Microstructure characterization of metallic materials processed by Equal Channel Angular Pressing (ECAP): an Electron Backscatter Diffraction (EBSD) analysis

This overview article discusses the Equal Channel Angular Pressing (ECAP) processing of different metallic materials. Particular emphasis is given to the microstructural evolution from the coarse grain (CG) to the ultrafine-grained (UFG) states throughout the electron backscattering diffraction (EBSD) technique. Iron-based alloys, such as duplex and 1020 low-carbon steels reached higher hardening with a lower deformation and lower non-ultrafine average grain sizes than the ultrafine pure iron condition due to fast grain fragmentation, i.e., more geometrically necessary dislocation (GND) grouping. Moreover, due to the magnesium adhesion, copper alloys reached superior mechanical properties compared to pure copper even when the initial grain size for as-cast alloys was over 1000 µm. On the other hand, low melting temperature (T MP) materials processed at 250°C, like the ZK60 magnesium and AA6082 aluminum alloys (i.e., homologous temperatures (TH) of 0.38T MP and 0.37T MP, respectively), showed grain refinement without reaching the ultrafine regime and mechanical softening due to the static and dynamic recrystallization phenomena. CP titanium also displayed heterogeneous grain sizes with average values of above 1 µm after four ECAP passes for temperatures ranging between 150°C and 400°C (TH between 0.09T MP ¹ 0.24TMP). The evolution of the GNDs suggested that the initial deformation stages of severe plastic deformation (SPD) by ECAP produced the most notorious density increments from 10 12 m¹2 to 1014 m¹2 , which level up at high deformations (more than four ECAP passes) around 1014 1015 m¹2 , explaining the fast and slow grain size reduction rates, respectively. The ECAP processing on different metallic material systems showed a larger grain fragmentation capacity in high melting points and alloyed materials, giving rise to steep yield strength increases and low ductility. The low ductility and grain size saturation correspond to a low capacity to create new grain boundaries manifested by the GNDs saturation in the UFG range.Peer ReviewedPostprint (published version

Continence technologies whitepaper: Informing new engineering science research

Advances in healthcare technology for continence have historically been limited compared to other areas of medicine, reflecting the complexities of the condition and social stigma which act as a barrier to participation. This whitepaper has been developed to inspire and direct the engineering science community towards research opportunities that exist for continence technologies that address unmet needs in diagnosis, treatment and long-term management. Our aim is to pinpoint key challenges and highlight related research opportunities for novel technological advances. To do so, we draw on experience and expertise from academics, clinicians, patients and patient groups linked to continence healthcare. This is presented in four areas of consideration: the clinical pathway, patient perspective, research challenges and effective innovation. In each we introduce seminal research, background information and demonstrative case-studies, before discussing their relevance to engineering science researchers who are interested in approaching this overlooked but vital area of healthcare

Microstructure and mechanical properties of a commercially pure Ti processed by warm equal channel angular pressing

A commercially pure (CP) Titanium alloy classified as Grade 1, was processed by Equal Channel Angular Pressing (ECAP) up to 4 passes in the temperature range of 450-150 degrees C.; The resulting microstructures were observed by Electron Back-Scattered Diffraction, revealing a bimodal grain size distribution consisting of small recrystallized grains of submicrometer size, with an average value of 0.3 mu m, and elongated bands of 1.4 mu m with different degree of substructure. Additionally the fraction of restored and deformed grains were evaluated as a function of processing temperature following an internal grain misorientation criterion, leading to an overall fraction of recrystallized grains between 40% and 20% in samples ECAPed at 450 and 150 degrees C, respectively.; The strengthening contributions of the grain size, equivalent oxygen content (O-eq) and Low Angle Grain Boundaries (LAGBs) to the yield stress were identified by the Hall Fetch and Taylor equations. The strengthening coefficient k of the Hall-Fetch relation was approximately 5 MPa mm(-1/2), with an increment of 0.44 MPa mm(-1/2) per 0.1 O-eq.-%, while the LAGB strengthening contribution was responsible approximately by half of the experimental yield stress values measured. (C) 2014 Elsevier B.V. All rights reserved.Peer Reviewe

Microstructure and mechanical properties of a commercially pure Ti processed by warm equal channel angular pressing

A commercially pure (CP) Titanium alloy classified as Grade 1, was processed by Equal Channel Angular Pressing (ECAP) up to 4 passes in the temperature range of 450-150 degrees C.; The resulting microstructures were observed by Electron Back-Scattered Diffraction, revealing a bimodal grain size distribution consisting of small recrystallized grains of submicrometer size, with an average value of 0.3 mu m, and elongated bands of 1.4 mu m with different degree of substructure. Additionally the fraction of restored and deformed grains were evaluated as a function of processing temperature following an internal grain misorientation criterion, leading to an overall fraction of recrystallized grains between 40% and 20% in samples ECAPed at 450 and 150 degrees C, respectively.; The strengthening contributions of the grain size, equivalent oxygen content (O-eq) and Low Angle Grain Boundaries (LAGBs) to the yield stress were identified by the Hall Fetch and Taylor equations. The strengthening coefficient k of the Hall-Fetch relation was approximately 5 MPa mm(-1/2), with an increment of 0.44 MPa mm(-1/2) per 0.1 O-eq.-%, while the LAGB strengthening contribution was responsible approximately by half of the experimental yield stress values measured. (C) 2014 Elsevier B.V. All rights reserved.Peer Reviewe

Graphical Bayesian models in multivariate expert judgements and conditional external Bayesianity

SIGLEAvailable from British Library Document Supply Centre-DSC:DXN011313 / BLDSC - British Library Document Supply CentreGBUnited Kingdo

Large deviations with applications to telecommunications

SIGLEAvailable from British Library Document Supply Centre-DSC:4335.26206(2000-27) / BLDSC - British Library Document Supply CentreGBUnited Kingdo

Caracteristicas de la deformacion en caliente de aceros TWIP

Postprint (published version

Identification of undeformed/deformed FeSi oxides scales by EBSD

Postprint (published version