A new experimental-numerical approach for studying the effects of gas pressure profile on superplastic forming characteristics of Al-Mg5.6 alloy

• Published in: International journal of advanced manufacturing technology Vol. 91; no. 5-8; pp. 1771 - 1780
• Main Authors: Fereshteh-Saniee, Faramarz, Fakhar, Naeimeh, Asgari, Mohammad, Mahmudi, Reza
• Format: Journal Article
• Language: English
• Published: London Springer London 01.07.2017; Springer Nature B.V
• Subjects: Aluminum base alloys; Bulging; CAE) and Design; Computer-Aided Engineering (CAD; Deformation; Engineering; Gas pressure; Heat treating; Industrial and Production Engineering; Industrial applications; Low pressure; Mechanical Engineering; Media Management; Original Article; Pressure dependence; Pressure effects; Strain rate; Superplastic forming; Superplasticity; Time dependence; Workpieces; Superplastic forming; Al-Mg 5.6 alloy; Pressure-time profile; Strain rate
• ISSN: 0268-3768; 1433-3015
• DOI: 10.1007/s00170-016-9871-y

Controlling the strain rate during superplastic forming is the main reason to implement time-variable gas pressure profiles. In the present research, a new approach is introduced for controlling the strain rate during free bulge forming. The approach was examined by performing the superplastic forming operation with the Al-Mg5.6 aluminum alloy as a valuable material in transportation industries. Free bulge forming operations were performed at 500 °C and a strain rate range of 8 × 10 −5 –5.7 × 10 −4  s −1 . The changes of the strain rate at the apex of the workpiece were numerically monitored during the deformation, and a new strategy to smooth these changes was implemented. New time-dependent pressure profiles were defined, and their influences on the forming time and uniformity of the deformed part were examined. Finally, the stepwise rising pressure function followed by a constant pressure at which the time of increasing ( T r ) was between 20 and 40% of the total time needed for merely applying that constant pressure was shown to provide the best results. This type of pressure profile can also improve the uniformity of thickness and save the process time, compared with forming at a constant low pressure. Moreover, this stepwise pressure function is easy to be practically employed in various industrial applications.