3D printing metal material and modification method thereof

Abstract

The invention provides a 3D printing metal material and a modification method thereof, and relates to the technical field of metal modification. According to the modification method of the 3D printing metal material, metal titanium / titanium alloy for laser 3D printing serves as an initial material, a wrapping material and a packaging layer are sequentially formed to obtain a synthetic block, and then the 3D printing metal titanium with high toughness is obtained through a direct high-pressure treatment process. The ultra-high pressure can inhibit long-range diffusion of atoms, so that coarsening of crystal grains at high temperature is avoided; meanwhile, grain refinement can be generated in the metal titanium / titanium alloy through high pressure, and therefore the strength of the metal titanium / titanium alloy is improved; the defects such as holes and microcracks in the metal component can be repaired through high pressure; more dislocation, twin crystal and other strengthened defect structures can be generated in the metal part at high temperature and high pressure; high-temperature heat treatment under high pressure can eliminate residual stress and distribution of a non-uniform phase, and the ductility is improved.

Description

Technical Field

[0001] The present application relates to the technical field of metal modification, and in particular to a 3D printing metal material and a modification method thereof. Background Art

[0002] Titanium and its alloys are high-performance metal materials with a series of significant advantages, such as light weight and high strength, which make titanium and titanium alloys ideal materials for manufacturing parts that require light weight and high strength; corrosion resistance, excellent corrosion resistance to a variety of corrosive media such as acids, alkalis, and salts, and can be used for a long time in harsh chemical environments without being corroded; good biocompatibility and good plasticity and processability. In short, titanium and titanium alloys are widely used in many fields such as aerospace, chemical equipment, automobile manufacturing, and medical equipment due to their series of significant advantages, and play an increasingly important role in the development of modern industry and science and technology.

[0003] 3D printing technology, also known as additive manufacturing, is a technology that constructs three-dimensional solid objects by stacking materials layer by layer. By digitally controlling the stacking path, it can directly manufacture complex components. Because its free forming ability fully meets the needs of high-end equipment and components for high integration, versatility, lightweight, and integration, it is considered a disruptive technology in the manufacturing field. Compared with traditional manufacturing, 3D printing technology has the advantages of strong complex structure manufacturing capabilities, high material utilization, high design flexibility, and high production efficiency. Due to the excellent performance of metal titanium / titanium alloys and the advanced nature of 3D printing technology, the use of 3D printing to prepare metal titanium components and products is in great demand in the aerospace, military, and biomedical fields.

[0004] However, due to the technical limitations of existing 3D printing itself, metal materials prepared by 3D printing still have shortcomings, which seriously restricts their widespread application as structural load-bearing parts.

[0005] Disadvantages of 3D printing: 1. It is almost impossible to produce samples without micropores at present; 2. The uneven distribution of phases and the strong texture of columnar crystal structure reduce the mechanical properties of the material and also lead to anisotropy; 3. 3D printed metal parts have cracks and high residual stress. Residual stress and anisotropy of microstructure will affect the performance of the material.

[0006] Traditional post-treatment methods usually reduce the strength of metal material components while improving their ductility, making it difficult to obtain metal materials with excellent strength and toughness. In addition, the heat treatment procedure is complicated and the cycle is long. Vacuum heat treatment is used to eliminate micropores, but this usually leads to changes in the microstructure, such as the growth and coarsening of β grains, and the fragmentation of the unique layered needle-like morphology. Hot isostatic pressing can repair microcracks, but it will lead to grain coarsening and precipitation of unfavorable phases, thereby weakening the mechanical properties of the material. Summary of the invention

[0007] The purpose of this application is to provide a 3D printing metal material and a modification method thereof, aiming to solve the problem that it is difficult to obtain a metal material with both strong and tough properties by existing post-processing means.

[0008] To achieve the above objectives, the present application provides a method for modifying a 3D printed metal material, comprising:

[0009] The initial 3D printed sample is placed in a wrapping material for pre-pressing to obtain a green body;

[0010] forming a packaging layer outside the green body to obtain a synthetic block, and baking the block;

[0011] The baked synthetic block is treated at a pressure of 1 GPa to 6 GPa and a temperature of room temperature to 500° C. for 1 min to 60 min to obtain a strong and tough 3D printing metal material.

[0012] In some embodiments, the baked synthetic block is treated at a pressure of 1 GPa to 6 GPa and a temperature of room temperature to 500° C. for 1 min to 60 min three times.

[0013] In some embodiments, the pressure increase rate and pressure decrease rate are independently 5 GPa / h to 20 GPa / h; the temperature increase rate and temperature decrease rate are independently 10°C / min to 300°C / min.

