Cast iron is a ferrous alloy that is made by re-melting pig iron, often along with substantial quantities of scrap iron, and taking various steps to remove undesirable contaminants. It is available in many different grades that are formulated to suit a wide range of applications. These include generator housing, industrial valves, thermal processing equipment, and engine blocks. Depending on the grade chosen, cast iron can provide an economical and efficient solution for many engineering challenges.
Cast iron is an alloy of iron, carbon, and other elements. In comparison to steel, it is generally much harder and brittle. Furthermore, it is not as well suited for welding. Although cast iron is technically a type of steel, its chemical makeup differs significantly and it is therefore considered as a separate material. This article will focus on gray cast iron and its various grades.
Gray cast iron is one of the most widely used types of cast iron. It is composed of a ferritic matrix with a higher carbon content than other cast iron grades. The result is a material that is extremely hard and strong yet also ductile when necessary. It is also relatively easy to machine due to its graphite content. Despite this, gray cast iron has some drawbacks, namely its intolerance to stress cracking, poor vibration damping, and susceptibility to corrosion.
Gray cast iron is further divided into different categories, each of which has different properties and applications. There are four main types:
Whiteheart cast iron has the highest tensile strength and hardness, making it ideal for use in machine parts that must withstand high stress, such as engine blocks, valves, and pump housings.
Malleable cast iron has higher ductility and toughness, which makes it suitable for parts that require high yield strength, such as bed frames and agricultural tools.
Chilled cast iron has superior wear resistance, making it suitable for parts that must withstand friction, such as pulleys and gears.
Compacted graphite iron is a special type of cast iron that has improved vibration damping characteristics. It is often used in automotive applications, such as connecting rods and intake manifolds.
In addition to the grades mentioned above, there are several more specialized grades of cast iron. These include Austempered Ductile Iron and Ni-Resist Iron, which offer improved mechanical properties, as well as Duplex Iron, which has a higher strength-to-weight ratio than other types of cast iron.
No matter what type of cast iron is chosen, it is important to select the right grade for the job to ensure the best possible performance. A knowledgeable metal supplier can assist with the selection process and provide a metal solution tailored to the specific application.
