Effects of the equal channel angular pressing (ECAP) on the fracture and fatigue parameters of Al-6063 alloy

In this paper, effects of severe plastic deformation (SPD) on the fatigue crack growth, mechanical properties, texture, roughness and fracture toughness of Al-6063 were studied. The Al-6063 alloy was deformed by ECAP process. The average grain size refined to less than 100nm. The textural study conducted before and after ECAP process. The fatigue crack growth tests were performed for different load range at same load ratio. The yield and ultimate stresses increased about 230% and 79% after ECAP process, respectively. The elongation reduced from 16.6% to 7% after four passes of ECAP process. The fatigue crack growth rate increased after first pass of ECAP process. The Paris equation parameters changed before and after ECAP but there is no significant change for different load ranges. The fracture toughness decreased after first pass of ECAP process. The atomic force microscopy (AFM) were used for measuring roughness. The scanning electron microscope (SEM) pictures were made for fracture surface study. The ductile and fissured fracture with large dimples were seen before ECAP process. The fracture surface with refined dimples observed after ECAP process.