Date of Award

2023

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

Walter Milligan

Committee Member 2

Stephen Kampe

Committee Member 3

David Labyak

Committee Member 4

Douglas Swenson

Abstract

Alloy 6082 aluminum is used for high-volume manufacturing in the automotive industry due to its high strength, impact performance, and corrosion resistance. However, given these improved properties, the alloy has decreased formability compared to other 6xxx series alloys, especially in the extrusion process. Controlling the dynamic recovery and recrystallization properties by changing the additions of Mg and Si can improve the hot deformation properties. Five alloys of varying Mg and Si concentrations between 0.6 to 1.2wt% Mg and 0.7 to 1.3wt% Si were made with constant concentrations of Cr, Fe, and Mn and the same homogenization heat treatment. The proposed alloys are tested using hot compression to identify the activation energy for hot deformation at temperatures of 400℃, 450℃, and 500℃ with strain rates of 0.1s-1, 0.01s-1, and 0.001s-1. The resulting compression samples are analyzed using EBSD to identify the fraction recrystallized. The results show that increasing Mg from 0.6 to 1.2wt% decreases the activation energy from 262 to 220 kJ/mol. In contrast, increases in Si from 0.7 to 1.3wt% decreased the recrystallization fraction and increased activation energy from 262 to 292 kJ/mol. An optimal composition range was identified to be a ratio of Mg to Si between 0.8 and 1, as all alloys close to this ratio had low recrystallized fractions and activation energies compared to other alloys tested for the select temperature and strain rate conditions.

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