What is equiaxed grain?

What is equiaxed grain?

Equiaxed crystals are crystals that have axes of approximately the same length. Equiaxed grains can in some cases be an indication for recrystallization. Equiaxed crystals can be achieved by heat treatment, namely annealing and normalizing.

How are equiaxed grains formed?

Equiaxed grains start to form from the fragments in front of the columnar zone. Initially the equiaxed grains are small and move along with the liquid. At around 40-50 seconds, the grains start sedimenting. The columnar front is blocked first at the bottom and then further up in the ingot.

What is columnar grain?

Columnar grains are long, thin, coarse grains created when a metal solidifies. rather slowly in the presence of a steep temperature gradient. Relatively few nuclei. are available when columnar grains are produced. Equiaxed and columnar grains.

What is equiaxed zone?

Equiaxed zone: Region within cast metals (usually the core of the casting) where the grains are approximately the same size in every direction. Equilibrium freezing temperature: Temperature when solidification of molten material occurs under standard thermodynamic conditions.

What is columnar to equiaxed transition?

The columnar to equiaxed transition (CET) is a microstructural transition that has to be controlled during certain solidification processes. CET models and microstructure selection maps, based on nucleation and dendritic growth models, are briefly described.

What causes dendritic growth?

Rapid dendrite growth is realized by the rapid movement of the liquid/solid interface toward the undercooled melt. Consequently, the formation of rapidly grown dendrites is the result of a large deviation of the chemical equilibrium state at the solidification front.

What are columnar dendrites?

These dendrites can in principle grow to the centerline of the casting, and during the growing, new dendrites may form from the higher order arms. This zone is called the columnar dendrite zone.

What is columnar structure?

Definition of columnar structure 1 : the structure of a mineral aggregate that is made up of nearly parallel slender columns and that is intermediate between an equant and acicular structure (as in some amphiboles)

What are columnar crystals?

Elongated crystals that grew at right angles to a surface.

What is the difference between equiaxed dendritic and columnar dendritic?

In equiaxed growth the solid±liquid interface is morphologically unstable leading in single phase solidifica- tion to dendritic grains, while in columnar growth, depend- ing on the local growth conditions, one may grow planar, cellular or dendritic morphologies.

Why are dendrites addictive?

Dendrite contains toluene, a sweet-smelling and intoxicating hydrocarbon. Apart from causing hallucinations, it prevents the consumer from feeling hungry or cold. More often than not, younger kids are coaxed into sniffing this glue by their older peers.

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