[0014] In some embodiments, the pre-pressing pressure is 100 MPa to 500 MPa, and the pressing time is 1 s to 20 s.

[0015] In some embodiments, the baking temperature is 120-220°C.

[0016] In some embodiments, the encapsulating material is selected from any one of hexagonal boron nitride, magnesium oxide, NaCl, and CsCl; and the purity of the encapsulating material is greater than 99%.

[0017] In some embodiments, the packaging layer includes a heating material, a heat-insulating material, and a pressure-transmitting medium nested in sequence; the packaging layer also includes a conductive cap disposed on the pressure-transmitting medium and connected to the heating material.

[0018] In some embodiments, at least one of the following conditions is met:

[0019] A. The heating material is a graphite tube material;

[0020] B. The thermal insulation material is selected from any one of dolomite tube, zirconium oxide, rhenium chromate tube, and zirconium oxide doped calcium oxide tube;

[0021] C. The pressure transmission medium is pyrophyllite;

[0022] D. The conductive cap includes any one of a copper column, an iron column, a molybdenum column, and a graphite column.

[0023] The present application also provides a 3D printing metal material, which is prepared by the above-mentioned 3D printing metal material modification method.

[0024] In some embodiments, the 3D printed metal material has a strength of 1000 MPa to 1100 MPa and an elongation of 5% to 20%.

[0025] Compared with the prior art, the beneficial effects of this application include:

[0026] The modification method of 3D printed metal materials provided in this application uses laser 3D printed titanium / titanium alloy as the initial material, sequentially forms a wrapping material and an encapsulation layer to obtain a synthetic block, and then obtains a strong and tough 3D printed titanium through a direct high-pressure treatment process. This is because ultra-high pressure can inhibit the long-range diffusion of atoms and prevent grain coarsening at high temperatures; at the same time, high pressure can cause grain refinement inside the titanium / titanium alloy, thereby improving its strength; high pressure can repair defects such as holes and microcracks inside metal components; high temperature and high pressure can cause more dislocations, twins and other strengthening defect structures inside metal parts; high-temperature heat treatment under high pressure can eliminate residual stress and the distribution of inhomogeneous phases and improve ductility.

[0027] The modification method of 3D printing metal materials in this application simplifies the process flow and eliminates the complex heat treatment process. Compared with the traditional heat treatment that takes several hours, this method can complete the treatment within one hour, shortening the production time, reducing the production cost, and facilitating large-scale production. The strong and tough metal titanium prepared by this method has improved strength and ductility at the same time, solving the difficulty of insufficient performance of existing metal parts and has a wide range of uses.

[0028] The 3D printing metal material provided in this application has both strength and toughness, with a strength of 1000MPa to 1100MPa and an elongation of 5% to 20%. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for use in the embodiments will be briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present application and therefore should not be regarded as limiting the scope of the present application.

[0030] Figure 1 This is a schematic diagram of the process of the modification method of the 3D printing metal material of the present application;

[0031] Figure 2 This is a schematic diagram of the structure of the synthesis block of this application;

[0032] Figure 3 This is a comparison chart of the tensile properties of the 3D printed titanium metal component before and after ultra-high pressure modification of this application;

[0033] Figure 4 This is a scanning electron microscope image of the 3D printed metal titanium component of Example 1 before and after high pressure treatment;

[0034] Figure 5 This is the electron backscatter diffraction pattern of the 3D printed metal titanium component of Example 1 before and after high pressure treatment.

[0035] Reference numerals:

[0036] 10-initial 3D printed sample; 20-wrapping material; 30-heating material; 40-insulating material; 50-pressure transmission medium; 60-conductive cap. DETAILED DESCRIPTION

[0037] As used herein:

[0038] "Prepared from" is synonymous with "comprising." As used herein, the terms "comprising," "including," "having," "containing," or any other variation thereof, are intended to cover a non-exclusive inclusion. For example, a composition, process, method, article, or apparatus that comprises the listed elements is not necessarily limited to only those elements but may include other elements not expressly listed or inherent to such composition, process, method, article, or apparatus.

[0039] The conjunction "consisting of excludes any unspecified element, step, or component. If used in a claim, this phrase renders the claim closed-ended so that it does not include materials other than those described, except for conventional impurities associated therewith. When the phrase "consisting of" appears in a clause of the body of a claim rather than immediately following the subject matter, it limits only the elements described in that clause; other elements are not excluded from the claim as a whole.

