Red Seal Welding Practice Exam

What material has a grain structure that appears very course and silvery?

1. Stainless steel

2. Aluminum

3. White cast iron

4. Bronze

The correct answer is: White cast iron

White cast iron has a grain structure that appears coarse and silvery due to its high carbon content. This grain structure is formed during solidification as the carbon atoms are unable to move, resulting in a large, crystal-like structure. Stainless steel, aluminum, and bronze do not have the same high carbon content and thus do not exhibit the same coarse and silvery grain structure as white cast iron. Additionally, stainless steel and bronze often have a different color and shine, while aluminum has a smoother surface.