Cast iron possesses several properties that contribute to its strength and hardness:
High carbon content: Cast iron typically contains a high carbon content ranging from 2% to 4%. The presence of carbon in the form of graphite flakes within the iron matrix gives cast iron its characteristic hardness. The carbon forms lamellar structures, creating a rigid matrix that enhances the material's strength.
Microstructure: Cast iron has a unique microstructure consisting of graphite flakes dispersed in a matrix of ferrite or pearlite. This microstructure provides strength and hardness to the material. The graphite flakes act as barriers to crack propagation, effectively hindering the propagation of fractures and increasing the material's resistance to deformation.
Compacted graphite iron: Some forms of cast iron, such as compacted graphite iron (CGI), exhibit a modified graphite structure. CGI has a combination of nodular graphite and compacted graphite, which provides improved mechanical properties, including higher strength and better resistance to thermal and mechanical shock.
Alloying elements: Cast iron can be alloyed with other elements to enhance its properties. The addition of alloying elements such as silicon, nickel, chromium, and molybdenum can improve strength, hardness, and resistance to corrosion and wear.
Thermal conductivity: Cast iron has good thermal conductivity, allowing it to distribute heat evenly. This property is advantageous in applications like cookware, where even heating is desired.
Abrasion resistance: Due to its hardness and strength, cast iron exhibits excellent resistance to abrasion and wear. This property makes it suitable for applications involving contact with abrasive materials or high-stress environments.
It's important to note that the specific properties of cast iron can vary depending on the type and composition of the iron and the manufacturing process employed. Different types of cast iron, such as gray iron, ductile iron, and white iron, have varying properties and applications.