Faculty Publications

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Author: search.filters.author.Shivananda Nayaka, H.Subject: search.filters.subject.Potentiodynamic polarization

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    Development, Characterization, Mechanical and Corrosion Behaviour Investigation of Multi-direction Forged Mg–Zn Alloy
    (Springer International Publishing, 2019) Anne, G.; Ramesh, S.; Kumar, G.; Sahu, S.; Ramesh, M.R.; Shivananda Nayaka, H.; Arya, S.
    In the present study, homogenized Mg−4%Zn (wt%) alloy was exposed to multi-direction forging (MDF) at 280 °C up to 5 passes successfully. Microstructural evolution, mechanical properties and corrosion behavior of the MDF-processed Mg−4%Zn alloy was investigated using different characterization techniques. Five passes of MDF (cumulative strain, ΣΔε = 3.45) led to the formation of ultrafine grain structure (grain size ~2.3 μm) with high angle grain boundaries (HAGBs) and high dislocation density. Corresponding ultimate tensile strength (UTS) and microhardness were observed to be 228 MPa and 88 Hv. Potentiodynamic polarization test results exhibited higher corrosion resistance (0.38 mm/y) in comparison with that of homogenized condition (1.33 mm/y). © 2019, The Minerals, Metals & Materials Society.
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    Microstructure Evolution and Mechanical and Corrosion Behavior of Accumulative Roll Bonded Mg-2%Zn/Al-7075 Multilayered Composite
    (Springer New York LLC barbara.b.bertram@gsk.com, 2017) Anne, G.; Ramesh, M.R.; Shivananda Nayaka, H.; Arya, S.B.; Sahu, S.
    Multilayered composite of Mg-2%Zn/Al-7075 was developed by accumulative roll bonding (ARB) of wrought Mg-2%Zn and aluminum 7075 alloy. The Mg-2%Zn/Al-7075 multilayered composite exhibited density of 2295 kg/m3 and an average grain size of 1 and 1.3 ?m in Mg-2%Zn and Al-7075 layers, respectively. A thorough microstructural characterization was performed on the composites by scanning electron microscope, electron backscatter diffraction (EBSD), transmission electron microscope and phase analysis by x-ray diffraction. In addition, mechanical properties were evaluated by microhardness and tensile tests. Corrosion behavior of the multilayered composite was examined using electrochemical polarization test. EBSD analysis showed the presence of ultrafine grains with high-angle grain boundaries. The composite exhibited a significant improvement in ultimate tensile strength (~1.82 times) and elongation (~1.5 times) as compared with Mg-2%Zn alloy, after four-pass ARB process. © 2017, ASM International.
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    Effects of combined multiaxial forging and rolling process on microstructure, mechanical properties and corrosion behavior of a Cu-Ti alloys
    (Institute of Physics Publishing helen.craven@iop.org, 2019) Ramesh, S.; Anne, G.; Shivananda Nayaka, H.; Sahu, S.; Arya, S.
    Combined multiaxial forging (MAF) and rolling was performed on Cu-3% Ti (wt%) alloy at room temperature with emphasis on microstructural evolution, improvement in mechanical properties, and corrosion resistance. Microstructural changes were confirmed from various characterization techniques, and co-related with mechanical properties. TEM analysis revealed high shear band density in the 3 pass MAF + 90% rolled sample appearing due to high strain. EBSD analysis revealed transformation to low angle grain boundaries from high angle grain boundaries. Maximum microhardness and UTS reached to 340 HV and 960 MPa, respectively in the processed samples. Significant grain refinement was observed in MAF processed Cu-3%Ti alloy, and after combined MAF + rolling, higher dislocation density and refinement of shear bands were observed. In addition, potentio-dynamic polarization test was used to study the corrosion behavior of the alloy. Scanning electron microscope (SEM) was used to analyze the corroded surface morphology. © 2019 IOP Publishing Ltd.