ABSTRACT
This chapter reports on the microstructure evolution and mechanical properties of 5052 Al alloy processed by rotationally accelerated shot peening (RASP). RASP-processed samples at various depths were characterized using cross-sectional transmission electron microscopy observations to reveal the microstructural characteristics at different levels of strain and strain rate, and thereby to uncover the underlying grain refinement mechanism. Systematic TEM observations showed that the critical sizes of subgrain/grain vary with the depth from the surface. Microstructure evolution and grain refinement in 5052 Al alloy induced by RASP were investigated systematically. The effect of RASP treatment on the mechanical properties of 5052 Al alloy sample is also studied. A deformation layer of 2 mm was formed by RASP treatment, indicating the effectiveness and high energy of RASP process. Different dislocation configurations, elongated subgrains, equiaxed subgrains and nano-sized grains were found along the depth from the sample surface. Dynamic recrystallization was primarily responsible for the nano-grain formation.
