Investigation of microstructural homogeneity and thermal stability of equal channel angular pressed and aged 2024 Al alloy

Download

index.pdf

Date

2014

Author

Kotan, Güher

Metadata

Show full item record

Item Usage Stats

158
views

126
downloads

Attributed primarily to its uniqueness, simplicity and ability for effective strengthening through grain refinement without reduction in cross sectional area, equal channel angular pressing (ECAP) has been known as one of the most important metal working process. The implementation of ECAP with precipitation hardening exhibits a promising strengthening mechanism to be applied to age-hardenable metals. On the other hand, the combined effect of precipitation hardening and excessive plastic strain is quite complicated and needs detailed investigations to understand the basics of strengthening mechanisms. In this respect, the experimental work in this thesis represents a substantial step forward to understand the strengthening mechanism resulted by a combined implementation of ECAP and precipitation hardening in aluminum 2024. In the first part of this study, various aspects of ECAP and post ECAP precipitation in comparison to solutionized and aged counterpart were investigated. Homogenization contribution of precipitation process was monitored via micro-hardness indentation and the degree of homogenization was characterized by hardness inhomogeneity index (HII). The variation of hardness, hence strain levels, observed in two different samples was also investigated considering level of back pressure, magnesium content and sample conditions. In the second part, the response of ECAPed and post-ECAP aged samples, when subjected to long term and moderate temperatures up to 1000 hours was investigated. A limiting temperature was suggested for the safe use of an ECAPed Al 2024. Throughout the study microstructural characterizations were performed using high resolution electron microscopy (HREM), scanning electron microscopy (SEM), electron backscatter diffraction (EBSD) and optical microscopy.

Subject Keywords

Aluminum alloys, Aluminum alloys, Metals, Electron microscopy.

URI

http://etd.lib.metu.edu.tr/upload/12618046/index.pdf
https://hdl.handle.net/11511/23915

Collections

Graduate School of Natural and Applied Sciences, Thesis

Suggestions

OpenMETU
Core

Analysis of magnesium addition, hydrogen porosity and T6 heat treatment effects on mechanical and microstructural properties of pressure die cast 7075 aluminum alloy Alat, Ece; Kalkanlı, Ali; Department of Metallurgical and Materials Engineering (2012) Aluminum alloys are having more attention due to their high specific stiffness and processing advantages. 7075 aluminum alloy is a wrought composition aluminum alloy in the Al-Zn-Mg-Cu series. Due to the significant addition of these alloying elements, 7075 has higher strength compared to all other aluminum alloys and effective precipitation hardenability characteristic. On the other hand, aluminum alloys have some drawbacks, which hinder the widespread application of them. One of the most commonly encounte...
Assessment of dynamic response FD algorithms by beam and plate FE computations Alaylioglu, H.; Oral, Süha; Alaylıoğlu, Ayşe (Elsevier BV, 1988-10) Improvement in understanding of the process of direct integration of the equations of motion through numerical dissipation parameter interaction is being regarded as one of the significant achievements of structural dynamics research over the past quarter century. The numerical software fraternity has extended one-step integration algorithms, emphasizing controllable approximation characteristics with respect to such factors as period elongation and amplitude decay. These studies have resulted in setting up...
Production and heat treatment of 6111 aluminum alloy sheet for car body panel application Sevimli, Aylin; Kalkanlı, Ali; Department of Metallurgical and Materials Engineering (2015) Aluminum is one of the major candidates to supply sufficient weight reduction without missing mechanical properties and performance. Therefore, studies have been focused on improving properties of aluminum in automotive application since 1920s. Heat treatable aluminum alloy are used in car body panels of automotive application such as 2xxx, 7xxx and 6xxx series aluminum alloys base on the mechanical properties. On the other hand, based on physical and economical properties 6xxx series aluminum alloys are wi...
Investigation of the effect of dissimilar channel angular pressing method to the mechanical and microstuctural properties of 6061 aluminum alloy sheets Kibar, Alp Aykut; Gür, Cemil Hakan; Department of Metallurgical and Materials Engineering (2010) Dissimilar Channel Angular Pressing (DCAP) method is an effective Severe Plastic Deformation (SPD) technique to improve the mechanical properties of sheets or strips by producing ultrafine grains. The aim of this study is to investigate the evolution of the microstructure and the improvement in mechanical properties of 6061 Al-alloy strips deformed by DCAP up to 5 passes. Mechanical properties such as hardness and strength have been observed to increase up to a certain strain level depending on the microstr...
Shear strength of cement-grout borehole plug Akgün, Haluk (2000-01-01) The theoretical normal stress and shear strength distributions along the plug-rock interfaces of axially loaded expansive cement-grout borehole plugs cast in rock cylinders, determination of interfacial shear strength parameters, and experimental analyses of plug-rock mechanical interactions are presented as a function of uniform curing and testing temperature and of borehole size. The results of the back analysis show that the angle of internal friction along the plug-rock interface remains almost constant...

Citation Formats

G. Kotan, “Investigation of microstructural homogeneity and thermal stability of equal channel angular pressed and aged 2024 Al alloy,” Ph.D. - Doctoral Program, Middle East Technical University, 2014.