COMPARING THE BAKE HARDENING OF NANO-GRAIN AA6056 WITH ITS COARSE-GRAIN STRUCTURE

Abstract

In preset work, the bake hardening behavior of 6056 aluminum alloy with nanostructured layer, produced by surface severe plastic deformation (SSPD), was compared with that of AA6056 with conventional coarse grain structure. Wire brushing process was employed in order to produce surface layers with nanograins. After formation of nanostructured surface layer, the structure was characterized using X-ray Diffraction (XRD) and scanning electron microscopy (SEM) techniques. According to the microhardness measurements, the depth of nanostructured layer, with the grains of 50-110 nm, was about 40-50 μm on each side of specimens. The bake hardenability of the produced nanostructured AA6056 was then studied. The results indicate an increase of about 40% in the bake hardening of nanograin AA6056 comparing to the bake hardening of coarse-grain AA6956. The maximum microhardness of nanograin layer was about 250 HV, whereas it was 65 HV for coarse-grain AA6056.