Effect of heat treatment on the mechanical and tribological properties of AA8090/6% SiCp composite

Abstract

AA8090, a certain type of Al-Li alloy, has been widely used in the aerospace industry because of its low density and high strength after heat treatment. In this research work, the AA8090/6% SiCp composite was produced by modified stir casting and then subjected to hot extrusion treatment. One part of the extruded rod was used to prepare the wear test samples and the remaining part was converted to strips with 2 mm thickness via hot rolling process. Three processes, including precipitation hardening with conventional heating, age hardening with rapid heating, and precipitation after directional quenching, were done on samples. The results of the mechanical properties revealed that precipitation hardening after directional quenching reduced the peak of hardness time from 16 to 6 h, increased the peak of hardness by 20%, and improved the tensile strength, yield stress, and elongation by 16%, 16%, and 40%, respectively. The results of wear test indicated that, at the load of 10 N, abrasive wear was the dominant wear mechanism. Increase in load showed delamination, and at the load of 30 N, a transition from mild wear to severe wear occurred due to a change in wear mechanism to adhesive wear. At this load, the samples without heat treatment showed the lowest wear rate in comparison to the samples subjected to heat treatment. By and large, the specimens heat treated with directional quenching among the other heat-treated specimens showed the higher wear resistance at all of loads.

Keywords

• aluminum-lithium
• composite
• heat treatment
• wear