N.A. Enikeev

Nanostructures in Materials Subjected to Severe Plastic Deformation

The chapter focuses on microstructural features of bulk nanostructured materials. The main principles of nanostructural design using severe plastic deformation techniques are discussed.

Superior Strength and Multiple Strengthening Mechanisms in Nanocrystalline TWIP Steel

The strengthening mechanism of the metallic material is related to the hindrance of the dislocation motion, and it is possible to achieve superior strength by maximizing these obstacles. In this study, the multiple strengthening mechanism-based nanostructured steel with high density of defects was fabricated using high-pressure torsion at room and elevated temperatures. By combining multiple strengthening mechanisms, we enhanced the strength of Fe-15 Mn-0.6C-1.5 Al steel to 2.6 GPa. We have found that solute segregation at grain boundaries achieves nanograined and nanotwinned structures with higher strength than the segregation-free counterparts. The importance of the use of multiple deformation mechanism suggests the development of a wide range of strong nanotwinned and nanostructured materials via severe plastic deformation process.

Multifunctional Properties of Bulk Nanostructured Metallic Materials

This chapter focuses on multifunctional properties of bulk nanostructured metallic materials and structure–properties relationship therein. The most important structural factors affecting mechanical, physical, and chemical properties of the nanomaterials are discussed, and the strategies to their further improvement are outlined. Special attention is paid to nanostructural design for simultaneous improvement of mutually exclusive properties.

Ultra-fine grained Al-Mg alloys with superior strength via physical simulation

The Al 5xxx alloys are widely used in form of sheets in marine, transport, and chemical engineering and, thus, they are often have to undergo hot/cold rolling as the final metal forming operations. Recent investigations have demonstrated that ultra-fine grained (UFG) Al 5xxx alloys have a significant potential for industrial applications due to their improved mechanical properties and enhanced corrosion resistance. However, the development of hot/cold rolling routes for the UFG Al alloys is very time consuming due to numerous experimental trials and very expensive due to higher cost of the UFG processed materials. In this work, physical simulation of cold rolling is applied to the UFG Al 5083 alloy obtained via equal channel angular pressing with parallel channels to analyze the effect of cold rolling on the microstructure and microhardness of the material. The cold rolling parameters are chosen based on the outcomes of physical simulation and the UFG Al 5083 alloy is successfully subjected to cold rolling resulting in superior mechanical strength of the material. It is concluded that physical simulation can significantly increase the efficiency of experimental work on development of thermo-mechanical processing routes.

High strength state of UFG steel produced by severe plastic deformation

An UFG austenitic stainless steel of type 316 was produced by high pressure torsion at two different temperatures. As a result different nanostructures were observed in the investigated alloy characterized by different grain size and dislocation density. It was reported that the steel processed at both temperatures was characterized by significantly enhanced strength, which, in case of the steel processed at 430?C, exceeds the value expected for the given grain size according to Hall-Petch relation. This extra-strength is supposed to be due to the observed nanostructural features as segregations/clusters of solutes in grain boundary area formed by severe plastic deformation.