Why friction stir welding become the protagonist of aluminum alloy welding technology?

As an excellent lightweight alloy, aluminum alloy has been widely promoted in China's industrial field in recent years. Since the physical and chemical properties of aluminum alloys are different from those of traditional industrial materials such as steel, there are some bottlenecks in the use of aluminum alloys under the traditional manufacturing process conditions. Only by adopting technological innovations and even revolutions can we overcome these bottlenecks and make the excellent performance of aluminum alloys shine in various industrial fields.

Connection technology is one of the bottlenecks in the manufacturing process of aluminum alloys. The traditional connection technologies include riveting and welding, and these two methods have obvious disadvantages in terms of efficiency and performance for aluminum alloys. How to use a connection method that is both efficient and high-performance, while being able to take into account both environmental protection and green manufacturing? Does this seem to describe a perfect technology, but does it actually exist?

Friction stir welding - This term is unfamiliar to most people. Friction stir welding, as an automatic solid-phase connection technology, overcomes the problems of low efficiency and poor sealability caused by riveting, and also changes the "satisfaction of water and soil" and operator's occupational health problems of fusion welding. Only 20 years after its introduction, this technology has achieved brilliant application achievements in various industrial fields worldwide.

Welding expert Guan Qiao once commented in a report: Friction stir welding, as a more advanced and popular welding method, has been extensively applied to the welding of aluminum alloy materials, becoming the best connection technology for aluminum alloys!

Why friction stir welding become the protagonist of aluminum alloy connection technology? What are the advantages of friction stir welding? What kind of innovation has gone through? Recently, the reporter interviewed one of the earliest professional leaders in the development of friction stir welding technology in China, director of the China Friction Stir Welding Center, and Guo Guohong, general manager of Beijing Forster Technology Co., Ltd.

The more the merrier

Many parties work together to help promote

Ruan Guohong recalls that the reason why friction stir welding can be introduced into China and has been rapidly promoted and applied is due to the high vision and strong support of the Guanqiao academicians and the continuous research and research after the introduction of friction stir welding technology by the Forster Company.

In 2001, the Academician Guan Bridge who was at Beijing Aviation Manufacturing Engineering Research Institute (625 institutes) of AVIC first encountered friction stir welding technology at the British Welding Institute (TWI). He believed that this revolutionary welding technology has a huge development prospect. . After returning home, Academician Guan Bridge immediately reported his thoughts to the leader. Under the strong advocacy of Academician Guanqiao, 625 decided to cooperate with the British Welding Research Institute to carry out friction stir welding research.

Lu Guohong, who was studying welding at a foreign country at the time, was the best leader in friction stir welding technology in the heart of the Guanqiao academician. After Guan Guanshi convinced him, Luan Guoyi returned to China without any hesitation and took up the development and promotion of the application of stirring friction in China. The task of welding. In 2002, AVIC Beijing Aviation Manufacturing Engineering Research Institute and the British Welding Research Institute signed a licensing agreement to establish the China Friction Stir Welding Center, Beijing Sai Foster Technology Co., Ltd. and Ruan Guohong as general manager. This year can be said to be the first year of development of friction stir in China.

Academician Guanqiao asked Guo Guohong to develop friction stir welding technology and promote friction stir welding technology. Ruan Guohong knows that if you want to develop friction stir welding technology, you must continue to research and innovate; if you want to promote friction stir welding technology, you can not rely on their own efforts.

Therefore, Ruan Guohong set the goals of the first service to major industrial colleges and research institutes. Ruan Guohong firmly believes that if the company wants to develop further, it must be market-oriented. So since the establishment of the company, Sai Foster has not only continuously researched and developed its technology, but has also first promoted it to major mainstream institutions for common development, such as Harbin Institute of Technology, Northwestern Polytechnical University, Tsinghua University, and Beijing. Universities such as the University of Aeronautics and Astronautics, the Institute of Metal Materials of the Chinese Academy of Sciences, Yanshan University and other industrial universities and related research institutes have reached cooperation to encourage them to set up friction stir welding research majors and train professionals to develop basic cultures in a relatively short period of time. The basic structure of technological research has been established.

In this, Sai Foster played the role of the “leader” of the China Friction Stir Welding Center to promote technology and market development.

After more than 10 years of technology and market development, the current Chinese companies that can provide friction stir welding technology are not only the Forster One, but most of the suppliers are the first users of Race Forster.

In the eyes of ordinary people, Sai Foster's original measures have cultivated potential competitors for himself. However, Ruan Guohong does not think so. “Only the firewood can be high for everyone, and the development and promotion of friction stir welding technology is also the same.” Frankly. Obviously, Ruan Guohong did not regard these peers as opponents, but as teammates on the road to welding technology innovation.

Everyone rowed open a big boat. Perhaps it is precisely because of this Foster's mind that it has been able to develop friction stir welding technology in China so strong. Today, Foster provides friction stir welding technology and equipment far beyond the research level provided by the original British Welding Institute.

