CN115430844A - Laser selective melting forming method for variable-layer-thickness metal part - Google Patents

Laser selective melting forming method for variable-layer-thickness metal part Download PDF

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CN115430844A
CN115430844A CN202211398525.6A CN202211398525A CN115430844A CN 115430844 A CN115430844 A CN 115430844A CN 202211398525 A CN202211398525 A CN 202211398525A CN 115430844 A CN115430844 A CN 115430844A
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printing
forming
thickness
layer
variable
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CN115430844B (en
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杜东方
肖峰
吴代建
李忠利
韩俊峰
胡雅清
杨茗潇
江毅
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Sichuan Engineering Technical College
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Sichuan Engineering Technical College
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    • BPERFORMING OPERATIONS; TRANSPORTING
    • B22CASTING; POWDER METALLURGY
    • B22FWORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
    • B22F10/00Additive manufacturing of workpieces or articles from metallic powder
    • B22F10/20Direct sintering or melting
    • B22F10/28Powder bed fusion, e.g. selective laser melting [SLM] or electron beam melting [EBM]
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B22CASTING; POWDER METALLURGY
    • B22FWORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
    • B22F1/00Metallic powder; Treatment of metallic powder, e.g. to facilitate working or to improve properties
    • B22F1/09Mixtures of metallic powders
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B22CASTING; POWDER METALLURGY
    • B22FWORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
    • B22F10/00Additive manufacturing of workpieces or articles from metallic powder
    • B22F10/80Data acquisition or data processing
    • B22F10/85Data acquisition or data processing for controlling or regulating additive manufacturing processes
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B33ADDITIVE MANUFACTURING TECHNOLOGY
    • B33YADDITIVE MANUFACTURING, i.e. MANUFACTURING OF THREE-DIMENSIONAL [3-D] OBJECTS BY ADDITIVE DEPOSITION, ADDITIVE AGGLOMERATION OR ADDITIVE LAYERING, e.g. BY 3-D PRINTING, STEREOLITHOGRAPHY OR SELECTIVE LASER SINTERING
    • B33Y10/00Processes of additive manufacturing
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B33ADDITIVE MANUFACTURING TECHNOLOGY
    • B33YADDITIVE MANUFACTURING, i.e. MANUFACTURING OF THREE-DIMENSIONAL [3-D] OBJECTS BY ADDITIVE DEPOSITION, ADDITIVE AGGLOMERATION OR ADDITIVE LAYERING, e.g. BY 3-D PRINTING, STEREOLITHOGRAPHY OR SELECTIVE LASER SINTERING
    • B33Y50/00Data acquisition or data processing for additive manufacturing
    • B33Y50/02Data acquisition or data processing for additive manufacturing for controlling or regulating additive manufacturing processes
    • CCHEMISTRY; METALLURGY
    • C22METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22CALLOYS
    • C22C19/00Alloys based on nickel or cobalt
    • C22C19/03Alloys based on nickel or cobalt based on nickel
    • C22C19/05Alloys based on nickel or cobalt based on nickel with chromium
    • C22C19/051Alloys based on nickel or cobalt based on nickel with chromium and Mo or W
    • C22C19/055Alloys based on nickel or cobalt based on nickel with chromium and Mo or W with the maximum Cr content being at least 20% but less than 30%
    • YGENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02PCLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P10/00Technologies related to metal processing
    • Y02P10/25Process efficiency

Abstract

The application discloses a selective laser melting and forming method for a variable-layer-thickness metal part, which comprises the following steps of: preparing alloy metal powder; importing the target printing model into slicing software, and setting slicing parameters; obtaining a slice printing file based on the slice parameters; guiding the first printed file into selective laser melting forming equipment, printing from a first initial forming layer number, pausing printing after printing to a first target thickness, and obtaining a second initial forming layer number based on the first forming layer number and a first forming height; guiding a second printing file into selective laser melting equipment, starting printing from a second initial forming layer number, pausing printing after printing to a second target thickness, and obtaining a third initial forming layer number based on the second forming layer number and a second forming height; and importing the third printing file into selective laser melting equipment, starting printing from a third initial forming layer number, and ending printing after printing to a third target thickness to obtain the thick metal part.

Description

Selective laser melting forming method for variable-layer-thickness metal part
Technical Field
The application relates to the field of metal powder manufacturing, in particular to a selective laser melting forming method for a variable-layer-thickness metal part.
Background
The selective laser melting technology is a technology for manufacturing parts by means of slicing and layering three-dimensional digifax of parts through special software, selectively melting metal powder layer by layer according to outline data by using high-energy laser beams after the outline data of each section is obtained, and performing melting solidification and accumulation layer by layer through powder spreading layer by layer.
