Shrinkage porosity in forging ingots is another common defect in steel ingots and one of the reasons, besides macrosegregation, why the manufacturer has to choose the right technology to improve the internal soundness of the ingot.

A porosity distribution map may help the technology designer to choose the right casting parameters to avoid shrinkage defects in steel forging ingots. The most employed method to predict the porosity area size and its location is the following Niyama criterion: