Metallerin sınırlı kanallı presleme ile aşırı plastik deformasyonu üzerine karşılaştırmalı bir çalışma

The main purpose of the present thesis is to reveal the microstructural refinement and mechanical behavior improvement of metallic materials, some of which are difficult to work, through severe plastic deformation. Constrained Groove Pressing is implemented in this study as a Severe Plastic Deformation method. Five different routes of Constrained Groove Pressing are planned to analyze the route effect on the materials. In this research, three different materials, namely AISI 304 stainless steel, Ti-15V-3Cr-3Sn-3Al and commercially pure zinc, are studied at room temperature. After microstructure and mechanical behavior of the samples are examined through optical microscopy, tension and erichsen tests and microhardness measurements, the underlying mechanisms are analyzed. CGP process of AISI 304 and Ti-15V-3Cr-3Sn-3Al results in a slight grain refinement while a comparatively high refinement has been observed for commercially pure zinc. Also, CGP routes have been significantly effective for only pure zinc samples in dictating grain sizes. After deformation, mechanical twinning activation has taken place for stainless steel and pure zinc samples. Twins recorded in AISI 304 with FCC lattice structure are thinner and sharper than that of commercially pure zinc with HCP lattice structure. Strain path is not considerably effective for AISI 304 samples. For pure zinc samples, twins are thinner for the routes A, C and D, compared to the other routes after the final pass. They are also rather thick and few in number after the first pass. Moreover, intensity of twins is relatively low for route E. It has been observed that CGP causes comparatively high strength increase in AISI 304 which has an FCC crystal structure, but lower increase in both Ti-15V-3Cr-3Sn-3Al and commercially pure zinc having BCC and HCP crystal structures, respectively. For AISI 304, the best strength improvement is nearly 41% occuring in TD for route C. For Ti alloy, the highest strength increase is about 16%, occurring in LD for routes D and E. For pure zinc, the best strength improvement is nearly 28% in TD belonging to route D. This study mainly aims to demonstrate the effect of several novel CGP routes on the metals having different crystal structures by analyzing the relationship between resulting microstructures and mechanical properties.