The existing selective laser melting technology mainly aims at printing the same layer thickness of the same part and cannot aim at printing metal parts with variable layer thickness.
Disclosure of Invention
The application mainly aims to provide a variable-layer-thickness metal part laser selective melting forming method, and aims to solve the technical problem that the existing laser selective melting technology cannot print the variable-layer-thickness metal part.
In order to solve the technical problem, the application provides: a laser selective melting forming method for a variable-layer-thickness metal part comprises the following steps:
preparing alloy metal powder; wherein the alloy metal powder is used as printing powder;
importing the target printing model into slicing software, and setting slicing parameters; obtaining a slice printing file based on the slice parameters; wherein the slicing parameters include a slicing layer thickness and a printing parameter; the slicing layer thickness comprises a first slicing layer thickness, a second slicing layer thickness and a third slicing layer thickness, the printing parameters comprise a first printing parameter, a second printing parameter and a third printing parameter, and the slicing printing files comprise a first printing file, a second printing file and a third printing file;
guiding the first printed file into selective laser melting forming equipment, printing from a first initial forming layer number, and suspending printing after printing to a first target thickness to obtain a first forming layer number and a first forming height; obtaining a second starting number of forming layers based on the first number of forming layers and the first forming height; wherein the number of the first initial forming layers is 1;
guiding the second printing file into selective laser melting equipment, starting printing from the second initial forming layer number, and pausing printing after printing to a second target thickness to obtain a second forming layer number and a second forming height; obtaining a third starting forming layer number based on the second forming layer number and the second forming height;
and guiding the third printing file into selective laser melting equipment, starting printing from the third initial forming layer number, and ending printing after printing to a third target thickness to obtain the variable-thickness metal part.
As some optional embodiments of the present application, the preparing the alloy metal powder includes:
preparing a first alloy metal powder by a vacuum gas atomization method; wherein the first alloy metal powder comprises: 20 to 24 weight percent of chromium, 8 to 9 weight percent of molybdenum, 3.5 to 4.5 weight percent of niobium, 5 to 6 weight percent of iron, 0.2 to 0.3 weight percent of aluminum, 0.4 to 0.5 weight percent of titanium, and the balance of nickel;
and carrying out vacuum drying treatment on the first alloy metal powder to obtain second alloy metal powder.
As some optional embodiments of the present application, the alloy metal powder is in a regular spherical or near spherical shape, has a particle size of 10 μm to 53 μm, and has an oxygen content of < 300ppm.
As some optional embodiments of the present application, the vacuum drying process parameters include: the drying temperature is 100 ℃, the drying time is 4-6 h, and the vacuum pressure is-6.0 MPa.
As some optional embodiments of the present application, the slice layer has a thickness of 20 μm to 60 μm;
the printing parameters comprise that the scanning deflection increment of each layer is 60-66 degrees, the diameter of a light spot is 60-100 mu m, the laser power of a scanning entity is 150-380W, the scanning speed is 800-1000 mm/s, and the scanning interval is 0.08-0.12 mm.
As some optional embodiments of the present application, during the printing, the substrate heating temperature is 100 ℃, the argon gas purity of the protective gas is 99.999%, the oxygen content in the chamber is less than 400ppm, and the pressure in the chamber is 0mbar to 25mbar.
As some optional embodiments of the present application, the second starting number of forming layers is obtained by the following relation:
Q 2 =1+(N 11 )/δ 2
wherein Q is 2 For the second initial number of forming layers, N 1 For the first number of printing layers, δ 1 Is the first slice layer thickness, δ 2 Is a second slice layer thick.
As some optional embodiments of the present application, the third starting number of forming layers is obtained by the following relation:
Q 3 =1+(N 22 )/δ 3
wherein Q 3 For the third initial number of forming layers, N 2 For the second number of printing layers, δ 2 Is the second slice layer thickness, δ 3 Is the third slice layer thickness.
As some optional embodiments of the present application, the importing the third print file into a selective laser melting device, starting printing from the third starting forming layer number, and ending the printing after printing to a third target thickness to obtain a variable-thickness metal part includes:
guiding the third printing file into selective laser melting equipment, starting printing from the third initial forming layer number, and ending printing after printing to a third target thickness to obtain a first printed piece;
and taking out the first printed part, and sequentially carrying out powder cleaning treatment, solid solution treatment and machining treatment to obtain the variable-thickness metal part.
As some optional embodiments of the present application, the solution treatment comprises: placing the print piece after the powder cleaning treatment in a vacuum degree of 1 × 10 -3 Pa~1×10 -4 Heating to 1100 +/-10 ℃ in a Pa vacuum furnace, and keeping the temperature for 1h to 2h; and after the heat preservation is finished, carrying out gas quenching, and taking out after the temperature is reduced to 300 ℃.
Compared with the prior art, the laser melting printing method for the variable-layer-thickness metal part can realize laser melting printing of the variable-layer-thickness metal part, so that the grain size grade of the surface of the obtained metal part can reach 8 grades, the surface roughness value can reach Ra3.2 mu m, the tensile strength at room temperature is not lower than 860MPa, the yield strength is not lower than 351MPa, and the elongation is not lower than 42%; therefore, the strength and the quality of the variable-layer-thickness metal part obtained by the method can meet the application requirements. The existing selective laser melting forming technology at present mainly comprises the steps of slicing a part in an equal layer thickness manner, namely, printing the part by using one layer thickness after the part is sliced; for some complex parts with larger forming sections, in order to consider the surface quality of some fine structures, on the premise of slicing at equal layer thickness, only small layer thickness can be adopted for printing, so that the time consumption of actual part printing is too long, the efficiency is low, and the printing cost and the printing period of the parts are increased; the method can be used for printing the parts with variable thicknesses, so that the forming efficiency of the parts is improved.
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Fig. 1 is a schematic flow chart of a method according to an embodiment of the present application.
Detailed Description
It should be understood that the specific embodiments described herein are merely illustrative of the present application and are not intended to limit the present application.
Selective Laser Melting (SLM) is a technique for manufacturing parts by additive manufacturing by using a high energy density laser as a heat source and by spreading powder layer by layer and laser heating and melting layer by layer. The method integrates computer aided design, laser selective cladding and rapid forming, can rapidly prepare parts with different materials and complex shapes, multiple varieties and small batches without any hard tool or model, has high density of the formed parts, has rapid solidification structure characteristics, can meet the direct use requirement, and has wide application prospect in the preparation of aerospace devices, aircraft engine parts and weapon parts. And parts with different parts composed of different materials can be obtained by changing the molding materials, and the intelligent preparation system of the materials can be developed by combining the parts with a computer. The exploration of the rapid forming technology for directly preparing the metal parts meeting the engineering use conditions is beneficial to the conversion from the rapid forming technology to the rapid manufacturing technology, and the application field of the rapid forming technology can be greatly expanded. In addition, by utilizing the advantage of layer-by-layer manufacturing, the exploration and manufacturing of parts with functional gradient, excellent comprehensive performance and special complex structures are also a new development direction. The combination of rapid prototyping technology and conventional manufacturing technology is also an important trend to form rapid product development-manufacturing systems.
However, the current selective laser melting technology mainly performs printing on the same layer thickness of the same part, and cannot perform printing on metal parts with variable layer thicknesses. With the continuous development of the SLM forming technology, the requirements on the forming technology and the forming efficiency of large-scale complex-structure parts by using the technology are more and more urgent, the existing SLM technology mainly divides the parts by equal layer thickness, namely, one layer thickness is used for printing after the parts are divided; for some complex parts with large forming sections, in order to take surface quality of some fine structures into consideration, on the premise of equal-layer thickness subdivision, only a small layer thickness can be adopted for printing, so that the time consumption for actual part printing is too long, the efficiency is low, the printing cost and the printing period of the parts are further increased, and the improvement of the competitiveness of SLM technology for printing the parts is not facilitated. Therefore, it is important to develop a forming method capable of forming a part having a variable thickness for a large complicated structure part.
Based on the above technical problem, as shown in fig. 1, an embodiment of the present application provides a selective laser melting and forming method for a variable-thickness metal part, including the following steps:
s10, preparing alloy metal powder; wherein the alloy metal powder is used as printing powder.
In a specific application, the preparing of the alloy metal powder in the step S10 includes:
s11, preparing first alloy metal powder by a vacuum gas atomization method; wherein the first alloy metal powder comprises: 20 to 24 weight percent of chromium, 8 to 9 weight percent of molybdenum, 3.5 to 4.5 weight percent of niobium, 5 to 6 weight percent of iron, 0.2 to 0.3 weight percent of aluminum, 0.4 to 0.5 weight percent of titanium and the balance of nickel;
and S12, carrying out vacuum drying treatment on the first alloy metal powder to obtain second alloy metal powder.
