Friction welding, friction stir welding) refers to the use of high-speed rotation of the heat generated by the friction welding set and the workpiece to be partial plastic welding materials, when welded with moving forward along the welding interface, is plastic material under the effect of welding with the rotation of the friction force from front to rear of welding fixture, and the welding formed under the extrusion of density of the solid phase welding seam.
Friction welding usually consists of the following four steps:
1,Mechanical energy is converted into heat energy;
2,Material plastic deformation;
3,Forging pressure under thermoplastic conditions;
4,Intermolecular diffusion recrystallization;
The main advantages of friction stir welding are as follows:
(1)The microstructure of welded joint has little change in heat affected zone.Low residual stress, welding workpiece is not easy to deformation;
(2)Able to complete a long weld, large section, different positions of the welding.Joint high;
(3)The operation process is convenient to realize mechanization, automation, simple equipment, low energy consumption, high efficiency, low requirements for the operating environment;
(4)No need to add welding wire, no need to remove oxide film before welding, no need to protect gas, low cost;
(5)Weldable crack sensitive material, suitable for heterogeneous materials welding;
(6)Welding process safety, no pollution, no smoke, no radiation, etc.
The biggest difference between friction stir welding and traditional fusion welding is that in the whole welding process, the temperature at which the energy of the metal to be welded increases does not reach its melting point, that is, the metal is in the state of thermoplastic to achieve forged solid phase connection.
Compared with traditional fusion welding, friction welding has the advantages of high quality of welding joints, such as welding seam strength and matrix material strength, high welding efficiency, stable quality, good consistency, and heterogeneous material welding.
Friction welding (friction stir welding) welding with its high quality, high efficiency, energy saving, pollution-free technical characteristics, in aviation, aerospace, nuclear energy, weapons, automobiles, electric power, Marine development, machinery manufacturing and other new technologies and traditional industries have been more and more widely used.