Effect of Alloying Element Vanadium and Chromium on Mechanical Properties and Microstructure of the Flake Graphite Cast Iron

摘要

Due to the increasing of environmental pollution, it is imperative to highly respect the importance of environmental protection. The alloying element chromium (Cr), which is often added to cast iron, is regarded as Class B carcinogen by U.S. EPA. Thus, it deserves attention to make more efforts on looking for substitutive alloying elements so as to make contribution on environmental protection. The objective of this research is to adopt the alloying element vanadium (V), which has the similar properties with chromium (Cr), as the substitutive target. The effects of alloying element vanadium (V) (0.02～0.5wt%) and chromium (Cr) (0.2～1.0wt%) on the mechanical properties and metallographic microstructures (matrix structure, morphology, size of graphite, etc.) of the flake graphite cast iron are investigated. The homogeneity and differences of these two alloying elements are also evaluated in this research. Experimental result shows that with the increasing of the alloying element chromium (Cr), the tensile strength will increase gradually at beginning. However, as the addition amount of the alloying elements chromium (Cr) is over 0.5 wt%, the tensile strength will decrease remarkably. Metallographic microstructures show that with the increasing of the alloying elements chromium (Cr), the amount of graphite will significantly reduce. As chromium (Cr) is over 0.5 wt%, the white cast iron structure will appear on the matrix, and which increases with the increasing of the chromium (Cr). The amount of graphite will be reduced and minute significantly by increasing the alloying element vanadium (V).