[0040] When an amount, concentration, or other value or parameter is expressed as a range, a preferred range, or a range defined by a series of upper preferred values ​​and lower preferred values, this should be understood as specifically disclosing all ranges formed by any pairing of any range upper limit or preferred value with any range lower limit or preferred value, regardless of whether the range is disclosed separately. For example, when a range of "1 to 5" is disclosed, the described range should be interpreted as including ranges "1 to 4", "1 to 3", "1 to 2", "1 to 2 and 4 to 5", "1 to 3 and 5", etc. When a numerical range is described in this article, unless otherwise stated, the range is intended to include its end values ​​and all integers and fractions within the range.

[0041] In these examples, parts and percentages are by mass unless otherwise indicated.

[0042] "Parts by mass" refers to the basic unit of measurement for expressing the mass ratio of multiple components. 1 part can represent any unit mass, such as 1g or 2.689g. If we say that the mass of component A is a parts and the mass of component B is b parts, it means the ratio of the mass of component A to the mass of component B is a:b. Alternatively, it means that the mass of component A is aK and the mass of component B is bK (K is an arbitrary number, indicating a multiple factor). It should not be misunderstood that, unlike the mass parts, the sum of the mass of all components is not limited to 100 parts.

[0043] "And / or" is used to indicate that one or both of the stated situations may occur, for example, A and / or B includes (A and B) and (A or B).

[0044] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, the meaning of "plurality" is two or more, unless otherwise clearly and specifically defined.

[0045] This application provides a modification method for 3D printing metal materials, please refer to Figure 1 ,include:

[0046] S100: placing the initial 3D printed sample into a wrapping material for pre-pressing to obtain a blank;

[0047] S200: forming a packaging layer outside the green body to obtain a synthetic block, and baking the block;

[0048] S300: treating the baked synthetic block at a pressure of 1 GPa to 6 GPa and a temperature of room temperature to 500° C. for 1 min to 60 min to obtain a strong and tough 3D printing metal material.

[0049] This application uses laser 3D printed samples as the initial material, and sequentially forms wrapping materials and encapsulation layers outside the initial 3D printed samples to obtain a synthetic block, and then obtains strong and tough 3D printed titanium metal through a direct high-pressure treatment process. This is because ultra-high pressure can inhibit the long-range diffusion of atoms and prevent grain coarsening at high temperatures; at the same time, high pressure can produce grain refinement inside titanium / titanium alloys, thereby improving their strength; high pressure can repair defects such as holes and microcracks inside metal components; high temperature and high pressure can produce more dislocations, twins and other strengthening defect structures inside metal parts; high-temperature heat treatment under high pressure can eliminate residual stress and the distribution of inhomogeneous phases, and improve ductility.

[0050] In some embodiments, the 3D printed sample in step S100 is, for example, a 3D printed metal titanium / titanium alloy component, and the wrapping material is selected from any one of hexagonal boron nitride, magnesium oxide, NaCl, and CsCl; the purity of the wrapping material is greater than 99%. The wrapping material is a material with good hydrostatic pressure (fluid or quasi-fluid state under high temperature and high pressure) and stable performance.

[0051] In some embodiments, the pre-pressing pressure in step S100 is 100 MPa to 500 MPa, for example, it can be 100 MPa, 200 MPa, 300 MPa, 400 MPa, 500 MPa or any value between 100 MPa and 500 MPa, and the pressing time is 1s to 20s, for example, it can be 1s, 5s, 10s, 15s, 20s or any value between 1s and 20s.

[0052] In some embodiments, the packaging layer in step S200 includes a heating material, a heat-insulating material, and a pressure-transmitting medium nested in sequence; the packaging layer also includes a conductive cap disposed on the pressure-transmitting medium and connected to the heating material.

[0053] In some embodiments, the heating material is a graphite tube material.

[0054] In some embodiments, the insulation material is selected from any one of dolomite tubes, zirconium oxide, rhenium chromate tubes, and zirconium oxide doped calcium oxide tubes.

[0055] In some embodiments, the pressure transmitting medium is pyrophyllite.

[0056] In some embodiments, the conductive cap includes any one of a copper column, an iron column, a molybdenum column, and a graphite column.

[0057] See also Figure 2 , Figure 2 Schematic diagram of the structure of the synthesis block in step S200, wherein 10 is an initial 3D printed sample, 20 is a wrapping material, 30 is a heating material, 40 is a heat-insulating material, 50 is a pressure-transmitting medium, and 60 is a conductive cap.

[0058] In a specific embodiment of the present application, the initial 3D printed sample 10 is a 3D printed metal titanium component, the wrapping material 20 is hexagonal boron nitride, the heating material 30 is a graphite tube material, the insulation material 40 is a dolomite tube, the pressure transmission medium 50 is talc, and the conductive cap 60 is a molybdenum column.

