There is, I think, something ethereal about i —the square root of minus one. I remember first hearing about it at school. It seemed an odd beast at that time—an intruder hovering on the edge of reality.

Usually familiarity dulls this sense of the bizarre, but in the case of i it was the reverse: over the years the sense of its surreal nature intensified. It seemed that it was impossible to write mathematics that described the real world in …

I and i

Processes of severe plastic deformation (SPD) are defined as metal forming processes in which a very large plastic strain is imposed on a bulk process in order to make an ultra-fine grained metal The objective of the SPD processes for creating ultra-fine grained metal is to produce lightweight parts by using high strength metal for the safety and reliability of micro-parts and for environmental harmony In this keynote paper, the fabrication process of equal channel angular pressing (ECAP), accumulative roll-bonding (ARB), high pressure torsion (HPT), and others are introduced, and the properties of metals processed by the SPD processes are shown Moreover, the combined processes developed recently are also explained Finally, the applications of the ultra-fine grained (UFG) metals are discussed

Severe Plastic Deformation (SPD) Processes for Metals

Twenty-five years of ultrafine-grained materials: achieving exceptional properties through grain refinement

In recent years, much progress has been made in the studies of nanostructured Al alloys for advanced structural and functional use associated both with the development of novel routes for the fabrication of bulk nanostructured materials using severe plastic deformation (SPD) techniques and with investigation of fundamental mechanisms leading to improved properties. This review paper discusses new concepts and principles in application of SPD processing to fabricate bulk nanostructured Al alloys with advanced properties. Special emphasis is placed on the relationship between microstructural features, mechanical, chemical, and physical properties, as well as the innovation potential of the SPD-produced nanostructured Al alloys.

Nanostructured aluminium alloys produced by severe plastic deformation: New horizons in development

Texture evolution in equal-channel angular extrusion

Numerical and physical modelling of plastic deformation in 2-turn equal channel angular extrusion

Microforming of normal, coarse grain (CG) metals leads to scale problems which originate from the fact that the grain size becomes comparable to the part size. A possible way of dealing with these problems is replacing CG metals with ultra-fine grained (UFG) metals. UFG metals can be produced in bulk by severe plastic deformation (SPD). This paper describes using UFG aluminium 1070 for preliminary trials of micro extrusion of a cylindrical cup. The process of producing bulk UFG aluminium by SPD is explained and the material obtained characterised. The preparation of micro billets for the extrusion operation is discussed. Backward extrusion is carried out for two types of material, CG and UFG. This enables a comparison of the material behaviour and product characteristics. Using UFG aluminium in microforming results in more uniform products with improved mechanical properties.

Micro-extrusion of ultra-fine grained aluminium

The effect of grain size and grain boundary misorientation on the corrosion resistance of commercially pure aluminium

Mechanical properties of AZ31B magnesium alloy were modified in this work by various processing routes of incremental equal channel angular pressing (I-ECAP) followed by heat treatment. Possible strategies for improving ductility and strength of the alloy were investigated. Processing by routes A and B C showed that texture plays predominant role in controlling mechanical properties at room temperature. Four passes of I-ECAP by route C followed by annealing enhanced ductility up to 0.35 of true strain. It was found that tensile twinning was important in accommodating strain during tensile testing, which resulted in a very good hardening behaviour. The yield strength was improved to 300 MPa by refining grain size to 0.8 µm in I-ECAP at 150 °C. The obtained structure and properties were shown to be stable up to 150 °C. True strain at fracture was increased to 0.2 after annealing at 150 °C without lowering strength.

Lech Olejnik

Papers

Numerical and physical modelling of plastic deformation in 2-turn equal channel angular extrusion

Micro-extrusion of ultra-fine grained aluminium

The effect of grain size and grain boundary misorientation on the corrosion resistance of commercially pure aluminium

The role of microstructure and texture in controlling mechanical properties of AZ31B magnesium alloy processed by I-ECAP

Simulation of wrinkling in sheet metal forming