Using friction heat welding originated a hundred years ago, after half a century of research and development by the friction welding technology has gradually matured, and enter the application stage. Since the 1950's friction welding true welding qualified welded joints since, with its high quality, efficient, highlighting the advantages of low consumption and environmental protection by all industrial power of attention. Friction welding country began in 1957, the birthplace of Harbin Welding Institute, is one of the first few countries in the world to carry out research on friction welding, we made a lot of impressive results.

The main advantages of friction welding technology comes down to the following aspects:
(1)
Good quality and stable joints. Welding process by the machine control, easy monitoring parameter setting, good repeatability, does not depend on skill level and attitude of the operator. Melt welding process does not occur, is a solid hot welding joints made of satin organization, the weld will not appear porosity, segregation and inclusions, cracks and other casting organizations crystal defects, welded joint strength is far greater than welding, brazing strength, meet or exceed the strength of the base material;

(2)
High efficiency. Weldment preparation usually less demanding, easily automated welding equipment, can be produced on the assembly line, each welding time in seconds, usually only a few tenths to tens of seconds, the other welding methods such as welding, brazing can not compared;
(3) energy, materials, and low consumption. Only the power required and conventional welding processes 1/5 to 1/15, no welding, flux, solder, shielding gas, not Required fields with metal, but also without a consumable electrode;
(4) good weldability. Especially for welding dissimilar materials, compared with other welding methods, friction welding has unique advantages, such as steel and copper, steel and aluminum, steel and brass, and so on;
(5) environmental protection, pollution-free. Welding process does not produce smoke or harmful gases, no splash, no solitary spark of light, no radiation.
Because of these advantages, friction welding technology touted as a future green welding technology.
Friction welding technology development in China and application status
After decades of development, the friction welding technology in the country now has a complete set of professional and technical scale include technology, equipment, control, inspection, and in the basic research has also created a certain amount of independent system.
1 Friction welding technology and Application

The current application of friction welding technology more widely, can be welded workpiece diameter 3.0 ~ 120mm and 8000mm? The large cross-section pipe, but also the development phase radial friction welding and welding technology, as well as friction stir welding technology. Not only can weld steel, aluminum, copper, but also successfully welded high temperature strength level vary greatly dissimilar steel and dissimilar metals, and the formation of low melting point eutectic and brittle compound of dissimilar metals. Such as high-speed steel - steel, heat-resistant steel - low alloy steel, high temperature, and gold - steel, stainless steel - mild steel, stainless steel - electromagnets and aluminum - copper, aluminum - steel. With the development of China's aerospace industry, but also accelerated the friction welding technology to penetrate these areas, carried out aero-engine rotor, landing gear structural parts, fasteners and other materials (Ln718
Ti17 300M GH159
GH4169) and friction welding technology test metals and ceramics, composites, superalloy, the brazing process some electrical materials have begun replaced by friction welding. Electromagnet - stainless steel, tungsten copper alloy. At present, China uses friction welding method of welding products include: friction welding serpentine pipe friction welding, valve industry valve flange and valve sealing seat of the boiler industry, the thrust bearing industry side bearing friction welding, tool industry drill , cutter, Reamer Friction Welding edge portion and the shank, automotive and locomotive engine industry bimetallic exhaust valve, valve mandrel, diesel preheating chamber nozzle, axle, torque tube, engine turbocharger shafts, shaft submersible pump, stainless steel water connector copper, aluminum and copper transition joints, textile machines shuttle core, spherical plain bearings, masonry tools, geological drill pipe, drill pipe, solid, hollow rod, aviation engine integrated gear, woodworking Multi-axis machine tool and so on.

2 Theoretical Studies and Engineering Application

The formation of scientific and technical personnel of high temperature plastic friction welding surface of the metal layer, flow, expand and welded joint formation mechanism of energy conversion and friction welding process control, a large section of drill pipe friction welding process and the strength and toughness of control, friction welded joints gray leaf spot defect formation mechanism and joint fracture morphology and fracture strain, aluminum - copper thin-walled tube mechanism and friction welding and weld joint performance compound phase formation mechanism and other aspects of a more in-depth fundamental research work.

