Abstract
	Structure-forming processes and hot deformation behavior of a ferritic stainless steel containing 25 % Cr were investigated. The model of mean equivalent stress values depending on temperature, strain and strain rate was developed using the results of the laboratory hot flat rolling tests (i.e. measured rolling forces). This model seems to be simple and accurate enough for its implementation in the on-line steering systems of operational rolling mills. Experiments showed that the examined steel in as-cast and as-rolled state had a considerable susceptibility to grain coarsening. That phenomenon is very difficult to eliminate because of substantial inhibition of the recrystallization processes. Due to high chromium content it is very hard to initiate complete recrystallization of deformed structure and thus refine the coarse grains forming during the heating before hot rolling in this ferritic steel. That fact exhibited during the hot strip rolling in the operational two-stand Steckel type rolling mill in Mittal Steel Ostrava a. s. as well as in laboratory simulation of conventional and/or one-heat rolling. Microstructures of industrial strips as well as laboratory rolled samples were very heterogeneous. Dynamic recrystallization can be almost excluded in discussed conditions and static recrystallization severely competes with a less efficient polygonization. Moreover, it is extremely complicated to recognize the structural consequences of recrystallization and recovery in the ferritic steel grades.