hitsauskiillon

Hitsauskiillon, also known as welding slag, is a byproduct formed during the welding process, particularly with shielded metal arc welding (SMAW) and flux-cored arc welding (FCAW). It consists of molten flux and impurities from the welding electrode and the base metal that rise to the surface of the molten weld pool and solidify. The composition of the slag varies depending on the type of flux used but typically includes metallic oxides, silicates, and fluorides.

The primary function of the flux, which forms the slag, is to protect the molten weld metal from atmospheric contamination by creating a gaseous shield and a molten slag blanket. This protection prevents the absorption of oxygen and nitrogen, which can lead to porosity and embrittlement of the weld. The slag also acts as a deoxidizer and scavenger, removing impurities from the weld pool. Additionally, certain flux compositions can contribute alloying elements to the weld metal, and the slag's insulating properties can help to slow down the cooling rate of the weld, which can be beneficial for controlling the microstructure and preventing cracking in some metals.

After the weld has cooled, the slag layer typically hardens and can be easily removed by chipping, brushing, or grinding. However, if the slag is not completely removed, it can remain trapped within the weld as an inclusion. Slag inclusions are considered a welding defect as they can reduce the strength and ductility of the weld and act as stress concentration points, potentially leading to failure under load. Proper welding technique, including correct travel speed and electrode angle, is crucial for minimizing slag entrapment.