Tensile and wear behaviour of precipitation hardened AA7xxx (Al-12 Zn–3 Mg-2.5 Cu) alloy

Abstract

In the present investigation, Al–12 Zn–3 Mg-2.5 Cu (AA7xxx series) alloy ingot has been fabricated by liquid metallurgy route and tensile and wears behaviour of Al–12 Zn–3 Mg-2.5 Cu alloy have been studied. Cast Al-12 Zn-3 Mg-2.5 Cu alloy reveals distribution of both soluble and insoluble intermetallic compounds in the α-aluminium matrix. In order to improve the mechanical properties and condition, the microstructural features and precipitation hardening (solutionizing and ageing) treatment have been carried out by keeping temperature and time as variables. Ageing treatment has been carried out at 120 °C with varying time interval. Tensile and hardness studies have been carried out on the aged alloys. Detailed microscopic analysis has been done using optical and electron microscopy (SEM and TEM) to understand the phase and structural evolution during ageing. There is a significant increment in strength and hardness at precipitation conditions with reasonable ductility, i.e., 603 ± 10 MPa and 6% elongation. Wear behavior of the alloy has been studied using the pin-on-disc technique with varying load and keeping sliding speed and time as constant. Wear rate of cast (4.11 X 10^-5mm³/m) condition is more than aged (3.21 X 10^-5mm³/m). Wear rate of cast is 20% more than aged conditions. Precipitation hardened alloy shows better wear resistance than cast and solutionized alloy.