Microstructures and Mechanical Properties of Steels and Alloys Subjected to Large-Strain Cold-to-Warm Deformation

The effect of large-strain cold-to-warm deformation on the microstructures and mechanical properties of various steels and alloys is critically reviewed. The review is mainly focused on the microstructure evolution, whereas the deformation textures are cursorily considered without detailed examination. The deformation microstructures are considered in a wide strain range, from early straining to severe deformations. Such an approach offers a clearer view of how the deformation mechanisms affect the structural changes leading to the final microstructures evolved in large strains. The general regularities of microstructure evolution are shown for different deformation methods, including conventional rolling/swaging and special techniques, such as equal channel angular pressing or torsion under high pressure. The microstructural changes during deformations under different processing conditions are considered as functions of total strain. Then, some important mutual relationships between the microstructural parameters, e.g., grain size vs. dislocation density, are revealed and discussed. Particular attention is paid to the mechanisms of microstructure evolution that are responsible for the grain refinement. The development of an ultrafine-grained microstructure during large strain deformation is considered in terms of continuous dynamic recrystallization. The regularities of the latter are discussed in comparison with conventional (discontinuous) dynamic recrystallization and grain subdivision (fragmentation) phenomenon. The structure-property relations are quantitatively represented for the structural strengthening, taking into account various mechanisms of dislocation retardation.

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This article critically reviews the effect of large-strain cold-to-warm deformation on the microstructures and mechanical properties of various steels and alloys. The focus is mainly on the microstructure evolution, with cursory consideration of deformation textures. The study covers a wide strain range, from early straining to severe deformations, providing a clearer understanding of how deformation mechanisms affect the structural changes leading to the final microstructures evolved in large strains. General regularities of microstructure evolution are shown for different deformation methods, including conventional rolling/swaging and special techniques such as equal channel angular pressing or torsion under high pressure. The article also reveals and discusses important mutual relationships between microstructural parameters, such as grain size vs. dislocation density, and pays particular attention to the mechanisms responsible for grain refinement during microstructure evolution under large strain deformation. The development of an ultrafine-grained microstructure during large strain deformation is considered in terms of continuous dynamic recrystallization, and its regularities are compared with conventional (discontinuous) dynamic recrystallization and grain subdivision (fragmentation) phenomenon. The article quantitatively represents the structure-property relations for structural strengthening, taking into account various mechanisms of dislocation retardation.