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Cooling curve thermal analyses and oxygen activity analyses for the estimation of microstructural properties of nodular cast iron

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2019
Çehiz, Cansın
Although nodular cast iron grades have mechanical properties competitive with plain carbon steel grades, they have advantage in terms of price due to relatively low raw material and energy costs. Therefore, they are widely used in various industries, especially in automotive, machinery, piping and wind power industries. High number of process variables affecting the solidification behavior of nodular cast iron melt makes it difficult to ensure the resulting microstructure, thus the performance of nodular cast iron products. Cooling curve thermal analysis and oxygen activity analysis are two industrially applicable methods which are considered to have a potential of providing information on the solidification behavior of nodular cast iron melt. In this study, chemical composition, cooling curve thermal analysis and oxygen activity analysis data were collected from the usual production process of Ferromatrix NV iron foundry in Kortrijk, Belgium. The collected samples were subjected to metallographic evaluation and tensile test in order to obtain data on the resulting microstructure and mechanical performance. The alloy EN-GJS-400-18 which is a ferritic nodular cast iron grade with high ductility, and the alloy EN-GJS-600-10C which is a solution strengthened ferritic nodular cast iron grade with both high strength and high ductility were examined. By processing the collected data, conclusions on the relation of the parameters with each other and their variation between the two alloy grades and between different inoculant additions were done.