Types Of Cast Iron And Its Properties
Cast iron is a very common material in engineering and it is obtained with special processes from iron ores. Cast iron is the iron-carbon alloys that includes carbon ratio around 2,11-6,4%. So there are bunch of types of cast irons between these ratio. In this article, we will explain the types of cast irons that generally used in such applications today.
What Are The Types Of Cast Iron?
- Gray Cast Iron: Gray cast iron has the biggest market around cast iron types. It includes 2.5-4% of carbon and 1-3% of silicon inside iron. There is a phenomenon in cast iron structure that is flakes of carbon elements. When gray cast iron is broken, these carbon flakes gives gray color on the surface of this cast iron. Gray cast iron has very good vibration damping property which is a attractive material at engine blocks, basis of tool machinery and applications that has vibrations must be eliminated like them. Gray cast iron is a very brittle material which means ductility of gray cast iron is very low. Compression strength of gray cast iron is much more high compared with tensile strength. Machinability of gray cast iron is also superior because of internal lubrication property.
- Ductile Iron: It has the same alloying element ratios with gray cast iron, but the geometric shapes or carbon that is created inside the ductile iron are spheroids, instead of flakes like in gray cast iron. This structure can be obtained with special chemical threatments at solidification phase. Ductile irons has ductile property as its name implies, and has very good wear resistance and high strength. Can be used in machinery components.
- White Cast Iron: The chemical composition of white cast iron has less amount of carbon and silicon, compared with other cast iron types. There are no such carbon flakes or spheroids in the structure of white cast iron. With rapid solidification, carcbon elements stay bonded with iron elements in the form of Fe3C which is called as cementite. Because of that, there is no carbon precipitation in white cast iron. When its broken, the color of teh surface is white that gives the name of white cast iron. White cas iron has very good strength, hard and brittle.
- Malleable Iron: If the white cast iron is heat treated to separate the carbon as graphite aggregates, malleable iron is obtained. The ductility of malleable iron is very high up to 20% of elongation.
- Alloy Cast Irons: Cast irons are also can be alloyed to obtain specific properties. For example, some of cast irons can be heat treated to obtain martensite microstructure. Corrosion resistant cast irons can be obtained with addition of chromium and nickel.
These are the general types of cast irons. Do not forget to leave your comments and questions about ‘cast irons’ below!