Theses and Dissertations
Issuing Body
Mississippi State University
Advisor
Horstemeyer, Mark F.
Committee Member
Martin, Holly J.
Committee Member
Stone, Tonya W.
Committee Member
Wang, Paul T.
Date of Degree
12-14-2013
Document Type
Dissertation - Open Access
Major
Mechanical Engineering
Degree Name
Doctor of Philosophy
College
James Worth Bagley College of Engineering
Department
Department of Mechanical Engineering
Abstract
In this study, a new consistent formulation coupling kinematics, thermodynamics, and kinetics with damage using an extended multiplicative decomposition of the deformation gradient that accounts for corrosion effects is presented. The technical approach used for modeling the corrosion behavior of magnesium alloys was divided into three primary steps. First, a predictive corrosion model was developed based on experimental corrosion observations. The experimentally-observed corrosion mechanisms of pitting, intergranular, and general corrosion on the AZ31 magnesium alloy were quantified in 3.5 wt.% NaCl immersion and salt spray environments using optical microscopy and laser profilometry to document the changes in the pit characteristics. Although both environments showed similar trends, the immersion environment was more deleterious with respect to intergranular and general corrosion. On the other hand, the salt-spray environment allowed deeper pits to form throughout the entirety of the experiments, which led to a substantial thickness drop (general corrosion) compared with the immersion environment. Next, the complete corrosion model based upon the internal state variable theory was formulated to capture the effects of pit nucleation, pit growth, pit coalescence, and general corrosion. Different rate equations were given for each mechanism. Following the formulation of the model, the aforementioned experimental work and experimental work on four other magnesium alloys (AZ61, AM30, AM60, and AE44), was used to validate the model.
URI
https://hdl.handle.net/11668/19031
Recommended Citation
Walton, Christopher Avery, "Creation of an Internal State Variable Plasticity-Damage-Corrosion Model Validated by Experiments with Magnesium Alloys" (2013). Theses and Dissertations. 1217.
https://scholarsjunction.msstate.edu/td/1217