Sulfide inclusion
Sulfide inclusions form when sulfur binds in steel. They reduce ductility and impact toughness but increase corrosion resistance.
Physical-Chemical Mechanism of Action
Sulfide inclusions form when sulfur is deposited in the steel as sulfides. This sulfur comes from the bound sulfur in the metal. The sulfides react with surrounding materials and can cause corrosion.
Metallurgical Relevance & Welding Risks
Sulfide inclusions reduce the through-thickness ductility and impact toughness of the steel, which can lead to cracks and fractures. However, they also improve corrosion resistance, as they can form a protective layer. If handled incorrectly during welding, sulfide inclusions can become coarser or new ones can form, further impairing the material.
Shop Practice & Action Guidelines
To minimize sulfide inclusions, it's important to check the steel quality before welding. Use a clean shielding gas atmosphere and avoid excessive temperatures, as these can release sulfur. For heavily loaded parts or in corrosion-prone environments, it's advisable to take special corrosion protection measures.