Let us understand the metallurgical aspects that are involved during welding and how welding flux works. Also, we will look at the process by which Spatter Cure helps refine the weld melt.
- Generally the steel contains 0.01 to 0.02 % oxygen; whereas, the oxygen content in the weld melt is as much as 0.2 to 0.3%. This excess O2 has an adverse effect on the mechanical properties of the weld metal, especially impact strength, besides formation of more FeO.
- In high-temperature metal joining processes (welding, brazing and soldering), the primary purpose of flux is to prevent oxidation of the base and filler materials. Flux prevents the formation of metal oxides. Additionally, flux allows solder to flow easily on the working piece rather than forming beads as it would otherwise.
- O2 contents in the weld metal varies with arc length, welding current and the type of shielding employed. The coating of the eloctrode promotes a shield of slag that is not adequate, even with standard quality of electrode, to have lower level of oxygen in the metal.
- Contact of air with the weld pool may also increase the nitrogen content in the weld melt, which is very harmful. These gaseous inclusions are responsible for bringing down the impact strength of the weld metal, which in turn causes weld failure.
- The coating of Spatter Cure SC-07 in the V -groove helps to remove this problem. In the weld pool, the coating acts as a flux. Thus when the arc is formed, this coating develops a film over the weld metal protecting it from the surrounding air that is by and large very active and hence the possibility of contact of the weld metal with oxygen and nitrogen of surrounding area is minimized. Thus, it helps to get a clean and dense weld with improved mechanical and metallurgical properties.
- Apart from protecting the weld pool from the surrounding atmosphere the coating (here it acts as a flux) partly removes oxygen from the molten metal because of the presence of De-Oxidizers in the compound.
- The oxides, being lighter than metals, formed by de-oxidation of the weld pool floats up and are removed along with the molten slag.