Effect analysis of heat treatments on electroplasticity of AA6082

Abstract

Manufacturing in automotive and aircraft industries are focused in improvement and cost reductions of forming processes such as stamping, drawing, and machining. Electrically assisted forming is a technique whereby metal is deformed while simultaneously electric current flow is induced. This recently developed process is presented as an alternative to traditional hot stamping manufacturing processes where larger ductility and reduction of maximum strength reduce the possibility of tearing or cracking during stamping by means of heat treatment. The effect of electroplastic employing electropulses on the mechanical properties of EN-AW 6082 aluminum alloy was studied. Various heat treatments were analyzed in order to examine comparatively different behaviors throughout the tensile test while electro-pulsing was induced. The structure of the study herein presents two main parts. The first part is the study of aging treatments of the AA6082 taking in interest the well-known industrial conditions which are the natural aging condition (T4), the artificial aging condition (T6) as well as others of non-industrial interest such as the overaging condition, as well as the condition of the alloy directly quenched from the solution heat treating (SHT). The results presented in this investigation showed a well-known differentiated behavior during tensile testing of solution heat treated, natural aging (T4), artificially peak-aged (T6) and overaged samples. It is important to mention as well that starting material is a sheet of thickness 1 mm from manufactured in a rolling process, by this fact the rolling direction has been also part of the investigation specifying the 0º, 45º and 90º respectively to the rolling direction in order to characterize anisotropy. The second part of this study has been focused entirely in the electroplastic effect utilizing electro-pulsing during tensile testing of AA6082 for each heat treatment above mentioned. The performance of electro-pulsing has been varying frequency and pulse-length in consequence the constant energy has been also varied due that both parameters are related to the last mentioned and so a broad range of considerations has been well-thought-out. The goals of this project are to measure as accurately as possible the variations caused by the electroplastic effect and those variations had been limited mainly to those two factors above mentioned: ductility and maximum strength. Mechanical behavior appears to be greatly modified in presence of an electric current and taking into consideration the known different structures of SHT, natural, artificial and overaged the analysis of interaction of electric-current and nano and/or microstructures/dislocations are still not well understood currently.