In engineering applications for a number of issues need to be solved to carry out the friction welding technology research topic. Experimental study on friction welding process in which the head is a thermomechanical treatment applied scientific research work have representation, the first to introduce the study of deformation strengthening and phase transformation strengthening by changing the combination of conventional continuous drive friction welding process in the field of friction welding, The welding process after welding heat treatment process with the implementation of the merger process, the welding heat and brake energy use in the friction welding machine friction welding head directly thermomechanical treatment, heat treatment device on the machine can be equipped with more effectively achieve the phase change of control conditions, such you can put in high temperature deformation friction welding process a large number of dislocations introduced by quenching the phase change firmly riveted Zhazhu full deformation strengthening conventional methods can not be achieved with a single Toughening effect and phase transformation strengthening the dual role made. Achieved without reducing the joint strength of the premise, toughness than leveling the quality of the base material, this technology not only improves the quality of welding and simplifying the process, reducing the number of post-weld heat treatment heating, reducing costs. The research is a world leader, currently on the sucker rod, tubing and drill pipe repair production was popularized. To control the aluminum - copper transition joints brittle layer, we studied the low-temperature friction welding and used in production. In recent years, within the superplastic temperature range below the transition temperature friction welding were studied, and achieved initial results; in welding quality monitoring, has developed a friction welding power controller and computer extremes quality monitoring devices. Computer quality monitoring device is an axial pressure welding process, spindle speed, friction torque, axial shortening weldment variation, time, welding temperature and deformation heat treatment temperature on the quality of welded joints of the main parameters to be monitored. In welding, friction welding process information and sensor technology, friction welding parameter calculation and real-time monitoring and closed-loop control of new materials, friction weld defect formation mechanism and mechanical behavior, strength and toughness of friction welding head control, friction welding physical parameters field ( technology and other aspects related to the test temperature, stress and strain fields) numerical simulation, and high-speed photography, spectrum analysis, also conducted a more systematic and thorough research.

FSW technology in recent years has aroused great attention of scientists, has launched a stirring of aluminum (such as rust-proof aluminum, wrought aluminum, hard aluminum, hard aluminum, etc.), copper, PVC plastic and other materials Friction welding research, while still active in research FSW alloy, magnesium alloy and ferrous metals, as well as mechanisms for FSW, microstructure, mechanical properties and friction stir welding class core technology and launched a thorough stirring research. And made certain engineering applications.

3 friction welding manufacturing and related technologies

China's existing six hundred sets of friction welding, mostly continuous drive friction welding machine. In recent years, due to the strengthening of the German KUKA, Nitto Zhushikuaishe, US companies such as MTI friction welding machine manufacturing companies to communicate with the introduction of the prototype, welder has used the hydraulic motor driven spindle system, a series of bearings - cylinder liquid balance rotary piston force balance, multi-plate clutch coating powder metallurgy, rolling guide and a programmable logic controller (PLC) control and other advanced technology, the welder manufacturing level has been greatly improved.

As the actual production. For other types of domestic friction welding machine has also been developed, such as welding equipment factory in Changchun developed a small tonnage of inertia welding, friction welding phase, Harbin Welding Institute developed with the thermomechanical treatment function and automatic tape machine quenching unit to fly hybrid friction welding edge devices, frequency control phase friction welding. Harbin Measuring & Cutting Tool Works developed a 20T double friction welding machine, China North Industries fifty nine Institute developed a small tonnage radial friction welding, Beijing FSW Technology Co., Ltd. developed a series of friction stir welding, etc. These Welder some technical indicators and manufacturing level has reached or close to the level of similar foreign welders.

Faced with the need of the domestic market, friction welding to the series production is also direction, the current domestic production of welding is the largest tonnage 1250kN, the minimum is 5KN. In short, the domestic welder series, variant few varieties are relatively simple, yet supercomputers and microcomputers. And welder matching deburring device, automatic loading and unloading device, post weld heat treatment, nondestructive testing devices, although there are different types, but these still relatively specialized, there is no universal standard series, to be constantly improved. China also has its own friction welding industry standard, with the improvement of manufacturing technology, this standard will be revised toward a higher level direction.

Looking friction welding technology development

Current development of friction welding technology still meet the needs of rapid development of the national economy. Next 5--10 years, China's friction welders more in-depth study authors also launched in welding, friction welding method of welding, friction welding applications friction welding equipment and materials.

