阅读说明：本技术 仿贝壳结构的高抗压钛合金构件和真空高能束流增材制造方法 (Shell-structure-imitated high-pressure-resistance titanium alloy component and vacuum high-energy beam additive manufacturing method ) 是由 周琦 顾锁林 徐俊强 于 2021-07-16 设计创作，主要内容包括：本发明为一种仿贝壳结构的高抗压钛合金构件和真空高能束流增材制造方法,通过钛合金晶粒组织特征仿贝壳的外层角质层、中层棱柱层和内层珍珠层结构。该构件中,仿贝壳分层结构的厚度占比为：仿角质层占比2％-5％,仿棱柱层占比85％-90％,仿珍珠层占比8％-10％。本发明制备的高抗压钛合金构件在微观晶粒的尺度上,仿贝壳的结构特征,完成了从柱状晶到等轴晶的均匀过渡,与常见的硬材和软材交替增材结构件,构成了在不同的尺度下的多层次微细增韧结构；本发明制备的高抗压钛合金构件突破常规只仿贝壳珍珠层的砖泥结构的思路,设计出仿贝壳角质层、棱柱层和珍珠层的三层抗压结构。(The invention relates to a shell-like high-pressure-resistant titanium alloy component and a vacuum high-energy beam additive manufacturing method. In the component, the thickness of the shell-like layered structure is as follows: 2-5% of imitated cuticle, 85-90% of imitated prism layer and 8-10% of imitated pearl layer. The high-compression-resistance titanium alloy member prepared by the invention imitates the structural characteristics of shells on the scale of microscopic grains, completes uniform transition from columnar crystals to isometric crystals, and forms a multi-level fine toughening structure under different scales with common hard material and soft material alternate material adding structural members; the high-compression-resistance titanium alloy member prepared by the invention breaks through the conventional thought of a brick mud structure only imitating a shell pearl layer, and designs a three-layer compression-resistance structure imitating a shell cuticle, a prismatic layer and a pearl layer.)

1. A shell-like high-compression-resistance titanium alloy component is characterized in that the structure of an outer layer cuticle, a middle layer prismatic layer and an inner layer pearl layer of a shell is imitated through the grain structure characteristics of titanium alloy.

2. The seashell-like structure high-pressure-resistant titanium alloy component as claimed in claim 1, wherein the seashell-like layered structure has a thickness ratio of: 2-5% of imitated cuticle, 85-90% of imitated prism layer and 8-10% of imitated pearl layer.

3. A vacuum high-energy beam additive manufacturing method of a shell-structure-simulated high-pressure titanium alloy component is characterized by comprising the following steps of:

(1) the additive substrate is a rolled TC4 titanium alloy plate;

(2) selecting TC4 and TA2 wires as raw materials, respectively loading the TC4 and TA2 wires or powder into vacuum high-energy beam additive equipment, and adjusting the beam spots of the vacuum high-energy beam and the states of the wires or powder;

(3) preheating the titanium alloy substrate to the temperature of 150-300 ℃ for red heating of the substrate;

(4) continuously adding the TC4 titanium alloy on the substrate according to the additive parameters until the thickness of the pseudo-prism layer is reached;

(5) continuously and discontinuously increasing the material TA2 on the TC4 material increase body until the thickness of the pearl-like layer is increased;

(6) repeating the steps (4) and (5), and adding a high-compressive titanium alloy member overlapped with the TA2 and TC 4;

(7) and after the material increase is finished, keeping a certain thickness of the imitated cuticle structure, and linearly cutting the rest part.

4. The vacuum high-energy beam additive manufacturing method of the shell-like structure high-pressure-resistant titanium alloy component according to claim 3, wherein the thickness of the substrate is greater than 10mm, the chemical composition of the TC4 titanium alloy rolled substrate meets the requirement of GB/T3620, and a double-wire mechanism or a double-powder-storage mechanism is adopted for vacuum high-energy beam additive manufacturing.