At present, China's friction stir welding technology has been successfully applied to high-end civil industrial fields such as aviation, aerospace, warships, and weapons, as well as power electronics and rail transit.

In the field of aerospace, Sai Foster Co., Ltd. has successively reached cooperation with China Aerospace First Institute, Aerospace 9 Institute, Aerospace 8 Institute, Aerospace 4 Institute, and Aerospace 7 Institute. It has been widely used in domestic space hosting companies and has realized various new models. The missiles are equipped with friction stir welding technology. At the same time, the mass of the friction stir welding shell is more uniform, which greatly improves the trajectory accuracy of the missile.

Then it was quickly applied in the field of track weight reduction. Under the recommendation of the Guanqiao academician, the locomotive companies affiliated to the China National Group Corporation, such as Zhuzhou Electric Locomotive Research Institute Co., Ltd., and Qingdao Sifang Locomotive & Rolling Stock Co., Ltd., were soon involved. Cars Changchun Railway Vehicle Co., Ltd., Tangshan Locomotive and Rolling Stock Co., Ltd. and other companies reached a cooperation. At present, all aluminum-alloy vehicles used in rail transit use the friction stir welding technology and equipment provided by Sai Foster.

Five advantages

Friction stir welding is developing rapidly

Friction stir welding, as a solid-phase connection method, is based on a welding method in the mode of numerical control machine tools, and it has irreplaceable technical advantages in terms of operability, precision, and pollution-free environmental protection.

First of all, friction stir welding technology is achieved in the plastic state of the material, product weld metallurgical consistency is high, the weld seam has no hot cracks, no inclusions, no porosity and other welding defects.

Secondly, the friction stir welding technology uses automated mechanical equipment for welding, which avoids dependence on the skilled worker's skill, realizes all-position welding automation, and improves work efficiency.

Third, friction stir welding technology does not require special treatment of the product to be welded, and no beveling, filler material, and shielding gas are required, which simplifies the welding process.

Fourth, the friction stir welding process does not produce defects such as smoke, spatter, ultraviolet rays, and electromagnetic radiation, and the welding process is green, environmentally friendly, and harmless.

Fifth, the residual stress in the weld of friction stir welding is low, and there is basically no deformation. The properties of the weld are close to the base material, and the mechanical properties are excellent, which improves the reliability of the weld.

In Europe, friction stir welding was first applied to the shipbuilding industry. Because aluminum alloy linings must be solved in order to manufacture aluminum alloy ships, the “skin horse phenomenon” was apt to occur with the welding method. (The hull structure is in the welding process. There will be some deformation, especially the outer plate and the superstructure. The welding deformation is particularly prominent, commonly known as the “skinny phenomenon”. This phenomenon not only causes the surface appearance of the hull to decrease, but also the material strength index does not meet the requirements, but stirs. The application of friction welding just solves this problem. Therefore, before China introduced friction stir welding, it had not been able to manufacture aluminum vessels. It was not until Beijing Forst Technology Co., Ltd. first applied friction stir welding technology on a certain type of missile launch boat to end China's failure to manufacture aluminum vessels. statement. At present, friction stir welding technology has been widely used in naval vessels and yachts. It can be said that due to the friction stir welding technology, the application of aluminum alloy in the field of ships can be continuously expanded.

Ruan Guohong revealed that in the case of a large-scale military project being trial-produced by the company, if the original welding method is used, more than ten welding seams are required, and one operator can complete the task within two days, and only two are needed if friction stir welding is adopted. It can be completed in hours and is of high quality and reliability.

As a new advanced, high-quality, and highly efficient welding method, friction stir welding technology can realize the butt joints, overlap joints, longitudinal seam welding, circumferential seam welding, variable thickness welding, unsupported double-sided welding, and space curve and surface welding of aluminum alloy materials.

According to different working environments, friction stir welding technology is also divided into friction stir welding, biaxial shoulder friction stir welding, static shoulder friction stir welding, no shoulder friction stir welding, plastic flow friction welding, material Surface Modification Treatment and Materials Superplastic forming and other welding methods and processing techniques can accomplish a variety of special welding operations.

In addition, the friction stir welding technology also made it impossible to say that aviation high-strength aluminum alloys could not be welded. As we all know, the high-strength aluminum alloy plates used in aircraft have been lapped using riveting technology, because all previous welding methods are not suitable for high-strength aluminum alloys. At present, Beijing Forster Technology Co., Ltd. has successfully realized the friction stir welding of 2XXX series, 5XXX series, 6XXX series and 7XXX series aluminum alloy materials, and is gradually applied to the aviation field.

Because of the irreplaceable advantages of friction stir welding, since the invention of the technology by the British Welding Institute (abbreviated as TWI) in 1991, its development speed has surpassed all other welding technologies and its development scale has also rapidly expanded. Friction stir welding is replacing welding and other traditional welding methods in the field of integrated welding of aluminum alloy structures.

