For the solid state welding process of friction welding, weld heat affected zone relatively, narrow, small grain, the weld quality is easy to control, low manufacturing cost. Half shaft to welding generation of forging, friction welding instead of CO2 gas shielded arc welding, can reduce the cost of. The transmission shaft, universal joint fork parts are made of CO2 gas shielded arc welding, the production efficiency is relatively low, if the friction welding process, without any filling of auxiliary materials, and is conducive to the improvement of the working environment, reducing pollution.

According to incomplete statistics, industrial developed countries the United States, Germany, Japan and some famous automobile manufacturing company, has more than 100 kinds of auto parts using the friction welding technology. At home, China heavy duty truck has cast steel axle housing and shaft friction welding. Friction welding technology used in home, be imperative. The next 5 to 10 years to increase efforts to develop some new friction welding method ( phase friction welding, linear friction welding, radial friction welding and friction stir welding ), and gradually improve and expand its scope of application.

In recent years, in order to adapt to the application of new materials and new structure, important progress has been made at home and abroad in friction welding and related technology, in which linear friction welding ( Linear Friction Welding ), friction welding ( Consumable Rod Frictionsurfacing ), friction stir welding ( Friction Stir Welding ), friction plug welding ( Friction Plug Welding ) etc. known as the " science friction ( Science Friction ) technique is the most representative of the advanced friction welding. These novel friction welding technology has not only expanded the scope of application of the friction welding, welding parts and improves the overall performance and reliability, make those difficult to weld welding or not welding material can obtain high quality. Research on advanced friction welding technique has great theoretical significance and engineering application value.

Friction stir welding is the Welding Research Institute of England ( The TWI WeldingInstitute ) in 1991 developed a patented welding technology. With the conventional friction welding, friction stir welding is the use of friction heat as heat source. The difference is that, friction stir welding seam welding process is composed of a cylinder shape into the workpiece, through high speed rotating head, and the welding workpiece material friction, so that the material temperature of junction increased softening, and the friction stir welding to complete.

Friction stir welding is a welding process of a new type of solid phase in aluminum alloy welding the poor, particularly suitable for welding plate, more attention at home and abroad in recent years, the technology has good welding quality, high productivity, without opening a groove plate, a welding, welding has been successfully used in aluminum, copper alloy sheet. Because of its energy-saving, clean, high quality, simple equipment and many other advantages, is to expand the application of. With the establishment of China FSW center, will be more and more Chinese enterprises more benefits from this revolutionary technology.

Technical characteristics of the mixing friction welding

Friction stir welding is a solid connection technology, compared with welding, welding of aluminum alloy have several outstanding advantages of friction stir welding: welding plate, do not need to open the V or U shaped groove weld on before, also do not need to prepare for the complex welding; welding deformation and internal force after the special small; welding without radiation, splashing and harmful gases generated; welded joint with excellent performance, no cracks, porosity and shrinkage defects in welds, can realize the full range of welding. Stirring friction welding is the biggest advantage : welding of high strength aluminum alloy which is not recommended by fusion welding.

Through continuous efforts of people, friction stir welding limitations to reduce unceasingly, but there are still some deficiencies, such as: the welding welding welding speed slow; welding must clamp, also need the backing plate; welding seam after leaving the keyhole; stirring head wear out quickly. At present, because the stirring head shaped refers to limit the rod material, friction stir welding is used only to connect aluminum alloy products. According to reports, the British Welding Research Institute of technology is developing titanium alloy friction stir welding. At present, the research and application of friction stir welding of aluminum alloy, steel and other major or high melting point materials. The United States of America MEGASTIR company developed with forced cooling device of polycrystalline cubic boron nitride PCBN stirrer, and the United States Department of energy cooperation in the development of friction stir welding steel pipe, and in 2003 will be the system used to connect the field steel alloy of natural gas pipeline.

The friction welding technology research

1 foreign research status

Although the friction stir welding technology is a new technology, from the invention in just 10 years, but because of its unique advantages, has achieved a breakthrough development and application in many fields of automotive, aerospace, marine, rail transportation, power electronics, construction, especially in aluminium alloy has got the large-scale industrial application. Typical examples include: the United States NASA Delta rocket series, the United States Eclipse small business machine, Ariane rocket engine, Norway aluminum alloy yacht, the Japanese Shinkansen etc.. Therefore, the friction stir welding technology is a very mature technology.

In Norway, has used the technology of welding speed boats for aluminum structure 20m; cryogenic vessel American Lockheed Martin Aerospace Corporation with the welding technology of the space shuttle external storage of liquid oxygen, at the Marshall Space Flight Center, has been using the technology of welding the large cylindrical container. However, FSW technology has extensive application prospects in the shipbuilding and marine industry and the aerospace industry, also have great potential for application in railway transportation, highway transportation, construction industry, electrical industry. The commercial application of the United States of America several automakers have investment to study FSW technology, including the possible application areas: bracket engine and chassis, hydraulic forming pipe fittings, spatial component, truck body, crane, fuel tank, caravan, motorcycle and bicycle frame, lifting box and magnesium, aluminum and magnesium alloy joints. With the in-depth research of FSW technology, its application in the field of industry will continue to expand.

2 of the domestic research status

At present the domestic auto industry production is used in many design and technology abroad has been mature application, to produce just 10 years, the industrial applications of applied only at the beginning of the FSW technology is still blank. But no matter from the vehicle performance and fuel consumption into consideration, lightweight is the development trend of the automotive industry, and aluminum alloy, magnesium alloy is one of the two alternative material mainly uses the lightweight of automobile development, the technology of FSW in the comparative advantage of magnesium alloy and other new type materials, the welding of aluminum alloy, it will it is one of the most important means to manufacture domestic auto industry.

