ORIENTATION AND STRAIN RATE EFFECTS ON THE MECHANICAL RESPONSE OF 2024 AT DIFFERENT MICROSTRUCRES

Plastic deformation and fracture mechanisms of Aluminum 2024 at different metallurgical states (T351 and stress relief) have been characterized under tensile and compression modes of loading. Attention has been given to the orientation effects along and through thickness of the rolled plate, while varying strain rates from 10^-4-10³ sec^-1.

Low and medium strain rates were applied using electro-mechanical and servo-hydraulic systems respectively, whereas the high strain rates achieved using the split Hopkinson bar technique. Acoustic emission (AE) method has been used in case of tensile mode as complementary information regarding deformation and fracture process sequence up to fracture. In addition, hardness test, optical and scanning electron microscopies have been utilized in order to get more understanding on the mechanical response with the orientation effect. FE method has been also applied in order to analyze the tensile specimen size effect.

The tensile experimental results indicated that the mechanical behavior was almost the same between parallel and perpendicular to the rolling direction, while the through thickness properties were found to be significantly lower, especially the ductile behavior. This an-isotropic behavior was attributed to the existence of high concentration of inter-metallic compounded through thickness. This finding was also supported by the AE results as reflected by the different AE response between the orientations. With respect to the strain rate, moderate effect on the yield stress was detected. Some minor microstructures effects were found with regard to the strain rate effect.