Application field and development trend of titanium alloy 3D printing technology
3D printing (3DP) is a kind of rapid prototyping technology, also known as additive manufacturing [1]. It is a technology to construct objects by layer-by-layer printing based on digital model files and using adhesive materials such as powdered metal or plastic. 3D printing is usually done using digital material printers. It is often used in mold manufacturing, industrial design and other fields to make models, and then gradually used in the direct manufacturing of some products. There are already parts printed using this technology. The technology is used in jewelry, footwear, industrial design, architecture, engineering and construction (AEC), automotive, aerospace, dental and medical industries, education, geographic information systems, civil engineering, firearms, and other fields.
3D printing, which emerged in the mid-1990s, is actually the latest rapid prototyping device using technologies such as light curing and paper layering. It works in the same way as ordinary printing. The printer is equipped with "printing materials", such as liquid or powder, which are connected to a computer and then stacked layer upon layer by computer control, finally turning the blueprints on the computer into real objects. This printing technology is called 3D stereoscopic printing.
Advantages of titanium alloy materials in 3D printing materials
01
High specific strength
Titanium alloys are only 60% as dense as steel, pure titanium is close to the strength of ordinary steel, and some high-strength titanium alloys exceed the strength of many alloyed structural steels. Therefore, the specific strength (strength/density) of titanium alloy is far greater than that of other metal structural materials, which can produce parts with high unit strength, good rigidity and light weight. Titanium alloys are used in aircraft engine components, frames, skins, fasteners and landing gear.
02
High heat intensity
The use of titanium alloy temperature is several hundred degrees higher than aluminum alloy, can be in 450℃ ~ 500℃ temperature long-term work. The operating temperature of aluminum alloy is below 200℃.
03
Good corrosion resistance
Titanium alloy works in humid atmosphere and seawater medium, its corrosion resistance is far better than stainless steel, pitting corrosion, acid corrosion, stress corrosion resistance is particularly strong.
04
Good low temperature performance
Titanium alloy can still maintain its mechanical properties at low temperature. TA7, for example, can maintain a certain plasticity at -253℃. Therefore, titanium alloy is also an important low temperature structural material.
Application of titanium alloy materials in 3D printing
Medical field
Titanium, known as "biophilic" metal, has the advantages of non-toxic and harmless, high temperature resistance, high corrosion resistance, high strength, low density, good biocompatibility, and its elastic modulus is close to that of human hard tissue, occupying "half of the realm of medical metals". At present, the application of titanium alloy 3D printing technology is mainly orthopedics and dentistry.
The 3D printing technology was first applied to the ship-borne fighter aircraft of the United States in 2001, and the bearing structural parts of the aircraft were produced through the 3D printing technology of titanium alloy and applied to aviation production. In 2011, the University of Southampton in the UK used 3D printing technology to produce the entire frame of a drone, including the wing, control panel and hatch. After 2012, the application of titanium alloy 3D printing technology in the aviation field has achieved unprecedented development. Titanium alloy parts are not only widely used in aircraft manufacturing, but also new titanium alloy materials begin to be applied in rocket, space shuttle and other space equipment.
Hand plate and mold field
3D printing also has unique advantages in the field of hand plate and mold. Compared with traditional production methods, 3D printing is controlled by computers and can control the size strictly according to 3D software drawing. For complex parts, there is no production path limit, can greatly reduce the model and mold preparation time, improve the accuracy and quality of the model, save a lot of time and money.
Development trend of titanium alloy 3D printing technology
Titanium alloy 3D printing technology, as a cutting-edge manufacturing technology, integrates design and manufacturing, has attracted wide attention in recent years, and has shown broad application prospects in aerospace, national defense military, biomedicine, automotive high-speed rail and other advanced fields. However, compared with the traditional manufacturing technology, the development history is only about 30 years. Compared with the world's advanced countries, there is still a big gap, such as: titanium alloy parts forming efficiency is low, precision has not reached a high precision level, equipment and material preparation cost is high, and still has not realized large-scale industrial and commercial applications, especially the problem of forming parts defects suppression. At present, the defects existing in the forming process of parts in our country. The research on spheroidization, cracks, pores, warp deformation and so on is still in the preliminary stage, and there are still a lot of urgent research work. The future development trend of titanium alloy 3D printing technology is as follows:
(1) In terms of materials, research and development of new spherical titanium alloy powder production equipment and preparation process, improve the quality of titanium alloy powder (particle size, sphericity, fluidity, gas inclusion, etc.), so as to improve the structure and mechanical properties of the parts. In addition, the cost is reduced by increasing the yield of powder and recycling of powder.
(2) In terms of equipment, on the one hand, the forming efficiency and accuracy of the equipment should be improved, and the cost should be reduced; In addition, we also need to develop large-scale industrial printing equipment to gradually realize large-scale production and application.
(3) In terms of testing, with the development of 3D printing parts to the direction of large size, complexity and precision, many traditional nondestructive testing methods have blind spots, so it is necessary to develop new nondestructive testing technologies; The on-line detection technology through real-time monitoring of organization and defect is one of the key research directions in the future. In addition, the establishment and improvement of nondestructive testing standards is the basis for the wide application of 3D printing technology.
(4) In terms of technology, further optimize the 3D printing technology, restrain the defects in the forming process, and improve the mechanical properties of the formed parts. In the process of forming, some key problems, such as the evolution law of internal stress, the behavior of deformation and cracking and the mechanism of defects, are still the problems that need to be studied emphatically in the future.
