Faculty Publications

Permanent URI for this communityhttps://idr.nitk.ac.in/handle/123456789/18736

Publications by NITK Faculty

Browse

Author: search.filters.author.Desai, V.Subject: search.filters.subject.Grain size and shape

Search Results

Now showing 1 - 5 of 5
  • No Thumbnail Available
    Item
    Effect of combined grain refinement and modification on microstructure and mechanical properties of hypoeutectic, eutectic and hypereutectic Al-Si alloys
    (Inderscience Publishers, 2015) Shivaprasad, C.G.; Kiran Aithal, K.; Narendranath, S.; Desai, V.; Mukunda, P.G.
    The effect of melt treatment owing to the combined addition of grain refiner and modifier on the microstructure and mechanical properties of Al-Si alloys having 7% (hypoeutectic), 12% (eutectic) and 15% silicon (hypereutectic) is studied. 1 wt. % of Al-1Ti-3B Master alloy was used as grain refiner. For modification of eutectic Si, 0.2 wt. % of Al-10Sr Master alloy was added to hypoeutectic alloy and 0.4 wt. % is added to eutectic alloy as well as hypereutectic alloy. Furthermore, refinement of primary Si in hypereutectic alloy was achieved by addition of 0.04 wt. % of phosphorus. The goal of this investigation is to determine the influence of combined addition of grain refiner and modifier on mechanical properties and qualitatively correlate with the microstructural changes. © 2015 Inderscience Enterprises Ltd.
  • No Thumbnail Available
    Item
    Influence of combined grain refinement and modification on the microstructure, tensile strength and wear properties of Al-15Si, Al-15Si-4.5Cu alloys
    (Carl Hanser Verlag Kolbergerstrasse 22 Munchen D-81679, 2015) Channappagoudar, S.; Sannayallappa, N.; Desai, V.; Venkateswarlu, V.
    Microstructure, tensile strength and dry sliding wear studies of Al-15Si, Al-15Si-4.5Cu alloys with and without grain refinement and modifications are presented. Experimental alloys such as Al-15Si and Al-15Si-4.5Cu were conventionally melted and gravity die cast. For grain refinement, 1 wt.% of Al-1Ti-3B and for modification, 0.17 wt.% of aluminum phosphide (AlP) and 0.4 wt.% of Al-10Sr were added to the alloy melt. The results reveal refined microstructure due to grain refinement, modification, improved hardness, higher tensile strength and better sliding wear. Moreover, Al-15Si-4.5Cu alloy (untreated and treated) showed improved mechanical properties as compared to conventional hypereutectic Al-Si alloy. © Carl Hanser Verlag GmbH & Co. KG.
  • No Thumbnail Available
    Item
    Influence of combined grain refinement and modification on the Microstructure, tensile strength and wear properties of Al-15Si, Al-15Si-4.5Cu alloys
    (Carl Hanser Verlag Kolbergerstrasse 22 Munchen D-81679, 2015) Channappagoudar, S.; Sannayallappa, N.; Desai, V.; Venkateswarlu, V.
    Microstructure, tensile strength and dry sliding wear studies of Al-15Si, Al-15Si-4.5Cu alloys with and without grain refinement and modifications are presented. Experimental alloys such as Al-15Si and Al-15Si-4.5Cu were conventionally melted and gravity die cast. For grain refinement, 1 wt.% of Al-1Ti-3B and for modification, 0.17 wt.% of aluminum phosphide (AlP) and 0.4 wt.% of Al-10Sr were added to the alloy melt. The results reveal refined microstructure due to grain refinement, modification, improved hardness, higher tensile strength and better sliding wear. Moreover, Al-15Si-4.5Cu alloy (untreated and treated) showed improved mechanical properties as compared to conventional hypereutectic Al-Si alloy. © Carl Hanser Verlag GmbH & Co. KG ISSN 1862-5282.
  • No Thumbnail Available
    Item
    Enhancement of resistance to galvanic corrosion of ZE41 Mg alloy by equal channel angular pressing
    (Wiley-VCH Verlag info@wiley-vch.de, 2020) Sekar, P.; Sanna, N.; Desai, V.
    The galvanic corrosion behavior of as-received and ECAPed ZE41 Mg alloy coupled with Al7075 alloy is investigated using zero resistance ammeter in three different corrosive environments, 0, 0.1, and 1 M NaCl, to mimic the conditions experienced in engineering applications. The mechanism of galvanic corrosion for the ZE41 Mg–Al7075 aluminum alloy is explained. It is observed that a robust surface film containing a composite layer of oxide/hydroxide of magnesium and aluminum is established in deionized water (0 M). However, only a single layer of magnesium oxide/hydroxide is detected in chloride-containing environments. Equal channel angular pressing (ECAP) improved the resistance to galvanic corrosion by 58% and 54% when compared with the as-cast counterparts in 0 and 1 M NaCl solution, respectively. In contrast, galvanic corrosion resistance decreased by 26% in 0.1 M NaCl after ECAP while the as-received samples evinced pits unfavorable to be used in engineering applications. ECAP is a promising method to combat galvanic corrosion encountered by ZE41 magnesium alloy used in automobiles and components of military vehicles. © 2019 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
  • No Thumbnail Available
    Item
    Analysing the combined effect of crystallographic orientation and grain refinement on mechanical properties and corrosion behaviour of ECAPed ZE41 Mg alloy
    (National Engg. Reaserch Center for Magnesium Alloys, 2020) Sekar, S.; Narendranath, S.; Desai, V.
    Two step equal channel angular pressing carried out on as cast ZE41 Mg alloy resulted in a remarkable grain refinement. As compared to grain size of 46 µm in as cast sample, refinement upto 2.5 µm was achieved after 8th pass equal channel angular pressing (ECAP). The combined effect of crystallographic orientation and grain refinement was investigated by analysing the mechanical properties and corrosion behaviour of ZE41 Mg alloy using electron back scattered diffraction (EBSD). The first stage comprises of 1st, 2nd, 3rd and 4th passes at a processing temperature of 300 °C while the 5th, 6th, 7th and 8th passes were ECAPed at 275 °C in second stage. The mechanical properties of ZE41 Mg 158 yield tensile strength (YTS), 230 ultimate tensile strength (UTS) and 7% elongation in as cast condition is enhanced to 236 YTS, 295 UTS and 19.76%, respectively, after first stage ECAP. The yield tensile strength deteriorated due to the effect of texture predominating grain refinement during the second stage ECAP. The corrosion resistance of ZE41 Mg was significantly enhanced by ECAP and is inferred from electrochemical impedance spectroscopy (EIS) and potentiodynamic polarisation results .The role of microstructure was minimal on corrosion behaviour of ZE41 Mg due to extra resistance when tested in 0 M NaCl. However, the influence of grain refinement greatly influenced the improvement in corrosion resistance of ZE41 Mg rather than crystallographic orientation observed from EBSD. In contrast, the crystallographic orientation predominated the effect of grain refinement during ZE41 Mg corrosion in chloride containing (0.1 M and 1 M NaCl) solutions. From the observation of results it is found that equal channel angular pressing has the dual advantage of improving mechanical properties and corrosion resistance of ZE41 Mg alloy. © 2020