In a specific application, the vacuum atomization method is that high-speed gas flow is utilized to act on molten liquid flow, so that kinetic energy of the gas is converted into surface energy of the molten liquid, and then fine liquid drops are formed and solidified into powder particles. In the specific application, the alloy metal powder is regular spherical or approximately spherical, the particle size of the alloy metal powder is 10-53 mu m, and the oxygen content is less than 300ppm. In a specific application, the vacuum drying treatment parameters comprise: the drying temperature is 100 ℃, the drying time is 4-6 h, and the vacuum pressure is-6.0 MPa. The alloy metal powder obtained by the method is used as printing powder to carry out subsequent step operation.
S20, importing the target printing model into slicing software, and setting slicing parameters; obtaining a slice printing file based on the slice parameters; wherein the slicing parameters include a slicing layer thickness and a printing parameter; the slice layer thickness comprises a first slice layer thickness, a second slice layer thickness and a third slice layer thickness, the printing parameters comprise a first printing parameter, a second printing parameter and a third printing parameter, and the slice printing files comprise a first printing file, a second printing file and a third printing file.
In the specific application, the SLM technology firstly designs a three-dimensional solid model of a part on a computer, then slices and layers the three-dimensional model through special software to obtain profile data of each section, and guides the data into a rapid prototyping device, and the device controls a laser beam to selectively melt metal powder materials of each layer according to the profile data to gradually stack the metal powder materials into a three-dimensional metal part. Therefore, in the embodiment of the present application, since the target metal part is a part with a variable layer thickness, the layer thickness values of the first slicing layer thickness and the second slicing layer thickness in step S20 are different, the corresponding first print parameter and the corresponding second print parameter are also different, and the corresponding first print file, second print file, and third print file are also different; and the first slice layer thickness corresponds to a first printing parameter and a first print file, the second slice layer thickness corresponds to a second printing parameter and a second print file, and the third slice layer thickness corresponds to a third printing parameter and a third print file. It should be noted that the method described in the embodiment of the present application is not limited to metal parts with two layer thicknesses, and the above-mentioned "first", "second" and "third" are only for illustration and do not limit the kinds of layer thicknesses at all. In specific application, the thickness of the slicing layer is 20-60 μm; the printing parameters comprise that the scanning deflection increment of each layer is 60-66 degrees, the diameter of a light spot is 60-100 mu m, the laser power of a scanning entity is 150-380W, the scanning speed is 800-1000 mm/s, and the scanning interval is 0.08-0.12 mm.
S30, guiding the first printed file into selective laser melting forming equipment, printing from a first initial forming layer number, and pausing printing after printing to a first target thickness to obtain a first forming layer number and a first forming height; obtaining a second starting number of forming layers based on the first number of forming layers and the first forming height; wherein the first initial forming layer number is 1.
In a specific application, during the printing in step S30 and step S40, the substrate heating temperature is 100 ℃, the purity of the protective gas argon is 99.999%, the oxygen content in the chamber is less than 400ppm, and the pressure in the chamber is 0mbar to 25mbar.
In a specific application, the second starting forming layer number is obtained by the following relation:
Q 2 =1+(N 11 )/δ 2
wherein Q is 2 For the second initial number of forming layers, N 1 For the first number of printing layers, δ 1 Is the first slice layer thickness, δ 2 Is a second slice layer thick.
Step S40, guiding the second printing file into selective laser melting equipment, starting printing from the second initial forming layer number, and pausing printing after printing to a second target thickness to obtain a second forming layer number and a second forming height; and obtaining a third starting forming layer number based on the second forming layer number and the second forming height.
In a specific application, the third starting number of forming layers is obtained by the following relation:
Q 3 =1+(N 22 )/δ 3
wherein Q is 3 For the third initial number of forming layers, N 2 For a second number of printing layers, δ 2 Is the second slice layer thickness, delta 3 Is the third slice thickness.
And S50, importing the third printing file into selective laser melting equipment, starting printing from the third initial forming layer number, and ending printing after printing to a third target thickness to obtain a variable-thickness metal part.
In a specific application, the step S50 of importing the third print file into a selective laser melting device, starting printing from the third starting forming layer number, and after printing to a third target thickness, ending printing to obtain a variable-thickness metal part includes:
step S51, importing the third printing file into selective laser melting equipment, starting printing from the third initial forming layer number, and ending printing after printing to a third target thickness to obtain a first printing piece;
and S52, taking out the first printed part, and sequentially performing powder cleaning treatment, solution treatment and machining treatment to obtain the variable-thickness metal part.
