is chill grain recommended for Co-based castings?

[sstef]

I was told the chill grain is preferred to improve mechanical properties. What about particular application such as statoric parts, used in industrial gass turbine? is it not recommended? What happens if grain size is very fine?

 

[EdStainless]

What alloy? What size part? What kind of service?

In general coarse grain material will have better creep resistance and fine grain better ductility.
If you have highly stressed high temp parts then ideally you don't want any grain boundaries across the direction of applied stress (columnar grains).
If you can't get this you need a compromise on grain size. With real course grains you often have too large of grain boundaries running crosswise. So slightly finer grain may actually give better service.

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