Final answer:
Three types of electrodes not used in shipbuilding are electrodes for ships' superstructures, container vehicle bodies, and tube trains.
Step-by-step explanation:
Three types of electrodes that are not used in shipbuilding include:
- Electrodes used for ships' superstructures: These structures are typically made of steel, which requires high-strength welding electrodes.
- Electrodes used for container vehicle bodies: These bodies also require high-strength welding electrodes to ensure structural integrity and durability.
- Electrodes used for tube trains (metro trains): Tube trains are typically made of aluminum or stainless steel, which require specialized electrodes for welding.
These types of electrodes are not commonly used in shipbuilding due to the specific requirements of welding different materials and structural components.