grafítjárn

Grafítjárn is a term of Icelandic origin that translates to "graphite iron". It refers to a type of cast iron that contains graphite in a particular form. Specifically, it is a ferromagnetic material where the graphite exists as flakes or nodules within the iron matrix. This microstructure significantly influences the properties of the material.

The presence of graphite flakes or nodules makes grafítjárn less brittle than white cast iron, which has its carbon in the form of iron carbide. This improved ductility allows grafítjárn to be machined more easily. The shape and distribution of the graphite particles are key factors determining the mechanical properties, such as tensile strength and impact resistance.

Grafítjárn is broadly categorized into two main types based on the form of graphite: gray cast iron, where graphite is present as flakes, and ductile iron (or nodular cast iron), where graphite exists as spherical nodules. Gray cast iron is known for its good damping properties and wear resistance, making it suitable for engine blocks and machine bases. Ductile iron offers superior tensile strength and ductility compared to gray cast iron, making it useful for applications requiring higher mechanical performance, such as pipes and crankshafts. The manufacturing process and subsequent heat treatments play a crucial role in controlling the graphite morphology and thus the final properties of grafítjárn.