5. The vacuum high-energy beam additive manufacturing method of the shell-like structure high-pressure-resistant titanium alloy component according to claim 3, wherein the TC4 titanium alloy substrate is in close contact with the workbench, and the vacuum degree of the vacuum chamber is 3 x 10^-2-5×10^-2MPa。

6. The vacuum high-energy beam additive manufacturing method of the seashell-like structure high-pressure-resistant titanium alloy component as claimed in claim 3, wherein the substrate is preheated to 150 ℃ and 300 ℃ before additive manufacturing to form equiaxed crystals distributed in an arc shape.

7. The vacuum high-energy beam additive manufacturing method of the shell-like structure high-pressure-resistant titanium alloy member according to claim 3, wherein in order to meet the size requirements of the bionic prism layer and the pearl layer, the TC4 part of the bionic prism layer needs to be added with a thickness of more than 20mm, the additive layers are not cooled, and when the material is continuously added with TA2 on the TC4 additive layer, the interlayer cooling time is kept unchanged for 10 min.

8. The vacuum high-energy beam additive manufacturing method of the shell-like structure high-pressure-resistant titanium alloy component according to claim 3, wherein in order to eliminate the anisotropy of the shell-like structure titanium alloy component in the horizontal direction, after each layer of additive is finished, the additive path is changed by 90 degrees, and then the next layer of deposition is carried out.

9. The vacuum high-energy beam additive manufacturing method of the shell-like structure high-pressure-resistant titanium alloy component according to claim 3, wherein the base plate is of a layered structure imitating a horny layer, the thickness of the base plate is kept to be 3mm after additive manufacturing is completed, and the excess part of the base plate is removed by linear cutting.

Technical Field

The invention relates to the field of bionic structure design and manufacture, in particular to a shell structure-imitated high-pressure titanium alloy component and a vacuum high-energy beam additive manufacturing method.

Background

The titanium alloy has a plurality of properties such as small relative density, high specific strength, excellent corrosion resistance, good high-temperature mechanical property and the like, so the titanium alloy is widely applied to the fields of aerospace, petrochemical industry, mechanical manufacturing and the like. Traditional structural material is difficult to satisfy the performance demand of high resistance to compression, and wherein high-pressure gas or liquid transport need pipeline under pressure possess high resistance to compression and corrosion resisting property simultaneously, and the utility model patent that the publication is CN201820630529.5 discloses a composite metal material structure that compressive resistance is strong, and the internal pressure through inside metal structure with the pipe-line delivery hole passes through the inner structure pipe and spreads to the middle part sealed tube, has increased the compressive property of pipeline. This external pressure may enhance the compressive properties of the titanium alloy component by being dispersed and transmitted into the interior of the component.

Because titanium alloy has high melting point and high chemical activity and is easy to oxidize, the traditional casting or forging technology is difficult to prepare the titanium alloy structural part. The vacuum high-energy beam current material increase technology has the characteristics of centralized heat source, high energy utilization rate, vacuum environment and the like, and has obvious advantages in the process of preparing titanium alloy. In the process of titanium alloy material increase, the heat dissipation speed of the substrate is high, equiaxed crystals distributed in an arc shape are formed at the joint of the deposition layer and the substrate, the temperature gradient and the heat flow density in the height direction are large along with the progress of the deposition process, and coarse columnar crystals are formed. The invention patent with publication number CN202010282733.4 discloses a method for structure refinement and isometric crystal transformation of a titanium alloy component manufactured by laser fuse material increase, which synchronously carries out ultrasonic impact micro-forging treatment layer by layer in the laser fuse process, solves the problem of generation of coarse columnar crystals in the titanium alloy material increase manufacturing process, but has low compound technical efficiency and high cost, and is not suitable for preparation of titanium alloy components with large sizes and complex structures. The invention patent with the publication number of CN201810506284.X discloses a process method for rapidly refining high-toughness beta titanium alloy grains, and the method obtains the high-toughness beta titanium alloy through low-temperature forging and solution aging treatment on the beta titanium alloy. Since the heat processing technology of the titanium alloy is complicated due to the large deformation resistance of the titanium alloy, the heterogeneous titanium alloy structural member with a complicated structure is difficult to produce by the method.

In the process of vacuum high-energy beam current material increase of the TC4 titanium alloy, columnar crystals with directionally grown beta-phase columnar crystals pass through each deposition layer, so that the metallurgical bonding between layers is realized, and in the subsequent pure titanium deposition process, the growth of the columnar crystals is inhibited and the columnar crystals are uniformly transited to isometric crystals. The texture characteristic can be used for simulating the structures of the outer stratum corneum, the middle prismatic layer and the inner pearl layer of the shell, so that the aim of preparing the high-compression-resistance titanium alloy component with the shell-like structure is fulfilled.

Research shows that the shell has extremely high strength and good toughness, and compared with natural mineral calcium carbonate, the mechanical property of the shell can be improved by several orders of magnitude, which shows that the good performance of the shell comes from the unique multilayer microstructure. The shell is divided into three layers, namely an outer stratum corneum layer, a middle prismatic layer and an inner pearl layer. The horny layer is mainly composed of hardened protein, and has two layers, the upper layer is a thin sheet layer, the sheet layer is nearly parallel to the surface of the shell, and the lower layer is an irregular block layer. The prismatic layer is composed of columnar calcite, and the surface of the calcite is provided with a large number of micron-sized holes and has a layered structure similar to that of iron rust. The pearl layer is a 'brick-mud' structure formed by stacking aragonite slabs and organic matters, and an obvious transition interface is hardly seen from the transition from the growth of the prismatic layer to the growth of the pearl layer.

The invention patent with publication number CN202010494894.X discloses a bionic shell material structure combining metal and nonmetal, wherein a structural hard layer and a structural support body are alternately laminated to form a composite structure with a multi-layer structural hard layer and a structural support body, the structure has great advantages in improving the toughness and the shock resistance of the material, but the combination between the metal and the nonmetal is weaker. The invention patent with publication number CN202010357914.9 discloses a shell-like mother-of-pearl material with a layered structure and a preparation method thereof, which combines a freeze casting technology and a carbonization technology to obtain the shell-like mother-of-pearl material with the layered structure, the obtained material has higher fracture toughness and durability, but the preparation steps are complicated and the uniformity is poor, so that the performance is far different from the real shell structure. The invention breaks through the idea that the traditional method is only limited to the brick mud structure of the shell-like pearl layer, designs the three-layer compressive structure of the horny layer, the prismatic layer and the pearl layer of the shell-like, and has more various stress dispersion paths compared with the single brick mud structure.

Disclosure of Invention

The invention provides a shell structure-imitated high-pressure-resistant titanium alloy component and a vacuum high-energy beam additive manufacturing method.

A shell-like high-compression-resistance titanium alloy component is characterized in that the structure of an outer layer cuticle, a middle layer prismatic layer and an inner layer pearl layer of a shell is imitated through a titanium alloy structure.

Further, the thickness of the shell-like layered structure is as follows: 2-5% of imitated cuticle, 85-90% of imitated prism layer and 8-10% of imitated pearl layer.

The principle of designing the shell-like high-pressure-resistant titanium alloy component is specifically that stress is dispersed to the imitated prism layer under the condition that the imitated horny layer is stressed, cracks are induced to expand along a grain boundary when columnar crystals of the imitated prism layer bear pressure parallel to the direction of the columnar crystals, the cracks reach an isometric crystal area of the imitated pearl layer and start to deflect, and when the pressure perpendicular to the direction of the columnar crystals is applied, a crack expansion path is prolonged, so that a stress action path is lengthened, and the stress is dispersed.