[0059] In some embodiments, the baking temperature in step S200 is 120-220°C, for example, it can be 120°C, 130°C, 140°C, 150°C, 160°C, 170°C, 180°C, 190°C, 200°C, 210°C, 220°C or any value between 120 and 220°C.

[0060] In some embodiments, the pressure in step S200 can be, for example, 1 GPa, 2 GPa, 3 GPa, 4 GPa, 5 GPa, 6 GPa or any value between 1 GPa and 6 GPa, the temperature can be, for example, room temperature, 100°C, 200°C, 300°C, 400°C, 500°C or any value between room temperature and 500°C, and the processing time can be, for example, 1 min, 10 min, 20 min, 30 min, 40 min, 50 min, 60 min or any value between 1 min and 60 min.

[0061] In some embodiments, in step S300 , the baked composite block is treated three times at a pressure of 1 GPa to 6 GPa and a temperature of room temperature to 500° C. for 1 min to 60 min.

[0062] In some embodiments, the pressure increase rate and pressure reduction rate in step S300 are independently 5 GPa / h to 20 GPa / h, for example, 5 GPa / h, 10 GPa / h, 15 GPa / h, 20 GPa / h or any value between 5 GPa / h and 20 GPa / h.

[0063] In some embodiments, the heating rate and cooling rate of the temperature in step S300 are independently 10°C / min to 300°C / min, for example, 10°C / min, 50°C / min, 100°C / min, 150°C / min, 200°C / min, 250°C / min, 300°C / min or any value between 10°C / min and 300°C / min. If the heating rate is too low, the processing cycle is too long; if the heating rate is too high, it is easy to affect the stability and safety of the equipment.

[0064] The present application also provides a 3D printing metal material, which is prepared by the above-mentioned 3D printing metal material modification method.

[0065] The 3D printing metal material provided in this application has both strength and toughness, with a strength of 1000MPa to 1100MPa and an elongation of 5% to 20%.

[0066] The embodiments of the present application will be described in detail below in conjunction with specific examples, but it will be appreciated by those skilled in the art that the following examples are only used to illustrate the present application and should not be considered as limiting the scope of the present application. If specific conditions are not specified in the examples, they are carried out according to normal conditions or the conditions recommended by the manufacturer. If the manufacturer is not specified for the reagents or instruments used, they are all conventional products that can be purchased commercially.

[0067] In the following embodiments and comparative examples, the large-cavity static high-pressure device is a domestic hinged six-sided top press, model DS6x 36MN, and the metal titanium / titanium alloy components used are all prepared by laser 3D printing equipment.

[0068] In the following embodiments and comparative examples, the heating material is a graphite tube material, the heat-insulating material is a dolomite tube, and the pressure-transmitting medium is pyrophyllite.

[0069] Example 1

[0070] This embodiment provides a method for modifying a 3D printed metal material, the steps of which include:

[0071] (1) Initial sample preparation

[0072] In the selected laser melting (SLM) printing equipment, pure titanium powder of 15-53 microns is hung in the forming area, and the program text required to print the cylindrical block of the metal part is input into the control system. The laser power is set to 150W and the scanning interval is about 100 microns. After melting and solidification, powder printing is performed again, and the printing and forming of the component is repeated many times.

[0073] (2) Package selection

[0074] Hexagonal boron nitride powder is selected as the packaging material to provide a hydrostatic pressure environment, and is dried and purified before use to remove moisture and impurities.

[0075] (3) Pre-pressing

[0076] The metal titanium component processed in step (1) is placed in the wrapping material purified in step (2) for pre-pressing, so that the wrapping material fills around the metal titanium component to obtain a pre-pressed blank. The pre-pressing pressure is 300 MPa and the holding time is 20 seconds.

[0077] (4) Synthetic block baking

[0078] The pre-pressed green body is placed in a nested pressure transmission medium, a heat-insulating material and a heating material to form a composite block, and the composite block is baked in a muffle furnace or an oven at 120° C. for 10 minutes.

[0079] (5) High temperature and high pressure treatment and removal of the package

[0080] The baked synthetic block is directly placed in a high-temperature and high-pressure device, the pressure is increased from normal pressure to 5 GPa at a pressure increasing rate of 15 GPa / h, and then the pressure is kept constant, and ultra-high pressure treatment is performed for 10 minutes under the conditions of pressure of 5 GPa and temperature of room temperature. After the treatment time is reached, the pressure is reduced to normal pressure at a pressure reducing rate of 12 GPa / h, and then alcohol and deionized water are used to ultrasonically remove impurities adsorbed on the surface, so as to obtain the strong and tough 3D printed metal titanium component of Example 1.

