Types of electrodes

In arc fusion welding consumable electrode used, made of cold-sized or hot wire diameter 0,3-12 mm, or cored wire. The electrodes are used as the electrode strip and plate.
Electrodes are classified according to the material, intended for welding some steel, the thickness of coating applied to the rod, types of coverage, the nature of the slag produced by melting, technical properties of the weld metal, etc.
Electrodes applied to all defined composition - cover. General purpose electrode coatings - the stability of burning arc and getting the weld metal with preset properties. The most important features are flexibility, strength, toughness, resistance to corrosion.
Coating has many important functions.
First, it is gas protection welding zone and raplavlennogo metal, which is formed during the combustion of gas-forming substances. It protects metal against raplavlenny oxygen and nitrogen. Such substances are introduced into the coating in the form of wood flour, cellulose, cotton.
Second, the metal weld pool deoxidation elements having a large affinity to oxygen than iron. These elements include manganese, titanium, molybdenum, chromium, silicon, aluminum, graphite. Deoxidizing are covering is not in pure form and in the form of ferro-alloys.
Thirdly, slag protection. Slag coating reduces the rate of cooling and solidification of the weld metal, thus the exit gas and inclusions.
Slag-forming components of the coating are titanium and manganese ore, kaolin, marble, silica sand, dolomite, feldspar, etc.
Fourthly, the alloying of the weld metal to give it special properties (increase of mechanical properties, wear resistance, heat resistance, corrosion resistance).
As an alloying element used chromium, nickel, molybdenum, tungsten, manganese, titanium.
In addition, to improve the performance of welding electrode coatings injected iron powder. Such powder facilitates the arc re-ignition, the rate of cooling of weld metal, which is beneficial for welding at low temperatures. The content of the powder can be up to 60% of the weight of the coating.
To secure the cover on the rod electrode commonly used binders - such as water glass.
To make the best plastic coating properties it allows a form of supplements - such as bentonite, kaolin, dextrin, mica, etc.
Depending on the materials to be welded, all electrodes are divided into the following groups:
A - welding alloyed steels with tensile strength over 600 MPa (five types: E70, E85, E100, E125, E150);
U - for mild and low-carbon structural steels B - for welding high-alloy steels with special properties;
T - for welding alloy heat-resistant steels - 9 types;
N - for deposition of surface layers with special properties - 44 type.
Guaranteed tensile strength of the weld metal is indicated in the figures mark the electrodes. For example, the name of the electrode, designated E42, says that it is designed for arc welding, the minimum tensile strength of weld metal - 420 MPa.
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