The friction stir welding process is the most compelling welding method since the advent of laser welding. Its appearance will bring about a major change in the connection technology of non-ferrous metals such as aluminum alloys. Welding aluminum alloys by friction stir welding have achieved good results. At present, friction stir welding of zinc, copper, titanium, low carbon steel, composite materials, etc. is being carried out in the United Kingdom, the United States and other countries. Friction stir welding has good application prospects in the aerospace industry.
(1) Stirring Head
The successful liquid cold plate design of the stirring head is the key to applying friction stir welding to a wider range of materials and welding a wider range of thicknesses. The following mainly discusses the development status of the mixing head. Generally speaking, the stirring head consists of two parts: the stirring probe and the shaft shoulder, and the material of the stirring head is usually made of a material whose hardness is much higher than that of the material to be welded, o that the wear of the stirring head can be minimized in the welding process. In the initial stage, the rational design of the shape of the mixing head is the key to obtaining a weld with good mechanical properties. The development of the stirring head mainly focuses on two aspects: one is the stirring head with threads, and the other is the stirring head with three grooves. In essence, both stirring probes are designed as cones, which greatly reduces the material roll-out of cylindrical stirring probes of the same radius. The stirring probe is reduced by 60%. If a certain smaller diameter stirring probe is used, the conical stirring probe can enter the weldment more easily through the plastic material than the cylindrical stirring probe, and reduce the stress concentration and fracture probability of the stirring head.
(2) Research Status
The application of friction stir welding on aluminum alloys is more and more extensive, and the research is also more and more in-depth. It not only involves the welding of various materials of the same kind but also studies a wide range of friction stir welding of dissimilar aluminum alloys. The welding thickness of aluminum alloys ranges from 1mm to 75mm. A large number of studies have been carried out on the corrosion properties, mechanical properties and microstructure of aluminum alloy welded joints. Friction stir welding is widely used in 6061Al/2024Al, 2024Al/Ag, 2024Al/Cu, 6061AI/Cu, and even in alloys such as 6061AI+20%Al2O3/cast aluminum alloy A339+10%SiC.
Friction stir welding, as a new method of multidisciplinary intersection, can develop longitudinal seam welding, circumferential seam welding, keyhole welding, variable section welding, self-supporting double-sided welding, spatial 3D curve welding, friction spot welding, refill friction stir spot welding, friction stir welding surface modification treatment, friction stir welding superplastic material processing and other connection processing methods and technologies.
Friction stir welding technology is widely used in my country's aerospace, ships, trains, automobiles, electronics, electric power and other industrial fields, creating considerable social and economic benefits, and providing better metal materials such as aluminum, magnesium, copper,titanium target, and steel. It provides domestic and foreign users with different types and uses of friction stir welding industrial product processing, including aerospace cylinder structural parts, aerospace thin-walled structural parts, ship-wide ribbed plates, high-speed train body structures, Large thickness radar panels, automobile wheels, container profile wall panels, various structural radiators and heat sinks, etc.