Flux inclusion
Slag inclusion from the electrode coating is a nonmetallic foreign body in the weld metal, formed from unmelted components of the electrode coating or the welding flux. This can lead to porosity and reduced strength levels.
Physical-Chemical Mechanism
The electrode coating consists of nonmetallic materials such as plastics or paper. This coating remains unmelted and forms a foreign body in the weld metal. It can enter the molten pool during the welding process and serve as a nucleation site for porosity.
Metallurgical Relevance & Welding Risks
Slag inclusion from the electrode coating leads to pores in the weld metal, affecting the strength and durability of the joint. Additionally, it can cause uneven cooling and thus hot cracks or a distorted weld structure.
Workshop Practice & Instructions
To avoid slag inclusion from the electrode coating, regularly maintain and inspect the electrodes. The coating should be clean and undamaged. If foreign bodies in the weld are suspected, perform a careful inspection and, if necessary, re-weld.