Doctoral Dissertations

Abstract

"The influence of friction stir processing (FSP), a microstructural modification tool, on the corrosion behavior of Al-Mg, Al-Mg-Sc, Mg-Al-Zn and Mg-Y-RE alloys has been studied. An attempt has been made to establish correlation between processing parameters and the subsequent microstructural evolution especially matrix grain size on the corrosion and stress corrosion properties of the alloys. A relationship between grain size and corrosion rate for Mg-Y-RE alloys was envisaged and power law type behavior was proposed. Ultrafine fine grained (UFG) microstructure showed one order magnitude lower corrosion rate.

Grain refinement achieved through different FSP parameters showed lower corrosion currents for Al-Mg alloy as compared to the base alloy. The significant increment in linear polarization resistance of UFG Al-Mg-Sc alloy has been attributed to modification in chemistry and grain refinement. The slow strain rate testing (SSRT) results indicated no stress corrosion susceptibility for FSP Al-Mg alloy. A critical grain size for Al-Mg alloys has been proposed to show optimum general corrosion resistance with no stress corrosion cracking (SCC) susceptibility.

AZ31 microstructures showed significant loss of ductility during SSRT in corrosive medium indicating high SCC susceptibilities. The higher SCC resistance of over aged Mg-Y-RE microstructure as compared to under aged and peak aged was attributed to the alteration in microchemistry and precipitate morphology in the matrix"--Abstract, page iv.

Advisor(s)

Mishra, Rajiv S.

Committee Member(s)

O'Leefe, Matthew J.
Newkirk, Joseph William
Miller, F. Scott, 1956-
Dharani, Lokeswarappa R.

Department(s)

Materials Science and Engineering

Degree Name

Ph. D. in Materials Science and Engineering

Publisher

Missouri University of Science and Technology

Publication Date

Fall 2012

Journal article titles appearing in thesis/dissertation

  • Corrosion behavior of a friction stir processed rare-earth added magnesium alloy
  • Effects of grain size on the corrosion resistance of wrought magnesium alloys containing neodymium
  • Effect of friction stir processing on corrosion behavior of AA5083 aluminum alloy
  • Stress corrosion cracking susceptibility of ultrafine grained Al-Mg-Sc alloy
  • Stress corrosion cracking susceptibility of ultrafine grained AZ31
  • Effect of aging on stress corrosion behavior of precipitation hardened wrought magnesium alloy

Pagination

xv, 177 pages

Note about bibliography

Includes bibliographical references.

Rights

© 2012 Gaurav Ramchandra Argade, All rights reserved.

Document Type

Dissertation - Open Access

File Type

text

Language

English

Subject Headings

Light metal alloys -- Stress corrosionFriction stir welding

Thesis Number

T 10021

Print OCLC #

843905457

Electronic OCLC #

908558061

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