CN104550949A - Method for rapidly forming Ti-6Al-4V three-dimensional metal parts by electron beams - Google Patents

Abstract

The invention relates to the technical field of electron beam processing, in particular to a method for rapid forming of Ti-6Al-4V three-dimensional metal parts by electron beams, and the method is suitable for the rapid forming preparation of Ti-6Al-4V metal parts with various complex structures. First, Ti-6Al-4V three-dimensional metal parts are prepared; then, the prepared three-dimensional parts are subjected to hot isostatic pressing at 800°C to 1000°C; finally, the titanium alloy parts are annealed at 700°C to 1000°C and 400°C ~600℃ for aging treatment. Through the above process, the Ti-6Al-4V complex structure three-dimensional parts with excellent comprehensive mechanical properties such as tensile strength higher than 900MPa, elongation higher than 10%, fatigue strength higher than 500MPa, and impact toughness higher than 30J/ ^cm2 can be obtained. , can be widely used in aerospace, medical and other fields.

Description

A Method for Electron Beam Rapid Forming of Ti-6Al-4V Three-dimensional Metal Parts

Technical field:

The invention relates to the technical field of electron beam processing, in particular to a method for rapid forming of Ti-6Al-4V high-performance three-dimensional metal parts by electron beams, and the method is suitable for the rapid forming preparation of Ti-6Al-4V metal parts with various complex structures.

Background technique:

Additive Fabrication via Electron Eeam Melting (AM-EBM) is one of the advanced manufacturing technologies that have developed rapidly in recent years. EBM technology uses the electron beam as the energy source, through the layered slice processing of the three-dimensional digital model of the part, it is discretized into a series of two-dimensional data files, and then according to the file information of each layer, the computer system controls the movement of the electron beam to move the metal powder one by one The layers are fused and accumulated, and finally a sample that is completely consistent with the design file is obtained. This technology embodies the comprehensive application of computer-aided design, numerical control, electron beam processing, new material development and other multi-disciplinary and multi-technical applications. It can quickly prepare metal parts with high precision and complex structure, and has high precision, high efficiency and high performance. It has a wide range of applications in aerospace, medical, chemical and other fields, and has received close attention from scholars and researchers from all over the world.

Compared with another rapid prototyping technology-laser rapid prototyping technology, the metal parts prepared by EBM technology have low residual internal stress and high forming efficiency, which has obvious advantages in the production of large-scale three-dimensional metal parts. However, the performance of parts produced by EBM technology is closely related to EBM process parameters, and different metals require corresponding process parameters for production and preparation. In the process of manufacturing samples by EBM method, the input energy, electron beam scanning speed and other preparation process parameters, as well as sample size and stacking direction, etc. will affect the melting and solidification rate of each layer, and then affect the structure and performance of the sample.

Due to the advantages of high specific strength, low elastic modulus, excellent corrosion resistance, and good biocompatibility, titanium alloys are widely used in medical and aerospace fields. In practical applications in the medical and aerospace fields, some metal parts with complex internal structures are often required. Machining these components using conventional machining methods is difficult and expensive for titanium alloys. The use of the EBM method for the processing and preparation of these metal parts has obvious advantages, and it can realize the efficient and rapid preparation of these parts on an industrial scale. At present, scholars from various countries have carried out research on the influence of the above factors on the structure and properties of EBM Ti-6Al-4V alloy products (Nikolas H, Timothy Q. Mater Sci Eng A, 2013; 573: 271; Nikolas H, Timothy Q. Mater Sci Eng A,2013;573:264; Murr L E, Esquivel E V, Quinones S A, Gaytan S M, Lopez M I, Martinez E Y, Medina F, Hernandez D H, Martinez E, Martinez J L, Stafford S W, Brown D K, Hoppe T, Meyers W, Lindhe U, Wicker R B. Materials Characterization, 2009;60:96). However, these studies are only limited to the influence of process parameters on the tensile properties of Ti-6Al-4V alloy, and lack of influence on fatigue properties, impact properties and notch sensitivity properties. In addition, the effects of post-processing (hot isostatic pressing and heat treatment) on EBM products on their mechanical properties have not been addressed.