A vacuum high-energy beam additive manufacturing method of a shell-structure-simulated high-pressure titanium alloy component comprises the following steps:

(1) the additive substrate is a rolled TC4 titanium alloy plate;

(2) selecting TC4 and TA2 wires as raw materials, respectively loading the TC4 and TA2 wires or powder into vacuum high-energy beam additive equipment, and adjusting the beam spots of the vacuum high-energy beam and the states of the wires or powder;

(3) preheating the titanium alloy substrate to the temperature of 150-300 ℃ for red heating of the substrate;

(4) continuously adding TC4 titanium alloy on the substrate according to the designed additive parameters until the thickness of the pseudo-prism layer is reached;

(5) continuously and discontinuously increasing the material TA2 on the TC4 material increase body until the thickness of the pearl-like layer is increased;

(6) repeating the steps (4) and (5), and adding a high-compressive titanium alloy member overlapped with the TA2 and TC 4;

(7) and after the material increase is finished, keeping a certain thickness of the imitated cuticle structure, and linearly cutting the rest part.

Furthermore, the thickness of the substrate is larger than 10mm, the chemical components of the TC4 titanium alloy rolled substrate meet the requirements of GB/T3620, and a double-wire mechanism or a double-powder storage mechanism is adopted for vacuum high-energy beam current additive manufacturing, so that the influence of wire replacement or powder replacement on the structure of the component in the additive manufacturing process is avoided.

Further, the TC4 titanium alloy substrate was brought into close contact with the stage, and the vacuum chamber was evacuated to a vacuum degree of 3X 10^-2-5×10^-2And MPa, the heat conduction direction of the titanium alloy component in the vacuum environment is convenient to control.

Further, the substrate is subjected to preheating treatment before material addition to form arc-shaped equiaxial crystals, so that the subsequent columnar crystal growth is facilitated.

Furthermore, in order to meet the size requirements of the bionic prism layer and the pearl layer, the TC4 part of the bionic prism layer needs to be added with a thickness of more than 20mm, the additive layers are not cooled, and when material TA2 is continuously added on the TC4 additive layers, the interlayer cooling time is kept unchanged for 10 min.

Furthermore, in order to eliminate the anisotropy of the shell-like structure titanium alloy component in the horizontal direction, after each layer of material increase is finished, the material increase path is changed by 90 degrees, and then the next layer of deposition is carried out.

Furthermore, the base plate is of a layered structure imitating a horny layer, the thickness of the base plate is kept to be 3mm after the material increase is finished, and the excess part of the base plate is removed by adopting linear cutting.

The preparation method of the shell bionic material has the advantages that:

(1) when the titanium alloy member prepared by the invention bears the pressure parallel to the columnar crystal direction, the crack is induced to expand along the grain boundary and reaches the equiaxed crystal region to start deflecting, and when the titanium alloy member bears the pressure vertical to the columnar crystal direction, the crack expansion path is prolonged, so that the stress action path is lengthened, the stress is dispersed, and the compression resistance of the member is improved;

(2) the invention fully exerts the stirring effect of the vacuum high-energy beam on the deposition layer, the columnar crystal area and the equiaxed crystal area of the high-pressure titanium alloy component are in uniform transition, and the gradient change of the tissue and Al and V elements is formed in the transition area, thereby conforming to the characteristic that no obvious transition interface exists between the shell pearl layer and the prismatic layer;

(3) the high-compression-resistance titanium alloy member prepared by the invention imitates the structural characteristics of shells on the scale of microscopic grains, completes uniform transition from columnar crystals to isometric crystals, and forms a multi-level fine toughening structure under different scales with common hard material and soft material alternate material adding structural members;

(4) the high-compression-resistance titanium alloy member prepared by the invention breaks through the conventional thought of a brick mud structure only imitating a shell pearl layer, and designs a three-layer compression-resistance structure imitating a shell cuticle, a prismatic layer and a pearl layer.

Drawings

FIG. 1 is a schematic structural diagram of a shell-like structure high-compressive titanium alloy member according to the present invention.

FIG. 2 is a schematic cross-sectional view of the shell-like three-layer structure of the present invention showing stress dispersion when the structure is pressed.

Fig. 3 is a cross-sectional view of the related structure of the anti-compression structural design element under different application conditions in the invention.

FIG. 4 is a diagram showing the variation of Ti, Al and V elements in the transition region between columnar crystal and equiaxed crystal.

FIG. 5 is a comparison of impact toughness of the shell-like structure prepared by the present invention and pure TC4 blocks in different directions.

FIG. 6 is a fracture morphology diagram of an impact sample prepared by the method of the invention.

Detailed Description

The technical solution of the present invention is fully described below with reference to the accompanying drawings of the present invention.

A shell-like high-compression-resistance titanium alloy component is characterized in that the structure of an outer layer cuticle, a middle layer prismatic layer and an inner layer pearl layer of a shell is imitated through a titanium alloy structure.

The thickness of the shell-like layered structure is as follows: 2-5% of imitated cuticle, 85-90% of imitated prism layer and 8-10% of imitated pearl layer.

The principle of designing the shell-like high-pressure-resistant titanium alloy component is specifically that stress is dispersed to the imitated prism layer under the condition that the imitated horny layer is stressed, cracks are induced to expand along a grain boundary when columnar crystals of the imitated prism layer bear pressure parallel to the direction of the columnar crystals, the cracks reach an isometric crystal area of the imitated pearl layer and start to deflect, and when the pressure perpendicular to the direction of the columnar crystals is applied, a crack expansion path is prolonged, so that a stress action path is lengthened, and the stress is dispersed.

A vacuum high-energy beam additive manufacturing method of a shell-structure-simulated high-pressure titanium alloy component comprises the following steps:

(1) the additive substrate is a rolled TC4 titanium alloy plate;

(2) selecting TC4 and TA2 wires as raw materials, respectively loading the TC4 and TA2 wires or powder into vacuum high-energy beam additive equipment, and adjusting the beam spots of the vacuum high-energy beam and the states of the wires or powder;

(3) preheating the titanium alloy substrate to 200 ℃ of substrate red heat;

(4) continuously adding TC4 titanium alloy on the substrate according to the designed additive parameters until the thickness of the pseudo-prism layer is reached;

(5) continuously and discontinuously increasing the material TA2 on the TC4 material increase body until the thickness of the pearl-like layer is increased;

(6) repeating the steps (4) and (5), and adding a high-compressive titanium alloy member overlapped with the TA2 and TC 4;

(7) and after the material increase is finished, keeping a certain thickness of the imitated cuticle structure, and linearly cutting the rest part.

Furthermore, the thickness of the substrate is larger than 10mm, the chemical components of the TC4 titanium alloy rolled substrate meet the requirements of GB/T3620, and a double-wire mechanism or a double-powder storage mechanism is adopted for vacuum high-energy beam current additive manufacturing, so that the influence of wire replacement or powder replacement on the structure of the component in the additive manufacturing process is avoided.

Further, the TC4 titanium alloy substrate was brought into close contact with the stage, and the vacuum chamber was evacuated to a vacuum degree of 3X 10^-2-5×10^-2And MPa, the heat conduction direction of the titanium alloy component in the vacuum environment is convenient to control.

Further, the substrate is subjected to preheating treatment before material addition to form arc-shaped equiaxial crystals, so that the subsequent columnar crystal growth is facilitated.

Furthermore, in order to meet the size requirements of the bionic prism layer and the pearl layer, the TC4 part of the bionic prism layer needs to be added with a thickness of more than 20mm, the additive layers are not cooled, and when material TA2 is continuously added on the TC4 additive layers, the interlayer cooling time is kept unchanged for 10 min.

