Influences of Cast Iron Microstructure on the Environment and Thermal Conductivity

Abstract

© 2020. All Rights Reserved. Foundry industry is a branch of industry which generates a huge quantity of wastes. Increase of raw materials prices (cast iron scrap, sand, energy resources) and cost for dumping load, it follows that the economic factors become very important arguments in the process of minimizing of wastes generation. Cast irons are among the most widely used materials due to their unique combination of mechanical and physical properties, while their cost is relatively low. According to the reports of "Census of world casting production" for the period 2004-2017 it can be concluded that the production volumes of gray cast iron with lamellar graphite (CILG) are significantly higher than the production of nodular graphite cast iron (NGCI), despite the higher mechanical characteristics of the latter. Gray cast iron (GCI) is used widely under conditions of prolonged and cyclic exposure to high temperatures due to its increased thermal conductivity. GCI is used in the manufacture of brake discs, cylinder blocks and cylinder heads. Due to the increased thermal conductivity, heat is quickly removed, thereby preventing thermomechanical fatigue, deformation and crack propagation, which allows cast irons to be used in more severe conditions, while extending the service life of a product. As the temperature rises, the strength and thermal conductivity of GCI decreases. Therefore, one should pay attention to compacted graphite iron (CGI) as a replacement for the traditional GCI. Although its thermal conductivity is lower, the increased strength justifies replacement. Consequently, the lower value of thermal conductivity observed in CGI requires improvement and additional research, which is the subject of this work.