Columnar zone

Figure 22.5 Classic grain structure of casting (or ingot) containing chill zone, columnar zone, and equiaxed zone. From Bower and Flemings [5].

Figure 4.5 Section through a solidification ingot showing the various solidification zones. The equiaxed zone forms near the mold walls. In the interior is the columnar zone, where crystal growth is in the direction of heat flow. (After Lalena and Cleary, 2005. Copyright John Wiley Sons, Inc. Reproduced with permission.)...

FIGURE 6.31 Typical micro structure obtained during ingot casting (1) chiU zone, (2) columnar zone, (3) equaixed grain zone. Adapted from Bower and Flemings 1967 [12]. 

The columnar crystals develop predominantly from the chill zone and show a strong preferred ciystallographic orientation which corresponds with the preferred crystallographic directions of dendritic growth. " Some few grains appear in the columnar zone which... 

Variation of the length of the columnar zone with the alloy content for comtantpouring temperature (Chalmers ). 

The regions of positive segregation have two characteristic forms. The outer bands are referred to as A-segregates and are arranged as rope-like stringers of segregation located on the surface of cones with their bases at the base of the ingot. They occur predominantly in a zone near and almost parallel to the end of the columnar zone. 

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