Inclusions
Inclusions are non-metallic impurities like oxides, sulfides, or silicates in steel. They impair toughness and can lead to cracks.
Physicochemical mechanism of action
Inclusions are foreign phases trapped in the metal during steelmaking or welding processes. They can consist of oxides (e.g., FeO), sulfides (e.g., FeS), or silicates (e.g., CaSiO3).
Metallurgical relevance & risks during welding
Inclusions act as internal notches and can negatively affect the mechanical properties of steel. They enlarge the grain structure, reduce toughness, and increase susceptibility to cracks and hot cracking. During welding, new inclusions can form through chemical reactions between the steel and the welding consumables.
Workshop practice & instructions
To minimize the impact of inclusions, maintain a clean welding environment and proper welding parameters. Avoid overheated welds, as this can lead to chemical reactions and the formation of new inclusions. For heavily contaminated steels, prior surface treatment or the use of deoxidizers is necessary.