Titanium alloy powder metallurgy process
Titanium and its alloys are widely used in aerospace, military industry, shipbuilding and other fields due to their low density, high specific strength, good biocompatibility and medium and high temperature stability, as well as good mechanical properties and excellent corrosion resistance. Traditional melt forging processing technology has advantages in preparing large-sized, simple-shaped titanium profiles or products. However, there are problems such as low yield, large waste of resources, and high production costs in preparing complex-structured, small and medium-sized titanium products. Powder near-net forming technology can exactly make up for this technical defect. Through the technical route of powder preparation and near-net forming, titanium alloy products of various sizes and structural characteristics can be manufactured in batches or customized. This type of small and medium-sized products has greater application potential and product added value in the fields of aerospace, military industry, medical care and civilian consumption. It is an important direction to promote the transformation of low-carbon and green manufacturing in the titanium industry in the future.
1. Pressing and sintering
The United States has been researching very early in the preparation of titanium alloy products by pressing and sintering titanium powder. Dynamet Technology has been committed to the production of titanium powder press-formed products. As shown in Figure 1, some products have been used on a small scale. The first powder metallurgy titanium product produced by the company was the Ti-6Al-4V alloy preform for the dome casing on Raytheon's Sidewinder missile. It later also produced powder metallurgy Ti-6Al-6V-2Sn alloy products for the Stinger. Missile warhead casing. my country's Northwest Nonferrous Metal Research Institute has more than 30 years of experience in research and development in the field of titanium powder near net shaping. The porous titanium products developed have been used in chemical industry, food and other fields.
2. Hot isostatic pressing
The hot isostatic pressing (HIP) process was invented by the Battelle Research Institute in the United States in the 1950s. This technology uses inert gas as the pressure transmission medium at a temperature of 850-2000°C and a temperature of 100-200 Under the synergistic effect of MPa air pressure, the technology of high-temperature pressing and sintering of products is currently the most important means to fully densify powder near-net shape titanium and titanium alloy structural parts. The products have uniform structure, no texture, no segregation, etc. Features.
The development of titanium alloy powder hot isostatic pressing technology abroad began in the 1850s. The Russian Light Metal Research Institute was the first in the world to develop a powder titanium alloy hydrogen pump turbine with an overall complex shape as early as the 1970s, and developed it in RD- It has been applied in the 0120 hydrogen-oxygen engine; the United States first realized commercial application in the aerospace field in the 1990s, and gradually expanded to the aviation and weapons fields, such as the connecting rod of PW's F110 engine, the Tomahawk cruise missile F107 Engine compressor rotors, Sidewind missile hoods, F107 cruise missile engine impellers, and Stinger anti-aircraft missile warhead casings, etc.
(a) Birmingham & R-R: V2500 titanium alloy casing (b) Synertech ELI TC4 impeller (c) Synertech ELI TC4 casing (d) Courtesy Turbomeca helicopter diffuser
3. Powder injection molding
Metal Injection Molding (MIM) technology can directly produce parts with or close to the final shape, avoiding or reducing machining, and significantly reducing preparation costs. Therefore, powder injection molding technology is one of the most effective technical means for batch preparation of titanium and titanium alloy application parts. 3C products in electronic communications (including mobile phones, smart wearables, eyeglass frames, and 5G signal components) are the main application areas of powder injection molding technology, accounting for 84.2%. At this stage, iron-based materials are mainly used, and the lightweight design and high-quality pursuit of materials are the main directions for the future development of 3C products. Titanium alloys have the characteristics of low density (the density is only half that of iron-based materials), high strength, and corrosion resistance, which can meet the needs of lightweight and high-quality design of future materials. According to statistics, the market size of China's titanium injection molding industry reached 680 million yuan in 2020. Based on demand-side investment and supply-side revenue growth, the market size is expected to reach 2 billion yuan in 2026, with an annual growth rate of 20.13%.
Huawei watch titanium alloy case Apple mobile phone titanium alloy frame
4. Additive manufacturing
Additive Manufacturing (AM) is a forming technology that accumulates points, lines and surfaces layer by layer. It is not affected by the complexity of the parts and can automatically, quickly and accurately complete the design and manufacturing of complex parts. Compared with traditional manufacturing technology, additive manufacturing has unique advantages in design freedom, complex part molding, and material utilization, making it a promising titanium alloy manufacturing technology. According to SmarTech analysis reports, the global metal 3D printing market reached US$3.3 billion in 2019, including 3D printing equipment, materials and services, and is expected to reach US$11 billion in 2024. Titanium alloy is the most important printing metal. Aerospace and military defense are the largest users of titanium additive manufacturing. It has been successfully used for the direct forming of small precision components of aerospace engines and large complex aviation components, such as space launch systems, aircraft wings, integral control surfaces and doors. , engine blades and other key aerospace equipment components.
Powder is the basic raw material for the above-mentioned powder metallurgy near-net forming process, and its cost and quality are the most important factors affecting the price and performance of powder metallurgy products. To this end, Beijing Zhongkehong Titanium New Material Technology Co., Ltd. has developed a new process for the preparation of fine titanium powder after three years of research and development, aiming at the technical bottlenecks of the traditional preparation process of titanium alloy powder being complex, expensive and low in fine powder yield. Completed the design and development of powder production-level equipment and achieved batch preparation of new high-quality titanium powder with controllable particle size. The powder fine powder yield has been increased from the traditional 35% to 80%, and the cost has been reduced by more than 40%. It can be applied to high-end manufacturing fields such as powder injection molding, additive manufacturing, and powder hot isostatic pressing. The main product types include pure titanium, GR5, BT20 and other brands of high-quality titanium-based powders with controllable particle sizes, as well as hydrogenated titanium-based alloy powders, hydrogenated dehydrogenation powders, customized metal-based composite material powders represented by titanium, etc. .
