Al-Mg-Si: Microstructural Analysis

2019 ◽  
Author(s):  
Marcello Cabibbo
Keyword(s):  
Plastic Deformation ◽  
Severe Plastic Deformation ◽  
Microstructural Analysis ◽  
Strengthening Effect ◽  
Angular Pressing ◽  
Zr Addition ◽  
First Case ◽  
Specific Modeling

This article presents two case studies referring to the severe plastic deformation applied to Al-Mg-Si alloys. In a first case study, an Al-Mg-Si alloy in a T6 temper is subjected to equal-channel angular pressing (ECAP), and all the microstructure strengthening contributions to the alloy yield stress are determined through specific modeling and then validated. In a second case study, two Al-Mg-Si alloys, one with Zr addition and a second with Sc-Zr addition, are subjected to ECAP after a T6 temper in an overaged status. In the second case, the role of the Zr- and Sc-Zr-containing nanometer dispersoids is described, and the related strengthening effect is modeled according to the models presented in the first case study.

An Investigation of Mechanical Properties and Microstructural Evolution in an Aluminum Alloy Processed by Severe Plastic Deformation

2014 ◽  
Vol 922 ◽  
pp. 610-615 ◽  
Author(s):  
Shima Sabbaghianrad ◽  
Terence G. Langdon
Keyword(s):  
Mechanical Properties ◽  
Plastic Deformation ◽  
Aluminum Alloy ◽  
Severe Plastic Deformation ◽  
Microstructural Evolution ◽  
Vickers Microhardness ◽  
Microstructural Analysis ◽  
Angular Pressing ◽  
Al 7075 ◽  
7075 Alloy

Processing by a combination of equal-channel angular pressing (ECAP) and high-pressuretorsion (HPT) was performed on disks of an Al-7075 alloy. The alloy was annealed at 753 K, processedby ECAP for totals of 4 passes and then processed by HPT under a pressure of 6.0 GPa up to amaximum of 20 turns. Measurements of Vickers microhardness showed reasonable hardnesshomogeneity after processing through 20 turns. It is demonstrated that the results from mechanicaltesting and microstructural analysis are consistent with the hardness measurements.

TECHNOLOGIES FOR MANUFACTURING NANOSTRUCTURED SURFACES

2020 ◽  
Author(s):  
Андрей Дмитриевич Бухтеев ◽  
Виктория Буянтуевна Бальжиева ◽  
Анна Романовна Тарасова ◽  
Фидан Гасанова ◽  
Светлана Викторовна Агасиева
Keyword(s):  
Plastic Deformation ◽  
Surface Modification ◽  
Severe Plastic Deformation ◽  
Pressing Pressure ◽  
Pressure Treatment ◽  
Structured Surfaces ◽  
Nanostructured Surfaces ◽  
Angular Pressing ◽  
Multilayer Composites ◽  
Compaction Of Powders

В данной статье рассматривается применение и технологии получения наноструктурированных поверхностей. Рассмотрены такие методы как компактирование порошков (изостатическое прессование, метод Гляйтера), интенсивная пластическая деформация (угловое кручение, равноканальное угловое прессование, обработка давлением многослойных композитов) и модификация поверхности (лазерная обработка, ионная бомбардировка). This article discusses the application and technology for obtaining nano-structured surfaces. Methods such as compaction of powders (isostatic pressing, Gleiter method), severe plastic deformation (angular torsion, equal-channel angular pressing, pressure treatment of multilayer composites) and surface modification (laser treatment, ion bombardment) are considered.

