Finding the right process, the one that will give us the best result and we will do it in less time. We must always optimize processes and more of the same in welding. We must find that type of weld that makes us achieve the results we want.
Here we are going to see the type of welding that will be the most suitable for welding 316L Stainless Steel Tube.
Manual arc welding with coated electrode or SMAW (Shielded Metal Arc Welding) for stainless steel
This type of welding is characterized by the maintenance and creation of an electric arc between the base material to be welded and a metal rod that we call an electrode.
During the process, the electrode is a coated wire. The welder controls the process manually over the length and direction of the arc that is established between the base metal and the end of the electrode.
The heat generated by the electric arc manages to melt both the coating and the 304 Stainless Steel Pipe rod of the electro. The combustion of the coating allows creating a protective atmosphere to avoid contamination of the material that we are melting.
The metal was coming from the metallic rod of the electrode that we are melting deposits its drops in the fusion bath. At the same time, the material that comes from the fusion of the electrode coating generates a slag. The slag due to viscosity will float on the fusion bath and protects it against any rapid cooling or contamination of the surrounding air. At the time that the cord is cold, the excess slag removal procedure will be carried out. Then the slag will be crusted on the surface of the cord.
The electrode coating performs other functions in addition to protecting the fusion bath:
Weld in various positions, decrease energy losses and improve welding efficiency. This is because the outer coating is not burned as fast as the electrode wire. It will generate something similar to a crater at the tip of the electrode, allowing the arc output to be concentrated and better controlling its direction.
The priming and stabilization of the arc are improved thanks to the chemical composition of the coating. The chemical is made up of sodium and potassium salts that ensure the presence and positive ions during the entire welding process.
The base metal and the electrode wire do not always have the same composition. The stripper that forms the coating allows alloys to be added to the weld metal to improve the mechanical characteristics of the bead.
A gaseous envelope is generated during the burning of the electrode coating. It allows oxygen and nitrogen to be dislodged from the molten metal, thus preventing oxidation of the weld bead.
The slag layer deposited on the melting bath and generated by the electrode coating. It protects the bath so that the bath is fluid and regulates the cooling speed. It results in a more optimal bead in terms of mechanical resistance and against corrosion.
For manual coated arc welding, the electrodes must be selected according to the base metal like 316 Stainless Steel Pipe to be welded first, and the type of coating.
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