Q1: Lead is poured into the joint between two- __________ pipes.

ANS:C - cast iron

Cast iron is a group of iron-carbon alloys with a carbon content greater than 2%. It is characterized by its relatively low melting point, good fluidity when molten, excellent castability, and high compressive strength. Cast iron is widely used in various industrial applications due to its favorable mechanical properties and cost-effectiveness. There are several types of cast iron, each with its own unique properties and applications:

1. Gray cast iron: This is the most common type of cast iron. It has a graphite microstructure, which gives it its characteristic gray color. Gray cast iron has good machinability, damping capacity, and thermal conductivity, making it suitable for applications such as engine blocks, pipes, and machinery components.
2. White cast iron: White cast iron has a cementite microstructure, which gives it a white, crystalline appearance. It is extremely hard and brittle, making it unsuitable for most applications. However, white cast iron can be alloyed to improve its properties and is sometimes used in applications where wear resistance is critical, such as grinding balls and mill liners.
3. Ductile cast iron (nodular cast iron): Ductile cast iron has graphite nodules dispersed throughout its microstructure, giving it enhanced ductility and toughness compared to gray cast iron. It retains many of the beneficial properties of gray cast iron, such as good machinability and damping capacity, while also offering higher tensile strength and impact resistance. Ductile cast iron is commonly used in automotive components, pipes, and structural parts.
4. Malleable cast iron: Malleable cast iron is produced by heat-treating white cast iron to convert the cementite into graphite nodules. This process imparts improved ductility and toughness to the material, making it easier to machine and form. Malleable cast iron is used in applications where ductility and shock resistance are important, such as pipe fittings, agricultural equipment, and hand tools.

Cast iron offers a combination of properties that make it suitable for a wide range of applications across various industries. Its versatility, affordability, and ease of production have contributed to its continued use in manufacturing and construction processes.