Introduction
This article provides an overview of the mechanical properties of ASTM A48 Class 30 Gray Cast Iron, which is commonly used in the United States. The term gray cast iron refers to a type of iron which has been treated to have a distinctive grayish color. The ASTM A48 standard is a designation of a variety of this type of iron, specifically Class 30 Gray Cast Iron, which has a tensile strength range of 242MPa – 414MPa. This article will discuss the history of the ASTM A48 standard, the properties of Gray Cast Iron, the composition of Class 30 Gray Cast Iron, and commonly used fabrication processes.
History
The ASTM International (formerly known as the American Society for Testing and Materials) is an organization that was founded in 1898 and is responsible for creating technical standards for a variety of materials and products. The ASTM A48 standard is one such standard, and it is used to designate the properties of certain types of gray cast iron. The ASTM A48 standard was created in 1951 in response to the need for a reliable and readily available material for mass production. It was quickly adopted as a standard for many industries, such as the automotive and aerospace industries, as it was able to provide consistent results and consistent production costs.
Properties of Gray Cast Iron
Gray Cast Iron has a number of distinct properties which have made it the preferred material for many applications. The most notable of these properties is its high strength-to-weight ratio. Gray Cast Iron has excellent tensile strength and impact toughness, making it ideal for parts which require strength with minimal weight. Additionally, Gray Cast Iron has good machinability and is relatively inexpensive to produce. It is also temperature resistant and has excellent wear resistance, making it a good choice for many applications.
Composition of Class 30 Gray Cast Iron
Class 30 Gray Cast Iron is composed of 2.4 to 2.9 weight percent carbon and 0.5 to 1.5 weight percent silicon. It also contains a variety of trace elements, such as phosphorus, sulfur, manganese, and chromium. The carbon and silicon content of Class 30 Gray Cast Iron give it its distinctive gray color, as well as its unique strength and wear resistance.
Fabrication Processes
Gray Cast Iron can be formed into a variety of shapes and sizes by a number of different fabrication processes. Sand-casting is the most common method of forming Gray Cast Iron parts, but it can also be machined, welded, and heat-treated. When heat-treating Gray Cast Iron, it is important to avoid temperatures higher than 1150°C, as this can cause the carbon to form a layer of graphite, which can reduce the strength of the material.
Conclusion
ASTM A48 Class 30 Gray Cast Iron is a common material used in a variety of different industries thanks to its high strength-to-weight ratio. It has excellent tensile strength and impact toughness, good machinability, temperature resistance, and wear resistance. The carbon and silicon content of Class 30 give it its distinctive gray color and its unique properties. Although Gray Cast Iron can be fabricated using a number of different processes, sand-casting is the most common method. When heat-treating Gray Cast Iron, it is important to avoid temperatures higher than 1150°C, as this can cause the carbon to form a layer of graphite which can reduce the strength of the material.
