Why inclusion control is necessary?


Impact properties are adversely affected with an increase in volume fraction of inclusion as well as inclusion length; spherical inclusions are better. Brittle inclusions or inclusions that have low bond strength with the matrix break up during early straining and create voids at the inclusion/ matrix interface.

Hot fatigue strength of high strength steel is reduced by surface and subsurface inclusions those have lower thermal expansion coefficient than steel

The hot workability of steel is affected by the low deformability of inclusions

Anisotropy of a property is caused by orientation of elongated inclusions along the direction of working. Macro inclusions of sulphides are desirable for better steel machining properties.

In view of the above, control of inclusion in steel is necessary. It must be mentioned and as pointed out earlier macro- inclusions are harmful and they must be controlled.