In a specific application, the powder cleaning treatment refers to: opening the cavity when the temperature in the cavity is reduced to the room temperatureAnd (4) taking out, cleaning the powder, vibrating the powder, and then blowing air to clean the powder. The solution treatment is as follows: placing the print piece after the powder cleaning treatment in a vacuum degree of 1 × 10 -3 Pa~1×10 -4 Heating to 1100 +/-10 ℃ in a Pa vacuum furnace, and preserving the temperature for 1h to 2h; and after the heat preservation is finished, carrying out gas quenching, and taking out after the temperature is reduced to 300 ℃. The mechanical processing treatment is as follows: and removing the substrate and the support by adopting mechanical processing methods such as linear cutting and the like.
Compared with the prior art, the laser melting printing method for the variable-layer-thickness metal part can realize laser melting printing of the variable-layer-thickness metal part, so that the surface grain size grade of the obtained metal part can reach 8 grades, the surface roughness value can reach Ra3.2 mu m, the room-temperature tensile strength is not lower than 860MPa, the yield strength is not lower than 351MPa, and the elongation is not lower than 42%; therefore, the strength and the quality of the variable-layer-thickness metal part obtained by the method can meet the application requirements. The existing selective laser melting forming technology at present mainly slices the part in equal layer thickness, namely, the part is printed by using one layer thickness after being sliced; for some complex parts with larger forming sections, in order to take surface quality of some fine structures into consideration, only a small layer thickness can be adopted for printing on the premise of slicing in a constant layer thickness, so that the time consumption of actual part printing is too long, the efficiency is low, and the printing cost and the printing period of the parts are increased; the method can be used for printing the part with the variable layer thickness, so that the forming efficiency of the part is improved.
The selective laser melting forming method for the variable-thickness metal part is described in detail with reference to the following specific embodiments:
the first target thickness was 0.9mm, the second target thickness was 8.1mm, and the third target thickness was 1mm as described in examples 1 to 3 below.
Example 1
(1) Preparing regular spherical or approximately spherical metal powder by adopting a vacuum gas atomization method, wherein the metal powder has uniform and consistent granularity, no impurities or caking, the particle size of the powder is 10-53 mu m, and the oxygen content is less than 300ppm; the metal powder consists of the following components: 20-21% of Cr, 8% of molybdenum, 3.5% of niobium, 5% of iron, 0.3% of aluminum, 0.4% of titanium and the balance of nickel, wherein the total mass percentage is 100%; and before the selective laser melting and forming, carrying out vacuum drying on the powder at the drying temperature of 100 ℃ for 4 hours under the vacuum pressure of-6.0 MPa.
(2) And (3) importing a 10mmx10mmx10mm test block model into Magics software, placing the test block model, setting the first slice layer thickness and the third slice layer thickness to be 0.02mm, and setting the corresponding first printing parameter and the corresponding third printing parameter to be: scanning deflection increment is 60 degrees, laser power is 150W, scanning speed is 800mm/s, scanning interval is 0.08mm, and slicing is carried out to form a first printing file and a third printing file with the thickness of 0.02 mm; the second slice layer thickness is set to a layer thickness of 0.06mm, which corresponds to the second printing parameters: scanning deflection increment is 63 degrees, laser power is 380W, scanning speed is 1000mm/s, scanning distance is 0.12mm, and slicing is carried out to form a second printed file with the thickness of 0.06 mm;
(3) Introducing a first printed file into selective laser melting forming equipment, mounting a substrate, a scraper, spreading powder, setting the heating temperature of the substrate to be 100 ℃, starting printing when the oxygen content in a cavity is lower than 400ppm and the pressure in the cavity is 0-25 mbar, and printing when the height is 0.9mm, namely N 1 =0.9/δ 1 When the layer number is =45, the printing is paused by clicking, and the current forming layer number 45 and the forming height are recorded;
(4) Import the second print file, set Slave Q 2 =1+(δ 1 *N 1 )/δ 2 Printing is started for the layer of =1+0.02 + 45/0.06=16, and the printing is performed until the height reaches 0.9+8.1=9mm, namely N + 2 =9/δ 2 =150, click pause printing, import third print file, set slave Q 3 =1+(δ 2 *N 2 )/δ 3 And (3) printing is started by =1+0.06 + 150/0.02=451 layers until printing is finished, so that the bottom part obtains 0.9mm, the upper part obtains a small layer thickness of 1mm, and the middle part obtains a large layer thickness of 8.1mm, thereby realizing variable-layer-thickness printing and considering unification of printing efficiency and printing quality.
(5) After printing is finished, the printing equipment is closed, the cavity door is opened when the temperature in the cavity is reduced to the room temperature, and after the printing equipment is taken out, the powder is cleaned by vibration firstly and then blown by air.