FIRST CASE SERIES OF VENOUS SINUS STENTING IN IIH PATIENTS IN WALES

2015 ◽  
Vol 86 (11) ◽  
pp. e4.113-e4
Author(s):  
Gauhar Abbas Malik ◽  
Yogish Joshi
Keyword(s):  
Intracranial Hypertension ◽  
Case Series ◽  
Headache Disorder ◽  
Venous Sinus ◽  
First Line ◽  
Venous Stenting ◽  
First Case ◽  
Sinus Stenosis

BackgroundIdiopathic Intracranial Hypertension (IIH), is defined by increased cerebral spinal fluid (CSF) pressure in the absence of other causes of intracranial hypertension. There has been recent interest in the role of intracranial venous sinus stenosis in IIH. The raised pressures in IIH are argued to worsen by the secondary appearance of the venous sinus stenosis.Objective5 patients have undergone endovascular pressure measurement in Wales and their clinical details including history, examination, initial management, neuroimaging pre- and post venous stenting, and follow-up (6–24 months) to provide the first case study of patients undergoing Venous sinus stenting in Wales.Methods5 patients with IIH refractory to first line treatments underwent venography and manometry and 4 patients underwent stenting of the venous sinuses after this procedure had shown a pressure gradient proximal to stenosis in the lateral sinuses.ResultsThree patients were rendered asymptomatic, two were improved including one patient unmasking a different headache disorder following treatment.ConclusionsStenting in venous stenosis provides a further treatment option to patients refractory to first line treatments with IIH. This case series highlights in selected cases treatment is promising with good outcomes.

MULTI-SCALE FINITE ELEMENT SIMULATION OF SEVERE PLASTIC DEFORMATION

2009 ◽  
Vol 23 (06n07) ◽  
pp. 1621-1626
Author(s):  
HYOUNG SEOP KIM
Keyword(s):  
Plastic Deformation ◽  
Finite Element ◽  
Severe Plastic Deformation ◽  
Constitutive Model ◽  
Dislocation Cell ◽  
Ultrafine Grain ◽  
Angular Pressing ◽  
Element Simulation ◽  
Ultrafine Grain Size ◽  
Ultrafine Grained

The technique of severe plastic deformation (SPD) enables one to produce metals and alloys with an ultrafine grain size of about 100 nm and less. As the mechanical properties of such ultrafine grained materials are governed by the plastic deformation during the SPD process, the understanding of the stress and strain development in a workpiece is very important for optimizing the SPD process design and for microstructural control. The objectives of this work is to present a constitutive model based on the dislocation density and dislocation cell evolution for large plastic strains as applied to equal channel angular pressing (ECAP). This paper briefly introduces the constitutive model and presents the results obtained with this model for ECAP by the finite element method.

scholarly journals Twisting of the Tail Rotor Shaft - A Case Study

2018 ◽  
Vol 778 ◽  
pp. 28-32
Author(s):  
Muhammad Shahzad ◽  
Tanveer Manzoor ◽  
Qanita Tayyaba ◽  
Ammad Hussain Qureshi
Keyword(s):  
Mechanical Properties ◽  
Plastic Deformation ◽  
High Strain ◽  
Microstructural Analysis ◽  
Sem Images ◽  
Rotor Shaft ◽  
Ansys Simulation ◽  
Strain Rate Loading ◽  
Rule Out

Presented results report the findings of a case study carried out to determine the possible factors that lead to the twisting of tail rotor shaft. The structural materials of the shaft was evaluated in terms of microstructural analysis and mechanical properties to rule out any material fault. The SEM images showed that the localized fractures at twist ends occurred without any significant plastic deformation. Moreover, there was no evidence of fatigue. Such behavior suggests that twist occurred under impact / high strain rate loading. Such loading conditions are not possible during the event to ground hitting. The Ansys simulation confirmed that the observed twisting can increase the stress at localized point in excess of UTS and cause fracture.

scholarly journals Chest CT as a Complement to RT-PCR to Confirm and Follow-up COVID-19 Patients

Medicinus ◽  
2021 ◽  
Vol 8 (1) ◽  
pp. 31
Author(s):  
Aziza Ghanie Icksan ◽  
Muhammad Hafiz ◽  
Annisa Dian Harlivasari
Keyword(s):  
Chest Ct ◽  
Rt Pcr ◽  
High Resolution Computed Tomography ◽  
X Ray ◽  
First Case ◽  
Chest X Ray ◽  
Polymerase Chain

