Date of Award
Doctor of Philosophy
Materials Science and Engineering
R. Bruce Thompson
Technology development in materials science, electrical engineering, NDE, mechanical engineering, and computer science, makes it possible to produce advanced materials of designed microstructure and properties. A control model for materials processing with NDE technology was proposed and a prototype of the high temperature EMAT measurement system was built. The example studied is the ultrasonic monitoring of recrystallization in 5XXX aluminum alloys. There are two distinguished textures in aluminum alloys, i.e., recrystallization texture and rolling texture. These two textures change in opposite directions during the hot rolling process: the rolling process will produce rolling texture, while the annealing process produces recrystallization texture. The control goal of the hot rolling process is to produce predefined texture and microstructure. Texture information is inferred from ultrasonic velocity measurements and the microstructure information is inferred from ultrasonic attenuation measurements. Several models in interdisciplinary fields are proposed and preliminary verification experimental results were presented. A pattern recognition technique was introduced to process OIM raw data, which results in a new algorithm to extract texture information. A new model was proposed to model the texture evolution during annealing. Several pieces of computer software were developed to process experimental data and to implement the models proposed.
Digital Repository @ Iowa State University, http://lib.dr.iastate.edu
Liu, Guizhong, "Ultrasonic monitoring of recrystallization: an example of in-situ process control with NDE " (2003). Retrospective Theses and Dissertations. 1445.