Nanoindentation study of the effect of cryogenic treatment on a AA6012 alloy subjected to ECAP.

The present work describes a study on the evolution of nano hardness and reduced elastic modulus, measured by nanoindentation techniques, on samples of AA6012 Aluminum Alloy subjected to severe plastic deformation (SPD) by progressive passes of Equal-Channel Angular Pressing (ECAP) using the route Bc. In particular, this study is focused on the role of the cryogenic treatment, carried out immediately before each pass of ECAP, on the mechanical properties of the AA6012 alloy after solutioning and plastic deformation. On the basis of the obtained results, it was possible to define the role of cryogenic treatment during secondary precipitation, comparing the behavior of the alloy when it is subjected to ECAP. It is evident, from the observation of cryogenically treated samples, as the abrupt cooling inhibits the motion of dislocations and, consequently, leads to better mechanical performance.