Grey cast iron
Grey cast iron is the most commonly used iron for casting due to its low cost, ready machinability and dimensional stability. It is an alloy of iron, carbon and silicon which provides good compressive strength and wear resistance. The grey colour is caused by graphite particles formed from the carbon which are separate from the iron matrix. Its chemical composition largely depends on the grade of the material, but generally consists of 0.3-4% carbon, 1-3% silicon and 0.2-2% manganese.
The most commonly used grade of grey cast iron is Grade30 (GG30), which typically contains 3% Carbon, 2% silicon and 0.8% manganese. It is suitable for applications where machinability and strength are important. The material is available in a range of standard dimensions and shapes, including round, rectangular and flat sections.
Grey cast iron is suitable for a wide range of applications such as automotive parts, pipes, valves and machine components. Its low cost and easy machinability make it the ideal material for low volume production runs. It is also popular in the manufacture of gears, bearings and other components for machinery.
Due to its low melting point and low carbon content, grey cast iron can be welded, brazed and soldered. It has excellent machinability and can be machined using a variety of tools. It is also relatively easy to cast using a variety of processes, including sand casting, die casting and permanent mold casting.
However, the material is less suitable for high temperature applications, as it tends to become brittle and fracture at temperatures above 300°C. It also has relatively low strength and wear resistance, meaning it is not suitable for applications subjected to high pressures or loads.
Grey cast iron is commonly used in accordance with the standards set by the GB/T4139-1987 specification. This includes requirements for chemical composition, tensile strength, yield strength and elongation. The standard also sets out parameters for surface finish, dimensional tolerances and castability requirements.
Grey cast iron is a versatile and cost-effective material that is suitable for a wide range of applications. Its easy machinability and low cost makes it the perfect choice for low volume production runs. However, due to its low strength and wear resistance, it is not suitable for applications subjected to high pressures or loads.
