An investigation of the effect of precipitate size distribution on mechanical properties of aluminum 6063 extrudates used for window frames

Abstract

This work focused on presenting an interpretation for the effect of precipitate size distribution on hardness and strength of the aluminum 6063 extrudates produced in local industry. The same heat treatment process applied in the local industry comprising solution treatment: keeping at 530°C for 4 hours, followed by age hardening treatment: keeping at 205°C for 150 minutes and air cooling, was carried out at laboratory scale. The average hardness and strength of heat-treated samples were measured as 66.5 HV and 210.5 MPa, respectively. Scanning Electron Microscopy - Energy Dispersive X-ray Spectroscopy (SEM/EDS) examination showed that secondary phase precipitates formed during this aging treatment belong to two types of precipitates, they are Silicon-Iron rich and Magnesium-Silicon-Iron rich precipitates. The average number of precipitates, precipitate size and area covered by precipitates were calculated by Image J software. Percentages of precipitates belong to three different size ranges were analyzed as 50.10 percent, 45.13 percent, and 4.77 percent for 0.0−0.2 μm,0.2−1.5 μm and above 1.5 μm , respectively. The present work can be extended towards the development of a mathematical model to relate the ageing parameters and precipitate size distribution to hardness and strength of Al 6063 extrudates.