On January 9, China Nonferrous Metals Industry Association organized an evaluation meeting on the project results of "uniform strengthening and toughening of magnesium / aluminum large thin-walled and high steel bars and 'long reinforcement' extrusion technology" completed by Central North University in Taiyuan, Shanxi Province. The meeting invited Wang Yide and Xie Jianxin, academicians of the Chinese Academy of Engineering, Jia Xing, vice president and secretary general of China Nonferrous Metals Industry Association, Lu Xin, former secretary general of the plastic Engineering Association, and other experts in the field of non-ferrous metal materials and processing to form an evaluation team.
The project is supported by the key projects of the National Natural Science Foundation and the National Defense "973" Program, and is oriented to the needs of the new generation of key models of national defense. The forging forming design concept based on the overall uniform strength and toughness and the bearing capacity of key parts is established based on the service conditions of components. An integrated control method of performance and precision is put forward, which can continuously refine and reasonably distribute the structure and "grow reinforcement" in the whole process from ingot opening to component forming. The main innovations include:
01. A new extrusion process for magnesium / aluminum lightweight large thin-walled high-bar components is proposed and developed, which solves the manufacturing technical problems of high-performance key components of aerospace equipment.
02. The control technology of microstructure uniformity of large size billet by expanding extrusion and upsetting was invented, which solved the problem of controlling the uniformity of microstructure composition of high alloyed magnesium / aluminum.
03. A complete set of extrusion forming equipment for large thin-walled high-bar components is invented and developed, and the precise forming and manufacturing of high-quality components is realized.
The technical specifications are as follows: the ratio of height to diameter of casting rod is more than 7, and the diameter of rare earth magnesium alloy billet is more than 600mm and the length is 1100 mm;. The forming force of the complex component is about 1 / 3 of that of the traditional extrusion, the inner ring bar is more than 60 mm, the load-bearing capacity of the rib is 1 / 1.5 times higher than that of the machine, the three-dimensional uniform consistency of mechanics is 95%, the material utilization rate is increased by 2 times, the qualified rate is more than 95%, and the mechanical cutting working time is reduced by 30%.
The technology has good reproducibility, high maturity and reliable quality, and the expert group believes that the overall technology of the project has reached the international advanced level.
The Precision forming Center of Central North University has been engaged in the research on the new forming technology and industrialization of aluminum-magnesium alloy complex components, and has done a series of pioneering work in the basic research and engineering application of precision plastic forming of lightweight components. The team has successively won the "National Defense Science and Technology Innovation team" and "Shanxi Science and Technology Innovation key team", built the Extrusion forming Technology Innovation Center for complex components of National Defense Science, Technology and Industry, and the Engineering Research Center of the Ministry of Education for Deep processing of magnesium-based Materials, and has formed a first-class R & D platform for R & D, testing and trial production of large-scale complex high-performance magnesium / aluminum alloy components. The theory and technology of directional distribution of fiber structure, continuous refinement of grains, uniform control of properties and composite extrusion with warm forming as the core are proposed to greatly improve the performance and material utilization of large and complex components. the problems of overweight and high cost of major national models are solved. It has created a precedent for the application of high-strength aluminum alloy in components with large impact load and high fatigue life, and solved the problem that a certain type of wheeled self-propelled gun, 8 × 8 wheeled chariot, individual weapons in mountain operations, missiles and other equipment can not be shaped. The aluminum alloy wheel rims of heavy combat vehicles and aluminum alloy seat plates of light 82 mortars end the history of steel components, the compressive bearing capacity of the shell of HQ series warheads is doubled, and the diving depth of torpedo cabin is increased from 400m to 600m under the premise of unchanged structural materials. The new forming technology and equipment of large and complex magnesium alloy components are invented, which solves the technical problems of low performance and can not be formed, and breaks through the bottleneck that the new generation of equipment lightweight wants to use magnesium alloy but can not be used. The developed heat-resistant magnesium alloy large-scale thin-walled inner rib shell has the same performance as Al-Li alloy and reduces weight by more than 20%. It has been used in the development of new strategic weapons; more than 50 kinds of magnesium alloy components have been applied in Shenzhou spacecraft, helicopters, new generation chariots, etc., and a magnesium alloy arson moment production line has been built, which provides a guarantee for the development and production of a new generation of equipment, and effectively improves the combat and technical indicators of high-end equipment and aerospace carrying capacity.
The person in charge, Professor Zhang Zhimin, is the chief of the "973" technology for national defense. Since graduating from Harbin University of Technology in 1982, he has been engaged in the research on the new forming technology and industrialization of aluminum-magnesium alloy complex components, and has successively won the eighth "Science and Technology Special Award of the Chinese Institute of military Industry" and "he Liang he Li Foundation Science and Technology Progress Award". As the first adult, he won 1 national second prize for scientific and technological progress, 3 first-class prizes for science and technology at the provincial and ministerial level, 10 second-class prizes, and authorized more than 80 national invention patents and 2 American invention patents. And a number of patents have been transformed, two WJ industry standards have been formulated, and the related research results have been published in domestic and foreign academic journals such as "Materials and Design", "Journal of Alloys and Compounds" and "Journal of Mechanical Engineering".