Cast Iron vs. Cast Steel

One of our clients asked me which one is better for cast iron vs cast steel. I will have to say, no one is better. The question is which one is more suited to your products.

First, let us know what is cast iron and cast steel.

Cast iron usually refers to gray iron, ductile iron and malleable iron. Which is an iron casting with carbon content higher than 2%.

Cast steel usually refers to normal carbon steel and alloy steel. Which is a steel casting with carbon content lower than 2%.

Therefore, no big difference from the chemical content and raw materials for cast iron vs cast steel. However, their physical properties have many differences.

The advantage and disadvantage of cast iron.

The grey cast iron’s good casting properties are:  good vibration damping, good wear resistance, good machinability and low notch sensitivity. However, its tensile strength and elongation are very low. So, it can only produce some metal parts with low physical requirements. Requirements such as protective cover, cover, oil pan, hand wheels, frame, floor, hammer, small handle, base, frame, box, knife, bed, bearing seat, table, wheels, cover, pump, valve, pipe, flywheel, motor blocks etc. As for the higher grades, grey cast iron can withstand greater load and a certain degree of tightness or corrosion resistance. This allows for some of the more important castings such as cylinder, gear, base, flywheels, bed, cylinder block, cylinder liner, piston, gear box, brake wheel, coupling plate, medium pressure valve, etc

The ductile iron and malleable iron have high strength, ductility and heat-resistance and toughness. So a wider application, in some cases, can replace the carbon steel. However, its production technology is high. The production process is more complex. This makes the production cost higher than normal grey cast iron and cast steel. Therefore, there are more casting defects for ductile iron. There are many fields that use ductile iron, such as pressure pipes and fittings, automotive applications, agriculture, road and construction applications and general engineering applications.

The advantage and disadvantage of cast steel.

The main advantage of cast steel is the design flexibility. The designer of the casting has the greatest freedom of design choices. This allows for complex shapes and hollow cross-section parts.

Cast steel has the metallurgy manufacturing flexibility and strongest variability. One can choose a different chemical composition and control that is adapted to the various requirements of different projects. This offers different heat treatment choices in the larger context of the mechanical properties and performance. Also offering good weld-ability and workability.

Cast steel is a kind of isotropic material and can be made into the overall structural strength steel castings. This improves the reliability of the project. Coupled with the design and weight, the advantages of short delivery time, price and economy gives cast steel a competitive advantage.

The weight range of steel castings is larger. Little weight can be only a few dozen grams of molten mold precision castings. The weight of large steel castings goes up to several tons, dozens of tons or hundreds of tons.

Steel castings can be used for a variety of working conditions. Its mechanical properties are superior to any other casting alloys, and a variety of high-alloy steel for special purposes. To withstand high tensile stress or dynamic load of components, it is important to consider pressure vessel castings. In low or high temperature, large and important part load key parts should give priority to steel castings.

However, cast steel has comparatively bad shake-suction, wear resistance and mobility. The casting performance, compared to cast iron, is bad. Also, the costs are higher than normal cast iron.

Therefore, for cast iron vs cast steel, they have their own advantages and disadvantages. Either should be chosen according to the application and their physical properties.