Focus on cutting-edge technology

A new market for friction stir welding

As the first company to develop friction stir welding technology, Beijing Sai Foster has always positioned itself as the leading edge in the development of friction stir welding technology. It is not afraid of difficulties and specializes in the "hard bones" of technology.

Because of this, its technical equipment is not only sought after in China, but also by foreigners. Under the efforts of Academician Guanqiao and the team of Ruan Guohong, Sai Foster not only provided nearly 200 sets of friction stir welding equipment systems for various fields in China, but also exported to 11 countries around the world, including German customers. 8 sets. Ruan Guohong said proudly: "In the field of welding, we have been importing German equipment for a long time. Nowadays, Germany imports friction stir welding equipment from China. This is an innovative breakthrough in China's welding development."

Ruan Guohong said that in early 2016, the company signed a contract for a German train manufacturing customer. The customer put forward very high requirements for the technical specifications and delivery time of the 30-meter-long large-scale friction stir welding equipment, but he did not hesitate to accept it.

“Because the demanding requirements of our customers are an improvement on our own level, we are not afraid of high demand and are not afraid of difficulty. Without the ever-increasing demands of customers, there will be no innovation in the development of friction stir welding technology. The friction stir welding technology and equipment provided far exceeds the technology provided by the British Welding Research Institute at that time. These are all due to the constant demand of customers and the constant innovation and research of the Forster researchers.” Obviously, Guo Guohong is very pleased. It is worthwhile to think that your efforts and rewards are worth it. Ruan Guohong said that after work, he still has to work with team members to work overtime. Five hours later, foreign customers need to communicate details with them. During the conversation with reporters, they also confirm with colleagues who are preparing materials.

Ruan Guohong’s team has long established the long-term strategic goal of the company: to be a professional modernized enterprise with international core competitiveness, to achieve the ultimate in friction stir welding, a single technology, and to achieve a truly international advanced level.

Under the leadership of Ruan Guohong, Beijing Sai Foster Technology Co., Ltd. has only 93 members and the number is small, but all of them are elites. Including 1 academician, 2 researchers, 7 doctors and 24 master's technical team.

It is precisely because of such a research and development team with advanced friction stir welding technology that they have mastered the basic friction stir welding technology, engineering technology and industrialization technology in China, and promoted the development and industrial application of friction stir welding technology in China. Reliable protection.

At present, friction stir welding technology has been applied in the main welding process of aluminum alloy materials in various fields. The mission of application in the general field has been basically completed, but Ruan Guohong has not stopped, and he will focus on expanding the scope in two extreme areas. Applications: Large and thick wallboard welding and small and thin product welding.

First, apply on heavy, very thick and very long products to solve the welding of all the big slabs now, as a supplement to the existing rolling and forging capabilities, such as achieving breakthroughs in large-scale wall structures. Now, Foster's friction stir welding technology can weld single-side welding 80mm thick plates, double-sided welding can reach 150mm thick plates, next year will continue to develop single-sided 85mm thick, double-sided 160mm thick, or even thicker The material welding technology is applied to the naval cutting-edge fields such as deep-sea torpedoes. Second, applications in the area of ​​very thin and small aluminum alloy materials, such as electronic packaging, micro heat sinks, and even nano materials.

In addition, Sai Foster will also vigorously develop robotics technology, classify existing technologies, realize digitization and intelligence, shorten equipment investment, and intelligentize products and technologies, such as supporting laser scanning in the future. The robot cooperates with the spot welding robot to realize welding on a large aircraft or a plurality of robots to cooperate with each other to realize a primary application of the robot friction stir welding technology.

It is reported that the commercial friction stir welding business aircraft manufactured by Eclipse of the United States has been put into mass production. It can be seen that in the design and manufacture of feeders and large-scale main aircrafts, friction stir welding is used for the integral manufacture of important structures, and the application surface is being developed. expand.

In China, Beijing Forster Technology Co., Ltd. after years of technical research, successfully achieved the friction stir welding of China's large aircraft floor structure, new fighter cabin, fuselage, flap structure and radar cold plate and other components. Currently, more than 10 kinds of friction stir welding aluminum alloy sidings have been successfully developed for a variety of new types of aircraft, which have significant advantages in terms of aircraft weight reduction, strength enhancement, and production efficiency improvement.

In the heart of Luan Guo, this is still far from enough. The dream of Yan Guohong is to create the Chinese's own full-friction friction welding aircraft as soon as possible.

Ruan Guohong’s dream is already on the road. He said that relevant departments are now studying the C929 aircraft materials and technology. Sai Foster is also cooperating with relevant departments to carry out friction stir welding on the testing and R&D of new generation aircraft materials. It may not be long before. Luan Guohong's dream will fly to the sky!

It is precisely because of the ever-pursuing dreams and the spirit of continuous innovation such as the Forster Company that the application of friction stir welding has developed today. It is believed that in the continuous hardships and difficulties of Ruan Guohong and his team, continuous innovation and development, friction stir welding technology will become more and more important in the aluminum application world, and it will surely expand the new journey for aluminum applications.