What is the role of welding rods

The welding rod consists of two parts: the metal welding core in the center and the surface coating.
Welding core: mainly plays the role of filling metal and conducting current.
Function of coating:
(1) The slag and gas produced when the coating melts isolate the arc space and the molten pool from the atmosphere;
(2) The metallurgical effect of the coating ensures the deoxidation, desulfurization and dephosphorization of the weld metal, and adds necessary alloy elements to the weld to give the weld certain mechanical properties;
(3) Make the welding rod have good welding processability.
In order to ensure the quality and performance of the weld, there are strict regulations on the content of each metal element in the welding core, especially the content of harmful impurities (such as sulfur, phosphorus, etc.), which should be strictly limited and better than the parent material. The welding rod consists of two parts: welding core and coating. Different types have different welding cores.

The composition of the welding core directly affects the composition and performance of the weld metal, so the harmful elements in the welding core should be as small as possible. Low carbon steel is generally used as the welding core for welding carbon steel and low alloy steel, and manganese, silicon, chromium, nickel and other components are added.
The reason for using low carbon is that on the one hand, the steel wire has good plasticity when the carbon content is low, and the wire drawing is easier. On the other hand, it can reduce the content of reducing gas CO, reduce spatter or pores, and increase the temperature of the weld metal when solidifying, which is beneficial to overhead welding.