A Comparative Study on Formability of a Different Thickness FSWed AA 5052 Blank by Conventional and EM Forming

摘要

Difficult-to-weld aluminum alloys of different thicknesses in thin sheets of 1 mm to 1.5 mm are welded by Friction Stir Welding and then mechanically analyzed. Successful welds are obtained at constant tool spindle speed of 1,500 r/min and at two tool traverse speeds of 68 mm/min and 93 mm/min. All the specimens failed at the weld region during tensile testing. Microstructure analysis suggests dynamic recrystallization with a finer grain size at the weld nugget and ductile modes of failure during tensile fracture with sharp sheared dimples at fracture surface. The welded blanks of AA 5052 H32 were then formed by an Electromagnetic Forming (EMF) process to characterize the forming behavior by high velocity forming. Furthermore, the EMF process was compared to a quasi-static forming process. It and a formability analysis were done in terms of a Limit Dome Height test and Forming Limit Diagram. It was found that the formability of welded blanks increases considerably with the EMF process, against the conventional process. However, the tensile strength of the welded blanks was lower than that of base materials, and hence, formability showed the same trend.