Tribological Characteristics of Thermomechanically Processed 7075 Al Alloy Through Nano-scratch Characterization

Abstract

Age-hardenable Al–Zn–Mg–Cu (AA 7075) alloys can be fortified by precipitation solidifying because of precipitation of the MgZn2 intermetallic stages. Furthermore, grain refinement and high dislocation density can also be opted for strengthening purposes. A low-temperature deformation enhances the dislocation density and also facilitates the grains recovery to strengthen the component. The present study combines artificial aging (at 120 °C) and sub-zero (∼−20 ˚C) temperature rolling to achieve strengthening. Various sequences and combinations of these mechanical and thermal treatments are performed and the effects of these treatments on the tribological characteristics of the alloy are studied by nano-scratch measurements. The tribological characteristics are indicated by coefficient of friction ( μ), plastic energy ( PE), recovery index ( η), recovery resistance parameter ( Rs), etc. of each sample. The widths of the scratch are further utilized to calculate the scratch hardness values ( Hs), wear resistance coefficients ( Rw) and the coefficient of wear ( K) with the help of Archard's equation.