After decades of development, the friction welding technology in domestic has the expertise, equipment, control the scale process, inspection, complete, and also formed a certain independent system on the basis of the theoretical study.

The widely application of friction welding technology in China, can weld diameter 3 ~ 120mm diameter of workpiece and 8000m large cross section tube, but also the development of phase and radial friction welding and friction stir welding technology. Not only can be welded steel, aluminum, copper, but also successfully welded dissimilar metal temperature, strength grade difference of dissimilar steels and dissimilar metals greatly and the formation of low melting eutectic and brittle compounds.

In recent years, friction stir welding technology has attracted the attention of scientists in China, has carried out on aluminum alloy ( such as antirust aluminum, aluminum, aluminum, aluminum etc.), friction stir welding of pure copper and PVC plastic materials such as titanium, while also actively carry out technology research of friction stir welding of magnesium alloy and steel alloy, at the same time, mechanism of friction stir welding, microstructure, mechanical properties and friction stir welding core technology of mixing first have carried out in-depth research, and achieved a certain engineering application.

Technology application

Since the invention of FSW, because of its good, microstructure of weld joint with excellent mechanical properties, have shown a strong creative vitality and broad prospects in the automotive, aerospace, shipbuilding and railway vehicle manufacturing field, and has been widely used.

1 road traffic

For road transportation industry, the application of FSW in the manufacturing field are mainly as follows: high speed train, railway train, subway cars and trams, container; main application in automobile engine, chassis, body bracket for automobile wheel hub, hydroforming tubes, accessories, car door preform, the space frame, car body, truck tail lifting platform, the car jack and armored car deck protection etc.. FSW study on industrialization of Alstom company in France and Denmark DanStir company is currently vehicle parts; Hitachi in single-layer and double-layer extrusion connection using the FSW technology, used in the manufacture of suburban express train vehicle; Sumitomo light metal company has F S W technology for metro vehicle, the welding workpiece length is more than 76m, and the bonding quality is good; the Japanese Sumitomo light metal production company FSW welding plate has been used in the manufacture of Japanese Shinkansen railway vehicles, at speeds of up to 285km/h, quality fully qualified.

2 Aerospace

In the field of aviation, aircraft components assembly connection uses a lot of riveting and bolt connection structure, such as the Airbus A340 aircraft on the use of more than 1000000 rivets riveting, if instead of using FSW, FSW has a faster speed than the manufacturing rivet, on the other hand, the reduction of FSW in the manufacturing process inventory parts at the same time, also greatly reduced the weight of the structure plane. In a word, the appearance of FSW technology provides a new way for the aerospace industry design and manufacturing, and gradually put into actual production.

2 shipbuilding

Shipbuilding and marine industry is FSW first two industrial areas of commercial applications, mainly used in the deck, side panels, waterproof wall, the hull, main components, helicopter landing platform, water stations, marine structures, sailing masts and structural parts. The traditional aluminum alloy material method of attachment for riveting and welding, riveting increases the manufacturing time, manpower and material consumption, and the aluminum alloy welding is easy to produce deformation, defects and dust, also limits the use of arc welding. So the development of FSW technology, the ship to replace traditional to preform modular manufacturing high integrated degree, strengthen manufacturing structure, is the development of shipbuilding technology and the revolutionary progress.

The 4 tool industry

In the production of a variety of drill bits, taps, reamers, knife first process, the country has more than 30 tool factory to adopt new technology of friction welding. The equipment used for domestic C20, C25, C40 friction welding machine or special tool for friction welding.

5 other areas

On the other hand, FSW also has many applications, such as aluminum alloy bridge, civil construction industry in the decorative panels, door and window frame, pipe, aluminum alloy reactor, heat exchanger; the electronics industry in the engine casing, electrical connectors, electrical appliance etc.. In addition, FSW is also used in the refrigerator cooling plate, kitchen appliances, " white " household articles and tools, natural gas and liquefied petroleum gas storage tank, household decoration etc..

In a word, the development and application of FSW technology has just begun, the future will have great potential application prospect.

Technology development trend

As a green welding technology revolutionary, FSW appears to have a great impact on the development of technology and promote the connection, the application rate has far exceeded the butt welding of metal -- from development to composite and steel materials, in welding of dissimilar materials also showed a good start. With the development of welding equipment and welding, the application of FSW welding materials will be more extensive, and can increase the welding speed, optimization of joint performance, reduce cost and realize automatic production.

Friction stir processing in the process of superplastic aluminum alloy thin crystal preparation and aluminum alloy microstructure modification shows that, it is a processing technology is very effective, most recently in composite material preparation, material synthesis has also shown a good application prospect. Believe that with the in-depth study, friction stir processing will become the material processing technology is a mature, versatile, and has been applied in the industrial field.

Development status of friction welding technology in our country is not adapt to the needs of the rapid development of the national economy. The next 5 to 10 years China's friction welder author also in material welding, friction welding method of welding, friction welding equipment and welding applications spread more in-depth study. The new development of friction welding process, namely the three-body friction welding, linear friction welding, friction stir welding and embedded friction welding.

Conclusion

Along with the people to the friction stir welding technology improvement of understanding, is expected in the near future, connecting the aluminum alloy, magnesium alloy, zinc alloy, titanium alloy and other light metal material mainly by the friction stir welding to complete, especially in the aluminum alloy car, rocket, aluminium alloy high speed train, aluminum alloy speedboats etc. the project of mixing.