maximum 6.67%
cast iron contain a considerable amount of carbon
The carbon content in cast iron typically ranges from 2% to 4%. This high carbon content is what gives cast iron its characteristic hardness and brittleness compared to other types of iron.
iron with 1.5% of carbon by volume or less is called carbon steel and above 1.5% it is called cast iron, hardmess increases with the carbon % i.e. cast iron is harder than carbon steel
Free carbon in cast iron refers to carbon that exists in its elemental form within the iron matrix. It appears as graphite flakes or nodules, contributing to the material's unique properties, such as high fluidity during casting and improved machinability. This free carbon distinguishes cast iron from other metals.
Steel is an alloy of carbon and iron. If the percentage of carbon is more than 2% then it is called cast iron.
grey
Cast iron is primarily composed of iron with a high carbon content (2-4%). The atomic structure consists of iron atoms arranged in a lattice structure, with carbon atoms occupying the spaces between the iron atoms. This combination of iron and carbon gives cast iron its unique properties, such as high strength and good wear resistance.
The main difference between cast iron and mild steel is the carbon content. Mild steel has a lower carbon content than cast iron. This makes cast iron brittle, while mild steel is much harder.
pig iron or cast iron having 4.5% carbon as an impurity wroght iron having 0.15% of carbon steel having 1% carbon
As far as i know, coolant is not required while machining cast iron because, carbon in cast iron is present in the form of graphite (which is a cooling agent - self cooling). Moreover the carbon content is high in cast iron.
carbon and silicon
Steel is iron mixed with carbon, the amount of carbon changes the specifications of the steel (strength, elasticity,...)