Metals can be strengthened by several methods at the expense of limited elongation. A simultaneous enhancement of strength and elongation is still a great challenge. In the present study, a precipitation hardenable Al 7075 alloy was subjected to rolling at liquid nitrogen temperature. The process parameters were optimized using Taguchi’s experimental design method. Orthogonal arrays of Taguchi, the signal-to-noise ratio and the analysis of variance were employed to find the optimal process parameter levels and to analyze the effect of these parameters on the mechanical properties. Confirmation test with the optimal levels of cryorolling parameters was carried out in order to evaluate the Taguchi optimization method . It was found that solution-treated at 480 degC for 5.5 hrs before the rolling, %80 rolling and 30 hrs holding time at 100 degC after the rolling led in the optimized properties. Ultimate strength was increased to 692 MPa (almost 100 Mpa more than that of the as received 7075 aluminum alloy) by applying the optimal parameters while %10 elongation was achieved. TEM studies of the cryorolled and aged samples showed finer and closely spaced strengthening precipitates with the average size of 9 to 14 nm on an ultra-fined grained (UFG) (100 to 600 nm) matrix. Wear behavior of the processed aluminum was examined using dry sliding wear test under a load of 10 N. The results demonstrated that the ultra-fine grained aluminum produced by the optimal parameters resulted in improved wear resistance. The fine grained structure as well as the nano-sized precipitates was found to be the reason of such suitable wear resistance. Keywords: Al 7075 alloy, cryorolling, UFG aluminum
