Table of Contents
Journal of Metallurgy
Volume 2012, Article ID 438659, 6 pages
http://dx.doi.org/10.1155/2012/438659
Research Article

Control of Carbides and Graphite in Cast Irons Type Alloy’s Microstructures for Hot Strip Mills

1Department of Materials Science and Engineering, Kyushu University, Fukuoka 819-0395, Japan
2Autonomous San Luis Potosi University, S. L. P., Mexico
3Kurume National College of Technology, Fukuoka 830-8555, Japan
4Oita National College of Technology, 1666 Maki, Oita 870-0152, Japan

Received 31 August 2011; Accepted 9 December 2011

Academic Editor: Hao Chen

Copyright © 2012 Sergio Villanueva Bravo et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

The carbide and graphite formation and redistribution of alloy elements during solidification were investigated on high-speed steel (HS) and Ni-hard type cast irons with Nb and V. The crystallization of hypereutectic HSS proceeds in the order of primary MC, γ+ MC, γ+ M6C, γ+ M7C3, and γ+  graphite eutectic, in hypoeutectic alloys proceeds in the order of primary γ, γ+ MC, γ+ graphite, γ+ M6C, and γ+ M7C3 eutectic, and in Ni-hard proceeds in the order of primary γ, γ+ MC, γ+ M3C, and γ+  graphite eutectic. The γ+  graphite eutectic solidifies with the decrease of V, Nb, and Cr and the increase of Si and C contents in residual liquid during solidification. The behavior in graphite forming tendency in the residual liquid is estimated by the parameter 𝐶𝑖𝐿𝑚𝑖. The eutectic graphite crystallizes at the solid fraction when 𝐶𝑖𝐿𝑚𝑖 takes a minimum value. The amount of graphite increases with the decrease in 𝐶𝑖𝐿𝑚𝑖 of initial alloy content in both specimens. Inoculation with ferrosilicon effectively increases the graphite content in both specimens.