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The effect of hot-deformation on mechanical properties and age hardening characteristics of Al-Mg-Si based wought aluminum alloys

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2006
Tan, Evren
Microstructural and mechanical characterizations of heat treatable Al-Mg-Si-Cu based wrought aluminum alloys have been studied. The aim of this work was to produce fine grained, high strength alloy by adjusting processing conditions: deformation, solutionizing and aging. First, primary characterization was carried out via SEM-EDS analyses and tensile tests. Then an extensive experimental study has been carried out on two sets of samples. The first set has been studied to determine the ideal conditions for solutionizing and aging processes by analyzing the variation of hardness with different solutionizing and aging time and temperature. The second set, have first been mechanically deformed by swaging at four different deformations and four different temperatures, then heat treated. The hardness measurements have been carried out before and after solutionizing and also after aging. Finally, recrystallization behavior has been investigated by measuring grain size before and after solutionizing treatment using image analyzer software. The initial characterizations showed that Mg2Si and complex iron, manganese bearing intermetallics were the primary particles observed in the α-Al matrix. Nearly 140HB hardness could be obtained with solutionizing at 530°C and aging at 175°C for 8 hours which was determined as the optimum treatment for obtaining peak hardness. When shaping (deformation) was concerned; strength loss was the overall outcome of any hot or cold deformation before solutionizing; which was most probably due to the destruction of the initial microstructure. Improvement in the percent elongation was the promising aspect of this application. Strength loss was increased for samples deformed at higher temperatures and higher reductions.