(6) The powder is cleared intoPutting the whole piece in a vacuum furnace, vacuumizing, heating to 1090 deg.C, and vacuum degree of 1 × 10 -3 ~1×10 -4 Pa, keeping the temperature for 1h, performing gas quenching after the heat preservation is finished, and taking out the steel when the temperature is reduced to below 300 ℃; after the solution treatment, the substrate is removed by a machining method such as wire cutting, and the support is removed, thereby obtaining a metal print 1.
The formed piece is subjected to mechanical property test by using the same batch of samples, the test method is GB/T228.1-2010, and the test result is shown in Table 1.
Example 2
(1) Regular spherical or approximately spherical metal powder is prepared by adopting a vacuum gas atomization method, the metal powder has uniform and consistent granularity, no impurities or caking, the powder particle size is 10-53 mu m, the oxygen content is less than 300ppm, and the metal powder consists of the following components: 22-23% of Cr, 9% of molybdenum, 4% of niobium, 6% of iron, 0.2% of aluminum, 0.5% of titanium and the balance of nickel, wherein the total mass percentage is 100%; before selective laser melting and forming, the powder is dried in vacuum at 100 deg.c for 5 hr and under vacuum pressure of-6.0 MPa.
(2) And (3) importing a test block model of 10mmx10mmx10mm into Magics software, placing the test block model, setting the thickness of the first cutting layer to be 0.03mm, and setting the corresponding first printing parameters as follows: scanning deflection increment is 65 degrees, laser power is 220W, scanning speed is 900mm/s, scanning interval is 0.10mm, and slicing is carried out to form a slice file with the thickness of 0.03 mm; the second slice layer thickness is set to a layer thickness of 0.06mm, corresponding to the second printing parameters: scanning deflection increment of 63 degrees, laser power of 380W, scanning speed of 1000mm/s and scanning interval of 0.12mm, and slicing to form a second printed file with the thickness of 0.06 mm; the third slice layer thickness was set to a layer thickness of 0.02mm, corresponding to the third print parameters: scanning deflection increment is 60 degrees, laser power is 150W, scanning speed is 800mm/s, scanning interval is 0.08mm, and slicing is carried out to form a third printed file with the thickness of 0.03 mm;
(3) Introducing a first printed file into selective laser melting forming equipment, mounting a substrate, a scraper, spreading powder, setting the heating temperature of the substrate to be 100 ℃, starting printing when the oxygen content in a cavity is lower than 400ppm and the pressure in the cavity is 0-25 mbar, and printing when the height is 0.9mm, namely N 1 =0.9/δ 1 If the layer number is not more than 30, clicking to pause printing, and recording the current forming layer number 30 and the forming height;
(4) Import second print file, set from Q 2 =1+(δ 1 *N 1 )/δ 2 Printing is started for the layer of =1+0.03 + 30/0.06=16, and the printing is performed until the height reaches 0.9+8.1=9mm, namely N + 2 =9/δ 2 =150, click pause printing, import third print file, set slave Q 3 =1+(δ 2 *N 2 )/δ 3 And the layer of =1+0.06 + 150/0.02=451 is printed until the printing is finished, so that the bottom part obtains 0.9mm, the upper part obtains a small layer thickness of 1mm, and the middle part is a large layer thickness of 8.1mm, the variable-layer-thickness printing is realized, and the unification of the printing efficiency and the printing quality is considered.
(5) After printing is finished, the printing equipment is closed, the cavity door is opened when the temperature in the cavity is reduced to the room temperature, and after the printing equipment is taken out, the powder is cleaned by vibration firstly and then blown by air.
(6) Putting the formed piece into a vacuum furnace, vacuumizing, heating to 1000 deg.C, and vacuum degree of 1 × 10 -3 ~1×10 -4 Pa, keeping the temperature for 1.5h, performing gas quenching after the heat preservation is finished, and taking out the steel when the temperature is reduced to below 300 ℃; after the solution treatment, the substrate is removed by a machining method such as wire cutting, and the support is removed, so that the metal print 2 is obtained.
The formed piece is subjected to mechanical property test by using the same batch of samples, the test method is GB/T228.1-2010, and the test results are shown in Table 1.
Example 3
(1) The metal powder with regular spherical shape or approximate spherical shape is prepared by adopting a vacuum gas atomization method, the granularity of the metal powder is uniform and consistent, no impurities or agglomeration exists, the particle size of the powder is 10-53 mu m, the oxygen content is less than 300ppm, and the metal powder consists of the following components: 24% of Cr, 8% of molybdenum, 4.5% of niobium, 6% of iron, 0.3% of aluminum, 0.5% of titanium and the balance of nickel, wherein the total mass percentage is 100%; and before selective laser melting and forming, carrying out vacuum drying on the powder at the drying temperature of 100 ℃ for 6h and under the vacuum pressure of-6.0 MPa.
