Selection of welding rod

Usually, it should be based on the chemical composition and mechanical properties of the composition of welded structural steel. Weldability and working environment (with or without corrosive media, high or low temperature) and other requirements, as well as the shape of the welded structure. Force and welding equipment (whether there is a DC welding machine) and other aspects of the comprehensive consideration to determine the choice of which electrodes.
In the selection of welding rods should pay attention to the following principles:

• a. The principle of equal strength – refers to the choice of electrodes for the tensile strength of the molten metal and the tensile strength of the welded base metal is equal or similar.
• b. Such as the principle of toughness – refers to the choice of electrodes deposited metal toughness and the toughness of the base metal to be welded equal or similar to the toughness of the base metal.
• c. The principle of equal composition – refers to the chemical composition of the selected electrode deposit metal in line with or close to the base metal.

In the determination of the strength of the electrode and then deciding to choose acid or alkaline electrodes, mainly determined by the complexity of the specific shape of the welded structure, the size of the thickness of the steel, the weldment load (static or dynamic load) and the crack resistance of the steel as well as get the difficulty of the DC power supply, etc. Generally speaking, for plasticity, impact toughness, and crack resistance requirements of high performance, low-temperature conditions of the work of the weld should be selected for alkaline electrode when subject to certain conditions and cannot clean up the mild steel weldment bevel at the rust. Oil and oxidized skin and other dirt should be used on the rust, oil, and oxidized skin sensitivity and anti-porosity performance of strong acidic welding rods.
Welding of dissimilar steels such as low carbon steel and low alloy steel, different strength levels of low alloy steel welding, generally use welding rods that match the lower strength steel.