[0081] The tough 3D printed titanium metal component of Example 1 was tested for tensile strength, which was increased from the initial 700 MPa to 1050 MPa, and the elongation was increased from 1% to 12%. Figure 3 Attached Figure 4 This is a scanning electron microscope image of a 3D printed titanium component before and after 5GPa high pressure treatment. Figure 5 This is the electron backscatter diffraction diagram of the 3D printed titanium component before and after 5GPa high pressure treatment. It can be seen that there are a lot of holes, cracks and uneven organization inside the 3D printed titanium before ultra-high pressure treatment ( Figure 4 Left part a), and the larger columnar crystals are obvious ( Figure 5 Left part c). After ultrahigh pressure modification, the internal holes and cracks are repaired ( Figure 4 The right part b), high pressure also makes the grains refined and homogenized ( Figure 5 The right part d) improves the mechanical properties of titanium.

[0082] Example 2

[0083] This embodiment provides a method for modifying a 3D printed metal material, the steps of which include:

[0084] (1) Initial sample preparation

[0085] In the selected laser melting (SLM) printing equipment, pure titanium powder of 15-53 microns is hung in the forming area, and the program text required to print the cylindrical block of the metal part is input into the control system. The laser power is set to 150W and the scanning interval is about 100 microns. After melting and solidification, powder printing is performed again, and the printing and forming of the component is repeated many times.

[0086] (2) Package selection

[0087] Hexagonal boron nitride powder is selected as the packaging material to provide a hydrostatic pressure environment, and is dried and purified before use to remove moisture and impurities.

[0088] (3) Pre-pressing

[0089] The metal titanium component processed in step (1) is placed in the wrapping material purified in step (2) for pre-pressing, so that the wrapping material fills around the metal titanium component to obtain a pre-pressed blank. The pre-pressing pressure is 300 MPa and the holding time is 20 seconds.

[0090] (4) Synthetic block baking

[0091] The pre-pressed green body is placed in a nested pressure transmission medium, a heat-insulating material and a heating material to form a composite block, and the composite block is baked in a muffle furnace or an oven at 120° C. for 10 minutes.

[0092] (5) High temperature and high pressure treatment and removal of the package

[0093] The baked synthetic block is directly placed in a high-temperature and high-pressure device. The pressure is first increased from normal pressure to 5 GPa at a pressure increasing rate of 15 GPa / h, and then the pressure is kept unchanged. The temperature is then increased to 500°C at a heating rate of 100°C / min and kept warm for 30 minutes. After the treatment time is reached, the temperature is first lowered to room temperature at a cooling rate of 100°C / min, and then the pressure is lowered to normal pressure at a pressure reducing rate of 13 GPa / h. Impurities adsorbed on the surface are then ultrasonically removed with alcohol and deionized water to obtain the strong and tough 3D printed metal titanium of Example 2.

[0094] The tough 3D printed titanium metal of Example 2 has a tensile strength increased from an initial 700 MPa to 1000 MPa, and an elongation increased from 1% to 19%. Figure 3 As shown, the mechanical properties of titanium are greatly improved.

[0095] Example 3

[0096] This embodiment provides a method for modifying a 3D printed metal material, the steps of which include:

[0097] (1) Initial sample preparation

[0098] In the selected laser melting (SLM) printing equipment, pure titanium powder of 15-53 microns is hung in the forming area, and the program text required to print the cylindrical block of the metal part is input into the control system. The laser power is set to 150W and the scanning interval is about 100 microns. After melting and solidification, powder printing is performed again, and the printing and forming of the component is repeated many times.

[0099] (2) Package selection

[0100] Magnesium oxide powder is selected as the packaging material to provide a hydrostatic pressure environment, and is dried and purified before use to remove moisture and impurities.

[0101] (3) Pre-pressing

[0102] The metal titanium component processed in step (1) is placed in the wrapping material purified in step (2) for pre-pressing, so that the wrapping material fills around the metal titanium component to obtain a pre-pressed blank. The pre-pressing pressure is 200 MPa and the holding time is 15 seconds.

[0103] (4) Synthetic block baking

[0104] The pre-pressed green body is placed in a nested pressure transmission medium, a heat-insulating material and a heating material to form a composite block, and the composite block is baked in a muffle furnace or an oven at 150° C. for 10 minutes.

[0105] (5) High temperature and high pressure treatment and removal of the package

[0106] The baked synthetic block is directly placed in a high-temperature and high-pressure device. The pressure is first increased from normal pressure to 3 GPa at a pressure increasing rate of 10 GPa / h and then kept constant. The temperature is then increased to 500°C at a heating rate of 100°C / min and kept warm for 30 minutes. After the treatment time is reached, the temperature is first lowered to room temperature at a cooling rate of 100°C / min, and then the pressure is lowered to normal pressure at a pressure reducing rate of 10 GPa / h. Impurities adsorbed on the surface are then ultrasonically removed with alcohol and deionized water to obtain the strong and tough 3D printed metal titanium of Example 3.

