An experimental investigation of the drawability of AA6082 sheet under different elevated temperature forming processes

The performed research has, for the first time, investigated and compared the drawability of AA6082 at a comparable temperature range between two elevated temperature forming processes: termed (i)Low Temperature Hot Form and Quench (LT-HFQ^®)or pre-cooled HFQ^®, patented by Adam et al. (2015)and (ii)Direct Heating Aluminium Forming (DHAF)which represents a refinement of conventional warm forming targeting a higher temperature range. A series of uniaxial tensile and cylindrical deep drawing experiments were conducted. According to uniaxial tensile test results, the most obvious work-hardening and reasonable ductility was observed under LT-HFQ^® at a deformation temperature of 350 °C and strain rate of 1 s⁻¹, which can enhance drawability. For deep drawing experiments, it was found that preheating conditions of each process prior to forming significantly affected forming characteristics and post-formed hardness of the alloy; both the achieved maximum Draw ratio (DR)and limit Blank Holding Force (BHF)at some specific process parameters were increased under LT-HFQ^®. Forming speed and temperature had significant effects on alloy deformation and thus drawability for both processes. In addition, by evaluating the post-formed hardness, process drawability and microstructural evolutions under different processes were simultaneously analyzed.