Thermal and microstructural characterization of a novel ductile cast iron modified by aluminum addition
来源期刊：International Journal of Minerals Metallurgy and Materials2020年第2期
论文作者：Gül?ah Akta? ?elik Maria-Ioanna T.Tzini ?eyda Polat ?.Hakan Atapek Gregory N.Haidemenopoulos
文章页码：190 - 199
摘 要：In high-temperature applications, like exhaust manifolds, cast irons with a ferritic matrix are mostly used. However, the increasing demand for higher-temperature applications has led manufacturers to use additional expensive materials such as stainless steels and Ni-resist austenitic ductile cast irons. Thus, in order to meet the demand while using low-cost materials, new alloys with improved high-temperature strength and oxidation resistance must be developed. In this study, thermodynamic calculations with Thermo-Calc software were applied to study a novel ductile cast iron with a composition of 3.5 wt% C, 4 wt% Si, 1 wt% Nb, 0-4 wt% Al. The designed compositions were cast, and thermal analysis and microstructural characterization were performed to validate the calculations. The lowest critical temperature of austenite to pearlite eutectoid transformation, i.e., A1, was calculated, and the solidification sequence was determined. Both calculations and experimental data revealed the importance of aluminum addition, as the A1 increased by increasing the aluminum content in the alloys, indicating the possibility of utilizing the alloys at higher temperature. The experimental data validated the transformation temperature during solidification and at the solid state and confirmed the equilibrium phases at room temperature as ferrite, graphite, and MC-type carbides.
Gül?ah Akta? ?elik1，Maria-Ioanna T.Tzini2，?eyda Polat1，?.Hakan Atapek1，Gregory N.Haidemenopoulos2,3
1. Department of Metallurgical and Materials Engineering, Kocaeli University2. Laboratory of Materials, Department of Mechanical Engineering, University of Thessaly3. Department of Mechanical Engineering, Khalifa University of Science and Technology
摘 要：In high-temperature applications, like exhaust manifolds, cast irons with a ferritic matrix are mostly used. However, the increasing demand for higher-temperature applications has led manufacturers to use additional expensive materials such as stainless steels and Ni-resist austenitic ductile cast irons. Thus, in order to meet the demand while using low-cost materials, new alloys with improved high-temperature strength and oxidation resistance must be developed. In this study, thermodynamic calculations with Thermo-Calc software were applied to study a novel ductile cast iron with a composition of 3.5 wt% C, 4 wt% Si, 1 wt% Nb, 0-4 wt% Al. The designed compositions were cast, and thermal analysis and microstructural characterization were performed to validate the calculations. The lowest critical temperature of austenite to pearlite eutectoid transformation, i.e., A1, was calculated, and the solidification sequence was determined. Both calculations and experimental data revealed the importance of aluminum addition, as the A1 increased by increasing the aluminum content in the alloys, indicating the possibility of utilizing the alloys at higher temperature. The experimental data validated the transformation temperature during solidification and at the solid state and confirmed the equilibrium phases at room temperature as ferrite, graphite, and MC-type carbides.
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