Beijing National University of Aeronautics and Astronautics' National Engineering Laboratory for Large-scale Metal Component Additive Manufacturing is led by the academician of the Chinese Academy of Engineering Wang Huaming. After more than 20 years of unremitting research, it is the first in the world to make new contributions to China's aero engine technology overtaking developed countries. Recently, it has successfully developed the world's largest laser additive manufacturing equipment with original core technology (forming capacity of 7 meters × 4 meters × 3.5 meters), and the world's largest 16 square meter 3D printing (a large bomber) an engine titanium alloy Strengthen the box. On January 18, 2016, the project "Laser Forming Technology for Large-scale Complex Integral Components of Aircraft Titanium Alloy" hosted by Academician Wang Huaming won the first prize of National Technology Invention.
According to the public information at home and abroad, Academician Wang Huaming has made significant progress in China ’s new generation of heavy and medium stealth fighter engine key components: high-temperature titanium alloy dual-performance integral impellers, using laser rapid forming dual-phase titanium alloy “special heat treatment” In the new process, laser additive manufacturing has produced an advanced aero engine titanium alloy monolithic disc with gradient structure and gradient performance, which has extremely excellent comprehensive mechanical properties.
The excellent combat performance of the new generation of high-performance military aircraft strongly depends on the application of advanced high-thrust-to-weight-ratio aero engines, and the integrated blade disk technology integrates engine blades, disks, and other parts into an integrated component, which can greatly reduce the number of parts and structure. Quality, thereby improving the power-to-weight ratio and reliability of the engine. According to some data, compared with the traditional tenon connection structure, each overall leaf disk can reduce weight by about 30%.
At present, the manufacturing method of the dual-performance integrated leaf disk technology is mainly welding, and the blades and disks with different properties are welded as a whole through linear friction welding and other technologies. However, the biggest problem with the welding method is that the connection area tends to become a weak link of the entire component, which is an important hidden danger for high-speed rotating parts of aero engines that emphasize high reliability and long life. With the development and maturity of additive manufacturing technology, it has been proposed that blades be grown directly on the disc body, and by using a coaxial powder feeding laser cladding method, a boss is pre-processed on the edge of the titanium alloy disc body and stacked layer by layer. Into titanium alloy blades.
Academician Wang Huaming's team has found through long-term research that during the titanium alloy laser additive manufacturing process, there are two dominant solidification modes in the solidification of the mobile molten pool: epitaxial growth at the bottom of the pool and heterogeneous nucleation on the surface of the molten pool. Active control can realize the active control of solidified grain morphology and mechanical properties of additive manufacturing metal components. The first molten pool method can obtain a directional growth of a full columnar crystal structure, which has excellent high-temperature durable creep properties; the second method can obtain a component with an isotropic solidified structure with excellent isotropic mechanical properties. These two methods can obtain the "reinforced concrete-like" mixed solidified grain structure through the artificial alternate arrangement. This kind of mixed solidified grain structure has not been reported so far at home and abroad, and traditional metallurgical forging technology cannot be prepared. This technology achieves precise control of the overall performance of the overall blade disc blade and disc body, especially the key transition area of the overall blade disc body to the blade, achieving a smooth and gradual transition in tissue performance and meeting the requirements of aero engine experts .
Academician Wang Huaming's team also conducted in-depth research on the follow-up heat treatment technology of the dual-performance integrated leaf disc technology of laser additive manufacturing. After special heat treatment, its plastic deformation resistance, especially crack propagation resistance is extremely excellent. Compared with traditional forged titanium alloys, its The fatigue crack propagation threshold is increased by 61%, and the fatigue crack growth rate is reduced by more than an order of magnitude. With the gradual maturity of the dual-performance integrated fan and high-pressure compressor blade disc technology for laser additive manufacturing, the additive manufacturing technology of high-temperature alloy turbine discs may become the next major technical difficulty to be solved by the academician Wang Huaming's team. Ultra-developed countries make new contributions