Precipitation behavior of sigma phase in 304 and 430 stainless steels as hot-rolled at 800$^{\circ}$C*

The effect of various reduction ratios on the precipitation of sigma phase in 304 and 430 stainless steels as hot-rolled at 800$^{o}$C have been investigated in this study. The sigma phase showed a dendrite --like morphology in the as received materials. A hot rolling process changed the morphology of sigma phase from dendrite-like to globular, especially at higher reduction ratio. The amounts of sigma phase in the stainless steels increased gradually at 800$^{\circ}$C with the increasing the reduction ratios from 0 to 75{\%}. The XRD analyses showed that a higher reduction ratio also enhanced the conversion of the delta (110) to sigma (542).