Journal of Materials Research and Technology (Nov 2020)
The influence of ECAP and HPT processing on the microstructure evolution, mechanical properties and tribology characteristics of an Al6061 alloy
Abstract
The microstructure evolution and mechanical properties of an Al6061 alloy severely deformed by equal channel angular pressing (ECAP) and high-pressure torsion (HPT) were studied. The grain refinement of ECAPed and HPTed samples down to ultrafine grains (UFG) with nano-size second phase and high angle grain boundaries increases the tensile strength with the transformation of the fracture mode into a shear mode and a decrease in the size of the dimples. The deformation process not only has an influence on the hardness increase but also on the hardness distribution patterns across the sample that was confirmed by finite element simulation (FEM) strain distribution maps. The increase of the hardness improves the wear resistance and frictional properties of the Al6061 alloy, obviously with more superiority of the HPTed samples. Wear mechanism transformed from adhesive, delamination, and plastic deformation into a combination of abrasive with a slight degree of adhesive wear after ECAP and HPT processing. Worn surface morphology and analysis of both samples and WC ball confirms wear results. Present results emphasize that HPT is the most effective method in enhancing wear characteristics of Al6061 samples.
