Date of Award

2021

Document Type

Open Access Master's Thesis

Degree Name

Master of Science in Materials Science and Engineering (MS)

Administrative Home Department

Department of Materials Science and Engineering

Advisor 1

Paul Sanders

Committee Member 1

Daniel Seguin

Committee Member 2

Walter Milligan

Committee Member 3

Thomas Wood

Committee Member 4

Helen Weykamp

Abstract

The homogenization of billets in the aluminum extrusion industry is a critical step that removes chemical segregation from casting, dissolves low melting point phases, forms nanoscale dispersoid phases, and promotes the beta to alpha transformation of iron particles in the matrix. With ever increasing use of aluminum extrusion in the automotive industry there is a constant need for increased efficiency and consistency in processing of extruded aluminum. The work in this thesis explores the effects of 10°C differences in the homogenization temperature on the formation of dispersoids in 6082 alloys used in the automotive industry. The role of dispersoids is to prevent the recrystallization of grains during extrusion giving a more uniform grain structure, improved mechanical properties, and improved corrosion resistance when compared to dispersoid-free alloys. This work found a 10°C increase in homogenization temperature resulted in a 5-15% decrease in dispersoid density, 5-10% increase in dispersoid size, and noticeable effect on mechanical and chemical properties. This effect was maintained regardless of the holding time, temperature, or ramp rate used for homogenization. Additional studies on the effects of two-step homogenizations found similar results on the variation in dispersoid density but had improved properties when compared to one-step homogenization cycles currently used in industry, shedding light on the importance of dispersoid nucleation mechanism in developing improved thermal processing of billets.

Available for download on Wednesday, November 30, 2022

Included in

Metallurgy Commons

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