Browsing by Author "Johnson, S."

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    Determining the solidification characteristics of Manganese bronze (MAB) alloy using computer-aided cooling curve analysis
    (Elsevier Ltd, 2022) Pranesh; Mohammed Anas, S.; Johnson, S.; Jose, R.; Sachin, B.; Cadambi, S.; Vijayan, V.; Karinka, S.
    Computer-aided cooling curve analysis (CACCA), known for its reliability and simplicity was used to study the material properties of manganese bronze (MAB) alloy. MAB alloy, due to its high strength and corrosion resistance, is a staple material for marine applications. Since the alloy is difficult to machine, non-heat treatable, and complex to fabricate, casting is the only cost-effective process of producing products of the material. As the literature is scant on the MAB's high-temperature properties, this study is aimed at determining the thermo-physical properties of the alloy required for casting simulation by carrying out Newtonian and Fourier analysis of the recorded temperature of the solidifying alloy from liquidus state. © 2022 Elsevier Ltd. All rights reserved.
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    Failures Investigation of Marine Propellers in Corrosive Environments
    (Springer Nature, 2021) Mirashi, V.U.; Johnson, S.; Hegde, S.; Vijayan, V.; Cadambi, S.
    Marine corrosion failure of fishing boat propellers made of cast Nickel Aluminium Bronze were investigated. Specimens extracted from the corroded propellers were characterized by optical microscopy, scanning electron microscopy, and energy dispersive spectroscopy. The alloy comprises several Fe3Al (κ1, κ2, κ4), NiAl (κ3) type intermetallic precipitates and β’ martensite embedded in Cu-rich α-matrix. Transverse sections of the corroded region showed two distinct zones; a non-uniform top oxide layer and a partially corroded zone with selective corrosion of the β’ martensite which run parallel to the κ3 precipitates. From the microstructural analysis it is adjudged that the aggressive local corrosion of the matrix is preceded by cracking of the oxide by erosion, cavitation, etc., A slow growth of the oxide layer follows that reduces the corrosion rate. However, the corrosion cycle repeats on erosion or cracking of the oxide layer when the propeller is used in marine waters. Coupon specimens immersed in actual marine conditions is presented that supports the above theory. © 2021, The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd.