We are often posed a question for our clients: which is better – Cast Iron or Cast Steel? The answer lies in which one is more suited to their product manufacture.

What is Cast Iron and Cast Steel?

First, we need to understand what Cast Iron and Cast Steel are. Cast Iron generally refers to ductile iron, malleable iron and grey iron and is nothing but iron casting with carbon composition higher than 2%. Cast steel refers to normal alloy steel and carbon steel; it is steel with carbon composition under 2%. Therefore, from a chemical content and raw materials point of view, there isn’t any significant difference between Cast Iron and Cast Steel.  However, the physical properties between the two differ with each other.

All about Cast Iron:

Cast iron possesses excellent wear resistance, low notch sensitivity, excellent vibration damping and machinability. This said cast iron is marked by low elongation and low tensile strength.  Therefore, only metal parts with low physical requirements: cover, protective cover, hand wheels, oil pan, floor, frame, small handle, hammer, box, handle, frame, base, table, bed, bearing seat, cover, wheels, valve, flywheel, pipe, motor blocks, etc can be produced with cast iron. Grey cast iron possesses greater load withstanding capabilities and a certain degree of corrosion resistance or tightness as for the higher grades. This holds good for castings including gear, cylinder, flywheels, base, cylinder, bed, piston, cylinder liner, brake wheel, piston, coupling plate, gearbox, medium pressure valve, et al.

The malleable iron and ductile iron show greater ductility, high strength, toughness and heat-resistance. In cases of wider applications, they can alternate carbon steel. The production technology, however, is high and the process bit complex. This means the production cost can go a notch higher than normal cast steel and normal cast iron. Therefore, casting defects are more for ductile iron. Several fields of applications such as pressure fittings and pipes, general engineering, ductile iron, agriculture, automotive applications, construction applications and road use ductile iron.

All about Cast Steel:

Cast steel has a major advantage – design flexibility.  The casting designer has greater design choices that give way for hollow cross-section parts and complex shapes. Cast steel has the greatest variability and metallurgy manufacturing flexibility. Different projects may involve different control and chemical composition. This provides various heat treatment choices in the bigger context of the mechanical performance and properties, in addition to workability and weldability. Cast steel, a form of isotropic material, can form structural strength steel castings, thereby improving the reliability and performance of the project. In addition to the weight and design, Cast steel offers low-cost design, shorter delivery time and economy.

Steel castings have a larger range of weight. A few dozen grams of molten mould precisions castings is lightweight. The weight can range up to several tons, dozens or hundreds of tons.

The mechanical properties of steel castings were superior to other types of casting alloys. There are high-alloy steels for special applications.  Pressure vessel castings are excellent to withstand dynamic load or tensile stress of components. In high or low temperature, important and large parts, load key parts are made of steel castings.

Compared to Cast Iron, Cast Steel has poor shake-suction, mobility and wear resistance. The casting performance is poor compared to Cast Iron. Also, the costs are comparatively higher.  Long words short, whether it is Cast Iron or Cast Steel, it has its own merits and demerits, and its selection is based on its physical properties and application.