corresponding optimal process parameter combination range.

[0014] In the above technical solution, the alloy described in step 1) is a copper alloy.

[0015] In the above technical solution, the copper alloy is a CuCrZr alloy, and the mass ratio of the components of the pre-alloyed powder of the copper alloy is Cu:Cr:Zr=98-99:0.7-1.4:0.3-0.6.

[0016] In the above technical solution, the pre-alloyed powder of the copper alloy is prepared by rotating electrode atomization.

[0017] In the above technical solution, in step 1), RENISHAW-AM400 selective laser melting rapid prototyping equipment is used to perform selective laser melting.

[0018] In the above technical solution, the first parameter range in step 1) uses three parameter variables, namely laser power, line spacing and exposure time, to experimentally prepare samples, and the value of each variable parameter in the first parameter range is 3 to 5.

[0019] In the above technical solution, the second parameter range in step 4) is 3 to 5 times the number of values ​​of the first parameter range.

[0020] In the above technical solution, the method further includes step 5): performing selective laser melting in the optimized process parameter range, then verifying the forming effect, and using a ZEISS AX10 optical microscope and an ST-100E fully automatic electronic densitometer to perform microstructure observation and density testing.

[0021] Compared with the prior art, the present invention has the following beneficial effects:

[0022] 1. The present invention determines the molten pool morphology and size corresponding to different process parameters through selective laser melting single-layer forming, and uses this as the reference data of the model to build a "process parameter-molten pool size" molten pool thermal field model, and uses a numerical simulation method to calculate the molten pool temperature field. Combined with the density and forming reliability analysis results, the appropriate temperature field window is found, and the formation of defects is predicted and avoided based on the temperature field analysis, so as to scientifically and efficiently optimize the forming process design and realize the optimization of alloy selective laser melting process, thereby solving the current problems of high process optimization cost and low efficiency;

[0023] 2. The present invention optimizes the number of values ​​of variables in the first parameter range and the second parameter range, prepares a single-layer sample within the first parameter range, obtains the morphology and size of the molten pool in a small range of parameters, provides a reference for the model, and can effectively improve the process optimization efficiency and reduce the optimization cost.

[0024] 3. By conducting block forming pre-experiments to prepare specimens within the first parameter range and performing numerical simulations within the second parameter range, the workload and experimental costs of parameter optimization can be effectively reduced. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 is a SEM image of the alloy powder used for selective laser melting in Example 1 of the present invention;

[0026] Figure 2It is the sample forming condition and microstructure morphology during the process optimization in the embodiment of the present invention, where (a) is the manufacturing process condition and (b) is the microstructure after corrosion.

[0027] Figure 3 5×5×5mm 3 Cube model.

[0028] Figure 4 This is a density analysis of the forming effect in the embodiment of the present invention, taking parameter power as an example.

[0029] Figure 5 It is the molten pool morphology and molten pool size of the single-layer forming cross-section in the embodiment of the present invention, where (a) is the molten pool size under the parameter combination of power P=330W, exposure time 120μs line spacing 90μm, and (b) is the molten pool size data statistics of different process parameters. DETAILED DESCRIPTION

[0030] The present invention is further described in detail below in conjunction with specific embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0031] Example 1

[0032] A method for optimizing laser process design for selective area of ​​copper alloy based on Abaqus thermal field analysis model, the method comprising the following steps:

[0033] Step 1) preparing alloy powder by rotating electrode atomization, the alloy powder is CuCrZr alloy powder, wherein the mass ratio of each component is Cu:Cr:Zr=98-99:0.7-1.4:0.3-0.6, and performing zone laser melting single-layer forming on alloy powders with different parameter combinations, collecting the alloy powder in a powder cylinder, installing a substrate and a scraper, turning on the exhaust device, filling with argon protection, ensuring that the oxygen content in the equipment is below 100ppm, and preheating the stainless steel substrate to 170°C, using QuantAM software to complete a 5×5×5mm 3 The cube model is established and the process parameters are set. After the model data is imported into the equipment, the equipment system automatically starts sample manufacturing. The sample is ground, polished and corroded along the cross section of the manufacturing direction. The microscopic morphology and molten pool morphology are observed under an optical microscope. In order to facilitate wire cutting processing and sample preparation observation, the height of the single-layer experimental sample is 2mm, and the optical microscope observation range is the molten pool size of the top single layer;

[0034] Within the first parameter range, three variable parameters of laser power, scanning line spacing and exposure time are selected as orthogonal test factors, and the value of each variable parameter is 3 to 5. In this embodiment, 5 laser powers (P / W: 310, 330, 350, 370, 390), 3 scanning line spacings (h / μm: 50, 70, 90) and 3 exposure times (θ / μs: 120, 150, 200) are included; the alloy powder is subjected to selective laser melting block forming using different parameter combinations to prepare samples, and the forming effect of the samples is analyzed, including density and printing reliability analysis. The printing reliability includes: forming quality, defects and microstructure, which are analyzed using a ZEISS AX10 optical microscope and an ST-100E fully automatic electronic density meter;

[0035] The density analysis method is as follows:

[0036] After wire cutting, the sample is placed in anhydrous ethanol for ultrasonic cleaning to remove impurities adhering to the surface and then dried. The sample is placed on the measuring table of the ST-100E fully automatic electronic density meter for weighing. After the reading is stable, press the key to record the data. Then the sample is placed in the hanging basket in the water tank for weighing. After the reading is stable, press the key to directly obtain the result and record the data to realize density analysis. Each sample is guaranteed to be measured at least 3 times, and the average value is taken to reduce the error.

