By means of welding electrode bring current to welding point. There is large number of types of metallic and nonmetallic electrodes. Properties of the received welding seam depend on type of electrode.
Welding by electrodes
Electrodes use in manual arc welding which remains main type of welding of metals also today. The electrode represents bar from metal or nonmetal with covering or without. One of the ends of bar is cleaned from covering and is inserted in the electroholder.
When welding between the end of electrode and welding surface there is electric arc. Very high temperatures, big intensity of interaction between the substances participating in melting are characteristic of welding process.
Use of electrodes gives the mass of advantages: - the weld turns out equal, without time and lack of penetrations; - the arch is very easily lit and supported; - the seam evenly becomes covered with slag which easily is removed after completion of work.
Types of welding electrodes
Welding electrodes are divided into melting and not melting. The melting electrodes can be only metallic, make them of aluminum, bronze, copper, cast iron and steel. Usually modern melting electrodes have covering, uncovered are used seldom and only in the gas protective environment. The covering of the melting electrodes gives optimum properties to weld, protects it from influences of the environment, improves burning of arch. The melting electrodes can be high-alloy, alloyed and carbonaceous. Not melting electrodes make of nonmetals (coal, graphite and others) and high-melting metals, for example tungsten.
In special the groups allocate special electrodes for welding of surface layers.
There are also special electrodes for welding of non-ferrous metals.
Marking
All electrodes have alphanumeric marking according to which it is very simple to pick up electrode, necessary for these works. Marking is approved by the corresponding state standard specifications. Electrodes are divided into several classes, electrodes of each class are intended for welding of certain materials. So, low-alloyed and carbon steels apply the electrodes designated by letter "U" to welding, structural steels cook electrodes of brand "L", high-alloy – "In", heatproof – "T".
Electrodes differ on admissible space use - some can be used in any situation, others weld only from below or from above.
Coating thickness of electrodes can be different, according to it they are separated into thin - averages – "With", thick – "Д", especially thick – are marked by the letter "M". Electrodes can have various type of covering, allocate rutile, cellulose, the main, the sour, mixed coverings.