Casting

: This article is about the manufacturing process. For other uses, see casting (disambiguation).

Cooling rate

The rate at which a casting cools affects its microstructure, quality, and properties.

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The products of sand casting and slurry-mold processes, often large with thick walls, generally cool slowly. This increases the metal's grain size, creating a coarse microstructure that lowers the strength of the casting. Coarse grains can allow elements of an alloy to separate, which also weakens the casting. But slower cooling keeps the casting metal liquid longer, which allows more gases and waste metal to escape, reducing the voids and inclusions that can weaken a casting.

Related Topics:
Sand casting - Grain size

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Conversely, the products of die casting and metal-mold processes generally cool more quickly, resulting in a fine microstructure with small grain and less alloy segregation but more trapped gases and inclusions.

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