In the United States, Cast Iron Round Bars are typically classified based on their grade, which indicates their specific composition, properties, and intended applications. Here are some common grades of Cast Iron Round Bars along with brief descriptions of their characteristics:

1. Gray Cast Iron:

Description: Gray cast iron is one of the most common types of cast iron. It is characterized by its graphite flakes, which give it a gray appearance when fractured.

Grades:

Class 20: Offers good machinability and damping capacity. Used in applications like machine bases and frames.

Class 30: Provides better strength and wear resistance compared to Class 20. Used in components like gears and machinery parts.

Class 40: Offers the highest tensile strength among gray cast iron grades. Suitable for applications requiring high strength and wear resistance.

2. Ductile Cast Iron (Nodular Cast Iron):

Description: Ductile cast iron has spheroidal graphite nodules in its microstructure, providing enhanced ductility and toughness compared to gray cast iron.

Grades:

65-45-12: Indicates minimum tensile strength, yield strength, and elongation. Commonly used in automotive and machinery components.

80-55-06: Offers higher strength and wear resistance compared to 65-45-12. Suitable for applications requiring increased toughness.

3. White Cast Iron:

Description: White cast iron is characterized by its white appearance due to the absence of graphite. It is hard and brittle, making it suitable for wear-resistant applications.

Grades:

Class I: Contains a significant amount of carbide in its microstructure, providing hardness and wear resistance. Used in applications like grinding balls and liners.

4. Malleable Cast Iron:

Description: Malleable cast iron is produced by heat-treating white cast iron or nodular cast iron to convert the carbon in the form of graphite nodules. It combines the strength of white cast iron with the ductility of nodular cast iron.

Grades:

Blackheart Malleable Iron: Heat-treated at low temperatures, offering high strength and wear resistance.

Whiteheart Malleable Iron: Heat-treated at high temperatures, providing better ductility and toughness.

5. High-Alloy Cast Iron:

Description: High-alloy cast iron contains alloying elements such as chromium, nickel, or molybdenum to enhance specific properties like corrosion resistance, high-temperature strength, or wear resistance.

Grades:

Ni-Hard: Contains nickel and chromium for excellent abrasion resistance. Commonly used in mining and cement industries for wear parts.

High Chromium Iron: Contains high chromium content for improved corrosion and wear resistance. Used in applications like pumps and valves.

6. Compacted Graphite Iron (CGI):

Description: Compacted graphite iron is a type of cast iron that has a microstructure between gray and ductile iron, with graphite in a compacted form. It offers a combination of strength, ductility, and thermal conductivity.

Grades:

Grade 450: Known for its high strength, thermal conductivity, and good machinability. Used in applications requiring high mechanical properties.

7. Austempered Ductile Iron (ADI):

Description: Austempered ductile iron is a form of ductile iron that has been heat-treated to achieve a structure of acicular ferrite and high carbon austenite.

Grades:

ADI 1050: Offers high strength, toughness, and wear resistance. Commonly used in heavy-duty applications like gears and shafts.

8. Pearlitic Malleable Iron:

Description: Pearlitic malleable iron is produced by annealing white cast iron or malleable iron to convert the carbon into a structure of pearlite.

Grades:

Pearlitic Malleable Iron: Provides good strength, toughness, and wear resistance. Used in applications where a balance of properties is required.

9. Ferritic Malleable Iron:

Description: Ferritic malleable iron is a type of malleable iron with a microstructure of ferrite and pearlite.

Grades:

Ferritic Malleable Iron: Offers good machinability, ductility, and impact resistance. Used in applications requiring these properties.

10. Hi-Silicon Moly Iron:

Description: Hi-silicon moly iron is a type of high-silicon iron with added molybdenum for improved strength and wear resistance.

Grades:

Hi-Silicon Moly Iron: Provides enhanced wear resistance and toughness. Commonly used in applications where high wear resistance is required.

These additional grades of cast iron round steel offer a range of properties and characteristics that cater to specific industrial applications where strength, ductility, wear resistance, and other performance factors are critical considerations.