ISSN 0967-0912, Steel in Translation, 2013, Vol. 43, No. 2, pp. 50–54. © Allerton Press, Inc., 2013. Original Russian Text © M.V. Chukin, A.G. Korchunov, M.A. Polyakova, A.V. Lysenin, A.E. Gulin, 2013, published in “Izvestiya VUZ. Chernaya Metallurgiya,” 2013, No. 2, pp. 46–51. 50 The benefits of nanostructures and ultrafine-grain structures in relation to their macrocrystalline coun- terparts have now been clearly established. The best approach to the formation of ultrafine-grain structure is intense plastic deformation. However, the develop- ment of production technologies for metal and alloy components with ultrafine-grain structure calls for a methodology able to predict the structure and mechanical properties obtained with a specific strain in intense plastic deformation. The fundamental prin- ciples underlying the formation of the structure and mechanical properties at large strain were outlined in [1–8] and elsewhere. Currently, various processes for intense plastic deformation have been thoroughly studied—such as equal-channel inclined pressing, intense plastic torsion, and helical extrusion—while new deformational processes for nanostructure forma- tion require multifactorial experiments to establish their engineering parameters. Within that framework, it is expedient to consider the quantitative assessment of the changes in structure and mechanical properties of metals and alloys on intense plastic deformation. Since structural carbon steels with nanostructures and ultrafine-grain structure has a distinctive combi- nation of strength and plasticity, they are promising for the production of high-performance metal compo- nents. In the present work, the effectiveness of intense plastic deformation for the creation of ultrafine-grain structure in structural carbon steel is assessed on the basis of the control parameters, the parameters of the initial blank, and the microstructure and mechanical properties of the steel produced. The production of specified ultrafine-grain struc- ture and mechanical properties in structural carbon steel may be assessed by means of an array of universal sets, including the input-variable module; the func- tional module corresponding to the object of control (the object module); and the output-variable module. The input-variable module must consist of variables corresponding to the initial mechanical properties of the steel and control variables characterizing the intense plastic deformation. The object module must include state variables characterizing the microstruc- ture of the deformed steel, which vary in the course of intense plastic deformation. The output-variable module must include variables characterizing the mechanical properties of the steel after intense plastic deformation. To formalize the comparison of the mechanical properties obtained after intense plastic deformation with the mechanical properties theoreti- cally attainable in intense plastic deformation, we must use the comparison and assessment module. This approach permits the use of various models for math- ematical description of the relations among the con- trol parameters and the parameters of the steel’s microstructure and mechanical properties in intense plastic deformation (Fig. 1). Processes of intense plastic deformation such as equal-channel inclined pressing, intense plastic tor- sion, and helical extrusion are characterized by con- siderable information regarding the relations among the control parameters and the mechanical properties of carbon steel with nanostructure and ultrafine-grain structure. The effectiveness I of control of the struc- ture and mechanical properties of steel with nano- structure and ultrafine-grain structure may be charac- terized by the stability of intense plastic deformation (1) where U and V are the control and state parameters; S is the stability of intense plastic deformation; λ i are IUV , ( ) S λ i δ K i 0 ( ) 2 i 1 = n ∑ λ i δ K i ( ) 2 i 1 = n ∑ ----------------------- max , = = Assessing the Effectiveness of Intense Plastic Deformation of Structural Carbon Steel M. V. Chukin, A. G. Korchunov, M. A. Polyakova, A. V. Lysenin, and A. E. Gulin Nosov Magnitogorsk State Technical University Received July 6, 2012 Abstract—The production of a specified ultrafine-grain structure and mechanical properties of carbon steel in intense plastic deformation is formalized. Stochastic and statistical models are considered for the descrip- tion of intense plastic deformation with different degrees of information regarding the relation between the control parameters and the mechanical properties of carbon steel with ultrafine-grain structure. A new approach is developed for assessing the effectiveness of intense plastic deformation of carbon steel. DOI: 10.3103/S096709121302006X