(2) And (3) importing a test block model of 10mmx10mmx10mm into Magics software, placing the test block model, setting the thickness of the first cutting film layer to be 0.02mm of the thickness of the first cutting film layer, and setting the corresponding first printing parameters as follows: scanning deflection increment is 60 degrees, laser power is 150W, scanning speed is 800mm/s, scanning interval is 0.08mm, and slicing is carried out to form a first printing file with the thickness of 0.02 mm; the second slice layer thickness is set to a layer thickness of 0.06mm, corresponding to the second printing parameters: scanning deflection increment of 63 degrees, laser power of 380W, scanning speed of 1000mm/s and scanning interval of 0.12mm, and slicing to form a second printed file with the thickness of 0.06 mm; the third slice layer thickness was set to a layer thickness of 0.03mm, corresponding to the third print parameters: scanning deflection increment is 65 degrees, laser power is 220W, scanning speed is 900mm/s, scanning interval is 0.10mm, and slicing is carried out to form a third printing file with the thickness of 0.03 mm; (ii) a
(3) Introducing a first printed file into selective laser melting forming equipment, mounting a substrate, scraping, spreading powder, setting the heating temperature of the substrate to be 100 ℃, starting printing when the oxygen content in a cavity is lower than 400ppm and the pressure in the cavity is 0-25 mbar, and printing to the height of 0.9mm, namely N 1 =0.9/δ 1 If the layer number is 45, clicking to pause printing, and recording the current forming layer number 45 and the forming height;
(4) Import the second print file, set Slave Q 2 =1+(δ 1 *N 1 )/δ 2 Printing is started for the layer of =1+0.02 + 45/0.06=16, and the printing is performed until the height reaches 0.9+8.1=9mm, namely N + 2 =9/δ 2 If =150, the user clicks to pause printing, imports a third print file, and sets slave Q 3 =1+(δ 2 *N 2 )/δ 3 And the layer of =1+0.06 + 150/0.03=301 starts to be printed until the printing is finished, so that the bottom part obtains 0.9mm, the upper part obtains a small layer thickness of 1mm, and the middle part is a large layer thickness of 8.1mm, the variable-layer-thickness printing is realized, and the unification of the printing efficiency and the printing quality is considered.
(5) After printing is finished, the printing equipment is closed, the cavity door is opened when the temperature in the cavity is reduced to the room temperature, and after the printing equipment is taken out, the powder is cleaned by vibration firstly and then blown by air.
(6) Putting the formed piece into a vacuum furnace, vacuumizing, heating to 1010 deg.C, and vacuum degree of 1 × 10 -3 ~1×10 -4 Pa, keeping the temperature for 2h, and then keeping the temperatureGas quenching, taking out after the temperature is reduced to below 300 ℃; after the solution treatment, the substrate is removed by a machining method such as wire cutting, and the support is removed, thereby obtaining a metal print 3.
The formed piece is subjected to mechanical property test by using the same batch of samples, the test method is GB/T228.1-2010, and the test result is shown in Table 1.
Meanwhile, in order to compare the method with the printing time of the part with the unchanged layer thickness, the printing test rod is adopted to perform printing tests on the layer thicknesses of 0.02mm, 0.03mm and 0.06mm respectively, and also perform mechanical property tests, the test method is GB/T228.1-2010, and the test results are shown in Table 1:
table 1:
Figure 2
compared with the prior art, the method can realize laser melting printing of the variable-layer-thickness metal part, so that the surface grain size grade of the obtained metal part can reach 8 grades, the surface roughness value can reach Ra3.2 mu m, the room-temperature tensile strength is not lower than 860MPa, the yield strength is not lower than 351MPa, and the elongation is not lower than 42%; therefore, the strength and the quality of the variable-layer-thickness metal part obtained by the method can meet the application requirements. Compared with the prior art that the printing time is shortened by only printing the same layer thickness, the method of the application improves the printing efficiency.
The above description is only a preferred embodiment of the present application, and not intended to limit the scope of the present application, and all the equivalent structures or equivalent processes that can be directly or indirectly applied to other related technical fields by using the contents of the specification and the drawings of the present application are also included in the scope of the present application.

