Superior combined strength and elongation by conducting elevated temperature constrained groove pressing on Al–Mg–Mn sheets

Abstract

Al 5083 alloy has widely been employed in marine and offshore engineering as well as production of various types of superplastically formed parts in aerospace and automotive industries. The constrained groove pressing (CGP) is also one of important sheet severe plastic deformation (SPD) technique. In this study, The CGP process has been performed on Al 5083 sheets at an elevated temperature and up to three cycles. Complementary experiments, namely metallography, precipitation evolution, hardness and tensile tests as well as fractography were conducted for various deformed and undeformed sheets. The 1-passed workpiece represented the minimum average grain size (AGS) 8 μm due to huge strain induction. By computing the inhomogeneity factor (IF), it was also found that the 2-passed sample was the most inhomogeneous worksheet with an IF of 6.3. By performing three CGP cycles, superior elongation of 56.2% combined with UTS of 309 MPa were achieved for the 3-passed sample, making this workpiece very suitable for conducting any subsequent metal forming process. This was mainly due to the precipitation evolutions of Al6(Fe,Mn) and Al3Mg2 particles. Moreover, fractography of various specimens showed that by performing greater number of CGP cycles, the fracture mechanisms changed to a ductile mode due to creation of tiny and deep dimples.