[0107] The tough 3D printed titanium metal of Example 3 was tested for tensile strength, which was increased from the initial 750MPa to 1000MPa, and the elongation was increased from 1% to 5%. Figure 3 As shown, the mechanical properties of titanium are greatly improved.

[0108] Example 4

[0109] This embodiment provides a method for modifying a 3D printed metal material, the steps of which include:

[0110] (1) Initial sample preparation

[0111] In the selected laser melting (SLM) printing equipment, pure titanium powder of 15-53 microns is hung in the forming area, the program text required to print medical titanium teeth is input into the control system, the laser power is set at 150W and the scanning interval is about 100 microns, and the powder is printed again after melting and solidification, and the printing and forming of the component is repeated many times.

[0112] (2) Package selection

[0113] Hexagonal boron nitride powder is selected as the packaging material to provide a hydrostatic pressure environment, and is dried and purified before use to remove moisture and impurities.

[0114] (3) Pre-pressing

[0115] The metal titanium component processed in step (1) is placed in the wrapping material purified in step (2) for pre-pressing, so that the wrapping material fills around the metal titanium component to obtain a pre-pressed blank. The pre-pressing pressure is 300 MPa and the holding time is 20 seconds.

[0116] (4) Synthetic block baking

[0117] The pre-pressed green body is placed in a nested pressure transmission medium, a heat-insulating material and a heating material to form a composite block, and the composite block is baked in a muffle furnace or an oven at 120° C. for 10 minutes.

[0118] (5) High temperature and high pressure treatment and removal of the package

[0119] The baked synthetic block is directly placed in a high-temperature and high-pressure device, and the pressure is increased from normal pressure to 5GPa at a rate of 15GPa / h, and then the pressure is kept constant. The ultra-high pressure treatment is carried out at room temperature for 10 minutes. After the treatment time is reached, the pressure is reduced to normal pressure at a rate of 12GPa / h, and then the pressure is increased to 5GPa again. The ultra-high pressure treatment is carried out three times. Then, alcohol and deionized water are used to ultrasonically remove impurities adsorbed on the surface, and a strong and tough 3D printed metal titanium tooth is obtained.

[0120] After ultra-high pressure treatment, the holes and cracks inside the titanium teeth were repaired, and the high pressure also refined and homogenized the grains, improving the mechanical properties of titanium. The strength of the tough 3D printed metal titanium component of Example 4 was increased from the initial 700MPa to 1100MPa after tensile testing, and the elongation was increased from 1% to 7%. Compared with a single high pressure treatment, the strength was slightly increased, but the elongation was slightly reduced.

[0121] Example 5

[0122] This embodiment provides a method for modifying a 3D printed metal material, the steps of which include:

[0123] (1) Initial sample preparation

[0124] In the selected laser melting (SLM) printing equipment, pure titanium powder of 15-53 microns is hung in the forming area, the program text required to print medical titanium teeth is input into the control system, the laser power is set at 150W and the scanning interval is about 100 microns, and the powder is printed again after melting and solidification, and the printing and forming of the component is repeated many times.

[0125] (2) Package selection

[0126] Hexagonal boron nitride powder is selected as the packaging material to provide a hydrostatic pressure environment, and is dried and purified before use to remove moisture and impurities.

[0127] (3) Pre-pressing

[0128] The metal titanium component processed in step (1) is placed in the wrapping material purified in step (2) for pre-pressing, so that the wrapping material fills around the metal titanium component to obtain a pre-pressed blank. The pre-pressing pressure is 300 MPa and the holding time is 20 seconds.

[0129] (4) Synthetic block baking

[0130] The pre-pressed green body is placed in a nested pressure transmission medium, a heat-insulating material and a heating material to form a composite block, and the composite block is baked in a muffle furnace or an oven at 120° C. for 10 minutes.

[0131] (5) High temperature and high pressure treatment and removal of the package

[0132] The baked synthetic block is directly placed in a high temperature and high pressure device, and the pressure is increased from normal pressure to 3GPa at a rate of 15GPa / h, and then the pressure is kept constant. The ultra-high pressure treatment is carried out at room temperature for 10 minutes. After the treatment time is reached, the pressure is reduced to normal pressure at a rate of 12GPa / h. Then, alcohol and deionized water are used to ultrasonically remove impurities adsorbed on the surface, and a strong and tough 3D printed metal titanium tooth is obtained.

