Friction welding is a pressure welding method. It’s when the end face reaches a thermoplastic state under the effect of heat generated by friction on the surfaces of the weldments, the upsetting is carried out rapidly to complete the welding.
1 Welding Process
(1) Relative motion of the weldment occurs.
(2) End contact occurs between the two weldments, which in turn generates frictional heat.
(3) When the end face reaches a thermoplastic state, quickly apply pressure to it to complete the weld.
2 Advantages
(1) High productivity, 5~6 times higher than flash butt welding.
(2) Stable quality and high dimensional accuracy of weldments.
(3) Low processing costs, power saving, no special cleaning of weldments required.
(4) Easy to mechanise and automate, simple to operate.
(5) No sparks, arcs or harmful gases.
Ⅱ Laser Welding
Laser welding is that using laser radiation to heat the surface, then the surface heat spreads to the interior through heat conduction, causing the workpiece to melt and form a specific molten pool, which forms a weld after solidification.
Advantages
(1) Fast and efficient welding.
(2) High welding precision, small deformation, easy to automate.
(3) No need to use electrodes, so no electrode pollution.
Ⅲ Plasma Arc Welding
Plasma arc welding is a welding method that uses the high energy density beam of a plasma arc as the heat source for welding. Plasma arc, also known as compression arc, is through the compression of the arc column, so that the energy is highly concentrated, the gases in the arc column are fully ionised.
1 Welding Process
The gas is heated by the arc and initially ionised, and then compressed at high speed through the water-cooled nozzle, increasing the energy density and ionisation to form a plasma arc. Due to the high heat and high penetration of the plasma arc, the workpiece at the welding place melts and a molten pool is formed, thus realising the welding of the workpiece.
2 Advantages
(1) High energy density, strong directionality of the arc, high melting capacity.
(2) Large depth-to-width ratio of the weld seam, small heat-affected zone.
(3) Stable arc combustion (stable even with low current).
(4) Low welding cost, no bevelling, no wire filling when welding thickness is small.
(5) Stable small hole effect, can better realise single-sided welding double-sided free forming.
Ⅳ Explosion Welding
Explosion welding is another solid-phase welding method that uses the heat of a chemical reaction as an energy source and utilises the energy generated by the explosion of explosives to join metals. Under the action of the blast wave, two kinds of metal can be accelerated and impacted to form a metallic bond in less than a second.
Among the various welding methods, explosion welding can weld the widest range of combinations of dissimilar metals. Explosion welding can be used to weld two metallurgically incompatible metals into a variety of transition joints. Explosion welding is mostly used for cladding of flat plates with considerable surface area and is an efficient method for manufacturing composite plates.