The knowledge about the characteristics of deformability (deformation resistance and plasticity) has for the technologist, as well as for the designer and researcher, a great practical significance, because they are important elements in establishing a correct technological process. The change of deformation conditions existing in the industrial process, such as the temperature and rate of deformation, are difficult to consider for correcting the deformability determined by testing. The chemical composition of the material influences the plasticity and its deformation resistance both by the nature and distribution of the alloying elements and by the phase transformations they produce. In this paper, through "deformability", we cover all properties characterizing the deformation behaviour of alloys. In this sense, "deformation resistance" is expressed through the unit strain required to produce a certain degree of plastic deformation, under the conditions of a particular diagram of tensions, deformations and deformation rates, in the absence of external friction forces. Plasticity, being the ability of metallic materials to deform plastic under the action of external forces, is influenced by a number of material characteristics (chemical composition, structure) and other factors characteristic of the deformation (temperature, degree and speed of deformation, applied mechanical scheme). Plasticity is characterized, in the torsion test, by the number of rotations made by the specimen until breakage. A number of methods have already been used for the study of deformability. This study includes the results of hot torsion tests conducted to find the plasticity and deformability characteristics of ferritic stainless steel (non–hardenable stainless steel, grade X6Cr17), which is a flexible grade of the stainless steel family with properties closely matching those of the more popular and expensive austenitic grade.