Therefore, it is necessary to study the influence of process parameters such as electron beam input energy, sample size, and post-treatment technologies such as hot isostatic pressing and heat treatment on the mechanical properties of Ti-6Al-4V alloy prepared by EBM method, so as to obtain efficient preparation of Ti-6Al with excellent mechanical properties. - The electron beam rapid prototyping method of 4V three-dimensional metal parts can better serve the medical, aerospace and other fields.

Invention content:

The purpose of the present invention is to provide a method for rapid forming of Ti-6Al-4V three-dimensional metal parts by electron beams, which solves the current problem of efficient and rapid preparation of complex structure Ti-6Al-4V three-dimensional metal parts.

Technical scheme of the present invention:

A method for electron beam rapid forming of Ti-6Al-4V three-dimensional metal parts, the specific steps are as follows:

(1) Preparation of Ti-6Al-4V three-dimensional metal parts, using Ti-6Al-4V powder as raw material, using electron beam molten metal forming technology to prepare Ti-6Al-4V block three-dimensional metal parts;

(2) Hot isostatic pressing treatment of Ti-6Al-4V three-dimensional metal parts, hot isostatic pressing treatment of Ti-6Al-4V three-dimensional metal parts at 800 ° C ~ 1000 ° C;

(3) Heat treatment of Ti-6Al-4V three-dimensional metal parts, annealing treatment of Ti-6Al-4V three-dimensional metal parts at 700 ° C ~ 1000 ° C and aging treatment at 400 ° C ~ 600 ° C, and finally obtain Ti-6Al with excellent mechanical properties -4V 3D metal parts.

In the step (1), a layer of Ti-6Al-4V metal powder is evenly spread on the surface of the substrate, and then the metal powder is melted and deposited layer by layer in a vacuum chamber with an electron beam. By controlling the electron beam melting process parameters, Build up the forming parameters until the entire 3D part is manufactured.

In the step (1), the Ti-6Al-4V powder is spherical with a diameter of 30 μm to 150 μm.

In the step (1), the range of process parameters of the electron beam molten metal forming technology is that the electron beam current is 5-30 mA, and the scanning speed is 1000-20000 mm/s.

In order to ensure that the overall structure and mechanical properties of the three-dimensional parts are uniform, the initial forming height of the parts should be controlled at 10 mm to 30 mm from the substrate. In order to ensure that the overall structure and mechanical properties of the three-dimensional parts are uniform, the stacking direction should be perpendicular to the direction of the substrate as much as possible. In order to ensure that the overall structure and mechanical properties of the three-dimensional parts are uniform, the wall thickness of the parts should be greater than 2mm.

In the step (2), the specific parameters of the hot isostatic pressing of Ti-6Al-4V are: the heating temperature of the hot isostatic pressing is 800°C-1000°C, the holding time is 1-3h, and the applied pressure is 100-200MPa, The cooling method is furnace cooling.

In the step (3), the heat treatment of the Ti-6Al-4V three-dimensional metal parts adopts two-step heat treatment in the two-phase zone, and the specific steps are:

(1) Two-phase zone annealing treatment;

(2) Aging treatment in the two-phase zone.

The equipment used for the two-phase zone annealing treatment is a vacuum heat treatment furnace, the heat treatment temperature is 700°C-1000°C, the holding time is 1-3h, and the cooling rate is 1-3°C/min;

The equipment used for the aging treatment in the two-phase zone is a vacuum heat treatment furnace, the heat treatment temperature is 400°C-600°C, the holding time is 1-3h, and the cooling rate is 8-15°C/min.

In the present invention, Electron Beam Melting technology (Electron Beam Melting) is referred to as EBM technology, which is an emerging advanced metal rapid prototyping manufacturing technology in recent years. Its principle is to import the three-dimensional solid model data of parts into EBM equipment, and then A thin layer of fine metal powder is laid flat in the working chamber of the equipment. After the high-energy electron beam is deflected and focused, the high-density energy generated at the focus makes the scanned metal powder layer generate high temperature in a small local area, resulting in metal particles Melting, the continuous scanning of the electron beam will make the tiny molten metal pools fuse and solidify, and connect to form linear and planar metal layers.

