Cast high-alloy stainless steels are most often specified for applications that involve service temperatures in excess of 650 degreesC. It is well known that these heat-resistant steels may yield precipitation of the hard and brittle sigma-phase, which can result in harmful influence on the mechanical properties of the alloy. The present study revealed that the precipitation of sigma upon heat treatments in the temperature range from 650 to 850 degreesC can be strongly accelerated by the preexistence of carbides in the steel, particularly those of the Cr23C6 and Cr7C3 type. However, the formation of sigma-phase upon the presence of Cr7C3 resulted markedly faster than that related to Cr23C7. On the other hand, it was found that Cr7C3 can be stabilized by faster cooling along the solidification temperature range; conversely, the microstructure obtained through a slower cooling rate predominantly bears Cr23C6-type carbides.