Alloy elements commonly used in grey cast iron

The alloy elements added in gray cast iron can be roughly divided into four categories, namely graphitization elements, carburizing elements, bead stabilizing elements and refined elements.
In the process of cast iron solidification, carbon, silicon, aluminum, sulfur, copper and nickel elements have a role in promoting the formation of graphite, which can be considered as graphitized elements. However, the efficiency of the elements is very different, for example, copper is about 20% of silicon. Nickel and copper also have dual roles: promoting graphitization during the cocrystal transition; inhibiting graphitization during the cocrystal transition, which helps to form more fine beads, so it can also be regarded as a stable element.
The effects of titanium are also complex. Generally speaking, titanium is a strong carbide forming element, but when its content is very small (e. g. <0.08%), its fine compounds can be used as the core of graphite, has the role of promoting graphitization.
Tin, antimony, manganese, molybdenum, chromium, vanadium and niobium can all hinder the precipitation and growth of graphite, enhance the tendency of forming carburns, and all belong to carburns stable elements. The effect of molybdenum is related to its addition amount. Molybdenum content in cast iron, <0.8%, the effect of molybdenum is mild, which is to make the pearlite refinement, the content is the carburization stable element. It is generally believed that the role of manganese is to increase the amount of cast iron beads and improve the strength of cast iron. In fact, manganese is also multifaceted, when the content is high, it will make the graphite thick, thus reducing the strength of cast iron.