Cast iron components contain more carbon and silicon than normal steel. With carbon content of about 2%-4%. In the four major types of cast iron (classified according to their graphite morphologies), gray cast iron is the most common. The higher carbon content makes cast irons be less ductile and more susceptible to cracking.
While many in the welding community consider cast iron to be difficult to weld, Afrox has circumvented this challenge by offering a suitable consumable and deposition technique for a particular cast iron application. Typical cast iron applications include machine bases, pump bodies, engine blocks, gears and transmission housings etc.
To facilitate a better understanding of these materials, they can be divided into five groups, based on composition and metallurgical structure: white cast iron, malleable cast iron, grey cast iron, ductile cast iron and alloy cast iron.
White Cast Iron
White cast iron derives its name from the white, crystalline crack surface observed when a casting fractures.
Malleable Cast Iron
Malleable cast iron is produced by heat treating white cast iron of a suitable composition. Iron carbide can decompose into iron and carbon under certain conditions.
Ferritic Malleable Cast Iron
At room temperature, the microstructure therefore consists of temper carbon nodules in a ferrite matrix, generally known as ferritic malleable cast iron.
Perlitic Malleable Cast Iron
If full graphitisation is prevented and a controlled amount of carbon remains in the iron during cooling, finely distributed iron carbide plates nucleate in the iron at lower temperatures.
Grey Cast Iron
Grey cast iron is one of the most widely used casting alloys and typically contains between 2,5% and 4% carbon and between 1% and 3% silicon.