Chiang Mai Journal of Science

     This experimental project is dealt with two high-strength aluminium alloys, termed Al2016, Al2618. Objective of this research is to contribute to a good clarifi cation on microstructural and tensile properties of distinct grades of Al2016 and Al2618 alloys to be used in the aerospace fi eld as skin materials. These two different grades of twin-rolled aerospace metallic materials were received for investigation after those were subjected to two different conditions of heat treatment processes namely artifi cially aging and overaging. Those four specially processed alloys are specifi ed as Al2016-T6510, Al2016-T7510, Al2618-T6510, and Al2618-T7510 based on the treatment. This article discusses the physical characteristics and tensile behavior of those alloys through the outcome of light microscopy test and tensile tests. Particle size variations and origination of grains play a major role in mechanical behavior. When comparing the various tensile properties of radial longitudinal and transversely oriented specimens of all specifi ed graded alloys possess almost a similar tensile behavior between each grade. Broken specimens of tensile tests were employed for investigating the fractographic conditions through scanning electron microscopy. As result, ductile ruptures were commonly registered in all the grades of materials whereas the evidence for intergranular fracture was found in Al2016-T6; and a transgranular fracture was noti ced in Al2016-T6. Amongst all the grades, a greater number of intergranular compounds were found in the Al2618-T6 alloy. T6 and T7 conditioned alloys of both grades revealed that the denseness of precipitation increases due to overaging, which in turn ends in declination of ductility. In general, other attributes of such T7 conditioned aluminium alloys have contributed well to elevated temperature applications especially, in stress corrosion cracking resistance.