Morphology

Globular shape is desirable: Certain inclusions like , oxysulphides, iron aluminates and silicates are globular.

Platelet shape: undesirable. Al deoxidized steels contain  in the form of thin films located along the grain boundaries.

Polyhedral inclusions are not very harmful.

Size of inclusions

There are micro inclusions  and macro-inclusions (size greater than . Macro inclusions are harmful. Micro inclusions are beneficial as they restrict grain growth, increase yield strength and hardness. Micro- inclusions act as nuclei for precipitation of carbides and nitrides. Macro- inclusions must be removed. Micro inclusions can be used to enhance strengthening by dispersing them uniformly in the matrix.