The graphite in grey cast iron is in the form of flakes. A major advantage of grey iron against many other materials including steel is its outstanding ability to damp vibrations. This is important not only for lessening the noise level from machines but also for damping stress levels in connection with variable loading. Furthermore, the lubricating effect from graphite promotes outstanding machinability and good resistance to sliding wear.
The major shortcoming of grey iron is its brittleness and components made from grey iron can not be subjected to high levels of loading.
GJL-250C is standardised in SS-EN 16482. The (discontinued) SS-designation is 0125. The SS-EN 16482 standard defines the levels for tensile strength and hardness for various dimensions. The addendum “C” indicates that the material has been continuously cast to distinguish from form-cast components. The continuous casting process is very flexible in terms of the section which can be manufactured. Round is most common but square, rectangular, half-rounds and other shapes are possible.
The microstructure and associated mechanical properties of grey iron are controlled principally by the cooling rate during solidification. In continuous casting, the surface of the bar is subjected to very fast cooling and the microstructure differs considerably from that closer to the bar centre. Hence, the standardised mechanical properties cannot be guaranteed in this surface zone which must be discarded. Relevant machining allowances are stipulated in SS-EN 16482.