[0037] Step 2) establishing an Abaqus model according to the experimental process parameters and the molten pool size obtained within the first parameter range, simulating the temperature field under a given heat input during the additive manufacturing process, and obtaining the model temperature field of the cross-section of the model along the manufacturing direction under different parameter combinations within the first parameter range;

[0038] Step 3) analyzing the relationship between the forming effect and the numerical simulation temperature field under the same parameters, wherein the forming effect includes the sample microstructure observed by optical microscopy and the sample density obtained by measurement;

[0039] Step 4) thermal field analysis and microstructure prediction of the copper alloy selective laser melting forming process within the second parameter range are performed, the thermal field temperature gradient and the temperature peak are calculated, the corresponding optimal process parameter combination interval is obtained, the density and printing reliability of laser melting forming within the second parameter range are predicted, and then the optimized process parameter interval is obtained; the value of each variable parameter in the second parameter range is 15 to 25, including 5 laser powers (P / W: 300, 305, 310, 315, 320, 325, 330, 335, 340, 345, 350, 355, 360, 365, 370, 375, 380, 385, 390), 3 scanning line spacings (h / μm: 50, 70, 90) and 9 exposure times (θ / μs: 120, 130, 140, 150, 160, 170, 180, 190, 200).

[0040] Step 5) Select some process parameters in the optimized process parameter range for selective laser melting to verify the forming effect, including optical microscopic observation of the microstructure and sample density testing.

[0041] The above is only a preferred embodiment of the present invention. It should be pointed out that, for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A selective laser melting additive manufacturing process optimization method based on Abaqus thermal field analysis model, characterized in that: The steps include: Step 1) preparing pre-alloyed powder of the alloy, and conducting block experiments and single-layer experiments of laser melting in the first parameter range, the block sample is used for density testing and microstructure observation, and the cross section of the single-layer sample is ground, polished, corroded and observed under a light microscope to obtain the molten pool size under different process parameters; Step 2) Based on the experimental process parameters and the obtained molten pool size, an Abaqus model is established, the heat source movement route is designed according to the actual experimental parameters, the heat input value is set, and the thermal field analysis of the model is performed; Step 3) combining the microstructure and density of the blocks formed by different parameters, analyzing the corresponding model thermal field conditions; Step 4) Perform thermal field analysis and microstructure prediction of the alloy selective laser melting forming process within the second parameter range, calculate the thermal field temperature gradient and temperature peak, and obtain the corresponding optimal process parameter combination range.

2. The selective laser melting additive manufacturing process optimization method based on the Abaqus thermal field analysis model according to claim 1, characterized in that: The alloy in step 1) is a copper alloy.

3. The selective laser melting additive manufacturing process optimization method based on the Abaqus thermal field analysis model according to claim 2, characterized in that: The copper alloy is a CuCrZr alloy, and the mass ratio of each component of the pre-alloyed powder of the copper alloy is Cu:Cr:Zr=98-99:0.7-1.4:0.3-0.

6.

4. The selective laser melting additive manufacturing process optimization method based on the Abaqus thermal field analysis model according to claim 3, characterized in that: The pre-alloyed powder of the copper alloy is prepared by rotary electrode atomization.

5. The selective laser melting additive manufacturing process optimization method based on the Abaqus thermal field analysis model according to claim 1, characterized in that: In step 1), RENISHAW-AM400 selective laser melting rapid prototyping equipment is used for selective laser melting.

6. The selective laser melting additive manufacturing process optimization method based on the Abaqus thermal field analysis model according to claim 1, characterized in that: The first parameter range in step 1) uses three parameter variables, namely, laser power, line spacing, and exposure time, to experimentally prepare samples.

7. The selective laser melting additive manufacturing process optimization method based on the Abaqus thermal field analysis model according to claim 6, characterized in that: The value of each variable parameter in the first parameter range is 3 to 5.

8. The selective laser melting additive manufacturing process optimization method based on the Abaqus thermal field analysis model according to claim 1, characterized in that: In step 4), the second parameter range is 3 to 5 times the number of values ​​of the first parameter range.

9. The selective laser melting additive manufacturing process optimization method based on the Abaqus thermal field analysis model according to claim 1, characterized in that: The method also includes step 5): performing selective laser melting in an optimized process parameter range, and then verifying the forming effect.

10. The selective laser melting additive manufacturing process optimization method based on the Abaqus thermal field analysis model according to claim 9, characterized in that: A ZEISS AX10 optical microscope and an ST-100E fully automatic electron densitometer were used for microstructure observation and density testing.

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