High-Alloy Iron Castings
The high-alloy irons can be categorized into two main groups: the high-alloy graphitic irons (covering both gray and ductile grades) and the high-alloy white irons. High-alloy irons are used in applications with demanding requirements, such as high resistance to wear, heat, and corrosion, or for combined properties. This article discusses the specification and selection of high-alloy irons. The common alloying elements and their effect on the stable and metastable eutectic temperatures are listed in a table. The article provides information on the compositions, properties and applications of high-alloy graphitic irons and high-alloy white irons.
Castability of alloys is a measure of their ability to be cast to a given shape with a given process without the formation of cracks/tears, pores/shrinkage, and/or other significant casting defects. This article discusses the factors which affect the fluidity of an iron melt: alloy composition and initial melt condition. Besides the basic alloy properties, the effective castability of high-alloy irons can be significantly improved through casting and casting system design. The article describes the product design and processing factors of high-alloy graphitic irons and high-alloy white irons. It explains the heat treatment of high-silicon irons for high-temperature service and concludes with a discussion on machining and finishing of high-alloy iron castings.