Abstract
The hot deformation behaviors of homogenized direct-chill (DC) casting 6061 aluminum alloys and Mn/Cr-containing aluminum alloys denoted as WQ1 were studied systematically by uniaxial compression tests at various deformation temperatures and strain rates. Hot deformation behavior of WQ1 alloy was remarkably changed compared to that of 6061 alloy with the presence of α-Al(MnCr)Si dispersoids. The hyperbolic-sine constitutive equation was employed to determine the materials constants and activation energies of both studied alloys. The evolution of the activation energies of two alloys was investigated on a revised Sellars’ constitutive equation. The processing maps and activation energy maps of both alloys were also constructed to reveal deformation stable domains and optimize deformation parameters, respectively. Under the influence of α dispersoids, WQ1 alloy presented a higher activation energy, around 40 kJ/mol greater than 6061 alloy’s at the same deformation conditions. Dynamic recrystallization (DRX) is main dynamic softening mechanism in safe processing domain of 6061 alloy, while dynamic recovery (DRV) was main dynamic softening mechanism in WQ1 alloy due to pinning effect of α-Al(MnCr)Si dispersoids. α dispersoids can not only resist DRX but also increase power required for deformation of WQ1 alloy. The microstructure analysis revealed that the flow instability was attributed to the void formation and intermetallic cracking during hot deformation of both alloys.
Highlights
Al-Mg-Si-Cu alloys (6xxx series alloys) have been widely applied in auto industry for their high specific strength, excellent formability, and corrosion resistance [1, 2]
The workability of alloys directly relates to their deformation conditions [6] and their chemical composition [7] and microstructure evolution. e processing maps based on dynamic material modeling (DMM) have been proved to be an effective approach to distinguish optimum processing domains with high power dissipation efficiency from instability domains associated with microstructural defects for hot deformed alloys [8, 9]
Convergent beam electron diffraction (CBED) patterns were used to measure the thickness of the observed transmission electron microscope (TEM) foils. e volume fraction of dispersoids of 6061 and WQ1 alloys were determined, using equation proposed by Li and Arnberg [18]
Summary
Al-Mg-Si-Cu alloys (6xxx series alloys) have been widely applied in auto industry for their high specific strength, excellent formability, and corrosion resistance [1, 2]. E α-Al(FeMnCr)Si dispersoids can effectively pin migration of dislocation and substructures and restrain recovery and recrystallization In these hot processings, the workability of alloys directly relates to their deformation conditions (i.e., temperature and strain as well as strain rate) [6] and their chemical composition [7] and microstructure evolution. The influences of α-Al(MnCr)Si dispersoids on activation energy evolution of corresponding alloys during hot deformation process remain rarely reported. E workability of both alloys was discussed in combination with processing maps and activation energy maps Microstructure evolution of both alloys was observed to reveal the mechanism by which dispersoids affect softening mechanisms and verify workability of the alloys during hot deformation. Convergent beam electron diffraction (CBED) patterns were used to measure the thickness of the observed TEM foils. e volume fraction of dispersoids of 6061 and WQ1 alloys were determined, using equation proposed by Li and Arnberg [18]
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