In the present invention, the electron beam melting metal forming equipment that adopts is conventional technology, as: the Arcam A1 electron beam melting EBM system (Electron Beam Melting) that Fan Yate Technology Co., Ltd. produces, and its process parameter scope is: electron beam current is 5 ～30mA, scanning speed is 1000～20000mm/s. The system is a fully automated system directly from CAD to finished product manufacturing. It is a mass production tool for three-dimensional titanium alloy parts with complex structures. Under the bombardment of high-energy electron beams, metal powder grows layer by layer, and the shape of each layer is determined by three-dimensional CAD control, using electron beam melting system, can achieve high melting capacity and productivity.

The tensile strength of the Ti-6Al-4V three-dimensional metal part prepared by the method of the present invention is higher than 900MPa, the elongation is higher than 10%, the fatigue strength is higher than 500MPa, the impact resistance is higher than 30J/cm ² , and its comprehensive mechanical properties are obviously higher than Castings and forgings.

Beneficial effects of the present invention:

1. The present invention adopts electron beam molten metal forming technology to prepare high-performance Ti-6Al-4V three-dimensional metal parts. The shape and internal structure of the product are completely controllable, and the preparation of individualized and complex three-dimensional metal parts can be carried out according to actual needs; The preparation process is simple, the cost is obviously lower than other preparation means such as mechanical processing, the production efficiency is high, and it is suitable for industrial scale production.

2. The present invention can obtain the complex structure Ti with excellent comprehensive mechanical properties by controlling the process parameters optimization, hot isostatic pressing and heat treatment in the process of preparing Ti-6Al-4V three-dimensional metal parts by the electron beam melting metal forming method. -6Al-4V three-dimensional metal parts have very broad application prospects in the fields of medical treatment and aerospace.

3. In the present invention, the Ti-6Al-4V three-dimensional metal parts are subjected to hot isostatic pressing at 800°C to 1000°C, and two-step heat treatment of annealing and aging at 400°C to 1000°C to obtain a tensile strength higher than 900MPa. The elongation rate is higher than 10%, the fatigue strength is higher than 500MPa, and the impact resistance is higher than 30J/cm ² . The mechanical properties of the EBM method Ti-6Al-4V three-dimensional metal parts are controlled by hot isostatic pressing and heat treatment processes, so as to obtain excellent Mechanical properties of large-scale and complex-structured titanium alloy three-dimensional components.

In a word, the method of the invention has simple process, low cost, high precision of formed parts, and is suitable for large-scale industrial production. The invention controls the mechanical properties of the Ti-6Al-4V forming material through electron beam process parameters, hot isostatic pressing process and heat treatment process, so as to obtain Ti-6Al-4V complex structure three-dimensional parts with excellent mechanical properties, which can be used in aerospace, medical and other fields have been widely used.

Description of drawings:

Figure 1(a) is the CAD model of the human skull;

Figure 1(b) is a Ti-6Al-4V human skull simulation piece;

Fig. 2 is the morphology of Ti-6Al-4V alloy powder;

Figure 3 (a) CAD model of chess pieces;

Figure 3(b) is a Ti-6Al-4V chess piece;

Figure 4(a) is the CAD model of the acetabular cup;

Figure 4(b) is the Ti-6Al-4V acetabular cup;

Figure 5(a) is a CAD hollow sphere model;

Figure 5(b) shows Ti-6Al-4V hollow spheres.

Detailed ways:

In the present invention, at first adopt CAD software to carry out model design, import the graphic file that designs then into Magics software and carry out graphic error correction and optimization, to guarantee the smooth progress of electron beam molten metal forming process; The abf format file is imported into the computer control system of the electron beam melting metal forming equipment, and the Ti-6Al-4V three-dimensional metal parts are prepared by using the electron beam melting metal forming equipment with Ti-6Al-4V powder as the raw material.

