Formability of Ultrafine Grained Metals Produced by Severe Plastic Deformation–An Overview

Abstract

Severe plastic deformation (SPD) techniques have attracted considerable attention due to their capability to refine the grain size of metals and alloys down to the ultrafine grained (UFG) regime. A characteristic feature of SPD processes is that they generate semi-finished parts such as rods or sheets, which require further shaping in order to become marketable products. One approach for the shaping of SPD processed materials is the use of metal forming processes, which can be a challenge with regard to the low work hardening rate and tendency to strain localizations of most UFG metals. This article summarizes the current state of knowledge on the formability and forming behavior of UFG metals under different loading scenarios, discussing both limitations and application potential. Furthermore, the interaction between microstructural aspects and the formability, such as the occurrence of strain localizations during and the role of heat treatments are also addressed. Given that the formability of UFG metals has received far less attention than other aspects so far, this work also aims at identifying apparent contradictions as well as scientific and technological questions that need to be addressed in future to expand the current knowledge of the field.

Review on Advances in Metal Micro-Tube Forming

“…Research into severe plastic deformation techniques (SPD) has attracted increasing interest over the past few years due to the potential of these methods to produce bulk nanostructured and ultra-fine-grained metals and metallic alloys [99][100][101][102]. Important objectives of corresponding investigations have been achievements in certain material properties that correlated with a reduced grain size, such as an enhanced material strength or superplasticity at lower temperatures [100,101]. The expected benefits of materials for micro-manufacturing, fabricated from SPD processes, are, aside from a reduction of grain size-related scaling effects, nearly homogeneous mechanical properties and a limited work hardening behavior [100].…”

“…Important objectives of corresponding investigations have been achievements in certain material properties that correlated with a reduced grain size, such as an enhanced material strength or superplasticity at lower temperatures [100,101]. The expected benefits of materials for micro-manufacturing, fabricated from SPD processes, are, aside from a reduction of grain size-related scaling effects, nearly homogeneous mechanical properties and a limited work hardening behavior [100]. Around 120 variants of SPD methods have been introduced up to now, providing metallic materials of different shapes, such as rods, bars, billets, tubes, or sheets [99].…”

Influence of Accumulated Strain on the Fracture Behavior of Low‐ and Medium‐Carbon Steels Processed by Equal‐Channel Angular Pressing

“…In recent years, researchers have devoted increasing attention to the production and use of ultrafine-grained (UFG) materials, which have useful properties that can be practically applied in various branches of science and technology. [1][2][3][4] Moreover, developments in industry and construction impose continually increasing requirements on the strength characteristics of steel used for manufacturing loadbearing parts and structures. A common way to improve the mechanical properties of such parts and structures is through the creation of complex high-alloy steels and the use of hardening heat treatment; however, these approaches ultimately lead to a significant increase in the cost of production, which is not always justified.…”

“…In recent years, researchers have devoted increasing attention to the production and use of ultrafine‐grained (UFG) materials, which have useful properties that can be practically applied in various branches of science and technology . Moreover, developments in industry and construction impose continually increasing requirements on the strength characteristics of steel used for manufacturing loadbearing parts and structures.…”

Microstructures and the Mechanical Properties of the Al–Li–Cu Alloy Strengthened by the Combined Use of Accumulative Roll Bonding and Aging

“…Since the primary use of A2020 aluminum-lithium (Al-Li) alloys began in aerospace applications in the 1950s [1], Al-Li alloys are of great interest to aerospace industries because those alloys are significantly lighter than other series of aluminum alloys, and thus can achieve more fuel-efficient aircrafts. To further extend to commercial applications, high-pressure torsion (HPT) has been used as a severe plastic deformation (SPD) process to obtain high-strength Al-Li alloys [2][3][4][5][6][7][8][9]. The authors successfully attained a hardness of >290 HV for an A2091 Al-Li-Cu alloy by a concurrent strengthening strategy using grain refinement and fine precipitation [3].…”