Cast Iron Design: Processes, Alloys and Properties

Abstract

Cast iron, especially ductile iron, is being used more and more in most countries of the world due to its excellent mechanical properties, castability, and good price. Cast iron alloys can be given a wide range of properties by changing the alloy composition, inoculation, and treatment, heat treatment, or cooling conditions. On a weight basis, most castings are made in gray cast iron. Some examples of gray and ductile iron products are shown in Fig. 1 [1]. The main factors for the high usage are good casting properties, low price, good cutability, and unique properties like damping and good tribology. Lamellar gray cast iron has very good damping capacity. This property is used in many components where damping of sound and vibration is important. Gray iron, also called lamellar graphite iron, is an iron–carbon–silicon alloy with different alloying elements. To understand the microstructure formations and to model them and other important phenomena, both the solidification and the solid-state transformations must be considered. These phase transformations are, to a large extent, affected by nucleation and growth kinetics which are dependent on, for example, handling of the melt, charge material, melting method, metal treatment, inoculation, pouring method, casting process and mold material, cooling power of the mold, and other factors. Many of these important material and process factors and combinations of them are still not fully understood today. Consequently, it is necessary that a foundry producing cast iron components has very strict process control in order to avoid unpredictable problems in production. When this is the case, it will also be possible to use simulation tools for predicting solidification sequence, microstructures, mechanical properties, as well as formation of defects.