The present invention will be described in further detail below in conjunction with the accompanying drawings and embodiments.

Example 1

As shown in Figure 1(a), the human skull model is designed using CAD software, and the wall thickness is 3 mm. Using Ti-6Al-4V alloy powder (Fig. 2, the powder diameter is 50-80 μm) as raw material, the Ti-6Al-4V human skull model was prepared by Arcam A1 electron beam melting equipment, and the electron beam scanning speed was 10000 mm/s. The electron beam current is 18mA, and the prepared Ti-6Al-4V human skull model is shown in Figure 1(b).

In this example, the prepared Ti-6Al-4V human skull model is subjected to hot isostatic pressing, the process is as follows: the temperature is 920° C., the pressure is 120 MPa, and the holding time is 3 hours.

In this embodiment, the prepared Ti-6Al-4V human skull is subjected to two-step heat treatment in the two-phase region:

(1) Two-phase zone annealing treatment Using a vacuum heat treatment furnace, the prepared Ti-6Al-4V human skull was kept at 800 °C for 1 h, and cooled to room temperature at a rate of 1 °C/min.

(2) The aging treatment in the two-phase zone uses a vacuum heat treatment furnace. The heat treatment temperature is 500 ° C for 3 hours, and the temperature is cooled to room temperature at a rate of 10 ° C / min.

In this embodiment, the relevant parameters of the tensile strength, elongation, fatigue strength, impact toughness and notch sensitivity of the Ti-6Al-4V human skull model are as follows: the tensile strength of the titanium alloy material is 1000MPa, the yield strength is 900MPa, and the elongation The rate is 11%, the fatigue strength is 530MPa, and the impact toughness is 32J/cm ² . The tensile strength, elongation, fatigue strength, impact toughness and notch sensitivity of the Ti-6Al-4V human skull model in this example are significantly better than the wrought and cast Ti-6Al-4V alloys reported in the literature.

Example 2

As shown in Figure 3(a), the chess piece model is designed using CAD software, and the thinnest wall thickness of the chess piece is 4mm. Using Ti-6Al-4V alloy powder as raw material (Fig. 2, the powder diameter is 50-80 μm), the Ti-6Al-4V chess piece was prepared by ArcamA1 electron beam melting equipment, the electron beam scanning speed was 13000m/s, and the electron beam The current is 20mA, and the stacking direction is perpendicular to the substrate direction. The prepared Ti-6Al-4V chess piece is shown in Fig. 3(b).

In this embodiment, the prepared Ti-6Al-4V human skull model is subjected to hot isostatic pressing, the process is as follows: the temperature is 950° C., the pressure is 100 MPa, and the holding time is 2 hours.

In this embodiment, the prepared Ti-6Al-4V chess pieces are subjected to two-step heat treatment in the two-phase region:

(1) Two-phase zone annealing treatment Using a vacuum heat treatment furnace, the prepared Ti-6Al-4V chess pieces were kept at 900°C for 1.5h, and cooled to room temperature at a rate of 2°C/min.

(2) The aging treatment in the two-phase zone uses a vacuum heat treatment furnace with a heat treatment temperature of 600°C, a holding time of 1h, and cooling to room temperature at a rate of 15°C/min.

In this embodiment, the relevant parameters of the tensile strength, elongation, fatigue strength, impact toughness and notch sensitivity of Ti-6Al-4V chess pieces are as follows: the tensile strength of the titanium alloy component is 980MPa, the yield strength is 880MPa, and the elongation 15%, the fatigue strength is 550MPa, and the impact toughness is 33J/cm ² . The tensile strength, elongation, fatigue strength, impact toughness and notch sensitivity of the Ti-6Al-4V chess pieces in this example are significantly better than the forged and cast Ti-6Al-4V alloys reported in the literature.

