Anisotropy of the Wear and Mechanical Properties of Extruded Aluminum Alloy Rods (AA2024-T4)

The anisotropy of the wear and mechanical properties of extruded aluminum alloy rods (AA2024-T4) were investigated by ball-on-disk wear testing, hardness and tensile testing, optical microscopy and field-emission scanning electron microscopy, and electron backscatter diffraction. The microstructure, particularly the grain size, grain morphology, and distribution of intermetallic compounds, differed according to the extrusion direction. The results show that the extruded aluminum alloy rod exhibits anisotropic wear and mechanical properties because of this microstructural anisotropy effect. The tensile tests showed that the yield strength, ultimate tensile strength, and elongation differed according to the extrusion direction. It was confirmed that the yield strength and ultimate tensile strength were the highest in the longitudinal of the specimens. In the hardness and thermal property testing, the transverse specimens showed the highest hardness, thermal conductivity, and specific heat capacity. In wear testing, the wear rate and friction temperature in each direction under equal wear conditions differed because of the microstructural anisotropy effect. As the vertical load and linear velocity were increased in all directions, the wear behaviors of abrasion wear and small delamination, adhesion wear and delamination, galling, and seizure occurred in sequential order. However, the point at which the wear behavior changed differed for each direction. The transition of wear behavior occurred more slowly for transverse specimens than those of the other two directions (LD, 45°).