DOI: 10.5176/2251-1857_M362
Authors: Pramod Kumar Sain, C.P. Sharma and A.K. Bhargava
Abstract:
The present investigation was primarily undertaken to develop low cost corrosion resistant irons by using indigenously available alloying elements and based on white cast iron route. The fact that difference in electrochemical potential between austenite and carbide is less than that between austenite and graphite and that of the possible elimination of graphitic corrosion were the basis of assessing the feasibility of developing low cost corrosion resistant white irons. In the investigated alloy, austenite was retained in as cast and heat treated condition. The stability and volume fraction of austenite increase with increase in heat treatment temperature/soaking time with a simultaneous decrease in the volume fraction of massive carbides. The decrease in volume fraction of massive carbides results in the availability of alloying elements. These alloying elements get dissolved in austenite with increase in heat treatment temperature and/or in soaking period. On cooling, enriched austenite gives rise to a dispersed phase due to decreasing solid solubility of alloying elements with decreasing temperature. Dispersed second phase, precipitated from the austenitic matrix, adversely influences corrosion behaviour due to unfavourable morphology and possibility of enhanced tendency towards galvanic corrosion. The corrosion resistance of the alloy in 5{6e6090cdd558c53a8bc18225ef4499fead9160abd3419ad4f137e902b483c465} NaCl solution was found comparable to that of Ni-Resist iron.
Keywords: Graphitic corrosion, Massive carbides, Dispersed carbides, Rounding off tendency, Disintegration of carbides
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