Example 3

As shown in Figure 4(a), the acetabular cup model was designed using CAD software. The surface of the acetabular cup has a porous structure with a thickness of 2 mm, and the thinnest part of the acetabular cup is 2 mm. Using Ti-6Al-4V alloy powder as raw material (Fig. 2, the powder diameter is 50-80 μm), the Ti-6Al-4V acetabular cup was prepared by Arcam A1 electron beam melting equipment, and the scanning speed of the electron beam was 12500 mm/s. The beam current is 25mA, and the stacking direction is vertical to the substrate. The prepared Ti-6Al-4V acetabular cup is shown in Fig. 4(b).

In this example, the prepared Ti-6Al-4V acetabular cup is subjected to hot isostatic pressing, the process is as follows: the temperature is 940° C., the pressure is 110 MPa, and the holding time is 2.5 hours.

In this example, the prepared Ti-6Al-4V acetabular cup is subjected to two-step heat treatment in the two-phase region:

(1) Two-phase zone annealing treatment Using a vacuum heat treatment furnace, the prepared Ti-6Al-4V acetabular cup was kept at 700°C for 3 hours, and cooled to room temperature at a rate of 1°C/min.

(2) The aging treatment in the two-phase zone uses a vacuum heat treatment furnace with a heat treatment temperature of 550°C, a holding time of 3h, and cooling to room temperature at a rate of 8°C/min.

In this embodiment, the relevant parameters of the tensile strength, elongation, fatigue strength, impact toughness and notch sensitivity of the Ti-6Al-4V acetabular cup are as follows: the tensile strength of the titanium alloy member is 1180MPa, the yield strength is 1100MPa, and the elongation 10%, the fatigue strength is 568MPa, and the impact toughness is 31J/cm ² . The tensile strength, elongation, fatigue strength, impact toughness and notch sensitivity of the Ti-6Al-4V acetabular cup in this example are significantly better than the forged and cast Ti-6Al-4V alloys reported in the literature.

Example 4

As shown in Figure 5(a), the hollow sphere is designed using CAD software. The wall thickness of the hollow sphere is 3 mm, and half of the hollow sphere is a porous structure. Using Ti-6Al-4V alloy powder as raw material (Fig. 2, the powder diameter is 50-80 μm), using Arcam A1 electron beam melting equipment Ti-6Al-4V hollow sphere, the electron beam scanning speed is 15000mm/s, the electron beam current It is 24mA, and the stacking direction is perpendicular to the substrate direction. The prepared Ti-6Al-4V hollow spheres are shown in Fig. 5(b).

In this embodiment, the prepared Ti-6Al-4V hollow spheres are subjected to hot isostatic pressing treatment, the process is as follows: the temperature is 920° C., the pressure is 120 MPa, and the holding time is 2.5 hours.

In this example, the prepared Ti-6Al-4V hollow spheres are subjected to two-step heat treatment in the two-phase region:

(1) Two-phase zone annealing treatment Using a vacuum heat treatment furnace, the prepared hollow spheres were kept at 750°C for 1 hour, and cooled to room temperature at a rate of 3°C/min.

(2) The aging treatment in the two-phase zone uses a vacuum heat treatment furnace with a heat treatment temperature of 450°C, a holding time of 2.5h, and cooling to room temperature at a rate of 9°C/min.

In this embodiment, the relevant parameters of the tensile strength, elongation, fatigue strength, impact toughness and notch sensitivity of the Ti-6Al-4V hollow sphere are as follows: the tensile strength of the hollow sphere is 1050MPa, the yield strength is 950MPa, and the elongation is 11 %, the fatigue strength is 550MPa, and the impact toughness is 33J/cm ² . The tensile strength, elongation, fatigue strength, impact toughness and notch sensitivity of the Ti-6Al-4V hollow spheres in this example are significantly better than the forged and cast Ti-6Al-4V alloys reported in the literature.

The results of the examples show that the method can be used to prepare Ti-6Al-4V three-dimensional components with complex structures, the process is simple, the cost is low, and it is suitable for mass production on an industrial scale. The obtained Ti-6Al-4V three-dimensional components have high tensile strength, high Toughness, high fatigue performance, high impact resistance, has very broad application prospects in the medical and aerospace fields.

