Iron is an inexpensive, easy-to-cast material. It is especially used in the manufacturing of pump houses, motor blocks and other pump parts.
Cast iron is especially used in pumps in the manufacturing of pump houses, motor blocks and other pump parts that are too complicated to produce in forged steel. This causes the manufacturing costs to become too high, resulting in a non-competitive price.
In grey iron, the graphite is dispersed throughout a ferrite or pearlite matrix in the form of flakes. Fracture surfaces take on a grey appearance (hence the name!). The graphite flakes act as stress concentrators under tensile loads, making it weak and brittle in tension, but strong and ductile in compression. Grey iron is used for the construction of motor blocks because of its high vibration damping ability.
Grey iron is an inexpensive material and is relatively easy to cast with a minimal risk of shrinkage. That is why grey iron is often used for pump parts with moderate strength requirements.