The influence of severe plastic deformation on tensile properties and fracture of Aluminum alloy ۶۰۶۱

In this paper, the tensile properties and fracture behavior of the bulk nanostructured/ultra-fine grained (BN/UFG) Aluminum alloy ۶۰۶۱ were investigated. Severe plastic deformation (SPD) by equal-channel angular pressing (ECAP) method was implemented to induce large plastic strain into the billets of Al۶۰۶۱ to produce BN/UFG aluminum alloy. The results revealed that the yield strength and the ultimate strength increase significantly after two passes of ECAP. However, after two additional passes, the yield and the ultimate strengths decrease slightly. This phenomenon was explained by generated analytical model for prediction of the mechanical properties of BN/UFG materials.Nevertheless, a noticeable increase in ductility and toughness was observed. Assessment of the fractured surfaces after tensile tests demonstrated the fracture mechanism in the samples before and after severe plastic deformation. The large and deep micro-voids which were present in the fractured surface of annealed specimens were replaced by small, well developed and uniformly distributed dimples after two ECAP passes. In addition, further increase in the number of ECAP passes caused the formation of parabolic shaped microvoids indicating the shear type fracture mode in the uniaxial tensile test.

Keywords:

Equal-channel angular pressing , Fractography , Nanostructured/ultra-fine grained Aluminum alloy , Severe plastic deformation , Tensile properties