Claims (10)

1. a method for electron beam Quick-forming Ti-6Al-4V 3-dimensional metal part, it is characterized in that, concrete steps are as follows:

(1) Ti-6Al-4V 3-dimensional metal part preparation, with Ti-6Al-4V powder for raw material, adopts electron beam melting rapid metallic prototyping technique to prepare Ti-6Al-4V block 3-dimensional metal part;

(2) Ti-6Al-4V 3-dimensional metal part hip treatment, carries out hip treatment to Ti-6Al-4V 3-dimensional metal part at 800 DEG C ~ 1000 DEG C;

(3) Ti-6Al-4V 3-dimensional metal part heat treatment, to Ti-6Al-4V 3-dimensional metal part 700 DEG C ~ 1000 DEG C carry out annealing in process and 400 DEG C ~ 600 DEG C carry out Ageing Treatment, the final Ti-6Al-4V 3-dimensional metal part obtaining excellent mechanical performance.

2. according to the method for electron beam Quick-forming Ti-6Al-4V 3-dimensional metal part according to claim 1, it is characterized in that, in described step (1), first at substrate surface uniform spreading one deck Ti-6Al-4V metal dust, then with electron beam, described metal dust is successively melted, deposits in vacuum chamber, by controlling electron-beam melting technological parameter, stack shaping parameter, until whole 3 d part manufacture completes.

3., according to the method for electron beam Quick-forming Ti-6Al-4V 3-dimensional metal part according to claim 1, it is characterized in that, in described step (1), Ti-6Al-4V powder is spherical, and diameter is 30 μm ~ 150 μm.

4. according to the method for electron beam Quick-forming Ti-6Al-4V 3-dimensional metal part according to claim 1, it is characterized in that, in described step (1), the process parameters range of electron beam melting rapid metallic prototyping technique is, electron beam current is 5 ~ 30mA, and sweep speed is 1000 ~ 20000mm/s.

5. according to the method for electron beam Quick-forming Ti-6Al-4V 3-dimensional metal part according to claim 2, it is characterized in that, for ensureing 3 d part global tissue and mechanical property evenly, part initial formation height should control at distance substrate 10mm ~ 30mm.

6. according to the method for electron beam Quick-forming Ti-6Al-4V 3-dimensional metal part according to claim 2, it is characterized in that, for ensureing 3 d part global tissue and mechanical property evenly, making stacked direction perpendicular to orientation substrate as far as possible.

7. according to the method for electron beam Quick-forming Ti-6Al-4V 3-dimensional metal part according to claim 2, it is characterized in that, for ensureing 3 d part global tissue and mechanical property evenly, part wall thickness should be greater than 2mm.

8. according to the method for electron beam Quick-forming Ti-6Al-4V 3-dimensional metal part according to claim 1, it is characterized in that, in described step (2), the design parameter of Ti-6Al-4V high temperature insostatic pressing (HIP) is: high temperature insostatic pressing (HIP) heating-up temperature is 800 DEG C ~ 1000 DEG C, temperature retention time is 1 ~ 3h, institute's plus-pressure is 100 ~ 200MPa, and the type of cooling is that stove is cold.

9. according to the method for electron beam Quick-forming Ti-6Al-4V 3-dimensional metal part according to claim 1, it is characterized in that, in described step (3), the heat treatment of Ti-6Al-4V 3-dimensional metal part adopts the heat treatment of two-phase section two step, and concrete steps are:

(1) two-phase section annealing in process;

(2) two-phase section Ageing Treatment.

10., according to the method for electron beam Quick-forming Ti-6Al-4V 3-dimensional metal part according to claim 9, it is characterized in that:

Described two-phase section annealing in process device therefor is vacuum heat treatment furnace, and heat treatment temperature is 700 DEG C ~ 1000 DEG C, and temperature retention time is 1 ~ 3h, and cooling velocity is 1 ~ 3 DEG C/min;

Described two-phase section Ageing Treatment device therefor is vacuum heat treatment furnace, and heat treatment temperature is 400 DEG C ~ 600 DEG C, and temperature retention time is 1 ~ 3h, and cooling velocity is 8 ~ 15 DEG C/min.