The main types of welding
Welding is a process that is implemented to make a joint between metal pieces through a thermal process that may or may not be accompanied by a mechanical action of pressure.
Autogenous and brazing
In autogenous welding, the base metal actively participates in the formation of the joint, reaching fusion or at least in the pasty state, as in forging welding.
There may or may not be the presence of filler metal as in the case of tig welding .
In brazing, on the other hand, the joint is created by connecting the edges of the pieces together by means of a filler metal with a lower melting point than that of the base metal.
For certain types of welding, such as arc welding (manual, automatic, under gas) or braze welding, it is necessary to prepare the edges to ensure that the welded joint covers the entire thickness of the pieces being joined.
Manual arc welding
This type of welding uses the electric arc that strikes between the electrode and the pieces to be welded as a source of heat.
Manual arc welding is performed by approaching the piece to be welded the electrode, which when current passes its end heats up strongly causing ionization of the surrounding air and facilitating the passage of current, this creates the voltaic arc, a which also occurs when the electrode is brought to a certain distance from the piece to be welded.
The types of autogenous welding
Autogenous submerged arc welding
This welding, also called continuous wire welding, derives from the manual one. In practice it consists in the fact that the electrode is replaced by a continuous bare wire. The electrode coating is replaced by a granular powder flux that covers the welding area and the arc body within the flux itself, for this reason submerged arc. Welding of this type can be carried out with direct or preferably alternating current.
It is an autogenous fusion welding, which uses the oxyacetylene flame as a thermal source, obtained by burning acetylene with oxygen by the oxyacetylene torch.
Electric resistance welding is an autogenous pressure welding method, which uses the heat developed by effect Joule as a thermal source. The two elements to be welded are pressed one on top of the other by water-cooled copper electrodes.
Autogenous welding by fusion which uses the heat deriving from the strongly exothermic reaction as a thermal source.
Special types of welding
Electron beam where the heat source is made up of an accelerated electron beam, or the impact of the electrons on the piece causes the metal to melt.
By explosion, it allows to create the union of two metals, for example a plating, using the pressure caused by an explosion.
Elettroscoria, is an automatic vertical welding procedure with submerged arc, used for welding thick metal sheets.
The glitter technique is used to join bars and tubes. The pieces clamped by electrodes are brought together and in the contact area a fusion is reached, this generates the projection of fused particles all around, or the sparkle. The flaps are then pressed against each other obtaining the union by forging.
Autogenic in focus
Autogenous fire welding, called boiling, where the pieces to be welded are heated with a flame until they reach a forging temperature, then they are pressed firmly against each other to create the union.