What type of cast iron can only be joined by braze welding?

• A. Malleable
• B. Gray
• C. Ductile
• D. White

Answer: (A)

Malleable cast iron is specifically designed to be joined through braze welding due to its unique composition and mechanical properties. This type of cast iron undergoes a process of heat treatment that renders it more ductile, allowing it to be shape-altered and welded at higher temperatures.

In braze welding, a filler metal is melted and flows into a joint without melting the base metal, which is essential for joining malleable cast iron since it can become brittle if excessive heat is applied. The process ensures that the integrity of the malleable cast iron is preserved while achieving a strong bond.

Other types of cast iron, such as gray, ductile, and white, have distinct characteristics that can result in different welding or joining methods. Gray cast iron, known for its excellent machinability, is typically joined by methods that may include welding processes that apply higher heat levels. Ductile cast iron is also weldable using techniques like arc welding but may require preheating or specific electrodes. White cast iron, on the other hand, is more challenging to weld due to its hard and brittle nature, typically necessitating different joining methods usually focused on mechanical connections rather than fusion welding or braze welding.

Thus, the reason why malleable cast