What is the difference between cast iron and cast steel?

The main difference in chemical composition between cast iron and cast steel lies in the carbon content and the content of other alloying elements.

Cast iron is an iron alloy containing 2% to 4% carbon, while cast steel is a steel alloy with a lower carbon content, typically containing 0.2% to 1.5% carbon.

Firstly, what is cast iron? Cast iron is an iron alloy containing 2% to 4% carbon, typically with other elements such as silicon, manganese, sulfur, and phosphorus. According to different element contents and compositions, cast iron can be divided into the following types:

1. Gray cast iron
Gray cast iron is the most common type of cast iron, which contains high carbon and silicon content, usually between 2% to 4% and 1% to 3%. The name gray cast iron comes from the gray fracture on its surface, which is caused by the presence of carbon in the form of graphite in cast iron. Gray cast iron is commonly used to manufacture machine tool beds, automotive engine cylinder blocks, and other large castings.

2. White cast iron
The carbon content of white cast iron is as high as 2% to 3%, but the silicon content is relatively low, usually below 0.5%. The name white cast iron comes from the white fracture on its surface, which is caused by the presence of carbon in the form of iron compounds in cast iron. White cast iron is commonly used in the manufacture of cutting tools and bearings.

3. Ductile iron
Ductile iron is a type of cast iron containing spherical graphite, with a carbon content typically between 2% and 4% and a silicon content below 1%. The name ductile iron comes from its spherical graphite morphology, which is due to the addition of elements such as magnesium or yttrium during the casting process. Ductile iron is commonly used to manufacture automotive parts, pipelines, and other castings that require high strength and wear resistance.

4. High alloy cast iron
High alloy cast iron is a type of cast iron that contains a large amount of alloying elements, such as chromium, nickel, molybdenum, and titanium. High alloy cast iron is commonly used to manufacture high-temperature and corrosion-resistant parts, such as aviation engine components and chemical equipment.

So what is cast steel? Cast steel is a steel alloy with a lower carbon content, typically containing 0.2% to 1.5% carbon, as well as other alloying elements such as chromium, nickel, molybdenum, and titanium. According to different element contents and compositions, cast steel can be divided into the following types:

1. Carbon steel
Carbon steel is a type of cast steel with a high carbon content, typically containing 0.2% to 1.2% carbon. Carbon steel is commonly used to manufacture mechanical parts, tools, and other components that require high strength and wear resistance.

2. Alloy steel
Alloy steel is a type of cast steel containing alloying elements such as chromium, nickel, molybdenum, and titanium. Alloy steel typically has higher strength, hardness, and corrosion resistance, and is commonly used in the manufacture of aircraft engine components, automotive parts, and other parts that require high strength and corrosion resistance.

3. Stainless steel
Stainless steel is a type of cast steel containing chromium, nickel, and other alloying elements, which has good corrosion resistance and high temperature strength. Stainless steel is commonly used in the manufacturing of chemical equipment, food processing equipment, and other parts that require high corrosion resistance.

4. High temperature alloy steel
High temperature alloy steel is a type of cast steel containing chromium, molybdenum, tungsten, and other alloying elements, which has good high-temperature strength and corrosion resistance. High temperature alloy steel is commonly used to manufacture aircraft engine components, gas turbines, and other parts that require high temperature strength and corrosion resistance.

After understanding the differences in material composition between cast iron and cast steel, there are also the following differences:

1. Strength: Cast iron has lower strength, while cast steel has higher strength.

2. Resilience: Cast iron has poor toughness, while cast steel has better toughness.

3. Processing performance: Cast iron has poor processing performance, while cast steel has better processing performance.

4. Corrosion resistance: Cast iron has poor corrosion resistance, while cast steel has better corrosion resistance.

Having said so much, do readers feel that cast iron is inferior to cast steel in all aspects?

Actually, cast iron has the biggest advantage of being cheap!

This is undoubtedly an undeniable advantage in industrial applications!

The price advantage of cast iron not only comes from the price advantage of materials, but also from the price advantage of manufacturing costs. The casting process of cast iron is relatively simple and cost-effective, usually using sand casting or metal mold casting.

However, cast steel generally adopts casting processes such as investment casting and vacuum casting, which are relatively complex and costly. However, the cast steel parts produced have high strength and toughness, making them suitable for some high-strength and high demand components.

Cast iron not only has a lower price, but also has better performance than cast steel.

1. Good casting performance
 Cast iron has good fluidity and is easy to cast into complex shaped parts. At the same time, the shrinkage rate of cast iron is relatively small, making it less prone to defects such as shrinkage and porosity.

2. Good wear resistance
Cast iron contains high levels of carbon and silicon, which gives it good wear resistance and is suitable for applications that require wear resistance.

3. Good shock absorption
Cast iron has good shock absorption performance and is suitable for some applications that require shock absorption performance.

Overall, the biggest advantage of cast iron over cast steel is its low material price and manufacturing cost.

Cast iron is suitable for applications with low strength, low toughness, and low cost, while cast steel is suitable for applications with high strength, high toughness, and high cost. Nevertheless, cast iron still has the advantages of good wear resistance and shock absorption performance.