DC is formed under the influence of constant tension, it can also exist only in a closed circuit. DC is vast in the technique. Most of the electronic circuits as a recharge are used by a constant current. There are cases when direct current, using inverters, is converted into alternating current. During the use of direct current, the welding of reverse and constant polarity is divided.
Direct polarity for welding. In this case, the electrodes are connected to a negatively charged pole, and they already serve as a cathode. The welded product itself is connected to a positively charged pole, and it will already serve as an anode. Such a variety of polarity is very extensively used, reducing the deterioration of properties and wear of the electrode. After all, almost 70% of warm energy is concentrated on the welded surface, that is, on the anode.
Reverse polarity when welding. In this case, the electrodes are connected to the positively charged poles and serve the anode, and the welded product itself is connected to the negatively charged pole and serves as the same cathode. Reverse polarity is used in welding metals on which an oxide film is reflected on the surface of the product. Such an oxide film has a fairly high melting point compared to the material itself.
With reverse polarity, in no case can you use high welding currents, because such a circulation significantly increases the wear of the electrode, which is undesirable in welding.
In addition to direct current, there may be impulsive, welding with direct polarity. Direct polarity for welding. Impulsive current use allows you to perfectly control the mass and size of the welding container (bath). Thanks to this method, even the thinnest sheets of metal can be welded with minimal distortion and deformation, an improved form factor, as well as a reduction in the risk of breaking material and gas penetration.
Welding became an argon -doped. This welding is great for welded work with carbon and alloyed steel, for primary passages during pipes welding, and it is also applicable in cases where an excellent appearance of welding products is needed. Direct polarity in welding will be used here.
Before welding, it is necessary to carefully prepare the surface of the welded product. When welding with steel, it is necessary to carefully clean and prepare the edges of the compounds.