نوع مقاله : مقاله پژوهشی
1 دانشجوی دکترا، مهندسی مکانیک، پردیس دانشکده های فنی، دانشگاه تهران، تهران
2 مهندسی مکانیک، پردیس دانشکده های فنی، دانشگاه تهران، تهران
عنوان مقاله [English]
In present research, the severe plastic deformation process of hydrostatic tube cyclic extrusion compression was applied through two passes on the aluminum alloy series 5052 tube, and after that the changes of microstructure and mechanical properties of tubes were studied. Hydrostatic tube cyclic extrusion compression process is able to improve the microstructure and the mechanical properties of tubular pieces. Also, this process has the potential to produce relatively long tubes. In this process, owing to the use of pressurized fluid between the tube and die, the friction force is eliminated in these regions. This facilitates the production of longer pieces. Also, in this process, higher hydrostatic compressive stresses are applied on the material causing the delay in the crack formation and propagation. Thus, higher strains can be applied on the material. After two passes of this process, some microstructural and mechanical properties were improved significantly. For instance, the yield strength and the hardness became 1.7, 2.6 and 2.1 times higher, respectively. Also, a loss of ductility of 16℅ was observed. The microstructure analysis revealed that after two passes of the process, the microstructure was changed from a coarse grain microstructure with an average grain size of about 360 μm to an ultrafine cell\subgrain microstructure with average size of about 635 nm.