Strain Hardening Behavior and Microscopic Fracture Mechanism in Multidirectional Cryoforged Al 2014 Alloy.

In the present work, Al 2014 alloy was subjected to multidirectional cryoforging (MDCF) and subsequently to annealing in the temperature range from 150 to 350 °C to investigate its influence on strain hardening behavior, macroscopic fracture mechanisms, and fracture toughness. The mechanical properties are correlated with the microstructural evolution after deformation and post-deformation annealing with the help of optical microscopy and transmission electron microscope (TEM) studies. Moreover, the process and annealed alloy's fracture mechanism is established using macrograph analysis and Scanned electron microscope (SEM) studies. The study reveals that the strain hardening ability, fracture mechanisms, and fracture toughness of the deformed and the post-annealed samples are influenced by the shear banding, combined recovery /recrystallization process, and evolution of second phase precipitates during annealing treatment at various temperatures. On investigating the tensile and fracture toughness properties, it was observed that these are retained up to the annealing temperature of 250 °C. In contrast, a significant drop in these properties was observed above this temperature. The macroscopic fracture mechanism of the multidirectional cryoforged (MDCFed) sample was dominated by shear fracture, while upon annealing, it gradually transformed to shear plus necking. [ABSTRACT FROM AUTHOR]