Segregation-It is a concentration of dissolved impurities in that portion of the metal which solidifies last. The dendrites which form are almost pure metal, and therefore the impurities become progressively more concentrated in the remaining liquid.
]wnor segregation-It is a local concentration of impurities at the crystal boundaries as shown in Fig. 11.2a. It causes overall brittleness of the castings.
Major segregation-It is a concentration of impurities in the central portion of an ingot asv shaped markings as shown in Fig. Il. 2b.
Inverse-V segregation-mis type of segregation may occur in very large ingots. In case when the
temperature gradient is very slight, the metal may solidify last in the intermediate portions of the ingot
causing inverted V-shaped markings as shown in Fig. 11.2c.
Non-me tallic inclusions-mese are the oxidized materials and sulfides in various combinations with
each other. They are a result of oxidizing reactions which take place during refining process. Some of
the reactions may be associated with the erosion of ladle or othbr refractories.
Diagonal crack-It is a pronounced crack following the interface of two different planes of
crystallization (Fig. 11.3a). These cracks are caused by thermal stresses, which have been attributed to
severe or uneven secondary cooling of slabs during their solidification.
Halfway crack-It is an intercolumnar crack occurring in positions approximate ly midway between
the outside and center of the slab (Fig. 11.3b).