Effects of Inoculation on the Pearlitic Gray Cast Iron with High Thermal Conductivity and Tensile Strength
School of Materials Science and Engineering, Tsinghua University, Beijing 100084, China
Key Laboratory for Advanced Materials Processing Technology, Ministry of Education, Beijing 100084, China
School of Nuclear Equipment and Nuclear Engineering, Yantai University, Yantai 264005, China
Author to whom correspondence should be addressed.
Materials 2018, 11(10), 1876; https://doi.org/10.3390/ma11101876
Received: 5 September 2018 / Revised: 24 September 2018 / Accepted: 28 September 2018 / Published: 1 October 2018
(This article belongs to the Collection Additive Manufacturing: Alloy Design and Process Innovations)
With the aim of improving the thermal conductivity and tensile strength of pearlitic gray cast iron, the influence of inoculation on structure and properties was experimentally investigated. Three group of irons with similar compositions were inoculated by Zr-FeSi, Sr-FeSi, and SiC inoculants, respectively. The metallographic analysis was used to measure the maximum graphite length, primary dendrites amount and eutectic colonies counts. For a certain carbon equivalent, it was confirmed that the thermal conductivity of pearlitic gray cast iron has a direct correlation with the maximum graphite length while the tensile strength was influenced mainly by the primary dendrites amount. The optimal structure and highest thermal conductivity and tensile strength were obtained by Sr-FeSi inoculant. MnS particles act a pivotal part in modifying the structure of gray cast iron. It was found that providing nucleation sites both for graphite and primary austenite is important to promote the thermal conductivity and strength. However, excessive nuclei (MnS particles) results in shorter graphite flakes and thus the depressive growth of primary dendrites.