2. Thesis and Dissertations
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Item Severe Plastic Deformation of AA2050 Al-Cu-Li Alloy by Multi-Axial Forging(National Institute Of Technology Karnataka, Surathkal, 2024) C., Jagadeesh; H., Shivananda NayakaThere is increasing scientific and industrial interest in development of bulk ultra-fine grained (UFG) alloys intended for structural applications. Multi axial forging (MAF) is one of the simple and most effective methods of severe plastic deformation (SPD) to improve the material properties. Aluminium Copper Lithium (Al-Cu-Li) alloys are known for their lightweight properties and serve as viable substitutes for conventional 2XXX and 7XXX series Aluminium alloys. In this research, we performed MAF on AA2050 Al-Cu-Li alloy and subsequently subject to artificial aging. Our investigation delves into the microstructural characterization, mechanical properties evolution, corrosion properties and wear properties observed during various MAF cycles and post MAF aging. Microstructural analysis is carried out through various techniques such as optical microscopy, scanning electron microscopy, transmission electron microscopy, electron backscatter diffraction, and X-ray diffraction. Further, mechanical properties are evaluated using tensile and micro hardness tests. Additionally, dry reciprocating wear testing were carried out using a ball-on-disc testing machine for both unprocessed and processed samples.Ccorrosion properties were evaluated using electrochemical polarization studies with Tafel extrapolation technique to determine corrosion rates. Microstructural studies revealed fine grain structures with the formation of of large density of deformation bands Upon MAF. Artificial aging of MAF processed samples resulted in a uniform distribution of fine T1 precipitates in the grain interiors. Microhardness tests shows a significant increase in hardness upto 6 passes with slight increase after 12 passes. With increase in number of MAF passes, enhancement in strength with a trade-off in ductility was observed. Artificial aging of MAF samples showed further increase in strengths, with slight increase in ductility. Overall, an increase in corrosion resistance was observed in all sample upon peak aging, with 12 pass + peak aged samples showing better corrosion resistance. Also, 12 pass MDF processed samples showed better wear resistance.