Claims (10)

1. A selective laser melting forming method for a variable-layer-thickness metal part is characterized by comprising the following steps:
preparing alloy metal powder; wherein the alloy metal powder is used as printing powder;
importing the target printing model into slicing software, and setting slicing parameters; obtaining a slice printing file based on the slice parameters; wherein the slicing parameters include a slicing layer thickness and a printing parameter; the slicing layer thickness comprises a first slicing layer thickness, a second slicing layer thickness and a third slicing layer thickness, the printing parameters comprise a first printing parameter, a second printing parameter and a third printing parameter, and the slicing printing files comprise a first printing file, a second printing file and a third printing file;
guiding the first printed file into selective laser melting forming equipment, printing from a first initial forming layer number, and suspending printing after printing to a first target thickness to obtain a first forming layer number and a first forming height; obtaining a second starting forming layer number based on the first forming layer number and the first forming height; wherein the first initial forming layer number is 1;
guiding the second printing file into selective laser melting equipment, starting printing from the second initial forming layer number, and suspending printing after printing to a second target thickness to obtain a second forming layer number and a second forming height; obtaining a third starting forming layer number based on the second forming layer number and the second forming height;
and guiding the third printing file into selective laser melting equipment, starting printing from the third initial forming layer number, and ending printing after printing to a third target thickness to obtain the variable-thickness metal part.
2. The laser selective melting forming method for thick-variable metal parts as claimed in claim 1, wherein the preparing of the alloy metal powder comprises:
preparing a first alloy metal powder by a vacuum gas atomization method; wherein the first alloy metal powder comprises: 20 to 24 weight percent of chromium, 8 to 9 weight percent of molybdenum, 3.5 to 4.5 weight percent of niobium, 5 to 6 weight percent of iron, 0.2 to 0.3 weight percent of aluminum, 0.4 to 0.5 weight percent of titanium, and the balance of nickel;
and carrying out vacuum drying treatment on the first alloy metal powder to obtain second alloy metal powder.
3. The selective laser melting forming method for thick variable metal parts according to claim 2, wherein the alloy metal powder is regular spherical or approximately spherical, the particle size of the alloy metal powder is 10-53 μm, and the oxygen content is less than 300ppm.
4. The selective laser melting and forming method for thick-variable metal parts as claimed in claim 2, wherein the vacuum drying parameters comprise: the drying temperature is 100 ℃, the drying time is 4-6 h, and the vacuum pressure is-6.0 MPa.
5. The laser selective melting forming method for the thick variable-layer metal part as claimed in claim 1, wherein the thickness of the slicing layer is 20 μm to 60 μm;
the printing parameters comprise that the scanning deflection increment of each layer is 60-66 degrees, the diameter of a light spot is 60-100 mu m, the laser power of a scanning entity is 150-380W, the scanning speed is 800-1000 mm/s, and the scanning interval is 0.08-0.12 mm.
6. The laser selective melting forming method for the thick-variable metal part as claimed in claim 1, wherein during the printing, the substrate heating temperature is 100 ℃, the argon gas purity of the protective gas is 99.999%, the oxygen content in the chamber is lower than 400ppm, and the pressure in the chamber is 0mbar to 25mbar.
7. The laser selective melting forming method for the variable-thickness metal part as claimed in claim 1, wherein the second initial forming layer number is obtained by the following relation:
Q 2 =1+(N 11 )/δ 2
wherein Q is 2 For the second initial number of forming layers, N 1 For the first number of printing layers, δ 1 Is the first slice layer thickness, δ 2 Is a second slice layer thick.
8. The laser selective melting forming method for the thick metal part with the variable thickness as claimed in claim 1, wherein the third initial forming layer number is obtained by the following relational expression:
Q 3 =1+(N 22 )/δ 3
wherein Q 3 For the third initial number of forming layers, N 2 For a second number of printing layers, δ 2 Is the second slice layer thickness, δ 3 Is the third slice layer thickness.
9. The method for selective laser melting forming of a variable-thickness metal part according to claim 1, wherein the step of introducing the third print file into a selective laser melting device, starting printing from the third starting forming layer number, and ending printing after printing to a third target thickness to obtain the variable-thickness metal part comprises:
guiding the third printing file into selective laser melting equipment, starting printing from the third initial forming layer number, and ending printing after printing to a third target thickness to obtain a first printed piece;
and taking out the first printed part, and sequentially performing powder cleaning treatment, solid solution treatment and machining treatment to obtain the thick-variable-layer metal part.
10. The laser selective melt forming method of claim 9, wherein said solution treatment comprises: placing the print piece after the powder cleaning treatment in a vacuum degree of 1 × 10 -3 Pa~1×10 -4 Heating to 1100 +/-10 ℃ in a Pa vacuum furnace, and preserving the temperature for 1h to 2h; and after the heat preservation is finished, carrying out gas quenching, and taking out after the temperature is reduced to 300 ℃.
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