<p><strong>Background : </strong>The first case of COVID-19 in Indonesia was recorded in March 2020. Limitation of reverse-transcription polymerase chain reaction (RT-PCR) has put chest CT as an essential complementary tool in the diagnosis and follow up treatment for COVID-19. Literatures strongly suggested that High-Resolution Computed Tomography (HRCT) is essential in diagnosing typical symptoms of COVID-19 at the early phase of disease due to its superior sensitivity  (97%) compared to chest x-ray (CXR).</p><p>The two cases presented in this case study showed the crucial role of chest CT with HRCT to establish the working diagnosis and follow up COVID-19 patients as a complement to RT-PCR, currently deemed a gold standard.<strong></strong></p>

Effect of Severe Plastic Deformation and Hardening on the Properties and Failure Mechanisms of Constructional Steel

2019 ◽  
Vol 945 ◽  
pp. 579-584
Author(s):  
Maria Z. Borisova
Keyword(s):  
Plastic Deformation ◽  
Impact Strength ◽  
Severe Plastic Deformation ◽  
Structural Steel ◽  
Negative Impact ◽  
Failure Mechanisms ◽  
Positive Influence ◽  
Constructional Steel ◽  
Angular Pressing ◽  
The Impact

The influence of severe plastic deformation on structural materials has been actively studied in recent years. Undoubtedly is the positive influence of this method on strength characteristics of materials. In addition, it is very interesting to influence of the severe plastic deformation on the mechanisms of fracture. One of the most common methods of severe plastic deformation is equal-channel angular pressing (ECAP). In this paper, the influence of different modes of ECAP on the strength of structural steel was studied. Also, the destruction of steel at different test temperatures was studied in detail. It is shown that the ECAP increases the strength of steel almost twice, but the plasticity of steel is reduced, which leads to fragility. Quenching can remove the negative impact of the ECAP on toughness of the steel and will increase the impact strength several times.

Role of Strain Gradient and Dynamic Transformation on the Formation of Nanocrystalline Structure Produced by Severe Plastic Deformation

2007 ◽  
Vol 539-543 ◽  
pp. 2787-2792 ◽  
Author(s):  
Minoru Umemoto ◽  
Yoshikazu Todaka ◽  
Jin Guo Li ◽  
Koichi Tsuchiya
Keyword(s):  
Plastic Deformation ◽  
Severe Plastic Deformation ◽  
Grain Refinement ◽  
Strain Gradient ◽  
High Pressure Torsion ◽  
Large Strain ◽  
Nanocrystalline Structure ◽  
Angular Pressing ◽  
Dynamic Transformation ◽  
Fine Grained Structure

Formation of nanocrystalline structure by severe plastic deformation has studied extensively. Although ultra fine grained structure (grain size larger than 100 nm) had been obtained in many processes such as heavy cold rolling, equal channel angular pressing (ECAP) or accumulative roll bonding (ARB), the formation of nano grained structure (< 100 nm) is limited to processes such as ball milling, shot peening or drilling. In the present study, high pressure torsion (HPT) deformation and drilling were carried out to understand the conditions necessary to obtain nano grained structure in steels. The results of HPT experiments in pure Fe showed that HPT has superior ability of strengthening and grain refinement probably due to a strain gradient but the saturation of grain refinement occurs before reaching nano grained structure. Drilling experiments in high carbon martensitic steel revelaed that nano grained ferrite forms at the drilled hole surface only when the transformation from ferrite to austenite takes place during drilling. Considering various other processes by which nano grained ferrite was produced, it is proposed that heavy strains with large strain gradients together with dynamic transformation are necessary to reach nano grained ferrite structure.

Sign in / Sign up

Export Citation Format

Share Document