Hot deformation behavior of friction-stir processed strip-cast 5083 aluminum alloys with different Mn contents

Fine grained 5083 aluminum alloy is the most common Al–Mg alloy for superplastic forming (SPF) of lightweight sheet metal parts in the automotive and aerospace industries. The fine grained sheet is industrially produced by massive cold rolling of conventionally rolled sheet stock at high cost. Friction stir processing (FSP) as a thermomechanical process is very effective in refining the microstructure of as-cast alloys such as that produced by continuous strip casting (CC). In this work, the effect of friction stir processing on the superplastic properties of three CC 5083 aluminum alloys, with different Mn content, has been investigated. The three alloys were friction stir processed. Very fine microstructures with grain sizes less than 3 μm were obtained. Tensile tests revealed elongations of over 600% at a high strain rate of 10−1 s−1 in all 3 alloys. The maximum tensile elongation of 800% was achieved in the alloy with the lowest Mn content at 490 °C and strain rate of 3 × 10−2 s−1. The stability of the microstructure was an important concern above 500 °C.