[0133] After ultra-high pressure treatment, the holes and cracks inside the titanium teeth were repaired, and the high pressure also made the grains refined and homogenized, improving the mechanical properties of titanium. The tensile strength of the tough 3D printed metal titanium component of Example 5 was increased from the initial 700MPa to 1050MPa after tensile testing, and the elongation was also significantly improved compared with that before treatment. Figure 3 shown.

[0134] Comparative Example 1

[0135] This comparative example provides a method for modifying a 3D printed metal material, the steps of which include:

[0136] (1) Initial sample preparation

[0137] In the selected laser melting (SLM) printing equipment, pure titanium powder of 15-53 microns is hung in the forming area, and the program text required to print the cylindrical block of the metal part is input into the control system. The laser power is set to 150W and the scanning interval is about 100 microns. After melting and solidification, powder printing is performed again, and the printing and forming of the component is repeated many times.

[0138] (2) Package selection

[0139] Hexagonal boron nitride powder is selected as the packaging material to provide a hydrostatic pressure environment, and is dried and purified before use to remove moisture and impurities.

[0140] (3) Pre-pressing

[0141] The metal titanium component processed in step (1) is placed in the wrapping material purified in step (2) for pre-pressing, so that the wrapping material fills around the metal titanium component to obtain a pre-pressed blank. The pre-pressing pressure is 300 MPa and the holding time is 20 seconds.

[0142] (4) Synthetic block baking

[0143] The pre-pressed green body is placed in a nested pressure transmission medium, a heat-insulating material and a heating material to form a composite block, and the composite block is baked in a muffle furnace or an oven at 120° C. for 10 minutes.

[0144] (5) High temperature and high pressure treatment and removal of the package

[0145] The baked synthetic block is directly placed in a high temperature and high pressure device, and the pressure is increased from normal pressure to 5 GPa at a pressure increase rate of 15 GPa / h, and then the pressure is kept constant, and then the temperature is increased to 1000°C at a heating rate of 100°C / min and kept at this temperature for 30 minutes. After the treatment time is reached, the temperature is first reduced to normal temperature at a cooling rate of 100°C / min, and then the pressure is reduced to normal pressure at a pressure reduction rate of 13 GPa / h. Then, alcohol and deionized water are used to ultrasonically remove impurities adsorbed on the surface, and the titanium tensile part of Comparative Example 1 is obtained.

[0146] The tensile strength of the titanium tensile part of Comparative Example 1 remained basically unchanged from the initial 700MPa after tensile testing, and the elongation increased from 1% to 4%. This was mainly due to the high temperature, which caused the grains to coarsen significantly and reduced the mechanical properties. Even if the holes and cracks were eliminated under high pressure, the strength did not increase significantly. When the set temperature does not match, the synergistic improvement of strength and ductility cannot be achieved.

[0147] Comparative Example 2

[0148] This comparative example provides a method for modifying a 3D printed metal material, the steps of which include:

[0149] (1) Initial sample preparation

[0150] In the selected laser melting (SLM) printing equipment, pure titanium powder of 15-53 microns is hung in the forming area, and the program text required to print the cylindrical block of the metal part is input into the control system. The laser power is set to 150W and the scanning interval is about 100 microns. After melting and solidification, powder printing is performed again, and the printing and forming of the component is repeated many times.

[0151] (2) High temperature annealing

[0152] The printed titanium metal part was placed in a vacuum tube furnace and subjected to vacuum annealing treatment at 800°C for 30 minutes. After the treatment time was up, the temperature was lowered to room temperature. Then, alcohol and deionized water were used to ultrasonically remove impurities adsorbed on the surface, and a titanium tensile part after treatment in comparative example 2 was obtained.

[0153] The tensile strength of the titanium tensile part after the treatment in Comparative Example 2 decreased from the initial 700MPa to 600MPa, and the elongation decreased from 1% to 0.5%. This is mainly because the simple temperature annealing treatment cannot repair the holes and cracks inside the metal titanium. When the temperature is too high, the grains are significantly coarsened, which reduces the mechanical properties.

[0154] Comparative Example 3

[0155] This comparative example provides a method for modifying a 3D printed metal material, the steps of which include:

[0156] (1) Initial sample preparation

[0157] In the selected laser melting (SLM) printing equipment, pure titanium powder of 15-53 microns is hung in the forming area, and the program text required to print the cylindrical block of the metal part is input into the control system. The laser power is set to 150W and the scanning interval is about 100 microns. After melting and solidification, powder printing is performed again, and the printing and forming of the component is repeated many times.

[0158] (2) Package selection

[0159] Hexagonal boron nitride powder is selected as the packaging material to provide a hydrostatic pressure environment, and is dried and purified before use to remove moisture and impurities.