Furthermore, in order to eliminate the anisotropy of the shell-like structure titanium alloy component in the horizontal direction, after each layer of material increase is finished, the material increase path is changed by 90 degrees, and then the next layer of deposition is carried out.

Furthermore, the base plate is of a layered structure imitating a horny layer, the thickness of the base plate is kept to be 3mm after the material increase is finished, and the excess part of the base plate is removed by adopting linear cutting.

Examples

The embodiment is a high-energy electron beam additive manufacturing method of a shell-like high-pressure-resistant titanium alloy component, which comprises the following steps:

(1) rolling the TC4 titanium alloy substrate to form a lamellar multi-orientation equiaxed crystal structure, wherein the chemical components of the TC4 titanium alloy rolled substrate meet the requirement of GB/T3620, the size of the substrate is 100mm multiplied by 60mm multiplied by 10mm, then polishing the surface of the substrate by a polishing machine, and removing oil stains on the surface of the substrate by absolute ethyl alcohol;

(2) respectively loading TC4 and TA2 wires into an electron beam double-wire additive manufacturing device, and adjusting the beam spot of an electron beam to coincide with the intersection point of the two wires;

(3) tightly fixing the substrate on a workbench of an electron beam fuse additive manufacturing system until the vacuum degree reaches 3 × 10^-2And when the substrate is MPa, setting the high voltage of an electron beam to be 60kV, the focusing current to be 1000mA, the scanning frequency to be 500Hz, the scanning range to be 500 percent, the scanning mode to be circular, the scanning speed to be 10mm/s, preheating the substrate and gradually increasing the beam current until the substrate generates red heat.

(4) Starting a TC4 wire feeder, depositing a TC4 titanium alloy wire on a substrate, wherein the wire feeding speed is 10mm/s, the height of a TC4 layer is controlled to be 1.2mm, the width of a deposition channel is 5mm, the lap joint rate between channels is 0.5, after each layer is deposited, the deposition path is changed by 90 degrees, the interlayer is continuously deposited, and cooling treatment is not carried out;

(4) continuously depositing TA2 wire on a TC4 deposition body, wherein the wire feeding speed is 12mm/s, the height of a TA2 layer is controlled to be 0.3mm, the width of a deposition channel is controlled to be 8mm, the lap joint rate between channels is controlled to be 0.5, after each layer is deposited, the deposition path is changed by 90 degrees, and the interlayer cooling time is kept unchanged for 10 min;

(5) repeatedly depositing TC4 and TA2 wires to finally add a high-pressure-resistance titanium alloy member overlapped by TC4 and TA2, wherein the total height of a TC4 deposit body is 270mm, and the total height of a TA2 deposit body is 27 mm;

(6) and reserving a substrate with the thickness of 3mm at the bottom of the titanium alloy component, and cutting off the part of the redundant substrate by adopting linear cutting.

By adopting the method of the embodiment, the shell-like titanium alloy member with good forming is obtained, interlayer fusion is good, no defects such as air holes and the like exist, and no oxidation phenomenon exists. Fig. 4 is a picture of the metallographic structure of the prepared member and the corresponding elemental changes of the transition region of TC4 and TA2, fig. 5 is a comparison graph of impact toughness of the shell-like structural member and a pure TC4 block in different directions, and fig. 6 is a fracture morphology graph of an impact specimen.

As can be seen from the figure, the β -phase columnar crystals in the TC4 additive region grow directionally across the respective deposited layers, while the columnar crystals are inhibited from growing in the transition region from TC4 to TA2, uniformly transitioning to equiaxed crystals. Compared with TC4 titanium alloy blocks manufactured by electron beam fuse additive manufacturing, the impact toughness of the shell-like titanium alloy structural part manufactured by the embodiment is improved by 73.3%, and the impact toughness is improved because cracks deflect among grain structures, so that a stress action path is lengthened, and the compression resistance of the structural part is improved.