1 material weldability

The main aim of difficult welding and weld those new welding materials, Friction welding Friction welding as titanium and stainless steel friction welding of titanium and aluminum, titanium and copper, the friction welding of high melting point materials, light metals Friction welding welding, friction welding powder alloy materials, new materials, friction welding, friction welding cast alloy steel with active metal friction welding, etc. materials. Friction welding of materials physics, chemistry, mechanics basic theory of metallurgy further study, to broaden the field of friction welding can weld material.
2 friction welding method
Next 5--10 years should increase efforts to develop new friction welding method, and gradually improve and expand its scope of application.
(1) phase of friction welding

It can be achieved with a phase of friction welding work required to expand the friction welding applications. Currently in production of parts such as a hexagonal cross-section, Octagon steel, automobile operating lever, spline shaft, fork, shaft ends with flanges etc. require phase of friction welding. Under the premise of electronic control technology and highly developed mechanical technology, developed for the large-tonnage phase of friction welding machine possible.
(2) linear friction welding

Linear friction welding technology, is two parts with a certain frequency and amplitude of the reciprocating motion of the welding heat is conducted, it can be rectangular, circular, polygonal cross-section of metal or plastic welded together. It can weld more irregular cross-section of members, such as turbine blades, etc., to carry out the study after linear friction welding principle, the vibration system dynamics, etc., for the development of large tonnage of friction welding preparation.
(3) the radial friction welding

Since its introduction of radial friction welding intermediate rotary push ring, not only changed the direction of the friction surface, but also by the relative rotation of the weldment pressure to a relatively fixed pressure, it is very suitable for welding long pipes, while it can The thin-walled copper ring is welded to the body wall of the bomb, enabling the upgrading of military products. To strengthen the future of the Radial friction welding management and momentary high flow hydraulic system for large tonnage radial friction welding machine developed theoretical foundation.
(4) FSW

Friction stir welding is a solid-phase technology connection technology in 1991 invention of the British Welding Institute, applied research it is light structure made in aviation, aerospace, shipbuilding, marine industry, weaponry and other areas of high-speed trains have been widely carried out. But also caused great attention of scientists, has undertaken a number of FSW research work in the future to the mechanism of FSW, microstructure, mechanical properties and friction stir welding class core technologies to expand deeper stirring the study. Expand the range of friction stir welding materials, in particular, to strengthen the research of dissimilar materials friction stir further expand FSW engineering applications. But also for friction welding, friction welding and embedding third body friction welding research.

3 friction welding equipment and engineering applications
With the wide application of friction welding technology, friction welding equipment also been a rapid development, in 2000 a total of more than 5,000 worldwide incomplete friction welding machine for welding production.
In order to adapt the welding of large and special parts, to the development of our large-scale and micro-friction welder. To meet the special purpose but also to develop inertia friction welding, frictional welding, friction stir welding, stud welding, friction welding and underwater vertical friction welding and other special friction welding machine. In the manufacturing and surveillance technology to the spirit of flexibility and automation design. Welder can add a lot of automation equipment and processing equipment, thereby creating a complete system highly flexible and automated to suit the various requirements of users. To strengthen the welding process quality assurance, in addition to the time control, the amount of deformation control, energy control, but also the development of special process control technology. The friction torque and acoustic emission monitoring technology.

In order to meet the requirements of welding automation of production, technology and research related peripherals should be strengthened. Such as different types of deburring devices, robots, or other loading and unloading equipment, heat treatment and non-destructive testing technology, the workpiece can before welding or machining after welding on the welding machine, and some even can be CNC machining. So that reliable operation of the production line. But also with the flexible manufacturing system (FMS) for use.

Friction welding automobile industry in the future will become the most dynamic market, the use of friction welding of parts with a turbocharger, airbags booster pumps, transmission and drive shaft gearbox, rear axle, exhaust valve, pneumatic system the use of cams. In mechanical engineering, friction welding mainly used to weld hydraulic drive member, such as a hydraulic cylinder, piston rod, in particular a welding flange and the valve body, in another track rollers, shock absorbers and gear pump rotor can also be manufactured using friction welding.

To increase the aircraft landing gear tube and rod friction welding, the main drive shaft of the rotor helicopter landing gear and high nickel alloy steel pipe shaft, double metal rivets Friction welding, aircraft hook bolts. Gradually expand the friction welding applications.
In conclusion

Throughout the development of domestic friction welding current situation, our country with the international advanced level, it is still lagging behind. Friction welding technology research and development in the country, promote the use of the work can not meet the needs of rapid development of the national economy in the face of the domestic market demand, international competition is becoming increasingly fierce, the majority of our friction welding technology workers, long way to go. In order to meet the needs of scientific and technological development and to shorten the gap with similar foreign products, in order to accelerate the modernization of friction welding technology. Friction welding technology to achieve their own development, strengthen the integration with other disciplines and interdisciplinary. We would like to join hands with our dedication to hold our friction welding today and in the future.