[0160] (3) Pre-pressing

[0161] The metal titanium component processed in step (1) is placed in the wrapping material purified in step (2) for pre-pressing, so that the wrapping material fills around the metal titanium component to obtain a pre-pressed blank. The pre-pressing pressure is 300 MPa and the holding time is 20 seconds.

[0162] (4) Synthetic block baking

[0163] The pre-pressed green body is placed in a nested pressure transmission medium, a heat-insulating material and a heating material to form a composite block, and the composite block is baked in a muffle furnace or an oven at 120° C. for 10 minutes.

[0164] (5) High temperature and high pressure treatment and removal of the package

[0165] The baked synthetic block is directly placed in a high temperature and high pressure device, and the pressure is increased from normal pressure to 5GPa at a pressure increase rate of 15GPa / h, and then the pressure is kept constant, and then the temperature is increased to 700℃ at a heating rate of 100℃ / min and kept warm for 30min. After the treatment time is reached, the temperature is first reduced to room temperature at a cooling rate of 100℃ / min, and then the pressure is reduced to normal pressure at a pressure reduction rate of 13GPa / h. Then, alcohol and deionized water are used to ultrasonically remove impurities adsorbed on the surface to obtain the titanium tensile part of comparative example 3.

[0166] The tensile strength of the titanium tensile parts in comparative example 3 remained basically unchanged from the initial 700MPa after tensile testing, and the elongation increased from 1% to 2%. This was mainly due to the high temperature, which caused the grains to coarsen significantly and reduced the mechanical properties. Even if the holes and cracks were eliminated under high pressure, the strength did not increase significantly. When the set temperature does not match, the synergistic improvement of strength and ductility cannot be achieved.

[0167] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit it. Although the present application has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present application.

[0168] In addition, those skilled in the art will appreciate that, although some embodiments herein include certain features included in other embodiments but not other features, the combination of features of different embodiments is meant to be within the scope of the present application and form different embodiments. For example, in the above claims, any one of the claimed embodiments may be used in any combination. The information disclosed in this background technology section is intended only to deepen the understanding of the overall background technology of the present application and should not be regarded as an admission or in any form of implication that the information constitutes prior art known to those skilled in the art.

Claims

1. A method for modifying a 3D printed metal material, characterized in that: include: The initial 3D printed sample is placed in a wrapping material for pre-pressing to obtain a green body; forming a packaging layer outside the green body to obtain a synthetic block, and baking the block; The baked synthetic block is treated at a pressure of 1 GPa to 6 GPa and a temperature of room temperature to 500° C. for 1 min to 60 min to obtain a strong and tough 3D printing metal material.

2. The method for modifying 3D printing metal materials according to claim 1, characterized in that: The baked synthetic block is treated three times at a pressure of 1 GPa to 6 GPa and a temperature of room temperature to 500° C. for 1 min to 60 min.

3. The method for modifying 3D printing metal materials according to claim 1, characterized in that: The pressure increase rate and pressure decrease rate are independently 5 GPa / h to 20 GPa / h; the temperature increase rate and temperature decrease rate are independently 10°C / min to 300°C / min.

4. The method for modifying 3D printing metal materials according to claim 1, characterized in that: The pre-pressing pressure is 100 MPa to 500 MPa, and the pressing time is 1 s to 20 s.

5. The method for modifying 3D printing metal materials according to claim 1, characterized in that: The baking temperature is 120-220°C.

6. The method for modifying 3D printing metal materials according to claim 1, characterized in that: The wrapping material is selected from any one of hexagonal boron nitride, magnesium oxide, NaCl, and CsCl; and the purity of the wrapping material is greater than 99%.

7. The method for modifying 3D printing metal materials according to claim 1, characterized in that: The packaging layer includes a heating material, a heat-insulating material and a pressure-transmitting medium which are nested in sequence; the packaging layer also includes a conductive cap which is arranged on the pressure-transmitting medium and connected to the heating material.

8. The method for modifying 3D printing metal materials according to claim 7, characterized in that: At least one of the following conditions is met: A. The heating material is a graphite tube material; B. The thermal insulation material is selected from any one of dolomite tube, zirconium oxide, rhenium chromate tube, and zirconium oxide doped calcium oxide tube; C. The pressure transmission medium is pyrophyllite; D. The conductive cap includes any one of a copper column, an iron column, a molybdenum column, and a graphite column.

9. A 3D printing metal material, characterized in that: Prepared by the modification method of the 3D printing metal material according to any one of claims 1 to 8.

10. The 3D printing metal material according to claim 9, characterized in that: The strength of the 3D printing metal material is 1000MPa to 1100MPa, and the elongation is 5% to 20%.

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